turning off an individual steam radiator

Joseph_4

I have a customer where one room gets extremly hot more than all others. customer wants an easy fix to turn it off completely.( not doing a heat loss calc on room to see if oversized cause she wont buy a new smaller radiator). I tried a varivalve on the closed position still too hot.) The 1 1/4 radiator angle valve seems to be broken so can't shut it off from there. My idea is, but want to know if will work and if are drawbacks, is just to take an 1/8 inch black nipple and cap and remove varivalve air vent and I learned at Dan H's steam seminar " Where air can't get out, Steam can't get in" rule. so shouldn't this work? or any other simple solutions?

Thanks Joe

BobC

Stopping one radiator

Putting in a 1/8" plug should stop that radiator from heating, if it doesn't then there must be a leak in the radiator.



Bob 

Dave in QCA

controlling a "Too Hot" radiator

The varivalve has pretty large venting capacity, even in the slowest position.  Plugging the air vent as you describe will work. Or, you could put a 1/8" pipe plug in the radiator, that will shut it off completely too.  With most air vents, you can turn them 1/2 turn so they are upside down and they will close.  However, the varivalve will not work this way.  You could install a Hoffman 1A and set it at the lowest setting and see if this helps.  Best solution would be a thermostatic valve, http://www.pexsupply.com/Danfoss-013G0140-Thermostatic-Rad-Valve-w-Vac-Breaker-1-Pipe-Steam-5551000-p 

This way the customer could turn the radiator on and off, or adjust the room termperature to suit

Rod

Controlling Over Heating

Hi- The Vari-Valves radiator vents don't shut off. They just have a minimum and maximum position so even on the minimum setting you are going to get heat,



An easy way to turn off a radiator is just turn the radiator vent upside down. This closes the vent.



You might also consider using a TRV (Thermostatic Radiator Valve) which will control the heat in an individual room to the temperature setting you choose. On a 1 Pipe steam system the TRV goes between the radiator and the radiator vent. It's important to get the TRV model made especially for a 1 pipe system. These have a vacuum vent which allows air to enter the radiator. I've attached a data sheet on 1 pipe TRVs.  Putting a TRV on a radiator adds cost and you still need a radiator vent but the added comfort and flexibility is well worth it. (One warning- Don't use a TRV in the same room as the boiler thermostat as it confuses the thermostat)  Have my radiators have TRVs .They stop the upstairs from over heating and also I can save fuel by lowering the heat in rooms I don't use.

- Rod

jpf321

not pretty but might work...

another thing you could try is putting an 1/8" ball valve inline between radiator and air vent. just keep in mind that if the valve is open, then it must remain open until all condensate has left the radiator otherwise the vacuum of the closed valve will hold condensate in the radiator. this means you can just open it, let a little heat in and then close it again.



if you go with a TRV, make sure you get the ones specifically for One-Pipe as Dave linked to above.

Brad White

Better Yet

If this is a one-pipe steam system, a thermostatic radiator valve is a neat fix. These valves, one per radiator, install into the vent tapping. The vent (one comes with the brand I use, the Macon "OPSK"), screws into the valve body. This is a vertical vent.



http://www.maconcontrol.com/opsk1204.html



The valve has a thermostatic head which slows or denies air in the radiator from seeing the vent, when the valve is toward closed. When the room is cool (below setpoint), the valve allows air to see the vent and escape. No air out, no steam or little steam in. (SOME steam will get into the first section or so, because the air is slightly compressed, but essentially not much heat.)



Now your radiator, your room, has high-limit control. Set the temperature to what you like, including the "Snowflake" setting. This last one will allow the room to drop to about 42F then the valve opens regardless to prevent freezing. The valves will NOT call your boiler on, it has to be running; these are strictly high-limit devices.



By thermally-actuating the radiator, if the room is satisfied, there is that much more steam to go elsewhere.



What I like about the Macon valves is that they have an integral vacuum breaker. Without this, the radiator can draw a vacuum and keep heating.



A detail: Other brands have vacuum breakers but in my opinion, they are on the wrong side of the vent. The Macon has the vacuum breaker between the vent and the radiator, so even if the vent is closed, the vacuum can be broken. Others have the vacuum breaker in a location that is dependent on the vent to draw air in. Thus if the vent is closed, no vacuum-breaking can occur. I am not sure if this design/feature is still in their current line of product, but the Macon valves satisfy my concerns. Not meant as disparagement of other brands, but just why I like the Macon product.

jpf321

a point about inlet valves

for the general audience, it's worth noting that a floor/inlet valve should either be FULLY open or FULLY closed in a 1-pipe system. Floor inlets should not be used as a way to control the heat of a 1-pipe radiator.



If such a valve is partially open, then the steam and condensate don't have enough room to share the opening as designed and this leads to possible problems. 

Rod

Macon & Danfoss TRVs

Just some notes on the two brands.  On the Macon TRV the vacuum vent is external and visible . On the Danfoss TRV the vacuum vent is internal (in built into the unit).

