closing off steam radiators not in use

vr608

Jamie Hall said:

vr608 said:

vr608 said:

(operational state of the shutoff valve aside)?

I guess my question is, assuming you had a brand new shutoff valve, is there a difference between closing the valve and mounting the vent upside down from the perspective of the boiler?

No. But this assumes that the brand new shutoff valve closes steam tight, and stays that way, every time. One can buy valves which do that. One can also buy, for a lot less money, valves which don't...

Understood, thanks. So for all intents and purposes the boiler will still be oversized for the radiation if either approach is used (closed supply or upside-down vent), correct?

vaporvac

yes. Is your house warm? I just can't imagine shutting off half the rads; wouldn't the heat just migrate to the cold with nothing gained?

Jamie Hall

vaporvac said:

yes. Is your house warm? I just can't imagine shutting off half the rads; wouldn't the heat just migrate to the cold with nothing gained?

You know, folks often don't think about that! But there is an added dimension which gets overlooked: not only does warmer, lived in air tend to migrate towards the colder rooms, but it takes its humidity with it. In some cases (I've seen it) this will condense in the colder rooms, and damages plaster (if you have it) as well as raising havoc with things like books, paintings, fine furniture, pianos... one can buy a lot of heat for the cost of restoring such things!

KC_Jones

What if you shut off rooms that just happen to have some plumbing running through the walls? People think they know where the plumbing is, but you would be surprised. Also how many times have we seen people posting about having the heating pipes freeze, if those can freeze anything can freeze. I just can't put any logic to shutting down radiators in a house. A TRV to cut back on the heat yes, but completely shutting them down has zero value IMHO.

Fred

I agree with what Jamie said. If the valve seals , either option is essentially the same

FXProglJr

vr608 said:

Jamie Hall said:

vr608 said:

ChicagoCooperator said:

vaporvac said:

Also with one pipe, turn the valve upside-down as opposed to off.

The vent, not the valve (in case that wasn't obvious).

Here's a question; I'm guessing by turning the vent upside down the boiler "sees" the same load? I thought steam was denser than air? Or is the load simply based on pressure?

The density of steam -- and air -- depends on the temperature. Actually, dry steam is less dense. However it doesn't really matter. By turning the vent upside down -- which keeps it from venting -- the boiler will see a smaller load, as the radiator(s) with those vents won't be able to vent the air, and hence won't be able to accept much steam.

Keep your pressure low!!! The cutout device on the boiler should turn it off when and if the pressure reaches 1.5 psi, no more than that.

Jamie, so what is the difference between closing the shutoff valve and mounting the vent upside down (operational state of the shutoff valve aside)?

well.....turning the vent upside down will certainly prevent it from venting and the radiator will not get very hot, but, with the vent upside down, will it break the vacume when the heating cycle stops?

KC_Jones

If it is closed while running you don't displace any air, you don't need to replace air you didn't remove. Also even if a little steam gets in (which could happen on a long run) the rest of the vents in the system will equalize when the cycle ends.

Fred

The suggestion to turn the vent upside down is also because many, many old valves don't actually close all the way when you turn them off. That lets steam into the radiator and then ptentially blocks condensate from running back down the partially closed valve, causing some hammer.