Turning off a hot radiator

wendi

My apartment has a steam radiator, that works very well. Heat is provided from 5AM - 11AM, and 5PM - 11PM. Several times, my apartment manager has warned me not to turn off the radiator when it is hot. This is a problem, since if I turn the radiator on at say, 6 PM, by 9 PM my apartment will be warm and toasty, but I can't shut the radiator until 11PM, resulting in my apartment being too hot. I'll confess to occasionally shutting the radiator while it is hot, without seeming to cause any problems, but I then worry that I'm damaging something. Is my manager telling me the truth, and if so, what is the problem with shutting a hot radiator?

BobC

Is there a sensor on the radiator that might be controlling the system? If there is you could try draping a heavy blanket over the radiator, that would halt convection and reduce the heat output considerably.

The other possibility is you have a thermostat or heat sensor that is controlling the system.

Bob

Mark N

Last year there was a thread about a radiator cover that has an integrated fan and thermostat to control heat output. This apartment would be a perfect application for it.

Mark N

Also when you shut of a hot rad you most likely will trap condensate in the rad. When you turn it back on it most likely will cause water hammer when it encounters the steam entering the rad.

KC_Jones

Mark N said:

Also when you shut of a hot rad you most likely will trap condensate in the rad. When you turn it back on it most likely will cause water hammer when it encounters the steam entering the rad.

In addition this could rob a small amount of condensate from returning to the boiler. If everyone did something like this couldn't the boiler then possibly go off on low water? The valve on the radiator IF it's one pipe system is not designed to control heat. It should be left open all the time. If it's a 2 pipe system that isn't always the case. This sounds more like an overall control/balance issue. Is your apartment manager a pretty decent person? Would they address issues like this? I agree with Bob generally it's easier to just do something on your own. The blanket trick can work pretty well just cover a varying amount of the radiator until you get it right.

Abracadabra

Mark N said:

Last year there was a thread about a radiator cover that has an integrated fan and thermostat to control heat output. This apartment would be a perfect application for it.

I think there was an article or blog that @DanHolohan‌ posted about this "invention". I haven't heard much about it though..

David Nadle

wendi, Do your neighbors in the same building also complain about being too hot? Do you see windows open a lot in the winter?

There are things your landlord could do that would help everyone in the building and save money. I don't have any advice on how to convince your landlord to help you... Perhaps tell them it's too hot too often and point them to this site for free advice.

If your apartment radiator has just one pipe connected to it, and an air vent on the opposite side of the valve you've been turning, there is something you can add to the radiator to automatically "turn it off" whenever the room is too warm. It's called a thermostatic radiator valve (TRV). There's lots of information in the archives here about what to buy and how to install it. Assuming you have one-pipe steam, it's low risk and not a permanent change to the radiator. With proper motivation, whoever maintains the air vents now can probably install it for you.

BTW if you do touch that radiator valve in the future, make sure it's always all the way open or all the way shut.

Waterbury Steam

Assuming this is a one pipe system, you can always turn off a radiator by turning the air vent upside down. That way you won't trap any condensate.

wendi

Thanks to all who commented. Let me elaborate... My radiator is a single pipe system; no control or thermostat in my apartment; I am one of twelve apartments in the building. My apartment manager is difficult to deal with, so I'd prefer not to involve him. I live in San Francisco, which has very variable weather. My windows face west, so on clear days, I get a lot of afternoon sun. Hence, some days, even in winter, I don't need any heat at all. Other days, especially when cloudy and cold, I look forward to the heat coming on at 5PM. Usually, the situation is somewhere in between. Ideally, I would like to be able to open the value (fully, of course) when I want heat, and then once the apartment is warm, shut the valve. I've done this occasionally, without any obvious ill effects, but because of my manager's admonishments, I worry that I might be causing damage that will lead to me having big trouble with the manager. So... my questions are: Can I do it routinely, and if not, why? Thanks again.

David Nadle

You really shouldn't, for the reasons given above. If you close the valve when the radiator is hot, you trap water inside the radiator. If you open the valve again later while the system is heating you may cause water hammer. Not for nothing but maybe he's difficult to deal with because he's asked you several times not to do it? If it caused no ill effects, how did the apartment manager know you had touched the valve?

As Waterbury Steam wrote, you could get yourself a set of Chanellock pliers and carefully twist the air vent upside down. That would keep steam from entering the radiator without trapping anything inside. Or you could look into replacing that vent with a TRV and be able to dial in a maximum temperature for the room.

wendi

Does turning the vent upside down to shut the heat work once the radiator is hot? It seems to me that it would only prevent the heat from starting, but not shut it once it got going.

Jamie Hall

Actually, oddly it does work to shut off the heat once the radiator is hot, although not as quickly as one might want. The trick is to figure out how far in advance!

Fred

You really don't want to turn the vent upside down on a regular basis. The tapping on old radiators just aren't made for those vents and that port to be used as a means of turning a radiator on and off. That's what the valve on the supply pipe is there for. You can not do any damage by using that valve but to ensure condensed water is returned to the boiler, you should shut that valve off before the scheduled run cycles so that steam can't get in the radiator or, if you want heat, open that valve and leave it open for a half hour after the heat cycle is complete. Of course you could put a TRV on the radiator but it will be obvious to the landlord that you tampered with his heating system. You might give him some literature on how TRV's work and offer to buy one if he'd allow you to put it on.

