Radiant System Expansion Tank

danh123

Hello,
I went down to my basement this morning and the expansion tank had burst and leaked water everywhere. We replaced the tank with a similar one. I noticed it says for non potable water and think we may have installed the wrong tank. My system is a buderus oil boiler and one water tank for domestic hot water and radiant heat. Do I need a tank for potable water? I think the previous tank may have been non potable also and that is why it didn't last long. It said installed 2014.

Thank you.

JUGHNE

If that is the only expansion tank in the basement then it is for the boiler. It does not need to be rated for potable water. Boiler water is not changed, should not have fresh water introduced on a regular basis.

If your DHW system requires an expansion tank then that separate tank needs to be rated for potable water as fresh water is always used for your DHW.

Jamie Hall

Are the potable water system and the radiant heat system hooked together? That's what it sounds like from your description.

I sincerely hope that that isn't true. If it isn't true, then the non-potable tank for the radiant is OK, and the radiant system should be running at perhaps 15 psi or so (check your gauge).

If it is true, then your radiant is running at whatever your domestic water pressure is -- on a well, for instance, typically 20 to 40 psi or 30 to 50, and if on city water it could be much higher. And you do need a tank rated for potable water.

You should seriously consider repiping, though, to separate the two systems.

danh123

It is the only expansion tank in the basement but I think the systems are linked. I have not been able to find someone in my area yet that is familiar with radiant heat and can explain the whole system to me and how everything works. I will post a picture tomorrow.

Boon

@danh123 Did you get it figured out?