Ceiling rads and Thermostatic Rad Valves

mweber

I have a single-pipe steam system and in my basement apartment I have two ceiling-mounted radiators. In my attempt to keep the temp even in the building as well as reduce energy costs, I have installed a Danfoss Thermostatic Radiator Valve to the one radiator in the living room as a trial.



The sad thing is that I have the setting at 68 but it is still getting upwards of 74 degrees and the radiator is definitely getting warm. I've verified that the valve is indeed closing, but somehow the radiator is still filling with steam.



I've been thinking that maybe the radiator doesn't get scavenged enough when the boiler shuts down and therefore it isn't getting enough room air into it which would block the steam as I've read in all of Dan's books ("where there is air, steam will not go" or something like that). I have verified that the TRV does seal off tightly, and I've made sure that the threads are sealed as well.



I have large vent valves everywhere in the system to vent things quickly, so it runs at VERY low pressure (so low that the 30psi gauge that the boiler installer used doesn't move and I cannot find a good, reasonable, 5psi gauge... suggestions??). All I have read in Dan's books talk about people incorrectly cranking up the pressure to get steam into radiators with defective vents, which appears to work when it really doesn't, so I don't believe that the low pressure is causing my issue.



Does anybody have any ideas? I would love to be able to control this and keep heating a little more uniform here in Chicago when our crazy weather changes.



Mike

BobC

Slow venting

As  I understand it thermostatic valves work best with slow air vents on them. If you vent them too fast and the radiator fills with steam it's to late to control the output of that radiator by shutting the vent off.



Bob

Jamie Hall

I hope you mean...

thermostatic radiator vents...



Thermostatic radiator valves are for two pipe systems.

BobC

Good catch

Yes I did mean thermostatic radiator vents not valves.



Getting old is really not a lot of fun.



Bob

nicholas bonham-carter

Low pressure gauge

Gaugestore.com sells them, and until you have one on, you will not know what pressure is in the system. Your 0-30 psi gauge may not be working. Their cost is much less than wasted fuel. Is this your building, or a rented apartment?--NBC

mweber

re: Ceiling rads, TRVs, and all the great input

BobC: Yep, that part I completely understand. However, the problem is that the setting is 68, the room is 72, and when the boiler is heating, so is my radiator that is not supposed to be getting hot at all because the valve is closed.



Jamie: Actually, no. I meant thermostatic radiator valve. It is a valve that has a vent attached to it, and it doesn't do the venting; it valves whether the vent vents or does not. I know... tomato, tomatoe.



Nicholas: Thanks for the link! I know the gauge is working because previously when my first floor unit had very slow vents in place, I would see about 1/2 psi on the gauge (and the first floor apartment would not heat compared to the other two floors). The pressuretrol is also set for 1.5psi max and 1psi diff, and it has NEVER triggered the boiler to shut off. And yes, this is my building. I have already reduced the energy consumption of this heating system from the previous owner by about 30%, so I'm heading in the right direction!



So, I'm still at a loss with my original question. Any others ready to chime in?

nicholas bonham-carter

stopping the heat

your basement probably has extra waste heat from the boiler coming through the walls. try putting  plugs in the vent tappings of the ceiling radiators, to see if that cools down the situation. are the steam pipes in the basement insulated?--nbc

mweber

the problem, moire specifically...

Nicholas--



Yep. All steam pipes are heavily insulated. And, the kitchen is between the boiler and the living room, and the kitchen is always cooler than the living room. I also have the boiler room vented to draw in outside air, so often that's cooler than even the kitchen (when the outside temp is quite low).



The problem I'm having is that the radiator is getting hot... not warm, but hot... filling with steam when the valve is [verified] closed, with its setting at 68 degrees and the room temp measured three inches from the valve's remote temp sensor coming in at 72+ degrees on four different digital thermometers... all measured when the boiler is off. In other words, the radiator is filling with steam when the valve that is supposed to prevent it has been verified closed. That is, if the temp in the room is 72 after the boiler has been off for several hours, the valve is set at 68 and verified closed, then the boiler kicks on, this radiator will still fill with steam and get hot while theoretically, it should not. That's the problem.



My only thought is that this is somehow due to the fact that the ceiling-mounted radiator is damn near horizontal and all the items in question: main valve, radiator, vent port, and TRV - are all on the same horizontal plane. OR, is this a problem due to the fact that the pressure is so low in the system and changing all the vents to slightly increase the pressure would alleviate the problem? I'm wondering if Dan Holohan has any input on this...

nicholas bonham-carter

trv problems

the vents, and perhaps the trv actuator are usually in the verical plane, so that may be the problem. try a slow hoffman 40 without the trv, and see if that changes things.

where is the thermostat located?--nbc

mweber

Thermostat location

Nicholas--



Do you mean the thermostat for the system, or the control for the TRV? The control for the TRV is located across the room from the radiator... it's a remote controller with a 16' coupler tube. The thermostat for the system is located in the boiler room with remote sensors in all four apartments. But, the thermostat for the system has absolutely nothing to do with this as it controls the boiler, not the TRV on the radiator.