Abracadabra

Jamie Hall said:

Actually, oddly it does work to shut off the heat once the radiator is hot, although not as quickly as one might want. The trick is to figure out how far in advance!

Jaime,

I'd think that once you have steam in the radiator, flipping the vent won't work because the condensing steam causes a vacuum sucking more new steam into the radiator. No?

SWEI

The radiator valve, BTW, should be fully open or fully closed on a one-pipe system.

Would a TRV be helpful here?

nicholas bonham-carter

I am sure this system, as badly maintained as it is, is probably short-cycling, and so therefore a vent turning will not cause the radiator to continue to heat beyond that point of turning.
Don't mention to anyone your method of heat control.--NBC

SWEI

http://www.supplyhouse.com/Honeywell-V2043HSL10-1-8-One-Pipe-Steam-Thermostatic-Radiator-valve-includes-air-vent
http://www.supplyhouse.com/Danfoss-013G0140-Thermostatic-Rad-Valve-w-Vac-Breaker-1-Pipe-Steam-5551000-p

DanHolohan

Abracadabra said:

Mark N said:

Last year there was a thread about a radiator cover that has an integrated fan and thermostat to control heat output. This apartment would be a perfect application for it.

I think there was an article or blog that @DanHolohan‌ posted about this "invention". I haven't heard much about it though..

Yes, you're thinking about Radiator Labs.

Bug512

We have this on our radiators on our second floor bedrooms. This limits the venting to air out of the radiator thus will limit the amount of steam in.

Honeywell Thermostatic Valve

Then this device is attached to the above and senses the room temperature

Google were to find them but Amazon also has them.

Link

Link

KC_Jones

Does the Honeywell have the vacuum breaker? I thought that needed to be added to get proper functionality? Someone can correct me if I am wrong on that one. I know the Danfoss valves have the vacuum breaker built in, but I didn't think the Honeywell ones did? The vacuum lets the air back in when the condensate forms otherwise a vacuum is created in the radiator and it will just let more steam in even with the vent closed.

Bug512

My thought would be, if the vent (thermostat) was not open because the room temperature was satisfied then it's a non issue since steam did not enter the radiator.
If the vent (thermostat) was open to let steam in then the condensate (droplets) will follow gravity even if there was a vacuum created.

I can't see how you can draw more steam into a radiator then what it can physically handle. Once the vent gets hot it closes.

Maybe over the long weekend I will bring my mamometer home and attach it to one of the radiators and see.

KC_Jones

When you make steam it expands at a rate of 1700:1 when you condense steam it collapses at the same rate. So if you have a TRV on the vent side and it is satisfied and closes the only opening left in the rad is the supply pipe. If the steam that is already present collapses then what happens if there is no vacuum breaker on the vent side? It will naturally draw more steam into the radiator since it can't pull from any other place. This is why the TRV needs the vacuum breaker. I thought I had read the Honeywell didn't have this feature, but I couldn't remember for sure. I know Danfoss does and not sure about any others on the market.

Bug512

Well, I guess we could research that some more but to the OP who wants to "control" their radiators I can cay that my post above with the links control the heat very well in our bedrooms.

So for some searching.

Bug512

Link to PDF

Search the document for "vacuum" looks like "Ensure vacuum breakers are installed on the steam
system risers. If vacuum breakers (that open to the
atmosphere at zero psig) are not installed, the system
can develop a negative pressure and pull steam back
into the radiators on resumption of steam."

So you are correct, we need vacuum breakers !

KC_Jones

I knew I had read that somewhere. The Danfoss brand valves come with the vacuum breaker. I have 2 of the Danfoss in my house. I only wanted to present it as info to the OP. As long as they work for you and you are happy that's all that really matters!

Bug512

Maybe this might be a better choice?

Link

Another link

Or we could place a vacuum breaker between the valve assembly and radiator.

Learned something new today.. thanks

David Nadle

supplyhouse.com carries the Danfoss TRV. The vacuum breaker is built into the 1PS adapter. Works very well for me.

Bug512

Do you have a link ?

David Nadle

supplyhouse.com/Danfoss-Thermostatic-Radiator-Valves-789000

You need a 013G0140 1PS adapter, a 013G8250 or equivalent operator with remote sensor, and a good straight vent, like a Gorton #5 or #6.

My only concern for wendi in this scenario is her mention of the heat being timed. If the boiler really runs for 6 hours without shutting off to let air back into the system, a TRV may not be effective.

KC_Jones

David Nadle said:

supplyhouse.com/Danfoss-Thermostatic-Radiator-Valves-789000

You need a 013G0140 1PS adapter, a 013G8250 or equivalent operator with remote sensor, and a good straight vent, like a Gorton #5 or #6.

My only concern for wendi in this scenario is her mention of the heat being timed. If the boiler really runs for 6 hours without shutting off to let air back into the system, a TRV may not be effective.

There was an article about this exact situation posted recently, but I can't find it. The boiler needs to cycle, the TRV needs the pressure to drop to 0 in order to open back up.