Steam Vent Sizes for Unique Configuration

scott1234

Weil-Mclain P-SGO-3 Series 3 - Oil-Fired Steam Boiler. 2 story house. Boiler in basement. Thermostat first floor. House is approximately 20' x 25' and the 2 floors are each 9' high.

I don't spend a lot of time on the first floor, so the three radiators there are all shut off. Does effectively removing an entire floor from the equation make it so that I should treat my second floor like a first floor when sizing the vents for the four radiators there?

EBEBRATT-Ed

Seems to me if you shut the radiation off on the first floor and the thermostat is on the first floor you will have high heating bills.

If you don't use the first floor I would shut the radiation (or some of it) off and move the thermostat to the second floor.

With steam you want to vent the mains as fast as possible and the radiation more slowly. But you should not restrict the venting in the room the thermostat is in

ethicalpaul

Yeah…don't you notice that the boiler keeps running long after the upstairs is warm enough?

To answer your question, I guess I'd start with Gorton/Maid O Mist size #6 on them and see how that goes. There's no reason I can think of to put smaller ones up there. This is often counter to the norm. For example, I have smaller ones on my upstairs radiators because the upstairs gets a lot of "free" heat from the downstairs, so the upstairs radiators don't have to do much.

Jamie Hall

I have two concerns here: first, how are you "shutting off" the downstairs radiators? If this is a one pipe system — which I imagine it is, since you mention vents — that must NOT be done by closing the inlet valves. That is just asking for trouble. Instead, turn the vents upside down. That will effectively stop them from heating, but won't risk accumulating condensate in the radiators.

Second, your boiler is now at least twice as big as it needs to be. Probably three times as big. The additional cycling is enough so that it will begin to waste fuel…

ethicalpaul

Oversized boilers are not optimal, for sure, 100% agree. But if a pressure control cuts back in before steam pressure is lost in the system, what is the wasted fuel? (I admit I'm thinking about gas atmospheric here. Is it different for oil-fired like this person has?)

And surely there is less wasted fuel than unnecessarily heating the downstairs just to avoid short-cycling, no?

No one would advise him to tear out a working boiler to avoid short-cycling, at least not that I've ever heard…

bburd

Depending on the climate, shutting off all rads on the first floor may risk freezing the water pipes. Fixing that will more than wipe out any savings in fuel. If it were my house I would monitor the temperature in the cooler areas very carefully.

Big Ed_4

Remove the vents on the radiators that you don't want to heat . Plug the hole with an 1/8" Brass plug and leave the valves open ….

Intall a wireless thermostat and bring it upstairs …