Mixing a hot water loop with one-pipe steam

ccstelmo · October 19

Someone told me a few years back that I think too much and should take a break. BUT ….

I'm definitely a newbie when it comes to steam but I was wondering what y'all think about the idea of setting a pair of close tees in the Hartford loop (1-1/4") and using a small pump (maybe even a Taco 003), to circulate water into a small heat exchanger, and heating a 200sf mudroom addition. (Three cold R-25 walls totaling 280sf, R-40 roof, unheated crawlspace below, 120sf of insulated windows, Delta T of 90, current boiler at 125K BTU is about 20% oversized).

It's just an idea. The fact is, I COULD extend an old, abandoned radiator loop of the existing steam system over in that direction and heat the mudroom room with steam. I'm just wondering what you all think of the idea. Remember, it's just a mudroom.

ccstelmo

mattmia2 · October 19

good idea, poor execution. you just take hot water out of the boiler and put it back in with some convenient tapings, the closely spaced tees thing wouldn't work. you can circulate boiler water directly in the hot water loop but you need to have the circulator below the water line and can't have auto air vents. you need a bypass to bypass a little return water in to the circulator so it is a bit cooler and doesn't cavitate. it will work better with a 3 piece circulator than a wet rotor because of the muck that tends to be in steam boiler water.

you could isolate it by using a tankless coil in the boiler. if you use a heat exchanger a shell and tube or small indirect will work better than a brazed plate hx.

Jamie Hall · October 19

Every once in a while some scheme for using the heat in the condensate comes up — and yours is a rather good one, as they go. Problem is… there is verry little heat to be had. Nothing like enough to heat even a very short loop.

As @mattmia2 says there, the best approach — and there are a number of ways to execute it — is to pipe a hot water loop directly off the boiler.

ethicalpaul · October 19

here is all the info you could ever need. I added two hot water radiant floor loops to my steam boiler with these instructions and I’m just a homeowner

https://www.heatinghelp.com/systems-help-center/how-to-run-a-hot-water-zone-off-a-steam-boiler/

EdTheHeaterMan · October 19

https://heatinghelp.com/systems-help-center/how-to-run-a-hot-water-zone-off-a-steam-boiler/

Here are several ideas of what you want to do

Mixing a hot water loop with one-pipe steam

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