TRV and Water Sound

FJL

I have a Danfoss TRV on a radiator.  It works well and keeps the room from overheating, which was a big problem last season.  But something odd happens every once and a while. 



Every so often, I'll heard the sound of running water.  Last few times it has happened, I went over to the rad to inspect.  The rad was ice cold.  The inlet valve and pipe coming up from the floor were also cold.  I guess that means that the air inside the rad is keeping the steam out.  This is happening while the boiler is running and sending steam through the building. 



I was confounded about the sound, but then noticed it was coming from the inlet valve.  I could see water bubbling up from the nut just underneath the knob.  Not enough to spill over the valve and onto the floor, but just enough to see a little bubbling of water and to feel it.  The water was not hot.



Since the rad was ice cold, I couldn't for the life of me figure out what was happening.  I should also say that I believe one other time the same thing was happening when steam appeared to have warmed the pipe leading from the floor into the inlet valve and maybe a little bit of the inlet valve itself.



Let me just say that this sound was not coming from the radiator and was not the gurgling sound that is so often the subject of threads.  I know that sound and that was not what I was hearing.



Can someone explain this?

jpf321

TRV model and location?

Which dTRV do you have and where is it mounted? 

FJL

Danfoss

I have the Danfoss, for one pipe steam, with vacuum breaker, mounted on the rad.

Bill_17

TRV and Water Sound

Try calling Danfoss' tech support line at 1.866.HVAC,

Big-Al_2

Packing Nut

If you have air or steam leaking around the radiator valve stem, don't blame the TRV, blame the stem packing.  You may be able to tighten the packing nut up a little bit and get it to seal again.  If it bottoms out before it seals, then you'll need to remove the nut (steam OFF) and add a little more packing material in the form of graphite packing "string" available at most plumbing places. 

FJL

Thanks

After posting my question, I was thinking about this again and thinking that this wasn't necessarily a TRV question, and that the valve probably does need to be tightened  or repacked.  I guess I was associating it with the TRV because there was at least one time it happened when I couldn't feel any steam in the rad or the pipe leading to it, and that caused me to wonder how I could be having water in that area, and that caused me to think it had something to do with the TRV.