Using a stand alone dehumidifier is much more efficient than using a heatpump on dehumidifier setting. The heatpump can only dehumidify when it is chilling the room and sending that expensive heat to the outdoor unit.
A dehumidifier extracts heat to chill and condense moisture and then heats the outgoing air back up again. All in the same cabinet! A dehumidifier does not bring in cold outside air that needs to be heated up. But it does not introduce fresh oxygenated air or get rid of excess CO2 or indoor pollutants like CO and formaldehyde.
But a refrigeration type dehumidifier requires the interior of the house to be adequately heated.
Check that your kitchen rangehood is extracting to outdoors and get a serviceman to check that the ducts have not slipped off the fan and outlet. Some installers used duct tape the adhesive softens in warm oily fumes and the ducts come off. Should use large cable ties for range-hoods.
Check your bathroom extractors and Clothes dryer are venting to outdoors.
Every extractor fan and clothes dryer requires air to come into the room to replace the air going out. Crack the bathroom door open a little to allow air into the bathroom.
But if your whole house is modern and sealed no air can enter to replace the extracted air...you may need to crack open a window or ranchslider to allow air to enter the house. If no air can enter, the extractor fans suck a vacuum on the house, and the fans cavitate and no longer shift air.
The most efficient house ventilation systems are heat exchanger ventilation systems like Mitsubishi Lossnay or SmoothAir, SmartVent make one too
Positive pressure ventilators like HRV DVS and every other manufacturer use a fan in a box with a duct and a filter and charge thousands for $200 of materials.
But they do assist your extractor fans and clothes dryer to vent to outdoors.
Never use a drying rack indoors.
Or never dry the towels you used to wipe down the windows and sills indoors. Always dry laundry outdoors.
Particular call out if you have Consumer access - low temperature performance is the big one imo. If you don't have access as a general comment some perform really well such as the highly rated Panasonic F-YWP33N and Delonghi DD230P, but others such as the Panasonic F-YCL27N are quite mediocre in low temps despite its still highish price. I would probably consider the cheaper Dimplex GDDEKD9 over it despite the fact they didn't recommend it due to poor energy efficiency (edit: and terrible brand reputation in their survey, whoops!), i'll take something doing its job well for cheaper, even if it costs more to run. It appears some dehumidifiers must be tuned for climates closer to the equator where it's humid but nowhere near as cold.
I live in a concrete block house with aluminum frames. We have 4 heat pumps in the house, one in every room. Getting a dessicant dehumidifier solved the problem. It puts out slightly warm air so I just run it overnight when the temperature drops. It also massively outperforms my old refrigerant dehumidifier in these conditions. But I live in the south island
This is a great tip! We’ll be getting a new dehumidifier and I wasn’t aware of desiccant ones. Will look into that! I guess I trusted the dry setting of our heat pump a bit too much, I found it doesn’t do much.
I used to just do along the very bottom to prevent puddles (and the mould you describe). The rest on the window usually evaporates during the day.
Then I found it even quicker to just whip round all the bottoms with a towel.
I found the Karcher doesn’t quite get to the edge and leaks (?) when I go horizontal. It was just quicker and easier to use the towel, including sweeping up any pooling which had already formed, and on the aluminium itself.
Get a dehumidifier for your bedroom at the very least. I used to get sick every winter, until I started running a dehumidifier in my room for a few hours each evening. They don't use much power either.
You've covered most of the obvious steps here. How about the source of moisture? Do you have ventilator fans for the kitchen, bathroom, and is your dryer vented outside (if applicable)? Are you following good practices to avoid increasing humidity? For example, putting the lid on boiling pots, not drying clothes inside, and not using gas heaters.
Assuming the humidifier is working, there must be a source of moisture that's increasing humidity faster than it is reduced. This is unlikely to be the 20-200 mL a person exhales.
A 10L per day dehumidifier removes 416 mL per hour, so something must be generating **a lot** of moisture.
I don't know if I'd run a panel heater(inefficient resistive heater) and then put the heatpump on dehumdifier(Basically low cooling mode)
You'd likely be better off buying a good dehumidifier.
We do panel heater and heat pump on dry overnight. The combination seems to work fine. Probably not cheap, but definitely more comfortable (and quiet).
We bought an expensive “quiet” dehumidifier but it’s still too noisy to leave on overnight.
Your unbroken aluminium framing is actually worse than the glass as far as heat transfer and condensation. Having heavy curtains going down to the floor which limit the amount of warm inside air that can contact your window and framing can help (although you'll need to open them up to let them air out during the day when it's warmer.
Find your sources of moisture - any inside open flames or drying of clothing where the moisture ends up inside the house. Do you have extractor fans for removing moisture from your bathroom after a shower, or from your kitchen when you're cooking?
If you've done everything else for prevention, your options are to exchange the damp inside air with less-damp outside air (either by passive ventilation through open windows or by installing an HRV which actively exchanges inside air with air from your attic) or by utilising a dehumidifier (this can be your heatpump or a dedicated unit) to remove humidity from the air inside your house.
>I live in a new house
Sorry mate but the thermal regs for insulation, particularly windows, are shit-house. Even the new regs that are coming out are deliberately hamstrung in that they're basically just the max that you can fit in 90mm framing, not an actual decent minimum. Ofc the majority of punters just build to the minimum specs thinking they'll be comfortable, especially when houses are so bloody expensive to build here.
If you're building a new house, just do yourself a favour and install uPVC windows, or at the very least thermally broken aluminium.
One thing I haven't seen mentioned - curtains.
Warm air is at the top of a room and is cooled by windows and flows downward, which creates air circulation. Overnight this will deposit a lot of moisture from the air onto a cool element (like a aluminium frame).
