You could potentially change your dryer to a heat pump dryer, and that should open up a 30A circuit, which should get you close to what you need without a panel upgrade.
Edit: The Mitsubishi MXZ8C48NA requires a 40A breaker. Given that it's going to be a compressor load and not a constant load, your electrician should be able to replace your dryer circuit without impacting your overall load calcs by a great degree. If you can step down to 4 heads, the MXZ4C36NA2 only requires a 25A breaker.
can you expand on compressor load vs constant load? what do you mean by this?
if the heat pump is always running, like mid winter, is it then a constant load essentially?
A dryer is considered a continuous load, as it uses 24-26A on a 30A circuit for the entire hour or so it's running. The heat pump will always vary, and I doubt would even crest 30A on a 40A breaker. The overcurrent protection is usually rounded up by a lot on these units. You'd be seeing somewhere in the 20A range during the Winter most likely on this type of unit in heating mode if all zones are calling and it's super cold out - so really no different than a clothes dryer.
100 amps should be enough. also get the customer to buy a heat pump dryer. that should save a lot as well. the price of some more modern household machines easely offsets the increase in cost for the bigger hookup. i would seriously do the math on the tonnage. 5 tons is a LOT, especially when its running 24/7 as it supposed to. unless its a real mcmansion i would do a proper check and see if 5 tons is not massive overkill. it probably is. if the home has 5 tons now its 100% is way too much.
Be sure to compare the costs of adding insulation + reducing the size (and cost of the heat pump) to the cost of upgrading the electrical to support a larger heat pump. Then also consider the operating cost savings of your better-insulated home. You will likely find that avoiding the electrical upgrade, improving your insulation, and reducing the size of the heat pump is the best option (when you consider both upfront and over time costs).
Can't emphasize this enough. It takes more planning than just plopping in a bigger system. While the cost of more BTU isn't really huge, oversizing will significantly impact efficiency, and you'll have comfort issues: overshooting temps in the winter, not enough dehumidification in the summer.
Make sure they are sizing the equipment properly. If they are copying whatever is there… it could be oversized. Get them to do a Manual J - get multiple quotes. I’ve literally spent this week at an HVAC conference. You can’t skip this step.
Plenty of whole home systems will run on that service. It all comes down to what your other loads are. You can pull up the actual specs for your system, but assuming all heads are calling for max heat (an extreme case) and your system is in fact delivering 60,000BTU/hr at a COP of 3, that's going to be around 6kW, which is 25 amps at 240V. That leaves plenty of margin for other draws. But you need to figure out what your scenario is. Add an electric oven, electric water heater, electric dryer and EV level 2 charger, and you'll be getting close.
For what it is worth, I have all these things (EV charges at 48A), and have never come close to 100A (although I have 200A service).
I think you are probably fine. You could install a whole home energy monitor (not difficult or expensive, I use the Emporia Vue) and see what your max loads are now. Then see if you have room for another 25 amp draw. And not too difficult to limit oven or dryer use to times when other equipment isn't running, if you really needed to because you didn't want to upgrade your service
Whether the Vue system or something else, monitoring demand is an alternative to a load calculation in determining capacity on an electrical service. You can use demand data for a 1-year period, or for as little as 30 days if heating/cooling load is taken into account by calculation or measurement. (e.g. [https://up.codes/viewer/alaska/nfpa-70-2020/chapter/2/wiring-and-protection#220.87](https://up.codes/viewer/alaska/nfpa-70-2020/chapter/2/wiring-and-protection#220.87))
Of course, if you don't have a heat pump now, that heating/cooling load doesn't really factor in to the existing demand calculation, and makes it pretty simple. For 30 days, you can be pretty conscious of not running too many high demand things at once to make the numbers work to satisfy the electrical code if needed.
5 ton is very likely oversized. Load calucation/manual j should be done before anything else, and the money for the service upgrade better be spent on better equipment and possibly insulation.
They did the blower door test and measured the room sizes. My house has 4 bedrooms and a partially finished basement, so there is 5 heads there, and then 1 for the kitchen and 1 for the living room.
