new Danfoss TRV Operators not controlling heat properly

Mike_about_heat

I just installed Danfoss Direct Mount Operators on the Danfoss TRV valve bodies that were on my radiators when I moved into my apartment 3 months ago.  After installing the Operators, I was looking forward to finally having radiators that didn't overheat the apartment. But I was sorely disappointed. 



It seemed (maybe) to work during the really cold spell (single digits F) a week or so ago, but as the weather's warmed (now in the 40s, has been in 50s) the TRVs are definitely not preventing the radiators from overheating.  They are allowing air to escape the vent even when a thermometer next to the TRV reads 75 degrees (and even when the Operator is set as low as the asterisk). The Operator’s basic function works; when the air is escaping the vent and I turn the Operators to a lower setting, the air flow stops. They just don’t control the apartment’s temperature properly.



Danfoss literature says that if the radiator overheats it’s due to (a) the vacuum breaker in the TRV valve body being gunked up or (b) the boiler being run at too high a pressure.  I'm also wondering whether (c) it's possible the valve bodies I have are

an older model that did _not_ include a vacuum breaker, and thus the radiator is continuing to fill with steam.  (I don't really understand vacuum breaker physics yet.)  The valve bodies have "4207" stamped onto the nut-like part closest to the radiator.  No Danfoss literature I've found mentions such a number.  Is it significant?



So I'm wondering what you suggest as next lines of attack to diagnose this problem.  Since I'm a tenant, I may have to work at convincing the responsible parties to figure things out.  Else I'm going to continue to open windows and pour their well-earned dollars out into the cold.



Any help would be appreciated.  Thanks!



Some more details:



My radiators are three tube Gurney, 38” tall, cast iron, with 6 and 7 sections respectively.  The apartment is 720 square feet with 9’ ceilings.  The radiators are free-standing, not enclosed.  The Operators are not blocked by furniture or curtains.



I've been told the valves never worked right.  No wonder that, if they didn't have Operators to actually make them "thermostatic"!  All they had was the simple grey caps that (I understand) ship with the valve bodies to protect the control pin.  Those caps didn't work to turn off the radiators; taping over the vent hole was more effective (and easier than closing the supply valve when I wanted to easily open and close them frequently, when acting as my own TRV).



The apartment frequently gets up to 78 degrees F, both before and after the operators.  I have tried various configurations.  I have opened the supply valves on 2 radiators.  Either radiator alone makes the place too warm on warm days, and is insufficient to heat the whole apartment on cold days.  When both are on simultaneously they make the place uncomfortably hot except on the recent single digit days. 



I've tried several settings on the Operators (3, then 2, then 1, now the asterisk).  Next I'll go back to taping over the air vent (simple but effective and easier than closing the supply valve).



I'm a tenant in a 3 story condo building.  I'm on the first floor and the boiler is under my bedroom or dining room.   I don't know where the building's thermostat is.  They keep the boiler room locked so I can’t go snooping on my own.



I'm guessing the valve bodies were installed in the 2006 condo conversion; the landlady doesn't seem to have known about them before I explained what they are.  The maintenance staff didn’t realize my valve bodies were Danfoss, thinking they were another brand.  It’s possible they pre-date the conversion, but at least one trustee didn’t recognize pictures of them so I’m guessing they aren’t in her unit.  So I don’t really know how old they are.



The TRV valve bodies look just like the picture on Pex Supply’s page for Danfoss "Thermostatic Rad Valve w/ Vac Breaker (1 Pipe Steam)" (013G0140), which is how I finally confirmed they were TRVs: <a href="http://www.pexsupply.com/Danfoss-013G0140-Thermostatic-Rad-Valve-w-Vac-Breaker-1-Pipe-Steam-5551000-p.%C2%A0">http://www.pexsupply.com/Danfoss-013G0140-Thermostatic-Rad-Valve-w-Vac-Breaker-1-Pipe-Steam-5551000-p. </a> The grey caps that were on them say “Danfoss” with a double headed arrow pointing at a – and a + symbol, respectively. 



The Operators were just purchased, so are known to be Danfoss "Direct Mount Operator" (013G8250) <a href="http://www.pexsupply.com/Danfoss-013G8250-Direct-Mount-Operator-5558000-p">http://www.pexsupply.com/Danfoss-013G8250-Direct-Mount-Operator-5558000-p</a>. 



The air vents on the TRVs are labeled "No. 31 Vent-Rite", which appears to be

<a href="http://www.phwarehouse.com/products/Vent%252dRite-Valve-Corp-%2331-1%7B47%7D8">www.phwarehouse.com/products/Vent%252dRite-Valve-Corp-%2331-1%7B47%7D8"-Vent%252dRite-Straight.html</a>



I guess we could replace the valve bodies with current ones from Pex, to remove the vac breaker questions.  And the maintenance guys should know the boiler pressure. 



Thanks again if you can offer other useful questions or make other suggestions!



Mike

Mad Dog_2

Could be all the things Danfoss lit mentions

I also worked on a system once that NEVER shut down during the heating season, and even with the working vacuum breakers, the never-ending supply steam never allowed the actuators a chance to cool down and stay shut. Mr Holohan HISSELFS! helped me figure this out. I solved it using a torque clock on the boiler to "break" up the cycles. Thats a tough one...you being the tenant. Perhaps when the heating season is over, the super will or allow you to, take them apart and see if they are gunked up..and if needed replace. Mad Dog

ChrisJ

TRVs

Please keep in mind I'm a homeowner not a pro and I only have two TRVs but these are my observations.