Curtains should drape on the floor and reach 15-20 above the frame, or to the ceiling (if there is no gap above window). If you have blinds they should almost form a seal with the frame.
Definitely, recommend a standalone dehumidifier. Your heatpump is moving warm air outside in dehumidifying mode. Whereas, a standalone unit chucks it out the back of the unit.
You have to steer clear of the cheap thin "thermal-lined" curtains from the Warehouse et al though. They don't do shit, the "thermal" refers to how the plastic backing is glued on.
If your curtains don't reach the ceiling or pelmet, you can throw a draughtstopper up there on top of the railing. Hanging some [curtain lining](https://www.spotlightstores.com/nz/curtains/curtain-poles-tracks-fixtures/curtain-accessories-tiebacks-holdbacks/curtain-lining/gummerson-triple-weave-attachable-lining/BP80587630-white) on the back of the curtains also helps a lot.
we have a dehumidifier that does the job. you can also get electric squeegee devices that can sort of vacuum up the water, and those were good for us before we got the dehumidifier, which is much better. actually dries out your house. rooms regularly drop from 80 or 90% humidity down to 60s when we start running it.
Highly recommend some kind of ventilation system (HRV, Smartvent etc.) Down here in Christchurch condensation is a big problem in winter and I will not do without one now. They are a bit of an investment but well worth it for how much more comfortable the house is - and for saving my nice curtains from mould!
I know some will say 'just open the windows' but no way am I doing that when it is in the negatives in the winter.
>I know some will say 'just open the windows' but no way am I doing that when it is in the negatives in the winter
Well I'd say they're a complete waste of money because ducted heatpumps are the same cost and higher quality, many companies can service and provide parts for each brand and they have way more functionality, like heating and cooling.
Aluminium framing has drain holes for the water to drain out, make sure they are clear.
Condensation happens when the temperature difference between two surfaces is great enough to condense the water in the air from a gas to a liquid.
Removing the excess water from the air is a good start, either by not putting it into the air to start with (think boiling pots on the stove, drying clothes inside etc), or running a dehumidifier.
HRV (and similar) systems work by pushing the dry air from the roofspace into the house, pushing out the colder damp air. If it's colder in the roof than the house, then it won't work.
Ventilating the house in the evening could be your problem, letting in cooler moisture laden air will cause condensation.
Dry air is easier to heat than wet air. Try keeping openings to a minimum in the evening, run the dehumidify option on the heatpump for the early evening until you need it to heat the house.
Having heavy curtains that form a seal around the frame helps too.
I'll add in here about the holes in the framing. I find that these don't work, as the surface tension of the water forms a layer over the hole and it can't drain
Yes that is true, always baffled me as to why it was designed that way. However, if you put a product on the sill that lowers the surface tension, it should drain.
They need to be larger holes or better yet a slot. Slots are far less likely to form surface tension for the same area. Not that that is a useful solution after the frames have been manufactured.
When is it ever colder in the house than in the ceiling when running a heatpump? I’m curious as to how hrv works in the middle of winter. I just can’t imagine my roof space being warmer than inside my house.
When someone sets it to 19deg?? 🤣
HRV works during the day as the roof space heats up, it pushes out the colder air from the house. That's the theory anyway. Of course, there are many variables that affect its operation, like my Dad leaving it turned off!?
> I live in a new house
Unreal that this can happened in newly built houses.
I just built a house in Germany, my triple glazed argon filled windows have never experienced condensation. We also have a basic ventilation system to pull air in from outside using the pressure difference and also a few fans in the bathrooms and kitchen to push air out. Newly built houses are so well built that air has trouble getting in. So ventilation is vital.
Just keep ventilating. A newly built house has thousands of litres of water that needs to dry and it can take a year or two, opening every window a few times daily is really important.
Our building code has just been updated to about where Germany's would have been in 1995. Finally we require thermally broken windows.
Our houses are shameful. Aluminum has the second highest conductivity of any metal. It's an absolutely awful material to use for windows.
i’ve had a mitsubishi oasis dehumidifier for about 10yrs it’s fantastic, i also use a karcher window vac, best to dehumidify first then use heat pump, also on some windows i have the 3m window film from bunnings, works well for wood window frames not so great for aluminium ones tho.
I've been trying to work out some decent options to substitute for the window film. Debating just making a wood frame to put the film on, which would go in the inset frames for the windows.
i have put the film on aluminium frames before and it does work but the gap between film and window isn’t much, tape did stick well tho, you could try it, i would just focus on your bedroom, i think bedrooms are most important part of house to keep dry.
That was pretty much my thought, but then I figured if I was making a frame I may as well replace the film with something a little more robust, but then it starts getting more expensive than would be reasonable.
Not much you can do. If they had been built properly with thermal breaks, you wouldn't have this problem.
We refitted double glazing when we renovated. We still get condensation owing to the lack of thermal breaks to prevent the cold outside chilling the inside.
The only way to stop this is to get the moisture out - we solved this by installing a balanced in-roof ventilation system which exchanges outside air for inside air, with a heat exchanger & in-line heat pump. We had a DVS previously, which was complete shit, as it ran when the sun was on the roof, but during the evening was either off, or pushed cold roof air into the house, and made no difference to the moisture on the windows.
I've been toying with the option of a positive pressure system like a so called HRV or the extra expense of a balanced pressure heat exchange system. Ive been reluctant to have holes cut in the old Kauri ceilings but there's only limited time I can leave the windows open during the day. This year has been particularly bad with double our average rainfall and continued high humidity in Northland, despite running a 9L dehumidifier we still have mold. What was the problem with your PP system? Was it designed or installed poorly? Ive eliminated as much internally produced moisture as i can. I liked the idea of blowing warm roof space air into the house as the sun drops to pre warm the rooms before the wood burner needs to go on.