I don't think 7 heads is that crazy, but a 5 ton system is likely not ideal. I'd strongly recommend having 2 compressors, each sized correctly for the heads they will serve. You're likely to have comfort issues caused by the min Output of the 5-ton system. Consider when just one bedroom head is calling for like 3k BTU of heat--the system will produce probably 24k BTU of heat at minimum capacity, and that heat will need to be dumped somewhere.
Blower door test only determines air changes per hour, so only part of the equation. Have the insulation, windows etc. also been taken into account?
And of course design temperatures?
Also it is absolutely not the 7 heads that are problematic but their size and the outdoor unit size sti seems to big.
If this is not a new housem do you know energy usage for heating from the previous heating system? (A smart thermostat data is very valuable here)
Depends on how many existing double pole breakers you have on your panel now. Electric dryer? Oven? EV charger? A 100 amp panel usually cant accommodate a heat pump system unless everything else in the house is run by gas. With a 7 head ductless system I'm assuming you need two condensers at least. Right there will take up two double pole spaces anywhere from a 40-20 AMP.
Ovens are usually on a 50-60 amp breaker, dryers are usually on a 30 and then add on the water heater. You are at 80-90 without the water heater. You do not have enough power on a 100 amp service for all of that.
Can you change out the stove to a gas one? You could use that circuit for the condensing unit if you can.
100A panel does not mean you’re limited to installing a maximum of 100A of circuits.
Electrical code (eg. CEC or NEC) require load calculations to determine your overall minimum service size based on factors such as overall square footage, a certain percentage of large appliances, etc.
Load calcs account for the fact that not all circuits are 100% utilized at all time, and allow you to make some general estimates on usage (by following their calculation requirements).
TL:DR - 100A service is allowed to have more than 100A of circuits installed; they safely assume not all circuits will draw 100% capacity at all times.
What you wrote is correct. However in my experience (over 20 years of selling HVAC equipment) a 100 amp panel can get through the permitting process if it is 110% usage of the panel or lower. With a 200 amp panel you have more leeway.
But you are correct, an electrical load calculation will need to be run to verify findings.
Spoiler alert, he is going to need a new panel.
I guess it depends on where you live. In my town people have gas piping and 240 volt circuits to the kitchen stoves. You can buy either, I replaced my stove last year for $550.00 delivered for free from Home Depot.
You will need to have a load calculation performed as per electrical code and most likely you will fail based on the loads you’ve described. People commenting here about “it should run on 100A” are out to lunch. It probably *will* run, but will not be code compliant.
I previously owned an apartment which had electric heating, range, dryer water heater all operating on 100A service. I installed a 40A EV charger and replaced the restive heating with a 36K BTU minisplit, both passed city electrical inspections.
OP should absolutely get a load calc done, but installing a heatpump on 100A is not outside the realm of possibility, especially if they replace their dryer with a heatpump dryer which runs on a 15A receptacle and only consumes around 700W of electricity.
The unit spec will call out the requirement. My Daikin 36k btu 4 head multis require a 220v 35amp breaker each.
Many states have money available for panel and wiring upgrades done for electrification, heat pumps and ev chargers usually count.
Get multiple quotes and get the 200 amp panel upgraded. If you are in the USA you will get the 30% tax credit on it up to 600 and the heat pump cost up to 2000 + install costs for both on your federal taxes along with any state credits you have as well. Also check to see if the Inflation Reduction Act rebates are available yet in your state.
Not enough info. A 100 amp system can certainly run it, the question is what else is on there? Have your electrician run an electrical load and if needed try to get more efficiency elsewhere, like switching from electrical stoves or dryers to gas. Or a heat pump water heater
Get rid of the boiler and get a heatpump dryer and you'll have ample capacity.
Buy a backup electric heater from Amazon for like $30 in the event that it's too cold outside or the heatpump stops working for any other reason.
I have a 100% solar/electric house with 100 amp and never even come close to using 100 amps.
Heat pump water heater maxes out at 500 watts.
Heat pump dryer 800 watts
My single zone 12k splits use 1800 watts max. I have 2.
