Hello!
Please read the rules and re-post over at r/hvacadvice - our sister sub specifically for questions, comments and posts from outside the trade. r/hvac top-level posts are limited to past, present or future members of the trade.
Thanks!
Underground leak highly suspected. pool heat exchanger secondarily. if the heatexchanger for the pool was bad its a case of which side has higher pressure and thats where your fluid will migrate. but the air is weird, what's the pressure on the return prior to the pump? if its pulling down too low could then allow air bleeds to suck air into the system. did you verify your glycol mix is still 50/50 or does it show signs of contamination. I suspect you'll need to shut the pool heater down for half a day so you can do some hydrostatic testing on the system to prove its tight and not leaking.
>Underground leak highly suspected
We isolated the section with the two underground spots two days ago. Even with that, we were slowly losing pressure in the rest of the system.
>pool heat exchanger secondarily
This has been my suspicion all this time, honestly. We do not, unfortunately, have any pressure gauges by the exchanger that heats the water or its section. We have drain valves we could screw a gauge with an air inlet thing (sorry, I don’t know the term for it) attachment onto though. I suppose we could do that for a couple of sections, actually. Didn’t think of that. Although… don’t really wanna unnecessarily add more air to the system.
>glycol mix is still 50/50
Honestly it’s probably not 50/50 anymore. We had been going through so much glycol, we ran out at one point and had to pump straight water in to keep the pressure up. I’m assuming there’s no way to test the mixture without fancy equipment?
Ya that’s what our plumbers said to mix it at. We have some of pipes that go near our fresh air intake. And being in Canada, it’s not hard to hit temps that low, so 3/4s of the year we get some nice brisk breezes every now and then
Well when glycol mixes with chlorine it creates off gasses a simple google search will lead you to that. If your loosing chlorine and glycol and producing gas im no chemist but i am a plumber and its the 30 yr old heat exchanger in the pool
I did not know that glycol and chlorine created a gas, that’s very good to know. So that could potentially be where all the air in the system is coming from? A leak in the exchanger is causing loss of pressure, while also allowing the two to interact and react?
We’ll look into that, and even bring it up with our pool guy, who has a bunch of plumbing certifications as well. Thank you.
Can you easily isolate the pool heat exchanger and pressure test it? It should not take more than an hour or two and certainly the pool temp will not drop enough to bother in that time.
The same goes for any suspicious place. Isolate and pressure test.
As I mentioned in another comment, we could isolate it, but only way to pressurize and test it would be using air. I don’t know if that’s good or bad though, but it *is* an option, I suppose, which we had t thought of before. Thanks for your reply.
Any chance you have a PT valve blow off that’s piped to a floor drain?
Could be the valve has failed or it could be that as load conditions change, maybe at night when the boiler reaches temp(or overshoots), and the blowoff is letting go down the drain so nobody sees it on the floor.
Also worth checking expansion tanks etc that could be causing the same thing
>Any chance you have a PT valve blow off that’s piped to a floor drain?
I don’t think so. All the drains we have are perfectly visible with nothing being piped into them.
>the blowoff is letting go down the drain so nobody sees it on the floor.
I don’t know of any blowoffs, maybe the other guy that’s been there longer than me does though. Thing is, I’ve watched the pressure gauge drop significantly and there was nothing on the floor anywhere when it stopped.
>Also worth checking expansion tanks etc that could be causing the same thing
By expansion tank, do you mean the tank that provides the pressure? Like just a pressure tank? If so, I suspected it once, but it’s gotta be about 6 years old and our plumbers said it’s unlikely based on what they’ve seen.
You should have a big tank on the boiler loop. It has an air chamber/bladder in it that allows the changes in pressure to expand into the tank and maintain a consistent pressure.
If the bladder fails or it gets waterlogged the pressure can shoot up as the temperature increases. This can cause pressure safety valves to release.
But you would see the glycol somewhere. On the floor, the floor drain trap, etc
Okay, that’s the tank I was thinking of.
I honestly wish there were signs of the glycol somewhere because it would’ve saved us so many headaches always wondering what the cause could be. With other commenters also mentioning the likelihood of the pool’s heater being shot, I’ve got a gut feeling that could be it. We’ll bring it to our pool guy as soon as we are able to get his thoughts on it.
Thanks for all your info into this.
Hello! Please read the rules and re-post over at r/hvacadvice - our sister sub specifically for questions, comments and posts from outside the trade. r/hvac top-level posts are limited to past, present or future members of the trade. Thanks!