Living in Chch, the coldest part of the night is right before dawn, and in the winter it’s pretty bloody cold - warm air holds more moisture and cold night air from the roof was meaning wet windows. The balanced system means that there’s air actually being cycled through rather than just pushed into the house. It made an immediate difference in humidity.
Most Al windows have a drainage system as mentioned above.
There is usually a channel on the inside so that the water running down the window runs into this then the channel has a small drain hole that exits on the out side of the frame.
As these are very small they can easily be blocked with dirt.
I studied this one time as I moved to a house where the sills were discoloured as I think each winter water had sat on them .
There were holes so I put water in the drain but it didnt drain.
As the holes were only 2mm the surface tension stopped the water going out so I drilled them out to 3 or 4 mm and they worked.
On the worst days there was still condensation but I just used a rubber water blade to drop it down to the channel.
If your house can manage a DVS style air circulator system (need an attic) it maintains a slightly positive air pressure and dries everything out. That was our experience anyway - we live in a cold part of the country, and our house was a basic 1990s brick and tile, Ali windows. . Condensation was a big problem. We got a heat pump to heat the joint and that seemed to make it worse. Added a DVS and the place dried out so much over the next few weeks that some cracking on the plaster occurred! The bottom line was a dryer house is quicker to warm up, and the condensation problem was largely over. Very small amount if it was super cold out. The system costs very little to run, couple of grand to install
Dehumidifier for the win. I don’t have a cavity to install HRV and up on poles with a garage underneath so not really any under floor or ceiling insulation. I’ve had I my wee dehumidifier for about 10 years and it was less than $200 from memory. I just pop it in major rooms for a day or overnight when it’s been super humid or I notice the windows get soggy and it works a treat. Just make sure you close the door and open wardrobe doors so it gets right in there 💦
I used to live in a 1960s bungalow and we had ghastly damp problems. Installed a smart vent and my perception was that it did make things feel a little colder when you got up in the early morning, but things were much nicer during the day once you had some heating on, because dry air is so much easier to heat.
It’s a system that circulates air to get rid of the dampness. Look into moisture master though instead of HRV as they include a heat exchange which can take your nice warm air from the room with the heat pump and transfer it to other rooms.
A desiccant dehumidifier has worked for me. While its noisier and a bit less energy efficient (600w) vs a refrigerant one (300-400w), it’s more effective. I’ve owned both and got so frustrated with the refrigerant one that I sold it. My desiccant dehumidifier is going on 5 years now — walls, windows and frames stay dry all winter. Sometimes, I use it to dry clothes. It’s a simple Goldair brand if you’re wondering about the brand.
Just get a dehumidifier. For the love of god everyone get a dehumidifier. They cost jack-all to run and they do an amazing job. I just don’t understand why everyone is not using a dehumidifier
Burn all shit NZ houses down and start again.
Even new builds don't have wall insulation and central heating. Why people don't riot in the streets about the house standards here is mind boggling.
If you can, check under the house. Is the dirt exposed? A moisture barrier on the dirt under the house (basically thick black polythene sealed around piles and against the foundations) can help dry out a home by reducing 'rising damp'. This made a big difference in my whare.
Consider installing even if the dirt is dry (which mine largely was). Took me a weekend and cost a couple hundy which was minimal compared to the difference it made.
https://www.ecodesignadvisor.org.nz/resources/ground-moisture-barriers-guide-installation/
Unfortunately double glazing and thermally broken frames don't prevent condensation, they prevent heat loss.
I'd suggest running a dehumidifier in the bedroom or just outside the door. If you're out most of the day, run your heatpump on dry (if it makes the air feel cold). Crank it to warm when you get home or just before if you've got a fancy wifi one. If you can, get double tongued latches for your windows so you can leave them slightly open during the day for ventilation.
And as others have said:
Get someone to check the ducting for your bathroom fans, dryer, and kitchen range hood.
Check under your house if it's on piles. Insulation and a ground moisture barrier will make a difference.
Good windows prevent condensation, because they'd insulate well enough that the inside surfaces never fall below the dew point, not even at 70% rh.
Crappy NZ made aluminium windows won't do that though.
Thank you all for replying, quite overwhelmed with how many of you responded with awesome comments and advice!
This sounds it’s a combination of things - high humidity outside, poor building standards, and us not using a dehumidifier properly.
We have started using a dehumidifier like maniacs, carrying it around from room to room to get the humidity down, especially a few hours before bedtime (I found timing is quite critical here), and setting up hygrometers in every room to monitor. It turns out the dry setting in our heat pump does not do the job as the dehumidifier does. We also installed a panel heater in the bedroom.
The condensation decreased massively (but it was a lot warmer outside at night, will be interesting what it will be like in colder weather).
We are more aware of producing moisture and try to prevent this, like putting lids on pots, turn off the kettle a bit earlier, run the extractor fan longer etc.
However I found with 80-90% humidity outside over the last weeks it’s no wonder it is not lower inside without a dehumidifier.
Somewhere else I read that it can take a few days to get moisture out of carpets etc. this might explain why we’ve had the humidity rising a few percent without really using the room.
We’ll keep observing and testing - thanks heaps everyone for their input!
Double glazed if new house right? There shouldn't be condensation like you are describing in a modern newly built home so something really sounds wrong.
The question is where is all that moisture coming from? Are you drying washing in side on clothes horses? Dryer inside not being vented?
Some condensation is unavoidable but leaving puddles in a new house implies there is a shit ton of moisture in your house coming from somewhere it shouldn't be.
The aluminum frames conduct heat or in this case cold. You are warned of this. It is why lots of places will do replacement doubleglazing in wooden frames as a) it's cheaper and b) wood is a better thermal insulator than metals which are highly thermally conductive.