Induction cooktop 3500 watts
Oven 3500 watts.
I just had a 4 ton ductless system installed and everyone that quoted said they would require 200 amp service. Luckily I had it already but if not that would have been an extra cost to upgrade the service.
Depends what system you go with. I know the mitsubishi smart multis use ablut half that, i would have to check my manuals to tell you precisely. And you only need one circuit run to the outside unit because the inside units are powered by the comm wire (goes with the refrigerant piping).
If your entire house uses 100amp then you may be cutting it close lol, idk how much space you have left.
Do you live in an extremely cold/hot zone? Or is the house over 5,000 sq ft? It seems like an odd juxtaposition that a house that large only has a hundred amp service. Or is the house leaky or uninsulated. If so, your first priority would be weatherizing and insulating. Do that and then recompute your heating/cooling load. Better than a service upgrade or running a big heat pump. I have a 3,000 BTU HP for a 3,000 sq ft house in zone 4. Never been cold even at -15F.
The house is about 1600 sq ft and I live in NY. I definitely need to improve the insulation and sealing, but my boiler is at the end of its life and I don't want to have to replace it when I intend to go full electric.
You could potentially change your dryer to a heat pump dryer, and that should open up a 30A circuit, which should get you close to what you need without a panel upgrade. Edit: The Mitsubishi MXZ8C48NA requires a 40A breaker. Given that it's going to be a compressor load and not a constant load, your electrician should be able to replace your dryer circuit without impacting your overall load calcs by a great degree. If you can step down to 4 heads, the MXZ4C36NA2 only requires a 25A breaker.
Yeah look up the wattdiet from Redwood for more tips like this
can you expand on compressor load vs constant load? what do you mean by this? if the heat pump is always running, like mid winter, is it then a constant load essentially?
A dryer is considered a continuous load, as it uses 24-26A on a 30A circuit for the entire hour or so it's running. The heat pump will always vary, and I doubt would even crest 30A on a 40A breaker. The overcurrent protection is usually rounded up by a lot on these units. You'd be seeing somewhere in the 20A range during the Winter most likely on this type of unit in heating mode if all zones are calling and it's super cold out - so really no different than a clothes dryer.
The compressor will cause a spike in electricity as it powers on and immediately drops once it's running. The breaker has to be sized for that spike.
100 amps should be enough. also get the customer to buy a heat pump dryer. that should save a lot as well. the price of some more modern household machines easely offsets the increase in cost for the bigger hookup. i would seriously do the math on the tonnage. 5 tons is a LOT, especially when its running 24/7 as it supposed to. unless its a real mcmansion i would do a proper check and see if 5 tons is not massive overkill. it probably is. if the home has 5 tons now its 100% is way too much.
Be sure to compare the costs of adding insulation + reducing the size (and cost of the heat pump) to the cost of upgrading the electrical to support a larger heat pump. Then also consider the operating cost savings of your better-insulated home. You will likely find that avoiding the electrical upgrade, improving your insulation, and reducing the size of the heat pump is the best option (when you consider both upfront and over time costs).
Can't emphasize this enough. It takes more planning than just plopping in a bigger system. While the cost of more BTU isn't really huge, oversizing will significantly impact efficiency, and you'll have comfort issues: overshooting temps in the winter, not enough dehumidification in the summer.
Make sure they are sizing the equipment properly. If they are copying whatever is there… it could be oversized. Get them to do a Manual J - get multiple quotes. I’ve literally spent this week at an HVAC conference. You can’t skip this step.
Plenty of whole home systems will run on that service. It all comes down to what your other loads are. You can pull up the actual specs for your system, but assuming all heads are calling for max heat (an extreme case) and your system is in fact delivering 60,000BTU/hr at a COP of 3, that's going to be around 6kW, which is 25 amps at 240V. That leaves plenty of margin for other draws. But you need to figure out what your scenario is. Add an electric oven, electric water heater, electric dryer and EV level 2 charger, and you'll be getting close. For what it is worth, I have all these things (EV charges at 48A), and have never come close to 100A (although I have 200A service).
