Hello Everyone. I had my pipes coming in and coming out of pool heater collapsed this weak. I replaced the collapsed pipes the second day. After one day of use, it collapsed again. Every thing was fine pump was working fine, skimmer basket was clean and the most important is my heater was not working in both incidents. Pipes-1 is the first incident. The Pipes-2 photo represents the second incident. Any one has a reason for the cause and how to fix it. I searched over the net. but I couldn't find an answer. I asked technicians, but the don't know or have a straight answer or a guaranteed solution. I appreciate your help.
Heater Pipe COLLAPSED!
- Thread starter adel_ashri
- Start date
Bill1974
Well-known member
This is the opposite of a water hammer. When the pump shuts off the pump and filter are restrictive and the inertia of the water in the return lines cause a negative pressure in the return lines as it tries to slow down. First I would replace the pipes with rigid PVC. Also check the output temperature from the heater. Also have the heater shut off and let the pump run for a few minutes to purge the heat out heater and get some cooler water though the pipes. You could also put a vacuum breaker on the line just after the heater outlet to prevent a vacuum from being created.
You may also have this issue with the return pipes in the ground. If the heater was running long enough and soil around the pipe is not fully supporting the pipe it may happen too.
I believe PVC is rated for 140°F but I think it gets pretty soft at that temp and it's gets de-rated quite a bit. CPVC would be much better. DESIGN & ENGINEERING DATA - Charlotte Pipe
You may also have this issue with the return pipes in the ground. If the heater was running long enough and soil around the pipe is not fully supporting the pipe it may happen too.
I believe PVC is rated for 140°F but I think it gets pretty soft at that temp and it's gets de-rated quite a bit. CPVC would be much better. DESIGN & ENGINEERING DATA - Charlotte Pipe
Thank you for your reply. The heater was not working at all. Actually it didn't work this year yet. I'm sure it was off. I have the connection on first phot like this for years and nothing like this happened before. I'm planning to replace the flex pipes with rigid one, but I saw an old thread had the same issue. I like the idea of adding vacuum breaker. Is it the same function as check valve that I installed in the second photo (at the filter line out to heater) to prevent such thing, but it also happened.
The heater was almost definitely on at some point.
Pipes don't just collapse like that unless they get very hot.
- May 23, 2015
- 24,463
- Pool Size
- 16000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Pentair Intellichlor IC-60
Yup. That’s overheated water damage. You need to check your heater function … it’s turning on without you knowing it which means some of the interlocks that would normally protect you from that situation are not working. In fact, given how odd the situation is, you would be well advised to cut all power to the heater and turn the gas off so that it cannot run. Then you can bring in a service person to check the heater top to bottom.
The person who discovered that, was the gas tech came to fix my heater because it is not turning on. That's why I'm positive there was no hot water in the system at all.
I disagree.
There was almost definitely hot water in the pipes.
They don't just collapse like that unless they are very hot.
- May 23, 2015
- 24,463
- Pool Size
- 16000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Pentair Intellichlor IC-60
Were you there when the technician “discovered” that and shown the pipes right away or was the tech there for a bit and then he showed you the damage?
It’s not hard to bypass the interlocks on a heater to get it to fire up when no water is flowing. Sometimes techs do that to check of the gas pressure is correct. If you fire it for too long without flow then the hot water sits in the exchanger for a while. Then the hot water hits the pipes without the pump running and they go soft. Then someone turns on the pump and the force is too much and the pipes collapse.
I’m not saying that is exactly what happened but unless the tech showed you that damage right away as soon as he arrived, it’s conceivable he screwed up and then hid his mistake by lying to you.
That is hot water damage, period. It either happened before or after the tech worked on the heater.
It’s not hard to bypass the interlocks on a heater to get it to fire up when no water is flowing. Sometimes techs do that to check of the gas pressure is correct. If you fire it for too long without flow then the hot water sits in the exchanger for a while. Then the hot water hits the pipes without the pump running and they go soft. Then someone turns on the pump and the force is too much and the pipes collapse.
I’m not saying that is exactly what happened but unless the tech showed you that damage right away as soon as he arrived, it’s conceivable he screwed up and then hid his mistake by lying to you.
That is hot water damage, period. It either happened before or after the tech worked on the heater.
Even if you could pull a perfect vacuum, the pipes are not going to collapse like that unless they are hot.
Also, note that the pipes from the pump to the filter did not collapse.
The heater came on and caused the pipes to collapse due to no flow or low flow.
Unless you were standing right there watching the pipes collapse and observing the heater to be definitely off, you don’t know that the heater did not come on.
What is the elevation of the system relative to the pool?
Also, note that the pipes from the pump to the filter did not collapse.
The heater came on and caused the pipes to collapse due to no flow or low flow.
Unless you were standing right there watching the pipes collapse and observing the heater to be definitely off, you don’t know that the heater did not come on.
What is the elevation of the system relative to the pool?
I was there. I took him to the heater and he noticed it right away and started to argue that is the cause my heater was not working. That's why I'm positive there was no hot water at all. The temperature outside was about 20c, so no way the water was hot or even warm. There is may be a suction as Bill1974 mentioned. Even there was a suction collapsed the old pipes, I don't think it was able to collapse the pipes at second time. I would like to mention that, there was no new equipment or modifications to the system at all. I'm the only one who is taking care of the pool and turn the pump on and off.
The heater was broken and cannot turn on, that's why I asked a gas tech to fix it. Pump, filter and heater are about 4' above the pool level
I'm positive that there was hot water.
The gas person probably got the heater to fire.
Were you watching the tech the entire time?
Why are you sure that it cannot turn on?
Were the gas and electric going to the heater turned off at the time?
Sounds like you have a faulty keypad or board that’s turning on the heater by itself. Had this happen once, the strange thing is whenever I walked by it, it fired up. It was also a Lxi. James is right the heater was on at some point. I would turn the gas valve or breaker off for the time being.
Because the all of gas nozzles were blocked by spiders. I just knew that from the technician. So It cannot be on by itself. the gas and electric going to heater were turned on.
I will do the for the sake of experiment, after I replace the pipes for second time. At the moment, I turned off the power from the whole system to avoid the pump from turning on accidently
It seems that everyone is convinced that the heater was on. It is for my benefit not to hide or saying not correct facts. So I assume my current situation has no solution as per my input.
Now, if it turned on by itself this time. Eventually, I will turn it on after fixing the damaged pipes. How I can avoid such thing from happening again other than turning the heater off before the pump with enough time to cool? What causes the vacuum? I appreciate the support from everyone
It seems that everyone is convinced that the heater was on. It is for my benefit not to hide or saying not correct facts. So I assume my current situation has no solution as per my input.
Now, if it turned on by itself this time. Eventually, I will turn it on after fixing the damaged pipes. How I can avoid such thing from happening again other than turning the heater off before the pump with enough time to cool? What causes the vacuum? I appreciate the support from everyone