When comparing them from a cost stand point - The Macon comes with its own radiator vent. The Danfoss doesn't come with a vent and you have to supply one or order one separately so keep that in mind when you are comparing costs.

  I have both types and both work very well. The Macon is slightly superior quality wise (less plastic)  though I would highly recommend either one.

- Rod

David Nadle

One more vote for a TRV

Adding one TRV really won't cost that much and it is the best solution for the too hot radiator. Plugging the vent might be fine in October and not so fine in January.



I have a couple of the Danfoss RA 2000 series with the remote dial/sensor. I don't know if they have the design issue Brad mentioned but they work very well for me.

Brad White

To be clear

on the vacuum breaker issue, the cut-away Danfoss sample I had, showed the vacuum-break path coming from the vent chamber. I had one issue with that, where the room was satisfied but the valve did not release because, we presumed, the valve body was still hot by conductance and kept the vent bellows closed. The radiator remained hot well after the burner cycle ended, this being the only radiator with the TRV.



(The room was always hotter than the others, largely because the radiator was over-sized with the room being an insulated attic room, which prompted this solution.)



The owner changed out the Danfoss with a Macon, with the vacuum breaker separate and with its own path, ignoring temperature. Vacuum released and the radiator heats like the others between cycles.



But I would far rather have any TRV than none!

David Nadle

Across the seat

Brad,

Danfoss claims they have a "patented 'across the seat'" vacuum breaker mechanism. I'm not exactly sure how it works but it looks like there's a small chanel in the valve body that bypasses the seat, and the vacuum is broken by the air vent through this channel even if the disc is seated.

Brad White

Well across my seat too then!

Always open to being corrected, but in that cut-away, that was not apparent nor explained. Might this be a new feature?

David Nadle

Not sure

Brad, I find the cutaway equally confounding. I'm not even sure I "corrected" you. I don't know how new the feature is but I think the RA 2000 series was brand new in around... 2003.

jpf321

begs another question....

this begs another question .. or maybe the question is moot ... but what is the air throughput capacity of the TRV? in looking at the cutout, it looks like very small (not full bore 1/8th") orifice opening from the rad to the vent. I say the point may be moot, because by the nature of the TRV operation, the opening is likely variable, but what is the wide-open throughput (venting capacity)?

Brad White

The cutaway I saw

was an actual valve body, cut open by a machine shop for purposes of demonstrating the interior. Let alone the drawing! But in fact, the across the seat path may be there.



As for the question regarding venting capacity, the paths seem to be at least 1/8", so could vent more than a vent itself might. In other words, negligible effect, but a good question.

Big-Al_2

Move it on Up?

I've never tried this, but I've seen it done by mistake.  What about relocating the existing vent from the correct position less than halfway up the radiator to the opening near the top where a vent would go on a hot water system.  It seems to me like it would close long before all the air was out, and effectively make the radiator heat less.



Would this be worth a try, even as an experiment? It wouldn't cost anything.

jpf321

good idea ... but

this would only work in the case of it being a "hot-water" rad which is connected across the top .. this wouldn't work on true steam column rads which are not connected across the top ..



if these rads are connected across the top, it may be a very good solution.

Big-Al_2

Yep.

You're right about that.  If it wasn't a hot water radiator, it wouldn't work . . . and it wouldn't have the higher vent tapping to begin with... 

jpf321

well this is all very interesting .. but

how about simply performing a full system balancing exercise and putting the proper sized vent on the rad(s) based on EDR and piping runout. someone already mentioned that the VariVent may not have been the correct choice to shut down a radiator, but I bet a Gorton 4 you may see some results.



according to the Gill & Pajek paper, the Heat Timer Varivent on "min" is still about 3x more flow than a Gorton #4. and the Hoffman 1A at smallest "#1" setting is just very very slightly less than G#4 .. the only thing smaller was a ventrite #1 setting #1 which according to the chart was "Off".

Rod

Vacuum Breaker

I've always thought that the large independent, top mounted vacuum breaker was a big plus to the Macon.  I was initially worried about fouling the small passageways of the internal vacuum breaker on the Danfoss as my radiators aren't all that clean though in actual use over several years I haven't had any problem with either model.

- Rod

David Nadle

Some things balancing can't fix

If you have a grossly oversized radiator and you slow down the venting you may have a room that's too cold in the fall and too hot in the winter. On a long cycle even a #4 vent will eventually fill a radiator that should never be filled. TRVs are a much better control in this situation; you can use a faster vent and not worry about overheating the room. The one-pipe valve body is 1/8 NPT so you can choose the vent you like. I have a straight Gorton #5 one TRV and a straight #6 on the other. 

jpf321

i see your point

i see your point .. and understand why a TRV might be a better solution to solve a different problem. I guess I was making an assumption about having the right rad for the room, but venting it too quickly.