My bet is that I could remove the TRV and plug the vent port in the radiator and it will still get hot. I don't have any 1/8" plugs, but I may stop at Big Orange Box store tomorrow and grab one for craps and giggles.

Bill_17

Ceiling radiators and TRVs

Don't forget that the air in the radiator is compressible so even with the TRV closing off the vent, some steam may migrate into the radiator under certain circumstances.  The overall piping layout, steam pressure and length of time the boiler fires are probably all related to the unwanted heat. 

Bill_17

double post

mweber

ANSWERS!

Thanks, Bill!! This is what I was thinking may be happening, but wasn't sure since Dan H says "where air is, steam will not go" or something along those lines. And, I think that once some steam gets into the radiator, it's fair game at that point as the steam mixes with air and aerated condensate is what leaves the radiator. It's proving that the TRVs are not as effective as I would like them to be, especially for ceiling-mounted rads.



Again, thanks for your response!

The Steam Whisperer (Formerly Boilerpro)

One thing to try.....

I have come to understand that the Danfoss one pipe TRV does not have a very effective vacuum breaker.  You may want to try a Macon/ Tunstall TRV which has a dedicated vacuum breaker that can let the radiator fill with air when the steam shuts off on a cycle to help prevent steam from entering the next cycle.

ChrisJ

TRVs, pressure, stuff

My system runs an ounce or two usually and I'm running two Danfoss TRVs.  One of them currently has a Gorton 6 vent on the riser to the radiator as well right by the inlet of the radiator.  When the TRV is shut, the radiator does not heat, at all.  When the TRV shuts during a cycle, the radiator does not advance anymore for the most part either.

I have not had any problems with the vacuum breaker in the Danfoss TRVs either, at least not yet.



Are you 100% sure you do not have any air leaks in the radiator which is allowing air to escape?



What I have learned is the setting in the dial of the TRV, is not nesecessarily accurate.   For example in my bedroom a setting of around 1.25 gives me 66-67F.  If I went by what the scale on the box claimed I would have 75+.  I mainly judged where to set it by blowing into it while turning the dial to see where it shuts at that given temperature.  Of course the cold wall also effects it some so it takes some tweaking.



I also found on one of the radiators, running anything faster than a Gorton 4 caused the room to overheat often.  This is why I switched to a #4 on the TRV and a #6 on the riser to get steam to the radiator fast.  Since then its worked pretty smoothly while another one has a Gorton 6 on it and seems to work fine as is.

mweber

Hmmm

ChrisJ--



I checked out your boiler pics... that's my boiler, but just a much smaller version. Apparently, Weil-Mclain ships with the standard 30psi gauge that you and I both have, and the 3psi gauge is what I need, like you have.



I guess it's possible that the radiator may have a leak between the sections, but I never get any leaks and lose very little water from the boiler, rarely needing to add water to the boiler. I think I will pick up some plugs and try plugging the vent hole and seeing what happens. If the rad heats, then maybe there is a leak in it indeed.



If possible, I would love to see how your riser vent is plumbed into the riser. Do you have a pic you can share on that one?

ChrisJ

Riser vent

Used an 1/8" NPT tap and a size Q drill bit. This is on a 19 section radiator.



Also, make sure the vacuum breaker on the TRV is functioning. This can be done by removing the TRV and sucking on it with your mouth with the knob turned low enough that you cannot blow through it. I know, using your mouth on radiator stuff, but it works. If it seems clogged, it can be cleaned by removing the cap on the bottom, though I have not had to do it yet. Make sure you dump all of the water out of it, otherwise you might get a nasty surprise. The vacuum breaker is designed to pull water out of the trv.



You must also have the TRV mounted as shown below. It cannot be sideways or upside down.

mweber

RE: riser vent

Thanks for the picture! I'm seriously considering doing this in my third floor apartment because that's the top of the riser for the second and third floor living rooms and front bedrooms.



My TRV is only a few months old, and it's installed correctly. Fortunately for me, before I even installed it, I wanted to see how the vacuum break works and I tested it by mouth as you describe (I get curious and make sure I test things). And, it's a one-way valve, and it definitely works. So, all is well on that front.



I'm thinking I may remove the valve and plug the rad to see what happens. I have a feeling there may be a leak in between the last two sections, even though I'm not losing water and have no drips or runs.



Have a great weekend, everyone!