Collapsed pvc into and out of heater
- Thread starter teckademic
- Start date
The heater must of kicked on somehow and the pump shut down, causing the boiling hot water in the heat exchanger to melt/warp pipes.
- Jul 21, 2013
- 65,789
- Pool Size
- 35000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Pentair Intellichlor IC-60
What model heater?
Is the heater controlled by any automation?
The heater ran at some point to melt those pipes.
Is the heater controlled by any automation?
The heater ran at some point to melt those pipes.
Raypak R406A NG heater.
No automation. It’s on the same timer as the pump and we just manually turn it on when we’re going to use it.
Can’t think of a time we would of had the heater on and not the pump, maybe pump was on but clogged. Guess I’ll be more careful and make sure heater is always off.
Thanks for the info everyone.
- Jul 21, 2013
- 65,789
- Pool Size
- 35000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Pentair Intellichlor IC-60
The left pipe is the inlet and the right pipe is the outlet.
The left inlet pipe looks more collapsed then the outlet pipe.
If the pipe would have overheated with the pump running the inlet pipe would not overheat and only the outlet pipe would collapse. The heater has a pressure switch. With your pump off the heater can still have pressure in its pipes and allow the heater to run. With no water flowing through it the heater will push hot water into both pipes, heating them until they are pliable and collapse.
Post pics of the timer box wiring and how the pump and heater are controlled by it.
Let's see if @JamesW has other thoughts.
The left inlet pipe looks more collapsed then the outlet pipe.
If the pipe would have overheated with the pump running the inlet pipe would not overheat and only the outlet pipe would collapse. The heater has a pressure switch. With your pump off the heater can still have pressure in its pipes and allow the heater to run. With no water flowing through it the heater will push hot water into both pipes, heating them until they are pliable and collapse.
Post pics of the timer box wiring and how the pump and heater are controlled by it.
Let's see if @JamesW has other thoughts.
MSchutzer
Silver Supporter
I would suggest that you might have a faulty pressure sensing switch in the heater. The pressure switch keeps the heater from firing if the pressure is to low (like when the pump is off).
If the heater was firing when the pump was shut off it should have shut down as soon as the pump pressure dropped. Yes the heat exchanger will still be hot, but if it stops firing when the flow stops I doubt that the residual heat is enough to heat the water hot enough to cause the pipes to melt, especially both the input and output pipes.
Both inlet and outlet pipes are collapsing which means water in excess of 160 degrees F sat in those pipes for an extended period.
To test the pressure switch you can turn the heater on with the pump off. The heater should not fire. If the heater tries to fire then turn it off immediately and replace the pressure sensing switch.
If the heater was firing when the pump was shut off it should have shut down as soon as the pump pressure dropped. Yes the heat exchanger will still be hot, but if it stops firing when the flow stops I doubt that the residual heat is enough to heat the water hot enough to cause the pipes to melt, especially both the input and output pipes.
Both inlet and outlet pipes are collapsing which means water in excess of 160 degrees F sat in those pipes for an extended period.
To test the pressure switch you can turn the heater on with the pump off. The heater should not fire. If the heater tries to fire then turn it off immediately and replace the pressure sensing switch.
Last edited:
Good advice posted above. Heated water radiates to both sides of the heater thru convection ive seen this happen before. A good extra step is shutting the gas valve off when not in use if your manually turning heater on and off anyway....your already standing there
Does the heater have an external bypass?
What is the heater elevation in relation to the pool?
Can you post more pictures of everything?
I would put a flow switch and not a pressure switch.
I would have a cooldown period of about 5 minutes from heater shutoff until pump shutoff.
What is the heater elevation in relation to the pool?
Can you post more pictures of everything?
I would put a flow switch and not a pressure switch.
I would have a cooldown period of about 5 minutes from heater shutoff until pump shutoff.
Here is the wiring. Bottom right wires are the heater, bottom left wires are the pump and far left is the SWG. Everything turns on by the timer. We use the manual switch on the heater to turn it on and off, but it doesn't get power unless the timer is on.
Attachments
Thanks. I will try to remember to get everyone to do that going forward. Would the temp sensor not cause the heater to stop heating once it reaches 90 and just slowly cool down and on, or does it get that hot sitting there?
It does not have an external bypass and I would say its about 4 feet higher than the pool surface.
Here is the setup of the pool piping.
Attachments
Most likely, the heater is running when the pump turns off.
This points to possibly a bad pressure switch.
Maybe someone adjusted it to make it work with the height difference.
This overheats the PVC and the suction from being above the pool causes the pipes to collapse.
I would put a flow switch and not a pressure switch.
I would have a cooldown period of about 5 minutes from heater shutoff until pump shutoff.
This points to possibly a bad pressure switch.
Maybe someone adjusted it to make it work with the height difference.
This overheats the PVC and the suction from being above the pool causes the pipes to collapse.
I would put a flow switch and not a pressure switch.
I would have a cooldown period of about 5 minutes from heater shutoff until pump shutoff.
- Jul 21, 2013
- 65,789
- Pool Size
- 35000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Pentair Intellichlor IC-60
It looks like an Intermatic timer is being used but the complete timer is not in the pic. The 156T4042A Heater Control Switch Kit should be added to the timer.
Timers - Further Reading
www.troublefreepool.com
The T101 or 104 timers can have an optional 156T4042A Heater Control Switch Kit[2] that will open the fireman's switch on the heater 20 minutes before the timer, usually controlling the filter pump, will shut off. The heater control will prevent the heater from operating EXCEPT when the Time Switch contacts are closed (automatically or manually).
Models that have the 24-Hour Mechanical Time Switch in Enclosure with Pool Heater Protection are:
- T101P201 - 120V SPST plastic enclosure with Pool Heater Protection
- T101R201 - 120V SPST metal enclosure with Pool Heater Protection
- T104P201 - 240V DPST plastic enclosure with Pool Heater Protection
- T104R201 - 240V DPST metal enclosure with Pool Heater Protection
The pump is IntelliFlo and it has its own timer, which might be part of the problem.
- Jul 21, 2013
- 65,789
- Pool Size
- 35000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Pentair Intellichlor IC-60
sktn77a
Gold Supporter
The pump should run for at least 5 min after the heater switches off or the collected heat in the heater will soften PVC pipes at the inlet and outlet.
Ask me how I know................
Ask me how I know................
True but that still puts blame on the pressure sensor switch, correct?
Probably.
I would put a flow switch and not a pressure switch.
I would have a cooldown period of about 5 minutes from heater shutoff until pump shutoff.
The usual cause for this is the pressure switch, yes, allowing the heater to continue to fire at low or no waterflow. Try the test MSchutzer described. As they are not expensive I would replace the pressure switch and then do not make any adjustments to it. I have seen people adjust the switch to compensate for the lower waterflow of a VSP and this, too, can cause the problem you see. The internal temperature of the heater in the firebox is right at 2000 degrees according to manufactures. That heat has to go somewhere and good waterflow is the answer or there are problems
While a pressure switch might be a good idea, modifying the safety system of a heater (of which the pressure switch is a part) is a very good way to accept any liability that may be incurred if there was a catastrophic failure. (Think insurance issues.) When heaters have this type of failure it is not a pretty site, I've seen it a couple of times over the years, including the lose of a garage with over a million dollars of classic cars.
The recommendation to cool the heater after use is a very good one, all heater manufacturers recommend it as well. Turn the heater off for at least 5 minutes before the pump. DO NOT change the valve to draw water from the cold pool if you have been using the spa. The thermal shock can cause damage to the heat exchanger (heater school 101).
Definitely get a flow switch on that. Adding the heater control as Allen suggested is great advice
