Danfoss HSA3 again!

[GeoffDS]

I suspect my Danfosss HSA3 Actuator, but before replacing it, I'd like to run through the symptoms to see if it might be a problem elsewhere (I had a new boiler installed last year, so I want to rule that out first).
The problem is the house is getting too hot.
Today, the room stat was off (satisfied) but boiler still running and radiators getting hot.
Cylinder stat was on (calling for heat) but 3-way valve was at position A for radiators (i.e. lever was free to move all the way to the bottom of travel).
At this point I checked the voltages at the HSA3 terminals as follows:
Blue Neutral
Orange 248v
Grey 133v
Brown/White 243v

I then turned the cylinder stat down so that it no longer called for heat. The valve moved back to position B under spring power and the voltages were then:
Blue Neutral
Orange 7v
Grey 240v
Brown/White 0v

Then I turned the cylinder stat back up again until it came on and measured again:
Blue Neutral
Orange 240v
Grey 124v
Brown/White 0v
The valve remained in position B (lever at the top).

It seems to me that the actuator is sticking in position A when it shouldn't, but these voltages looked odd, especially the 133v and 124v.
Are these voltages what you would expect? Is the valve sticking in position A, or is this what should happen with these voltages?
Does it sound like a fault with the actuator, or is the new boiler feeding some odd voltage instructions to it. (Actuator and valve are about two years old).
Any advice welcome.
Thanks
Geoff

 

[stem]

The easiest way to check the valve, but only if you are competent to do so, is to disconnect the valve wiring (note what wire goes where so that you can put it back afterwards) and wire it manually using a 'safeblock', or junction box / terminals connected to a plug with 3A fuse in, to see what happens. Sometimes odd voltages do occur when valves are connected to the rest of the system. This test will identify if the valve is working correctly, or not.

Connect your multimeter across a neutral and the orange wire.

Then, connect the blue (neutral) and earth (if HS3A has one. Can't remember off hand) the valve should stay at the hot water only position. Orange wire = 0v. Leave these connections in place for the rest of the tests, and then;

Also connect the brown/white wire to live (central heating required) the valve should wind over to the central position. Orange wire = 0v. (They grey wire should not be connected to anything at this point)

Finally connect the brown/white wire (central heating required) and the grey wire (hot water not required) to live and the valve should wind fully across to the central heating only position. when it gets to the end of its travel, orange wire = 230v

 

[DP]

Brown wire should not have 240 on it for HW demand. 240 is applied to it by CH call which will drive it to mid position if HW call active.