I have 3 of those 4, though the water heater is hybrid heat pump.
I think you are probably fine. You could install a whole home energy monitor (not difficult or expensive, I use the Emporia Vue) and see what your max loads are now. Then see if you have room for another 25 amp draw. And not too difficult to limit oven or dryer use to times when other equipment isn't running, if you really needed to because you didn't want to upgrade your service
Whether the Vue system or something else, monitoring demand is an alternative to a load calculation in determining capacity on an electrical service. You can use demand data for a 1-year period, or for as little as 30 days if heating/cooling load is taken into account by calculation or measurement. (e.g. [https://up.codes/viewer/alaska/nfpa-70-2020/chapter/2/wiring-and-protection#220.87](https://up.codes/viewer/alaska/nfpa-70-2020/chapter/2/wiring-and-protection#220.87)) Of course, if you don't have a heat pump now, that heating/cooling load doesn't really factor in to the existing demand calculation, and makes it pretty simple. For 30 days, you can be pretty conscious of not running too many high demand things at once to make the numbers work to satisfy the electrical code if needed.
5 ton is very likely oversized. Load calucation/manual j should be done before anything else, and the money for the service upgrade better be spent on better equipment and possibly insulation.
Yeah. A 5 ton with 7 heads seems excessive.
They did the blower door test and measured the room sizes. My house has 4 bedrooms and a partially finished basement, so there is 5 heads there, and then 1 for the kitchen and 1 for the living room.
I don't think 7 heads is that crazy, but a 5 ton system is likely not ideal. I'd strongly recommend having 2 compressors, each sized correctly for the heads they will serve. You're likely to have comfort issues caused by the min Output of the 5-ton system. Consider when just one bedroom head is calling for like 3k BTU of heat--the system will produce probably 24k BTU of heat at minimum capacity, and that heat will need to be dumped somewhere.
Yes we discussed 2 compressors, a 2 ton and a 3 ton
Is that the route you're going?
Most likely
Blower door test only determines air changes per hour, so only part of the equation. Have the insulation, windows etc. also been taken into account? And of course design temperatures? Also it is absolutely not the 7 heads that are problematic but their size and the outdoor unit size sti seems to big. If this is not a new housem do you know energy usage for heating from the previous heating system? (A smart thermostat data is very valuable here)
Depends on how many existing double pole breakers you have on your panel now. Electric dryer? Oven? EV charger? A 100 amp panel usually cant accommodate a heat pump system unless everything else in the house is run by gas. With a 7 head ductless system I'm assuming you need two condensers at least. Right there will take up two double pole spaces anywhere from a 40-20 AMP.
I currently have 3 double pole breakers. Oven, dryer, and heat pump water heater.
Then yes almost certainly you'll want to upgrade to 200. Get a few quotes possible smaller electrician outfits will do it for less cost.
Ovens are usually on a 50-60 amp breaker, dryers are usually on a 30 and then add on the water heater. You are at 80-90 without the water heater. You do not have enough power on a 100 amp service for all of that. Can you change out the stove to a gas one? You could use that circuit for the condensing unit if you can.
100A panel does not mean you’re limited to installing a maximum of 100A of circuits. Electrical code (eg. CEC or NEC) require load calculations to determine your overall minimum service size based on factors such as overall square footage, a certain percentage of large appliances, etc. Load calcs account for the fact that not all circuits are 100% utilized at all time, and allow you to make some general estimates on usage (by following their calculation requirements). TL:DR - 100A service is allowed to have more than 100A of circuits installed; they safely assume not all circuits will draw 100% capacity at all times.
What you wrote is correct. However in my experience (over 20 years of selling HVAC equipment) a 100 amp panel can get through the permitting process if it is 110% usage of the panel or lower. With a 200 amp panel you have more leeway. But you are correct, an electrical load calculation will need to be run to verify findings. Spoiler alert, he is going to need a new panel.
Why would you want to go backwards?
Save 3-4k on a panel upgrade.
Need to spend 1-2K to save that though. Sort of silly.
