Should inlet pipe be warm

[Buffapool]

After my pump and has been off for a while the PVC pipe from my filter to my heater inlet gets noticeably warm to the touch even after the heater has been manually switched off for hours. The pilot is on that side of the heater with the inlet and outlet but the outlet pipe doesn't seem to be any warmer than the rest of the plumbing. Is this normal and I just never noticed or a sign of some issue that needs to be addressed? If so, any suggestions on what it might be?

I searched and didn't see anything similar and the pipe hasn't collapsed/melted (yet) like some other posts.

 

[ajw22]

Welcome to TFP.

What model heater are we discussing?

Post pics of your equipment pad.

 

[Buffapool]

Thanks. It's Raypak 266A. The manual mentions that the outlet should be warmer than the inlet when running but I didn't see anything about temperatures when everything (heater and pump) is off.

 

[ajw22]

You have a laser thermometer you can point at the pipes and get actual temperatures?

 

[Buffapool]

When the pump was running and the heater had been off for over a day both pipes were 80 degrees. About an hour after the pump shut off the inlet was 100 degrees and the outlet was 82. The difference felt bigger to my touch the other day though I didn't think to use the infrared thermometer on it to get #s then. Is that normal and I should go back to not feeling the pipes or could it indicate an issue I should try to fix before it causes some damage.

 

[1poolman1]

When the pump was running and the heater had been off for over a day both pipes were 80 degrees. About an hour after the pump shut off the inlet was 100 degrees and the outlet was 82. The difference felt bigger to my touch the other day though I didn't think to use the infrared thermometer on it to get #s then. Is that normal and I should go back to not feeling the pipes or could it indicate an issue I should try to fix before it causes some damage.

When the heater is off does the pump shut off at the same time? Those older heaters retained a lot of heat in the refractory material and that is transferred to the water in the heat exchanger when it isn't moving and for some reason that heat always seems to go to the inlet side of the plumbing more than the outlet. It has almost always been that side of the plumbing I have had to replace when there is heat damage on a customer's system.
Do you cool the heater before turning the pump off? That residual heat, that you paid for, can just go into the pool by turning the heater off and letting the pump run for at least half an hour on a heater of that age.
A temperature of 100 isn't going to hurt anything.

 

[Buffapool]

Thanks!