Relief Valve Needed ???

Brian_18

Do I need to install a pressure relief, and traditional boiler feed regulator on an isolated zone heated from a HX? I have a 900 sq ft attached garage, which when I built it always planned to heat it with radiant. (tube loops already in slab). The heat load of the garage is not very high due to extensive insulation, and my desire to only keep it warm enough to keep the cars melted and dry, maybe 40 – 45 degrees. I’m thinking of isolating the garage from my system with a HX, which will receive it’s heat from a return of an existing radiant area. My thinking is that the existing radiant area is very near the garage, and it normally runs at a 5 degree delta T, so why not use some of that heat to do the garage (yes acording to my calculations, the existing radiant zone has sufficient flow, and can handle the extra load of the garage) It also will allow me to fill the garage zone with glycol if I so decide. It seems that I can fill the zone from the purge connections, and let the expansion tank & spirovent take over from there. Comments?

Brad White

YES

Any isolated body of water in a closed water system needs a relief valve and expansion means by ASME code.

Brian_18

Thanks Brad nice to have a place to ask

Thanks Brad nice to have a place to ask these questions. I'll add a relief valve What's your opinion on the need for a fill/make-up regulator-valve ?

Brad White

Mixed bag on automatic filling

I am getting away from automatic filling where a local inspector allows. If you had a leak, even a small one over time, with automatic fill (and absent a good accurate feedwater meter) you would never know it or would accept a minor ongoing leak and fill situation as normal. It is not normal and would cause untold corrosion. In glycol systems it will dilute it to the point of false security.

What we specify in our office on glycol systems is an automatic fill pump with a reservoir. Neptune on larger systems, Axiom on smaller systems, even houses and even houses without glycol.

Where automatic filling is required, we install a flow alarm with 30 second delay so that a leak can be alarmed but false alarms during routine filling can be avoided.

Personally, I say, seal the system and watch a defined small reservoir or cold pressure for fluid loss. Watching for pressure loss in an operating system is useless and can mask a legitimate leak.

That's my $0.02 anyway!

Brian_18

your $0.02 is priceless to me

Brad: Thanks for your guidance & expertise !!