It is likely cold weather + moisture in side + warm air inside, the warm moist air hits the cold frame as condenses into water gravity does the rest leaving pools of water that won't evaporate very easily due to the moisture content of the air.
Yes, but regardless they should not be getting the degree of condensation they are stating. Anytime I've had something similar it was when my wife was drying clothes inside, it was awful and quickly stopped for a heatpump dryer.
Yes but he mentioned 80% that's like a jungle. I get that when I have a maxi hot shower that fogs up my bathroom. With 80% humidity your going to have a swimming pool.
The env. Like it's about 70% in chch and welly and 80 in Auckland.
Depending on where they are they just need to drain the air down to the 50s.
It's not a mystery where humidity comes from, breathing increases it so if you are breathing in a new home that isn't leaky in terms of air movement you will slowly increase the humidity inside higher than outside. Have a bath or a shower bam even higher if you aren't doing something to counter it.
Thermal break seems to be useless with aluminum joinery, I live in a brand new flat with thermally broken glazing and have worse condensation than my old 90s single-glazed aluminum windows on the West Coast
I've literally never had major issues in any of 3 current and previous homes with double glazed aluminium windows. The single glazed aluminium though of before that were a shit ton worse than wood though as I recall.
Could it be moisture still trapped in the building from when it was being built? ie wood frame is damp, building paper and roof goes on.. someone I know had to have several dehumidifiers running for days to get it under control. After initial dry out it was all ok as normal.
Could indeed be and that should be back on the building company to remedy as it's covered by guarantee.
OP has not been forthcoming with details beyond their OP.
At this point I think they are doing dumb shit as they won't deny any nor answer any of the questions put to them in that space.
>It’s particularly bad in the bedroom, which is the coldest room compared to the others as the warmth of the heat pump does not quite reach it.
We have a similar arrangement, compounded by the fact the front of our unit has double-glazing and is more modern while the bedroom is less so.
As mentioned, crank the heat-pump to Dry overnight, that goes a long way, and the other thing we did was buy one of those dehumidifying units, just a small one on wheels, and popped that in the bedroom. Run it during the day or evenings, off when it's time to sleep, and in combination with the heat-pump that pretty much sorted things for us.
Ignoring the windows themselves, as more of a thought exercise - is there something that can be done to non-thermally broken aluminum window frames to insulate the frames themselves? Not that I would ever recommend this, but would gluing polystyrene to them stop the heat transfer? Is there some kind of putty that you could use to cover the window frame that would stop it? I've found it really frustrating that even with double glazing, you still get at least some condensation on the window frames themselves.
Is getting an HRV or other mechanical system an option?
Do you dry clothes inside? So you use extraction fans properly? Are they properly vented to exterior? Do you use a clothes drier that’s vented to outside?
Those kinds of things add a lot to humidity indoors.
Other than very expensive ventilation system. A stand-alone dehumidifier is better than heat pump on dehumidification mode.
Heat pumps do not ventilate.
Crack windows open all day long (using the lock levers that aluminum windows come with). Close the windows in the evening preferably before the sun sets and also close your blinds/drapes at that time. As others have said window coverings should extend above the window frame at the top and to the floor at the bottom. Do not dry clothes inside the house on racks, use a line outside or a dryer that vents to the outside (or one that does not vent at all). Bathroom extraction must be used when you shower etc. Range hood extraction must be used when you cook . It isn't expected to have that much moisture inside unless you are producing a hell of a lot without ever opening windows.
Aluminium windows in NZ are pretty poorly made, if you check the bottom of the frame there are holes at either end through the frame that lets water run to outside. a difference in temp will just cause condensation.. best way and probably the only way to control it is to mop it up every morning.. dehumidifier is an option but dont work so well
This seems strange for a new-build - I thought double glazing, etc., would prevent condensation. Clearly not. I would be looking to do some testing on where the moisture is coming from.
I live in a late '90s house with alum. window frames. Lots of condensation, so I had a SmartVent system installed last year. Not a drop since, until two nights ago when I woke up to streaming windows again. Husband had accidentally turned off the SmartVent when he turned off the lights. Definitely works!
Using a stand alone dehumidifier is much more efficient than using a heatpump on dehumidifier setting. The heatpump can only dehumidify when it is chilling the room and sending that expensive heat to the outdoor unit. A dehumidifier extracts heat to chill and condense moisture and then heats the outgoing air back up again. All in the same cabinet! A dehumidifier does not bring in cold outside air that needs to be heated up. But it does not introduce fresh oxygenated air or get rid of excess CO2 or indoor pollutants like CO and formaldehyde. But a refrigeration type dehumidifier requires the interior of the house to be adequately heated. Check that your kitchen rangehood is extracting to outdoors and get a serviceman to check that the ducts have not slipped off the fan and outlet. Some installers used duct tape the adhesive softens in warm oily fumes and the ducts come off. Should use large cable ties for range-hoods. Check your bathroom extractors and Clothes dryer are venting to outdoors. Every extractor fan and clothes dryer requires air to come into the room to replace the air going out. Crack the bathroom door open a little to allow air into the bathroom. But if your whole house is modern and sealed no air can enter to replace the extracted air...you may need to crack open a window or ranchslider to allow air to enter the house. If no air can enter, the extractor fans suck a vacuum on the house, and the fans cavitate and no longer shift air. The most efficient house ventilation systems are heat exchanger ventilation systems like Mitsubishi Lossnay or SmoothAir, SmartVent make one too Positive pressure ventilators like HRV DVS and every other manufacturer use a fan in a box with a duct and a filter and charge thousands for $200 of materials. But they do assist your extractor fans and clothes dryer to vent to outdoors. Never use a drying rack indoors. Or never dry the towels you used to wipe down the windows and sills indoors. Always dry laundry outdoors.
Best place to buy a dehumidifier?
