Installed TRVs and now I have loud resonation at 9:15 AM every day.

TonyDestro

System is a simple two pipe system, it used to be a gravity system and is all CI rads. I put Macon TRVs on the supply side of all radiators except in the room with the thermostat. At 9:15AM, every day, when the system is heating from 62 degrees to 70 degrees, a loud resonating hum begins through the large oversized pipe work from the old gravity system. It was not doing this before and it is too loud to tolerate. Boiler Pressure looks ok. Relief valve works. I tried turning down the temperature max limit and that seems to have helped some. The hum continues even if the burner has stopped firing, which leads me to think the circulator is the cause. It only happens during its work to raise the temperature in the morning.

I can stop it by turning down the thermostat, or closing the isolation valve on the return side of the boiler where the circulator is. I believe both the circulator and boiler are over-sized for the house. The circulator is a taco 007 that came with the weil mclain cg boiler.the circulator is probably too fast too.


What do I do first?

mattmia2

My first thought is that the circulator is trying to pump through only that one radiator without a TRV and its high pressure and velocity (and mostly closed trvs) on the other radiators but they should be cold and open on recovery. Maybe it is something with those radiators are hotter than normal on recovery and heating and closing down the trvs.

You could try recording the TRV settings and opening them fully and see if it still happens. Then you can look at an auto adapting circulator or a pressure bypass.

EBEBRATT-Ed

What @mattmia2

Perhaps your pump is to large. Maybe a delta P pump or a pressure by pass.

Try keeping a couple of TRVs open and see if that helps

TonyDestro

The valve on the radiator in the room with the thermostat is absolutely ancient. I'm not sure of it's position, It may not be fully open and it is in a position where a cabinet was built next to it and I will have to cut the cabinet to remove it and to insert a spud wrench to replace it.

I will turn all TRVs to max and see what conspires in the morning.

Update: I was able to get the ancient valve to turn all the way open by loosening the packing and using a mini pipe wrench on the valve stem, it was only about 3/4th open.

PC7060

I’d double check to make sure one of the TRV isn’t on the return side.  I had a similar problem (wow, it was loud) and traced it down to TRV on the return. Moved to supply side and all is quiet 

JUGHNE

PC, could you tell that by temp diff on the pipes?

That is supply from return pipes.

Things can get switched or hidden in the basement.

Rich_49

Could I ask why in the world you have TRVs everywhere except for on one radiator and are using a setback , a DEEEEP setback at that ? Put a TRV on the radiator without one , set it to where you like it , let everyone else set theirs where they like it and use the thermostat as a high limit .

PC7060

JUGHNE said:

PC, could you tell that by temp diff on the pipes? That is supply from return pipes. Things can get switched or hidden in the basement.

Traced the pipes in the basement to figure out the flow direction. It was pretty easy to figure which radiator was the culprit since the reverse flow would push valve open and the TRV spring snapped it closed (rinse and repeat).   It was occurring 4-5 time per second continually under certain conditions.

The radiator valve was originally plumbed in on the return side so that where the TRV ended up because I assumed the valve was the supply side like all of the others. I know, never assume.  

EdTheHeaterMan

PC7060 said:

I’d double check to make sure one of the TRV isn’t on the return side.  I had a similar problem (wow, it was loud) and traced it down to TRV on the return. Moved to supply side and all is quiet 

Agree with PC. I experienced the same problem after installing TRVs on every radiator except the one in the coldest room. I placed the thermostat in that cold room and everything was resolved temperature wise and saved the building owner over $3000,00 in fuel usage in one year. But the noise from one of the TRVs was disturbing. I even asked the building owner (who lived in one of the first floor rooms) if the 150 year old house was haunted? I told her it must be a ghost. But I found that one of the old radiator valves was installed on a return. I put the TRV in the same place... Swap to the other side and the problem went away. I still think the house was haunted... by the old lady's mother

TonyDestro

The system satisfied this morning without the reverberation. The TRVs were all set to max except for one. I guess that means get a new pump. (or one of the rads is plumbed backwards as you've suggested!) I may wait to install it as I am planning on replumbing the boiler in the spring, putting the pump on the supply side, installing a dirtmag/air separator, put in a new expansion tank and eliminate the old-style expansion tank which is currently on the return.

I'm almost certain all TRVs all on the supply, but i will look again.

Everywhere I've looked has told me to do it that way, including this site. "No TRVs where the thermostat is located."

I suppose turning the TRV in the bedroom down for sleeping without a setback would be fine.

This is not a large system. Some idiot eliminated two CI rads and the boiler was sized for those so there are only 5 of them. The one in the room with the thermostat (dining room) is the largest. I'm going to try to get those radiators back in place if I stay in this house, but that is going to require a major renovation to get the room to do it. I may also add a radiator in the garage and basement.

mattmia2

TonyDestro said:

This is not a large system. Some idiot eliminated two CI rads and the boiler was sized for those so there are only 5 of them. The one in the room with the thermostat (dining room) is the largest. I'm going to try to get those radiators back in place if I stay in this house, but that is going to require a major renovation to get the room to do it. I may also add a radiator in the garage and basement.

Since it is hot water with a cast iron boiler you could use any number of other types of emitters from panel radiators or baseboard to an air handler or kick space heater on their own zone or zones to heat the area with the missing radiators.