Over pumping Danfoss thermostatic radiator valves

TonyVee

Question for you wet heads. I have a customer with...
3" gravity mains with a 1" open bypass at the farthest point (about 70' away)
Danfoss thermostatic valves on every radiator.
They split the system in half left to right.
there are Taco 1400 series pumps on supply side.
Some of the radiators are overheating.
Could it be the oversized pump or simply bad thermostats?
I didn't install any of this and the customer is not very trusting.
They will occasionally blow 6 amp fuses in a SR 502 relay.
I was going to start with 0010 pumps and see if that helps. at least the fuses wont blow anymore. Then my plan was to address overheating radiators.

Jamie Hall

If a radiator is overheating, either the thermostatic valve is not correctly adjusted or is malfunctioning or, if it is a remote sensor, the sensor may not be properly located. I doubt very much that you could ever get enough pressure differential with the pumps you are using to overcome a Danfoss valve.

Depending on the specific pumps in the 1400 series, if two or more are running at once yes, you could blow the fuse. Those are, however, big pumps -- I can't imagine that you'd need either that much flow or head in that system.

Dave H_2

OK, first thing first:
What's changed in the system? I mean 1400 circs haven't been around in a while or has this been an ongoing issue?

The 1400 is a rather large circ but that doesn't mean it's not needed for the project. How large is the connected load/boiler?

Also, the last two numbers of the 1400 circ will detail its performance curve.



Dave H.