TRV not working

question

I purchased a danfoss Thermostatic Rad Valve w/ Vac Breaker (1 Pipe Steam). My steam pressure is below 1 psi and it seems the room is getting way to hot (79 degrees).The dial is set to the lowest setting. The radiator is pitched properly . Why is the air coming thru the valve which lets the steam into the radiator.

EBEBRATT-Ed

How about a few pictures of the install. Do you have the actuator screwed on tight? Is the radiator in an enclosure

question

TThis is two different radiators 

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EBEBRATT-Ed

@question

You showed two different radiators. Are you having problems with both of them? Do the air vents close when the steam gets their? Are you sure the boiler has 1 psi max? Gauges can lie.

I suppose it's possible you have a defective valve or actuator, looks like they are installed correctly

Maybe take the actuator off and see if the valve moves

question

I have a new vaporstat after replacing one that was set at 1psi and went off at 2.5 psi. The air vents are only supposed to open if its below the set temperature. Since it is 79 degrees it should stay closed the whole time. The problem is the steam is still filling up the radiator and heating the room.

Alan (California Radiant) Forbes

Those TRV's will prevent air from leaving the radiator once the boiler shuts off and steam stops coming into the radiator. But if the boiler never shuts off, steam will continue coming into the radiator and heating/over-heating the room. You've got to have an off-cycle for air to fill the radiator again.

I've put timers on the boiler to allow this to happen once or twice an hour.

question

The boiler shuts off when it reaches the set point on the vaporstat.  It goes back on when the pressure gauge reads zero pressure. I’m posting two pictures one which shows when the boiler shuts off on pressure the second showing the pressure when it goes back on. 

KC_Jones

It appears you bought the incorrect operator for the steam TRV.  That looks like the operator for a hot water TRV valve.  If I was a betting man I’d say that’s your problem.  Here’s a link to the correct operator for a steam TRV vent.

https://www.supplyhouse.com/Danfoss-013G8250-Thermostatic-Radiator-Valve-Operator-Valve-Mounted-Dial-Sensor

EBEBRATT-Ed

It says to leave the actuator set on #5 and push it in until you here it click while mounting

question

kc Jones- it is the correct trv.  The item you shared the link to is part of mine.  It is installed on the valve body of the trv. It snaps on and then you tighten a set screw like Eberatt posted.  

neilc

is it possible ?
is it possible the TRV, being on the floor, is that much cooler down there, and your feeling the warmth at face level?
is there a cold draft from in under the baseboard?
I had this bad in my house till I caulked it to the floor.
or cold air dropping, or drafting, from the window?
are the vent threads sealed into the trv?
I don't see tape or goop

Clance

hi - I'm a home owner that just installed 2 Danfoss TRVs...
@KC_Jones may be correct that you could have the wrong one. Look closely at yours - which has the set
screw to tighten on what looks like metal... and then look at the one from the link that KC posted... the end is plastic not metal and has no set screw to tighten.

The ones that I bought are like the one KC shows. Below is a pic of mine installed.
I'm mot sure how yours works but I believe the set screw makes it "Tamper resistant" Maybe try loosening or taking out the set screw and setting the dial...?

Also, I did have the same issue of one of mine heating the radiator completely when set low, it turned out to be my installation - I didn't push the control knob all the way in/onto the valve insert. I probably would not have realized this if I didn't have another one to look at and compare.

Heres a link to the PDF of Danfoss TRVs which shows all their TRVs/TRV Parts.
https://assets.danfoss.com/documents/99867/AF163386458944en-US0101.pdf

Clance

I noticed you have Varivalve vents, which can be fast venting.

I read somewhere that venting TRVs too fast can result in overheating the radiator because the fast venting prevents the TRV from closing properly. Have you tried a very slow vent like a Maid O'mist #4 (that's what I'm using) or at least turning the Varivalve vent all the way down. From what I read, Varivalve Vents don't fully close but maybe if the Varivalve is set at lowest it might be slow enough to allow the TRV to close and allow it to operate.

Clance

My third thought - @Jamie Hall posted the following on a discussion discussion I started :

The first thing to do is to get the venting correct so that the rooms stay close to what you would like. TRVs will not compensate for poor balance. If a radiator is heating too fast, the usual fix is to put a smaller vent on it.

So, you might take off the TRV, loose the fast venting Varivent in favor of something like the Maid O'Mist kit that has the 5 different orifices and start with the #4 and move up if necessary. Then once confidant your system is balanced re-install the the TRV without tightening down the "Tamper Resistant" set screw.

Here is the Maid O'Mist to which I referred (MAID O'MIST 0220-5L ADJ Angle Steam Valve):
https://amazon.com/OMIST-0220-5L-Angle-Steam-Valve/dp/B003DV3AGE/ref=cm_cr_arp_d_product_top?ie=UTF8

Sorry to have posted 3 separate entries... after thought is my strong-suit

EBEBRATT-Ed

@Clance
good information

Clance

@EBEBRATT-Ed  - that’s because you all are such insightful teachers.  Couple of weeks ago I didn’t even know what a TRV was
And that’s what makes this site great! 

question

The TRV that I purchase is a bit different than the one in the photo. It is a tamper resistant model ( https://www.supplyhouse.com/Danfoss-013G8240-RA2000-Tamper-Resistant-Valve-Mounted-Dial-Sensor ) The body is the same. https://www.supplyhouse.com/Danfoss-013G0140-Thermostatic-Rad-Valve-w-Vac-Breaker-1-Pipe-Steam-5551000-p

The TRV opens / closes a valve which lets the air come out through the air vent. If the valve is closed the air can not escape thereby not letting the steam into the radiator. With the varivalve in the closed position it vents slowly. My thought is the valve should not let any air out so no steam should be getting thru. I have decided to put pipe dope on the vent and trv to see if there was any air coming thru before the trv. I was using the white ptfe tape. Now i will use first the tape then the pipe dope. If it was letting air thru before the valve the steam could then get into the radiator.

@neilc- That was a good thought about there being a cold draft but there is none.

Jamie Hall

It is quite true that when a TRV closes no more air should come out of the radiator. However, that does not mean that more steam can't get in -- and keep heating the radiator. As the steam that is in there condenses, more steam will come in and the radiator will keep right on heating at whatever it was doing when the cycle started.

Now when the cycle stops, if the TRV should let air back in (or, if not, other vents on the system will) -- but if, when the next cycle begins, the TRV is already closed, no air will come out and the radiator won't heat.

This, in a thumbnail, is why it is essential that the system be balanced properly first. A TRV can't compensate for a poorly balanced radiator.

Clance

Did you happen to Read the article linked below by Dan Holohan it's insightful- it also mentions that higher system pressure is an issue. And as I mentioned earlier I read somewhere that too fast of a radiator vent will not give the TRV enough time to close and could keep it from closing.
Here's the Holohan article:
https://heatinghelp.com/systems-help-center/rethinking-trvs-for-steam-systems/

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@ clance- I had some bad experiences with maid o mist air vents in the past . Maybe they were a bad batch but I had 12 of them crack on the body which then caused leaks throughout the building and damaging the wooden floors. They all broke at different times . I was recommended to try the hofmann 41 which is a slow venting Air valve.

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It seems to have gotten somewhat better with putting the pipe dope on the threads along with the tape. My guess is there maybe a small leak in the packing nut on the shutoff valve and or the union.