Thread: Infloor System with Water Heater

There is an infloor heat system that is using a Bradford White water heater for the heat source. All is installed well, and there is a pressure reducing valve as well as an expansion tank. The original TPR valve is present, which is a 150 PSI, 210 F valve. Should this valve be replaced with a 30 PSI pressure relief valve? Or, as an alternative, should there be an additional 30 PSI relief valve installed on the system, and the original TPR valve left alone? My thinking was that with the pressure reduced to 12 PSI input, the 150 PSI seems way too high to be of much use.

I really should put together a sheet on this but I just don't seem to have the time. This is something that comes up too often these days
- some water tanks are rated for this type of use others are not; looked into this a couple months ago, can't remember brands, seems to come down to warranty or no warranty
- reducing the TPR PSI doesn't seem like a good idea since I think the tank will be operating on typical pressures; pressure will likely vary depending on set up; I should have a better answer but don't right now
- you don't mention a pump; this should have a small Taco or B&G recirc pump
- is the floor tubing legit or some BS tubing
- could you see how tubing was installed? in joist cavities or in subfloor? is there nail protection
- also important; did they install an auto air bleeder or way to bleed manually? without bleeding capability this will be a problem
- should have also installed a temp and pressure gauge
- drain cock on water line to be able to drain if necessary
I'm sure I'm missing something but need to get dinner started

Originally Posted by Jim Robinson

There is an infloor heat system that is using a Bradford White water heater for the heat source. All is installed well, and there is a pressure reducing valve as well as an expansion tank. The original TPR valve is present, which is a 150 PSI, 210 F valve. Should this valve be replaced with a 30 PSI pressure relief valve? Or, as an alternative, should there be an additional 30 PSI relief valve installed on the system, and the original TPR valve left alone? My thinking was that with the pressure reduced to 12 PSI input, the 150 PSI seems way too high to be of much use.

I guess my first question would be... Why would you want to replace the TPR valve? You need to go with what the water heater manufacturer requires. Keep in mind that the TPR valve does not really control the pressure in the system. It is to keep the tank from blowing up if it malfunctions.

All of the under floor heating systems that I see being installed now are made with PEX and for the most part they are part of the potable water supply, a tempering valve helps to control the water temp in the underfloor part of the system.

Originally Posted by Scott Patterson

I guess my first question would be... Why would you want to replace the TPR valve? You need to go with what the water heater manufacturer requires. Keep in mind that the TPR valve does not really control the pressure in the system. It is to keep the tank from blowing up if it malfunctions.

All of the under floor heating systems that I see being installed now are made with PEX and for the most part they are part of the potable water supply, a tempering valve helps to control the water temp in the underfloor part of the system.

Well, my thoughts are that the pressure is cut to 12 PSI coming into the system, so the TPR set for 150 will never go off. I guess the easiest thing to do if you wanted to would be to add an additional RV set for 30 PSI on the system, and leave the TPR on the water heater alone. HePEx would be typical here, and it looks like it is rated for 73 deg F at 160 PSI. That's kind of where I was coming from on the lower pressure RV. If the water heater were to fail, you could exceed the PEX ratings.

This was a separate system, all was fine with the rest of it.