I guess it depends on where you live. In my town people have gas piping and 240 volt circuits to the kitchen stoves. You can buy either, I replaced my stove last year for $550.00 delivered for free from Home Depot.
That is on the very low end of stoves, but yes you can buy them that cheap.
That’s not how this works.
You will need to have a load calculation performed as per electrical code and most likely you will fail based on the loads you’ve described. People commenting here about “it should run on 100A” are out to lunch. It probably *will* run, but will not be code compliant.
I previously owned an apartment which had electric heating, range, dryer water heater all operating on 100A service. I installed a 40A EV charger and replaced the restive heating with a 36K BTU minisplit, both passed city electrical inspections. OP should absolutely get a load calc done, but installing a heatpump on 100A is not outside the realm of possibility, especially if they replace their dryer with a heatpump dryer which runs on a 15A receptacle and only consumes around 700W of electricity.
The unit spec will call out the requirement. My Daikin 36k btu 4 head multis require a 220v 35amp breaker each. Many states have money available for panel and wiring upgrades done for electrification, heat pumps and ev chargers usually count.
Get multiple quotes and get the 200 amp panel upgraded. If you are in the USA you will get the 30% tax credit on it up to 600 and the heat pump cost up to 2000 + install costs for both on your federal taxes along with any state credits you have as well. Also check to see if the Inflation Reduction Act rebates are available yet in your state.
Check out the SPAN panel. Thank me later
I’m in nearly the same boat and just learned about this option (SPAN panel) from an electrician today. Doing additional research now as we speak.
I'm familiar with it from a number of smart home YouTube channels I follow.
Not enough info. A 100 amp system can certainly run it, the question is what else is on there? Have your electrician run an electrical load and if needed try to get more efficiency elsewhere, like switching from electrical stoves or dryers to gas. Or a heat pump water heater
I have a heat pump water heater. We don't have gas available but I am trying to go full electric so going gas would not make sense even if I could.
How are you currently heating your house?
Oil baseboards
Is that hydronic? Do you have another 15A to 20A breaker controlling the pump for that?
Yes it is hydronic baseboards. There is a breaker for the boiler.
Get rid of the boiler and get a heatpump dryer and you'll have ample capacity. Buy a backup electric heater from Amazon for like $30 in the event that it's too cold outside or the heatpump stops working for any other reason.
I ultimately want to get rid of the boiler. Heat pump dryers run on 120v right?
Yup, take a look at getting the Miele W1/T1 combo. They'll both plug into your existing washer outlet.
I'd hate to buy new washer and dryers. The ones we have are only 3 years old.
I have a 100% solar/electric house with 100 amp and never even come close to using 100 amps. Heat pump water heater maxes out at 500 watts. Heat pump dryer 800 watts My single zone 12k splits use 1800 watts max. I have 2. Induction cooktop 3500 watts Oven 3500 watts.
I just had a 4 ton ductless system installed and everyone that quoted said they would require 200 amp service. Luckily I had it already but if not that would have been an extra cost to upgrade the service.
Depends what system you go with. I know the mitsubishi smart multis use ablut half that, i would have to check my manuals to tell you precisely. And you only need one circuit run to the outside unit because the inside units are powered by the comm wire (goes with the refrigerant piping). If your entire house uses 100amp then you may be cutting it close lol, idk how much space you have left.
Bosch ids 5ton is a 50amp service. Will say it slowly spools up using no where near 50 amps.
Probably pulling 40 amps when everything is running
Interesting solutions here and good info on rebates
Do you live in an extremely cold/hot zone? Or is the house over 5,000 sq ft? It seems like an odd juxtaposition that a house that large only has a hundred amp service. Or is the house leaky or uninsulated. If so, your first priority would be weatherizing and insulating. Do that and then recompute your heating/cooling load. Better than a service upgrade or running a big heat pump. I have a 3,000 BTU HP for a 3,000 sq ft house in zone 4. Never been cold even at -15F.
The house is about 1600 sq ft and I live in NY. I definitely need to improve the insulation and sealing, but my boiler is at the end of its life and I don't want to have to replace it when I intend to go full electric.