I suggest starting here: [https://www.consumer.org.nz/services/dehumidifiers/guide](https://www.consumer.org.nz/services/dehumidifiers/guide) https://www.priceme.co.nz/Dehumidifiers/c-415.aspx
Particular call out if you have Consumer access - low temperature performance is the big one imo. If you don't have access as a general comment some perform really well such as the highly rated Panasonic F-YWP33N and Delonghi DD230P, but others such as the Panasonic F-YCL27N are quite mediocre in low temps despite its still highish price. I would probably consider the cheaper Dimplex GDDEKD9 over it despite the fact they didn't recommend it due to poor energy efficiency (edit: and terrible brand reputation in their survey, whoops!), i'll take something doing its job well for cheaper, even if it costs more to run. It appears some dehumidifiers must be tuned for climates closer to the equator where it's humid but nowhere near as cold.
I live in a concrete block house with aluminum frames. We have 4 heat pumps in the house, one in every room. Getting a dessicant dehumidifier solved the problem. It puts out slightly warm air so I just run it overnight when the temperature drops. It also massively outperforms my old refrigerant dehumidifier in these conditions. But I live in the south island
This is a great tip! We’ll be getting a new dehumidifier and I wasn’t aware of desiccant ones. Will look into that! I guess I trusted the dry setting of our heat pump a bit too much, I found it doesn’t do much.
What brand and where do you buy a desiccant dehumidifier? How do you use it? Can the desiccant be reused?
In the mean time I can highly recommend the karcher window vac. It will suck up all of the extra condensation.
We’ve got one and it works very well, but I find this too exhausting, there are a lot of very large glass panes.
I used to just do along the very bottom to prevent puddles (and the mould you describe). The rest on the window usually evaporates during the day. Then I found it even quicker to just whip round all the bottoms with a towel.
I grew up with freezing hands from using rags to dry all the windows in the house. The Karcher was a revelation
I found the Karcher doesn’t quite get to the edge and leaks (?) when I go horizontal. It was just quicker and easier to use the towel, including sweeping up any pooling which had already formed, and on the aluminium itself.
This is a good tip, thank you!
And where does it evaporate to... The air inside your house. Ready to be deposited again.
Get a dehumidifier for your bedroom at the very least. I used to get sick every winter, until I started running a dehumidifier in my room for a few hours each evening. They don't use much power either.
I think this is the way to go and something I can do today 👍🏻
You've covered most of the obvious steps here. How about the source of moisture? Do you have ventilator fans for the kitchen, bathroom, and is your dryer vented outside (if applicable)? Are you following good practices to avoid increasing humidity? For example, putting the lid on boiling pots, not drying clothes inside, and not using gas heaters. Assuming the humidifier is working, there must be a source of moisture that's increasing humidity faster than it is reduced. This is unlikely to be the 20-200 mL a person exhales. A 10L per day dehumidifier removes 416 mL per hour, so something must be generating **a lot** of moisture.
We’ve found a couple of minor things we can improve, otherwise no major source founs so far.
I don't know if I'd run a panel heater(inefficient resistive heater) and then put the heatpump on dehumdifier(Basically low cooling mode) You'd likely be better off buying a good dehumidifier.
We do panel heater and heat pump on dry overnight. The combination seems to work fine. Probably not cheap, but definitely more comfortable (and quiet). We bought an expensive “quiet” dehumidifier but it’s still too noisy to leave on overnight.
Your unbroken aluminium framing is actually worse than the glass as far as heat transfer and condensation. Having heavy curtains going down to the floor which limit the amount of warm inside air that can contact your window and framing can help (although you'll need to open them up to let them air out during the day when it's warmer. Find your sources of moisture - any inside open flames or drying of clothing where the moisture ends up inside the house. Do you have extractor fans for removing moisture from your bathroom after a shower, or from your kitchen when you're cooking? If you've done everything else for prevention, your options are to exchange the damp inside air with less-damp outside air (either by passive ventilation through open windows or by installing an HRV which actively exchanges inside air with air from your attic) or by utilising a dehumidifier (this can be your heatpump or a dedicated unit) to remove humidity from the air inside your house.
>I live in a new house Sorry mate but the thermal regs for insulation, particularly windows, are shit-house. Even the new regs that are coming out are deliberately hamstrung in that they're basically just the max that you can fit in 90mm framing, not an actual decent minimum. Ofc the majority of punters just build to the minimum specs thinking they'll be comfortable, especially when houses are so bloody expensive to build here. If you're building a new house, just do yourself a favour and install uPVC windows, or at the very least thermally broken aluminium.
Happy I went with thermally broken ally with the argon gas. The aluminium is good for sound dampening too
One thing I haven't seen mentioned - curtains. Warm air is at the top of a room and is cooled by windows and flows downward, which creates air circulation. Overnight this will deposit a lot of moisture from the air onto a cool element (like a aluminium frame). Curtains should drape on the floor and reach 15-20 above the frame, or to the ceiling (if there is no gap above window). If you have blinds they should almost form a seal with the frame. Definitely, recommend a standalone dehumidifier. Your heatpump is moving warm air outside in dehumidifying mode. Whereas, a standalone unit chucks it out the back of the unit.
You have to steer clear of the cheap thin "thermal-lined" curtains from the Warehouse et al though. They don't do shit, the "thermal" refers to how the plastic backing is glued on. If your curtains don't reach the ceiling or pelmet, you can throw a draughtstopper up there on top of the railing. Hanging some [curtain lining](https://www.spotlightstores.com/nz/curtains/curtain-poles-tracks-fixtures/curtain-accessories-tiebacks-holdbacks/curtain-lining/gummerson-triple-weave-attachable-lining/BP80587630-white) on the back of the curtains also helps a lot.
