Danfoss Making Noise - Not Anymore!

[Medman]

My Danfoss valve is making a noise when it opens and closes (keeping return temp to the boiler at 140*) that sounds like the song of the killer whale. Since the thermostatic valve in the Danfoss is always self adjusting for the temp, it is nearly constant once the boiler reaches 150* or above.
It isn't really a problem because the boiler is in the garage, but I haven't read on here that others have the same problem. It seems to be working OK, but I wonder if it is recirculating too much water to the boiler as well based on the temp difference between the boiler output and the loop temp. I have a ball valve in series with the bypass - should I try throttling back the amount of hot supply water which can be circulated through the Danfoss back to the boiler? This would increase my loop temp but might drop my return temp below 140*

Any thoughts?

 

[Nofossil]

I was considering replacing my bypass valve with a Danfoss - I think I'll wait to hear what other users have to say.

Of course, it would be an interesting control system challenge to get it to play recognizable songs..... like
this.

 

[Medman]

Thanks for the laugh. If my system was worth the millions that car is, maybe I would have the free time to figure out how to get it to play a tune. For now, it sounds like I am holding a pod of humpbacks hostage in my garage.

 

[drizler]

Just a though here, could it be air in the line that needs bleeding off?

 

[rickh1001]

Medman,

I have the Danfoss valve, and have not had any problems whatsoever, and no noise for sure. It is a remarkably simple and effective valve, and works perfectly for keeping the boiler return water at temp. It really is the key element to being able to effectively add storage, and it is relatively cheap, simple and elegant.

Although I don't know if it could cause your problem, did you install the thermostatic valve with the bulb facing towards the boiler return? The hot water coming from the cross-over piping between the supply and return should be coming down over the sensing bulb. If it is installed the other way, the bulb will sense the cold water from the storage tank. This might make it open too slowly, perhaps creating only a narrow passageway that could make noise. Anyway, no noise from mine, so I'm not sure what might be causing the problems in yours.

 

[atlarge54]

I have Danfoss mixing valves on my DHW outlet and my floor radiant manifold. I installed them with unions for easy service and haven't touched them in 4 years. This morning I got out the install and maint. info. sheet and they recommend to clean and silicone grease yearly. My DHW is soft and heating system is pressurized. How often does anyone mess with theirs?

 

[Medman]

I should have clarified - I am referring specifically to the Danfoss TV valve used to control the temp of the boiler return.

I took the valve apart yesterday. There was a minimal amount of sediment in the housing, not enough to cause a problem. Boilerman, I was thinking the same thing once I got it apart. Although I installed the valve according to the instructions and the label, the valve appears to me to be installed backwards. The thermostat inside is similar to an automotive thermostat. It has a wide, flat disc with a spring on one side and a contoured "bulge" on the other side. The thermostatic element is surrounded by the spring and causes a pin to extend when heated. The pin pushes on the bulge, causing the disc ant the thermostatic element to move in the direction of the spring, compressing the spring.
As installed, the spring and thermostatic element is immersed in the cooler return water so the valve does not open until the entire valve housing heats up. Also, the disc has to move against the flow of water to operate so system flow is trying to force it closed. Also, unlike an auto thermostat, there are no holes in the disc to allow a small flow through the thermostat even when closed. These factors I think cause the "singing" and the pipe banging I am experiencing when the valve operates.

I don't know if I can turn the thermostat and its brass housing around in the valve, but I think I will try it. The difficult part is getting the system cooled down, and the two gallons of water lost when opening the housing. Even though I have an air separator at both high points of the system it takes me forever to get all of the air out again.

As an alternative, I can get a 113* element for the valve. I don't know if this would be too low, but when operating at full load I am only seeing a 35* drop from supply to return at the valve, so I don't think there is much danger of cold shock to the boiler. I also don't have make-up water feed in automatically, so no danger of that temp differential either.

 

[Medman]

An Update:

Last night I was able to confirm that the TV is indeed installed backwards. I was able to use my bypass valve and isolation valves to essentially reverse the flow of water through the valve and it operated normally.
The instruction sheet included with the valve (but not on the web) shows two installation options. "Typical Installation" follows the label on the valve itself. "Gravity/Large Volume" installation shows the valve in backwards to the label on the valve. Both installations require a balancing valve installed in the bypass pipe, which I have. This valve is adjusted to allow the least amount of flow through the Danfoss while still providing boiler return temps above 140*F.

I think what is happening in my case is that the valve is not opening until the housing heats enough to allow the valve to operate - typically about 155-160 on the gauge. When it does open, the disc is fighting the flow (8 gpm @ 17 ft head) causing the "singing". as soon as some of the cool return water hits the valve it closes, causing a pipe shudder that shakes the whole boiler, etc.

I am going to call Danfoss this morning to see whether I can just rotate the guts 180* inside the housing. When I had it apart before it looked possible. I do not want to tear apart the plumbing again.

I will post pics later today.