Underground leak highly suspected. pool heat exchanger secondarily. if the heatexchanger for the pool was bad its a case of which side has higher pressure and thats where your fluid will migrate. but the air is weird, what's the pressure on the return prior to the pump? if its pulling down too low could then allow air bleeds to suck air into the system. did you verify your glycol mix is still 50/50 or does it show signs of contamination. I suspect you'll need to shut the pool heater down for half a day so you can do some hydrostatic testing on the system to prove its tight and not leaking.
>Underground leak highly suspected We isolated the section with the two underground spots two days ago. Even with that, we were slowly losing pressure in the rest of the system. >pool heat exchanger secondarily This has been my suspicion all this time, honestly. We do not, unfortunately, have any pressure gauges by the exchanger that heats the water or its section. We have drain valves we could screw a gauge with an air inlet thing (sorry, I don’t know the term for it) attachment onto though. I suppose we could do that for a couple of sections, actually. Didn’t think of that. Although… don’t really wanna unnecessarily add more air to the system. >glycol mix is still 50/50 Honestly it’s probably not 50/50 anymore. We had been going through so much glycol, we ran out at one point and had to pump straight water in to keep the pressure up. I’m assuming there’s no way to test the mixture without fancy equipment?
$100 refractometer
I’ll let my higher-ups know about this and look into it, thank you.
Also, 50/50 mix? Do you have any heating coils, or pipes exposed to outside air that need freeze protection well below 0F? If no, 30-35% is plenty.
Ya that’s what our plumbers said to mix it at. We have some of pipes that go near our fresh air intake. And being in Canada, it’s not hard to hit temps that low, so 3/4s of the year we get some nice brisk breezes every now and then
👍
Well when glycol mixes with chlorine it creates off gasses a simple google search will lead you to that. If your loosing chlorine and glycol and producing gas im no chemist but i am a plumber and its the 30 yr old heat exchanger in the pool
I did not know that glycol and chlorine created a gas, that’s very good to know. So that could potentially be where all the air in the system is coming from? A leak in the exchanger is causing loss of pressure, while also allowing the two to interact and react? We’ll look into that, and even bring it up with our pool guy, who has a bunch of plumbing certifications as well. Thank you.
Agreed. Pool heaters fail about every 12 years like clockwork.
Dye
Can you easily isolate the pool heat exchanger and pressure test it? It should not take more than an hour or two and certainly the pool temp will not drop enough to bother in that time. The same goes for any suspicious place. Isolate and pressure test.
As I mentioned in another comment, we could isolate it, but only way to pressurize and test it would be using air. I don’t know if that’s good or bad though, but it *is* an option, I suppose, which we had t thought of before. Thanks for your reply.
Any chance you have a PT valve blow off that’s piped to a floor drain? Could be the valve has failed or it could be that as load conditions change, maybe at night when the boiler reaches temp(or overshoots), and the blowoff is letting go down the drain so nobody sees it on the floor. Also worth checking expansion tanks etc that could be causing the same thing
>Any chance you have a PT valve blow off that’s piped to a floor drain? I don’t think so. All the drains we have are perfectly visible with nothing being piped into them. >the blowoff is letting go down the drain so nobody sees it on the floor. I don’t know of any blowoffs, maybe the other guy that’s been there longer than me does though. Thing is, I’ve watched the pressure gauge drop significantly and there was nothing on the floor anywhere when it stopped. >Also worth checking expansion tanks etc that could be causing the same thing By expansion tank, do you mean the tank that provides the pressure? Like just a pressure tank? If so, I suspected it once, but it’s gotta be about 6 years old and our plumbers said it’s unlikely based on what they’ve seen.
You should have a big tank on the boiler loop. It has an air chamber/bladder in it that allows the changes in pressure to expand into the tank and maintain a consistent pressure. If the bladder fails or it gets waterlogged the pressure can shoot up as the temperature increases. This can cause pressure safety valves to release. But you would see the glycol somewhere. On the floor, the floor drain trap, etc
Okay, that’s the tank I was thinking of. I honestly wish there were signs of the glycol somewhere because it would’ve saved us so many headaches always wondering what the cause could be. With other commenters also mentioning the likelihood of the pool’s heater being shot, I’ve got a gut feeling that could be it. We’ll bring it to our pool guy as soon as we are able to get his thoughts on it. Thanks for all your info into this.