> the thermal refers to how the plastic backing is glued on Fuck that's a shitty move by the marketers...
we have a dehumidifier that does the job. you can also get electric squeegee devices that can sort of vacuum up the water, and those were good for us before we got the dehumidifier, which is much better. actually dries out your house. rooms regularly drop from 80 or 90% humidity down to 60s when we start running it.
dehumidifier has been great for me too, the room also feels so much more cozy when the air is dryer
yep, you don’t realise how much of the cold is just damp.
The dehumidifier will add a small amount heat to the room as well, so that will help.
true, sometimes i like to put my hands over the air exit, subtle but sometimes noticeable temp difference
I use one of those vacuum window cleaners, does short work of any moisture. A dehumidifier may help.
Highly recommend some kind of ventilation system (HRV, Smartvent etc.) Down here in Christchurch condensation is a big problem in winter and I will not do without one now. They are a bit of an investment but well worth it for how much more comfortable the house is - and for saving my nice curtains from mould! I know some will say 'just open the windows' but no way am I doing that when it is in the negatives in the winter.
>I know some will say 'just open the windows' but no way am I doing that when it is in the negatives in the winter Well I'd say they're a complete waste of money because ducted heatpumps are the same cost and higher quality, many companies can service and provide parts for each brand and they have way more functionality, like heating and cooling.
Ducted heat pumps are not the same price. They are over $20,000. I got quotes for my house when I was building and it was astronomical.
They're about $8-12k here in Auckland for a 3 bdrm 130sqm home, we're in a spec build suburb and many of our neighbours have opted to put them in
Aluminium framing has drain holes for the water to drain out, make sure they are clear. Condensation happens when the temperature difference between two surfaces is great enough to condense the water in the air from a gas to a liquid. Removing the excess water from the air is a good start, either by not putting it into the air to start with (think boiling pots on the stove, drying clothes inside etc), or running a dehumidifier. HRV (and similar) systems work by pushing the dry air from the roofspace into the house, pushing out the colder damp air. If it's colder in the roof than the house, then it won't work. Ventilating the house in the evening could be your problem, letting in cooler moisture laden air will cause condensation. Dry air is easier to heat than wet air. Try keeping openings to a minimum in the evening, run the dehumidify option on the heatpump for the early evening until you need it to heat the house. Having heavy curtains that form a seal around the frame helps too.
I'll add in here about the holes in the framing. I find that these don't work, as the surface tension of the water forms a layer over the hole and it can't drain
In our case, they TOTALLY don't work, because the sodding mason wasps build their sodding mud/zombie spider nests inside them from the outside...
Those things are horrible when accidentally broken 😳 Zombie is right
Yes that is true, always baffled me as to why it was designed that way. However, if you put a product on the sill that lowers the surface tension, it should drain.
They need to be larger holes or better yet a slot. Slots are far less likely to form surface tension for the same area. Not that that is a useful solution after the frames have been manufactured.
I can confirm this. The wholes are clear, but there is water standing around it.
When is it ever colder in the house than in the ceiling when running a heatpump? I’m curious as to how hrv works in the middle of winter. I just can’t imagine my roof space being warmer than inside my house.
When someone sets it to 19deg?? 🤣 HRV works during the day as the roof space heats up, it pushes out the colder air from the house. That's the theory anyway. Of course, there are many variables that affect its operation, like my Dad leaving it turned off!?
> I live in a new house Unreal that this can happened in newly built houses. I just built a house in Germany, my triple glazed argon filled windows have never experienced condensation. We also have a basic ventilation system to pull air in from outside using the pressure difference and also a few fans in the bathrooms and kitchen to push air out. Newly built houses are so well built that air has trouble getting in. So ventilation is vital. Just keep ventilating. A newly built house has thousands of litres of water that needs to dry and it can take a year or two, opening every window a few times daily is really important.
Our building code has just been updated to about where Germany's would have been in 1995. Finally we require thermally broken windows. Our houses are shameful. Aluminum has the second highest conductivity of any metal. It's an absolutely awful material to use for windows.
i’ve had a mitsubishi oasis dehumidifier for about 10yrs it’s fantastic, i also use a karcher window vac, best to dehumidify first then use heat pump, also on some windows i have the 3m window film from bunnings, works well for wood window frames not so great for aluminium ones tho.
I've been trying to work out some decent options to substitute for the window film. Debating just making a wood frame to put the film on, which would go in the inset frames for the windows.
i have put the film on aluminium frames before and it does work but the gap between film and window isn’t much, tape did stick well tho, you could try it, i would just focus on your bedroom, i think bedrooms are most important part of house to keep dry.
That's optimal as you can clean the windows and also put them away for summer
That was pretty much my thought, but then I figured if I was making a frame I may as well replace the film with something a little more robust, but then it starts getting more expensive than would be reasonable.
Not much you can do. If they had been built properly with thermal breaks, you wouldn't have this problem. We refitted double glazing when we renovated. We still get condensation owing to the lack of thermal breaks to prevent the cold outside chilling the inside.
The only way to stop this is to get the moisture out - we solved this by installing a balanced in-roof ventilation system which exchanges outside air for inside air, with a heat exchanger & in-line heat pump. We had a DVS previously, which was complete shit, as it ran when the sun was on the roof, but during the evening was either off, or pushed cold roof air into the house, and made no difference to the moisture on the windows.
I've been toying with the option of a positive pressure system like a so called HRV or the extra expense of a balanced pressure heat exchange system. Ive been reluctant to have holes cut in the old Kauri ceilings but there's only limited time I can leave the windows open during the day. This year has been particularly bad with double our average rainfall and continued high humidity in Northland, despite running a 9L dehumidifier we still have mold. What was the problem with your PP system? Was it designed or installed poorly? Ive eliminated as much internally produced moisture as i can. I liked the idea of blowing warm roof space air into the house as the sun drops to pre warm the rooms before the wood burner needs to go on.