 

[sfriedri]

I have the Danfoss TV installed in my system on the return side with a 140F thermostat and it works fine. Mine was delivered without the thermostat installed, so I also had to make sure that I installed the thermostat in the right direction. With the thermostat installed correctly, the spring and thermostat pellet should be on the boiler return side of the valve. This allows the flow from bypass loop to heat the thermostat pellet and this will open the valve enough to mix in some flow from storage for an overall mixed temperature of 140F returning to the boiler. If you look carefully at the cross-section diagram provided with the valve, you can see the cross-section of the spring of the thermostat represented as little circles, and these are on the boiler return side of the valve.

In my system my boiler circulator is between the Danfoss valve and the boiler return.

 

[Medman]

deleted double post

 

[Medman]

See below. In this configuration, the Danfoss is bypassed allowing full flow to the loop. Note diagram on label. My Danfoss came fully assembled.

 

[Medman]

Danfoss valve instruction sheet. I found it with other documentation after piping was complete. I only read it after I started having problems. Instructions? We don't need no stinking instructions!

 

[Medman]

My plan for tonight's teardown of the valve (if possible):

Current setup on the left, correct setup on the right.

 

[cvanhat]

well i got that part right. mine is like the pic on the right. so i guess i got a bad thermostat. thanks all

 

[stee6043]

Medman, correct me if I'm wrong but the only difference between the standard application and the "large volume" application is the added bypass line and the added/relocated pumps???? The valves appear to be in the same orientation in both applications. Port 1 toward the boiler, port 3 toward the bypass and port 2 toward system return. In the diagram they don't seem to suggest the direction of the actual thermostat changes for either application??

 

[Medman]

Yes, you are right. The direction of port 2 does not change. It seems that in my valve, port 1 and 2 are reversed. I am going to try reversing it tonight and see how it performs.

 

[stee6043]

Gotcha. Let us know how you make out. That would be quite painless if you could simply pop the cover and spin the thermostat around. Hopefully it works for you. I suppose there is a reason they include the diagram as well as the sticker. Perhaps they've had problems with the sticker and/or thermostat not being installed right in the past??? ha. Good luck....

 

[Medman]

Painless, but not dry...

I will report on my progress as it happens.

 

[Medman]

Well, I can report success turning the guts of the valve around. System was cool - 64*F when I got home. I took the cover off as before, removed the brass insert, thermostat and spring, got soaked, and installed the parts in the opposite direction. After refilling the system and getting out the air, I lit the EKO. If you notice in my pics the piping is all up near the ceiling. Within ten minutes of lighting, I had 110* water thermosiphoning through the piping - this has never happened before.
After half an hour, temp in the near boiler piping is 135* on the supply and return. Temp on the Danfoss return port is still about 70*F. At 140, the pump turns on and water starts circulating to the loop. Within two minutes, the loop is up to 115*F and the boiler has cooled to 135* - pump off again. Fifteen minutes later the whole system is up to 150*, so I start pulling heat from the coil in the house.
It has now been a few hours - the house is warm, the boiler is hot, and there is still wood left inside. I am amazed at the difference having that valve in the right way can make.

I hope my experience will help others who receive this valve already assembled. Check the orientation of the thermostat inside!
FYI, Danfoss did not return my phone call today. We'll see if they call back at all.

 

[stee6043]

Great news! Congrats on your success. I'm sure someone someday will have this same problem and you'll save them from tearing half their near boiler piping apart.

 

[Medman]

Update - because water is now flowing as it should, I still had live coals this morning after 7.5 hours burn, and the hous was still at set temp. I was able just to load again and was gasifying in under two minutes. Water temps above 150*F before loading. With this improvement in performance I am on target now for wood consumption.
Storage is the next challenge.

 

[Redox]

Good for you on figuring this out! If it makes you feel better, I've seen this done wrong dozens of times by experienced fitters. Even the engineers screw it up occasionally! :roll:

Chris

 

[VeggieFarmer]

As an alternative, I can get a 113* element for the valve. I don't know if this would be too low, but when operating at full load I am only seeing a 35* drop from supply to return at the valve, so I don't think there is much danger of cold shock to the boiler. I also don't have make-up water feed in automatically, so no danger of that temp differential either.

Any opinions on whether the 113 degree element might be an improvement? I'm assuming it could be retrofit inside of the same valve housing.

I currently have the 140 degree element as well and have been surprised at how much it mixing it does, even at 158 degrees, when it claims that "most of the flow will be through the system." I lose 10 degrees F between the boiler jacket and the storage tank inlet (35 feet away) until the storage tank temp reaches 150 or so. Since the goal of storage is to run the boiler wide open and create a nice temperature differential across the heat exchanger, this choking off by the TV valve is most unwelcome.

Then again, I don't want to damage the boiler if a 113 degree return is going to be too low...

 

[rickh1001]

VeggieFarmer,

I believe the EKO manual calls for a minimum inlet temp of 140F. If you go lower, you might risk condensation or cresote formation in the HX.

 

[Chris S]

Coming in on this post late...
Veggie farmer, I have the same problem- " danfoss instructions state once the valve is open most of the flow is to the sytem" I need the flow to the system becuse the storage I installed is effectively 100' away, and it seems that it is easier for the danfoss valve to recirculate the water than send it where I want it.
I agree with the importance of the valve, but having something you can't see (not exactly sure what position it's in at a given time) makes troubleshooting difficult