Hydronic heating supply

Ballyroebuck

Hi - I'm installing a hydronic heating system mainly comprised of a Taco X-Block and DiaNorm radiators.  It's an old house with mainly galvanized pipes however there is a pex pipe coming from the hot water heater.

My question is, can I tap into the hot water pex to supply the hydronic heating system.  Can 120F water damage the RP backflow?  Any other issues using hot water to supply the hydronic heating loop?

STEVEusaPA

for clarification

1. The pex coming from the hot water heater? Is this on the domestic side?  Or is this on an indirect with the pex coming from the boiler.  If it's pex on the domestic, it probably doesnt have an oxygen barrier, so no you shouldnt use it.  Check the writing on it and let us know.

2. When you say 'tap into to supply the hydronic heating system', do you mean for initial fill and make up water13? If so, you could, but piped correctly, after initial fill/purge, then shortly after, you really shouldnt need much make up water. My valve has been closed for 2 years, never added water. Just make sure you have a LWCO installed.

Ballyroebuck

Hydronic heating supply

Thanks Steve - I was asking if I could use a hot water line for the initial fill and make-up water (feeding the RP backflow and presure reducing valve --then off to the radiators) instead of the usual cold water line.



Bob

STEVEusaPA

sure

I don't see why not.

Ballyroebuck

Hydronic Supply

I had to change the supply from the hot water pipe to the cold.  Thermal expansion had the RP constantly dripping.  When changed to use cold water supply the drips ended.