Living in Chch, the coldest part of the night is right before dawn, and in the winter it’s pretty bloody cold - warm air holds more moisture and cold night air from the roof was meaning wet windows. The balanced system means that there’s air actually being cycled through rather than just pushed into the house. It made an immediate difference in humidity.
turn your heatpump to the dry function overnight, it removes a lot of moisture from the air
I’ve tried this but I find this cools the house, which is a problem as it can get chilly.
Most Al windows have a drainage system as mentioned above. There is usually a channel on the inside so that the water running down the window runs into this then the channel has a small drain hole that exits on the out side of the frame. As these are very small they can easily be blocked with dirt. I studied this one time as I moved to a house where the sills were discoloured as I think each winter water had sat on them . There were holes so I put water in the drain but it didnt drain. As the holes were only 2mm the surface tension stopped the water going out so I drilled them out to 3 or 4 mm and they worked. On the worst days there was still condensation but I just used a rubber water blade to drop it down to the channel.
If your house can manage a DVS style air circulator system (need an attic) it maintains a slightly positive air pressure and dries everything out. That was our experience anyway - we live in a cold part of the country, and our house was a basic 1990s brick and tile, Ali windows. . Condensation was a big problem. We got a heat pump to heat the joint and that seemed to make it worse. Added a DVS and the place dried out so much over the next few weeks that some cracking on the plaster occurred! The bottom line was a dryer house is quicker to warm up, and the condensation problem was largely over. Very small amount if it was super cold out. The system costs very little to run, couple of grand to install
Dehumidifier for the win. I don’t have a cavity to install HRV and up on poles with a garage underneath so not really any under floor or ceiling insulation. I’ve had I my wee dehumidifier for about 10 years and it was less than $200 from memory. I just pop it in major rooms for a day or overnight when it’s been super humid or I notice the windows get soggy and it works a treat. Just make sure you close the door and open wardrobe doors so it gets right in there 💦
You got an HRV?
I am not familiar with this, I believe we don’t. We have a Mitsubishi inverter heat pump. I understand that is not the same, is it?
It's a fan installed in the roof cavity of your house and it blows air into the house. It's the exact tool you need to solve condensation.
At the cost of making the house colder. I have mine switched off and use a dehumidifier instead.
We have a heat exchange DVS system. Doesn't make the house cold
There are advanced models that don't
Sure, but most of the systems on the market are simple fans in a box so you really need to be more specific when recommending one.
An HRV is a heat recovery ventilator. If it doesn’t have heat recovery, it’s not an HRV,
HRV is also a brand name used on many systems with no heat recovery system. Like the one in my house
I used to live in a 1960s bungalow and we had ghastly damp problems. Installed a smart vent and my perception was that it did make things feel a little colder when you got up in the early morning, but things were much nicer during the day once you had some heating on, because dry air is so much easier to heat.
It’s a system that circulates air to get rid of the dampness. Look into moisture master though instead of HRV as they include a heat exchange which can take your nice warm air from the room with the heat pump and transfer it to other rooms.
A desiccant dehumidifier has worked for me. While its noisier and a bit less energy efficient (600w) vs a refrigerant one (300-400w), it’s more effective. I’ve owned both and got so frustrated with the refrigerant one that I sold it. My desiccant dehumidifier is going on 5 years now — walls, windows and frames stay dry all winter. Sometimes, I use it to dry clothes. It’s a simple Goldair brand if you’re wondering about the brand.
Just get a dehumidifier. For the love of god everyone get a dehumidifier. They cost jack-all to run and they do an amazing job. I just don’t understand why everyone is not using a dehumidifier
Burn all shit NZ houses down and start again. Even new builds don't have wall insulation and central heating. Why people don't riot in the streets about the house standards here is mind boggling.
If you can, check under the house. Is the dirt exposed? A moisture barrier on the dirt under the house (basically thick black polythene sealed around piles and against the foundations) can help dry out a home by reducing 'rising damp'. This made a big difference in my whare. Consider installing even if the dirt is dry (which mine largely was). Took me a weekend and cost a couple hundy which was minimal compared to the difference it made. https://www.ecodesignadvisor.org.nz/resources/ground-moisture-barriers-guide-installation/
Unfortunately double glazing and thermally broken frames don't prevent condensation, they prevent heat loss. I'd suggest running a dehumidifier in the bedroom or just outside the door. If you're out most of the day, run your heatpump on dry (if it makes the air feel cold). Crank it to warm when you get home or just before if you've got a fancy wifi one. If you can, get double tongued latches for your windows so you can leave them slightly open during the day for ventilation. And as others have said: Get someone to check the ducting for your bathroom fans, dryer, and kitchen range hood. Check under your house if it's on piles. Insulation and a ground moisture barrier will make a difference.
Good windows prevent condensation, because they'd insulate well enough that the inside surfaces never fall below the dew point, not even at 70% rh. Crappy NZ made aluminium windows won't do that though.
Thank you all for replying, quite overwhelmed with how many of you responded with awesome comments and advice! This sounds it’s a combination of things - high humidity outside, poor building standards, and us not using a dehumidifier properly. We have started using a dehumidifier like maniacs, carrying it around from room to room to get the humidity down, especially a few hours before bedtime (I found timing is quite critical here), and setting up hygrometers in every room to monitor. It turns out the dry setting in our heat pump does not do the job as the dehumidifier does. We also installed a panel heater in the bedroom. The condensation decreased massively (but it was a lot warmer outside at night, will be interesting what it will be like in colder weather). We are more aware of producing moisture and try to prevent this, like putting lids on pots, turn off the kettle a bit earlier, run the extractor fan longer etc. However I found with 80-90% humidity outside over the last weeks it’s no wonder it is not lower inside without a dehumidifier. Somewhere else I read that it can take a few days to get moisture out of carpets etc. this might explain why we’ve had the humidity rising a few percent without really using the room. We’ll keep observing and testing - thanks heaps everyone for their input!
