Danfoss HSA3 Mid position valve problem

Joined
2 Dec 2012
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Location
Lincolnshire
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United Kingdom
I've just fired up my central heating system after having to re plumb the downstairs due to broken pipes in the concrete floor. It's a Y plan system with a Danfoss HS3 valve.

When I turn it on, all is good for around 30 seconds to a minute, then the valve actuator starts clicking and gets hot on the top. This also makes all the electrical outputs pulse on and off so the boiler and pump both switch off. I dropped the actuator off, the valve turns freely, and the same thing happens with the clicking and pulsing with the actuator off the valve.

I had a brand new spare that I bought a while back as I heard these frequently pack up, so I wired up the new actuator and put it on the valve. Exactly the same thing happened again, it ran OK for about a minute and then started clicking and pulsing.

When the override switch is on, everything runs fine, but obviously there is no proper control so it's not ideal. Any suggestions anyone? It seems strange that both have done exactly the same thing. I have checked all electrical connections for tightness and the voltages etc are OK.

Many thanks
 
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Right...think I've fixed it!

Left it running for a few hours on the override, then released it and it wasn't doing it, bingo I thought !

Then realised the heating wasn't turning off, it turned out I had wired up the cylinder stat wrong, I blindly followed the Danfoss Y plan diagram online and the pin numbers in my cylinder stat were different. All sorted now, I hope!
 
so did you install the system originally ? how was the stat wired different and not noticed before ,you only repaired a leak on the heating system ( flow or return ) . if i read it right
 
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While it was all off, I also moved the junction box for the heating about 4 inches lower, as it wasn't fixed to anything and it allowed me to fix it to the skirting board. I took the opportunity to number up all the connections as per the Danfoss diagram I found to make it easier to fault find in the future...just didn't expect to cause a fault whilst doing it!
 

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