It seems to me that TRVs mainly work by either cutting steam supply completely or allowing it but they do very little modulating.   I could see them working really well in a building that cycles the boiler once per hour.  As previously mentioned if the boiler doesn't cycle they flat out won't work.  Also I've seen mine still allow a radiator to heat a small amount with as little pressure as 2 oz even though the TRV was completely shut.  Low pressure and cycles are a must.  The radiator I have this issue with also has a Gorton #6 vent installed on the pipe right near the radiator so its a special situation because the steam ends up right at the base of the radiator in the first place.



If yours has the brass plug in the bottom then it has a vacuum breaker.  You can test this by removing the TRV from the radiator and blowing through it.  With it turned down so you cannot blow through it, try to suck and see if the vacuum breaker will allow air to be drain through it in reverse, it should allow it.   These tests will also allow you to see approx. where the TRV is shutting in relation to the number on the knob.  If you cannot suck air through the TRV with it set low enough that you cannot blow through it in the forward direction, remove the brass plug and make sure everything is clean.



Using the proper vent speed is also important, one of mine has a Gorton #4 while another has a Gorton 6.  If you vent too fast, it will over heat every time.

Mike_about_heat

brass plug

@ChrisJ - thanks for the 'brass plug' info.  Mine have them.  (I'm assuming you mean like in the Pex Supply photo; the nut on the bottom of valve body below the pipe to the air vent.)  I'll see if I can find my pipe wrench, to remove a valve body and do the tests you suggest. (after turning off the supply valve!)  Actually, will ask the super since I'll need teflon tape (yes?) to put it back on.  And I'll ask him about the system pressure. 



I hope (@Mad Dog) it's not _everything_ that's out of whack!    But I appreciate it could be a complicated conjuction of conditions. I really don't want to wait for the end of the heating season to fix this.

ChrisJ

Ouch

Please avoid using a pipe wrench.



I use a large adjustable wrench as it won't nick or damage the plated brass body. As you said I use teflon tape on the threads, usually 4 or 5 wraps of the thin white stuff as I prefer that on small things like this.



Yep that small brass bolt in the bottom is shown in the pexsupply photo though I think they show it upside down. That unscrews (no tape needed) and has a little ball in it that acts as a check valve. The ball is held in so it won't fall out when you remove it.

Mike_about_heat

Oops

Looked up terms... I didn't mean a pipe wrench; I don't have one.  I meant a tongue and groove wrench, but was thinking it had smooth jaws.  I have an adjustable wrench, but will have to find my tool box in the storage unit that has stuff from the house I had. Don't have much call for tools as a tenant.  Best solution - ask the super!  But thanks for the heads-up.

stevep

Cleaning

I've found that after a couple seasons my Danfoss TRV's require a cleaning. It seems that during extreme cold temps, when the radiators are running hot all the way across, an infinitesimal amount of steam makes it into the TRV and over time this can cause the unit to gunk up just enough to make it start misbehaving. I imagine wet steam might cause problems as well.



To clean, I fully disassemble and soak all the parts in vinegar, then brush with a toothbrush and rinse well.



The images below show before and after cleaning. The vacuum breaker consists of the little ball thingy and the small passages drilled through the threads in the bottom and rear ports.

Bill_17

Danfoss TRVs

You should try calling Danfoss technical support, the problem is likely related to  debris in the vacuum breaker but there is a short list of things you can do to test them.  866.375.4822 

grantland

Came upon this post while searching for a solution to my similar issue and wanted to post how I fixed my problem.

Isolated my TRV and blew through the radiator end with the vent end in the vertical position and the operator pin compressed. Noticed that air was still leaking, so I knocked the brass vacuum cylinder area a few times with a wrench. Blew through the radiator again and verified a good seal.

I'll monitor it for the next few cycles, but if you don't hear back it worked well.

I also talked to Danfoss technical support and they mentioned if knocking on the vacuum cylinder didn't work, they suggested to disassemble and clean the vacuum cylinder. If that didn't work, contact them for a warranty repair/replacement.

EBEBRATT-Ed

Find out the operating pressure it is likely too high. Clean the valves and reinstall and try it. call Danfoss with all the information model ##ss etc and have them check the compatability

nicholas bonham-carter

The Danfoss TRV’s, like the Heatimer steam control are bandaids, which can only function on well balanced and maintained systems, of which these systems are not good examples.
They are likely over pressured, and under-vented, owned, and managed by people who are ignorant of the principles of good maintenance, uncaring of the longevity of their equipment, indifferent to the comfort and safety of the tenants, and oblivious to the economies which could result with a little care!!
These are the buildings which should be identified, and encouraged to improve. Unfortunately, the owners may not be in the building for the long haul, but merely a short period of ownership. They sweep the problems under the carpet, without correction, until it’s time to sell.—NBC

gfrbrookline

I have 2 of these units installed in my Condo building. Both do well and keep the rooms from overheating. I did find a problem with them overheating when new but swapped the air vent with Hoffman No. 41's, worked perfectly ever since and almost silent. My vaporstat is set to 14oz cut out which also helps.