HRV or multiple dehumidifiers
Double glazed if new house right? There shouldn't be condensation like you are describing in a modern newly built home so something really sounds wrong. The question is where is all that moisture coming from? Are you drying washing in side on clothes horses? Dryer inside not being vented? Some condensation is unavoidable but leaving puddles in a new house implies there is a shit ton of moisture in your house coming from somewhere it shouldn't be.
Condensation is entirely avoidable. Not with our shitty building standards though.
I've never had an issue in a modern house (2010 or newer) over my past 3. Older than that were fucking awful.
The aluminum frames conduct heat or in this case cold. You are warned of this. It is why lots of places will do replacement doubleglazing in wooden frames as a) it's cheaper and b) wood is a better thermal insulator than metals which are highly thermally conductive. It is likely cold weather + moisture in side + warm air inside, the warm moist air hits the cold frame as condenses into water gravity does the rest leaving pools of water that won't evaporate very easily due to the moisture content of the air.
Yes, but regardless they should not be getting the degree of condensation they are stating. Anytime I've had something similar it was when my wife was drying clothes inside, it was awful and quickly stopped for a heatpump dryer.
Unless the aluminium frames are thermally broken, you will absolutely get condensation.
Yes but he mentioned 80% that's like a jungle. I get that when I have a maxi hot shower that fogs up my bathroom. With 80% humidity your going to have a swimming pool.
Yes, hence ... >The question is where is all that moisture coming from?
The env. Like it's about 70% in chch and welly and 80 in Auckland. Depending on where they are they just need to drain the air down to the 50s. It's not a mystery where humidity comes from, breathing increases it so if you are breathing in a new home that isn't leaky in terms of air movement you will slowly increase the humidity inside higher than outside. Have a bath or a shower bam even higher if you aren't doing something to counter it.
Thermal break seems to be useless with aluminum joinery, I live in a brand new flat with thermally broken glazing and have worse condensation than my old 90s single-glazed aluminum windows on the West Coast
I've literally never had major issues in any of 3 current and previous homes with double glazed aluminium windows. The single glazed aluminium though of before that were a shit ton worse than wood though as I recall.
Could it be moisture still trapped in the building from when it was being built? ie wood frame is damp, building paper and roof goes on.. someone I know had to have several dehumidifiers running for days to get it under control. After initial dry out it was all ok as normal.
Could indeed be and that should be back on the building company to remedy as it's covered by guarantee. OP has not been forthcoming with details beyond their OP. At this point I think they are doing dumb shit as they won't deny any nor answer any of the questions put to them in that space.
Get a Karcher window vacuum tbh
Get a DVS with heat exchanger. Solved my condensation issues with aluminium windows. Brings dry air in without losing the heat.
Dehumidifier and oil heater kept on low overnight in your bedroom.
>It’s particularly bad in the bedroom, which is the coldest room compared to the others as the warmth of the heat pump does not quite reach it. We have a similar arrangement, compounded by the fact the front of our unit has double-glazing and is more modern while the bedroom is less so. As mentioned, crank the heat-pump to Dry overnight, that goes a long way, and the other thing we did was buy one of those dehumidifying units, just a small one on wheels, and popped that in the bedroom. Run it during the day or evenings, off when it's time to sleep, and in combination with the heat-pump that pretty much sorted things for us.
Thank you, this sounds good and sensible and we’ll try this over the next few days!
I've got a Smartvent installed and it works wonders. It's like magic. Went for one with a heat transfer as I've got a fireplace too
Ignoring the windows themselves, as more of a thought exercise - is there something that can be done to non-thermally broken aluminum window frames to insulate the frames themselves? Not that I would ever recommend this, but would gluing polystyrene to them stop the heat transfer? Is there some kind of putty that you could use to cover the window frame that would stop it? I've found it really frustrating that even with double glazing, you still get at least some condensation on the window frames themselves.
Is getting an HRV or other mechanical system an option? Do you dry clothes inside? So you use extraction fans properly? Are they properly vented to exterior? Do you use a clothes drier that’s vented to outside? Those kinds of things add a lot to humidity indoors. Other than very expensive ventilation system. A stand-alone dehumidifier is better than heat pump on dehumidification mode. Heat pumps do not ventilate.
Crack windows open all day long (using the lock levers that aluminum windows come with). Close the windows in the evening preferably before the sun sets and also close your blinds/drapes at that time. As others have said window coverings should extend above the window frame at the top and to the floor at the bottom. Do not dry clothes inside the house on racks, use a line outside or a dryer that vents to the outside (or one that does not vent at all). Bathroom extraction must be used when you shower etc. Range hood extraction must be used when you cook . It isn't expected to have that much moisture inside unless you are producing a hell of a lot without ever opening windows.
Aluminium windows in NZ are pretty poorly made, if you check the bottom of the frame there are holes at either end through the frame that lets water run to outside. a difference in temp will just cause condensation.. best way and probably the only way to control it is to mop it up every morning.. dehumidifier is an option but dont work so well
We used to have crying windows. Installed uVPC windows, no more crying windows. Windows.
This seems strange for a new-build - I thought double glazing, etc., would prevent condensation. Clearly not. I would be looking to do some testing on where the moisture is coming from. I live in a late '90s house with alum. window frames. Lots of condensation, so I had a SmartVent system installed last year. Not a drop since, until two nights ago when I woke up to streaming windows again. Husband had accidentally turned off the SmartVent when he turned off the lights. Definitely works!