Danfoss boiler protection valve.

[huffdawg]

I have a 140 danfoss boiler protection valve , it always seems to send 150 water to boiler anybody else have the same issue with theirs? Thinking of trying a 130 thermistat if they make one.

Huff

 

[Fred61]

Huff,
A danfoss equipped with a 140 degree thermostat will be closed at 140 and only allow circulating water to be pumped through the bypass until the automotive thermostat senses 140 degree boiler temperature or above. If your return water temperature or your boiler water is above 140 there is no way you're going to get 130 degree return water. If you had a 130 degree element it would allow 130 degree water through at first but then as the boiler and return water rises the flow will be above 130. So if your return water is 150 then it can't be lowered to 130.

You can't have the return temperature lower than what the system is at. Or did I misread your post?

 

[huffdawg]

Huff,
A danfoss equipped with a 140 degree thermostat will be closed at 140 and only allow circulating water to be pumped through the bypass until the automotive thermostat senses 140 degree boiler temperature or above. If your return water temperature or your boiler water is above 140 there is no way you're going to get 130 degree return water. If you had a 130 degree element it would allow 130 degree water through at first but then as the boiler and return water rises the flow will be above 130. So if your return water is 150 then it can't be lowered to 130.

You can't have the return temperature lower than what the system is at. Or did I misread your post?

 

[huffdawg]

Not sure if you can make out the temps on that graph Fred. If you can, u will see that once the boiler in temps reach 150f or higher, that it is around 10 degrees higher than the buffer bottom temp. "Buffer bottom" temp is the temp the water enters the danfoss and "boiler in" temp is the temp after the danfoss. You would think that if the danfoss is fully closed that there would be no mixing with the boiler out water and the temp would be the same on both sides of the danfoss.

 

[huffdawg]

I think I remember a post by Bob Rohr and he stated that he changed his thermistat out to a 130f and it closed at 140f after.. Correct me if I'm wrong on the closing or opening I cant remember which way they operate.

 

[mustash29]

They make 6 different thermostats for them.

http://s3.supplyhouse.com/product_files/193B1701-Submittal.pdf

It sounds like it is not closing fully. Chunk of debris stuck in it? Failed element? I've had a few car thermostats fail over the years, never open or shut but always stuck in the middle somewhere.

 

[Fred61]

You've lost me for the moment. Haven't had my second cup of coffee yet. Trying to build your set-up in my mind.

 

[huffdawg]

You've lost me for the moment. Haven't had my second cup of coffee yet. Trying to build your set-up in my mind.

(broken link removed)

thats pretty much it except I have replumbed the buffer tank to storage tank piping with opposed circs

 

[Mike Fromme]

You have the VTC valve or the older TV valve?

 

[huffdawg]

You have the VTC valve or the older TV valve?

Pretty sure its the older one , bought about 6 yrs ago.

 

[Mike Fromme]

My older '140' TV valve also sends 150 degree water back to the boiler.


I had the thermostat go bad and wanted a quick replacement.

Interestingly the '140' danfoss thermostat is stamped 72c (162 f)... Danfoss goes by when they begin to open while auto and marine thermostat go by when they are fully open... So I bought a 160 degree marine thermostat which worked fine until I got a danfoss replacement.

So you should be able to find Auto or marine thermostats with different ratings at any auto parts store for a few bucks to try.


Here's the stant that I used


https://www.amazon.com/dp/B000E43A1S/?tag=hearthamazon-20