Mystified by a 3 port valve problem

[timeman]

I am trying to figure out what's going on with my daughter's heating system. It's on a 3-port Danfoss valve HSA3. The problem is that when in hot water mode, the radiators also get hot. I took the head of the valve and have checked that the motor moves into the 1/8th position as well as the full quarter turn when calling for the relevant hot water/heating mode on the boiler controller, and it does. I also checked that the valve itself could be rotated by hand, and it can. I am stumped; I can't believe that the rotating valve itself has broken and isn't swivelling, but that's the only conclusion I've come to.
Any other suggestions would be appreciated.

 

[cross thread]

The valve body can pass, incorrectly piped ( has it just started doing this)have you a gate valve on the heating circuit after the valve? If so shut it and see if it still gets warm.

 

[timeman]

Hi
This is a house that they have just moved into. there isn't any form of isolation; the gate valve looks more recent than the rest of the install. My only other thought was that maybe the valve head is 180 degrees out. i.e, put on the wrong way, but I can't think that's the case. I haven't found a suitable photo to see if that's been done, but the "A, B, AB on the valves is also on the same side as the HSA3 sticker, not the diagram showing the radiator and tap symbols. there are no isolators of any kind, so I'm

faced with having to drain everything down, which I want to avoid like the plague. if it gets drained down, I might look to fit 2 separate valves, which might mean a bit of pipe work rejigging.

 

[CountryFan]

Could be a wiring issue or a faulty programmer. You could always bung the system to prevent partial drain down.

 

[foxhole]

Check wiring , had lots of weird stuff happen with my old system , turned out to be just two wires reversed causing the problem .

 

[fixitflav]

I am trying to figure out what's going on with my daughter's heating system. It's on a 3-port Danfoss valve HSA3. The problem is that when in hot water mode, the radiators also get hot.

All the rads returns must be commoned before the HW cylinder return connection. If not, there'll be the symptoms you describe. Can you do a sketch of the system showing the relevant connections?

 

[Madrab]

Do both output legs (A+B) of the valve get hot at the same time from cold?

 

[timeman]

Thanks for the comments/suggestions. I am not staying at my daughter's (where the problem is), so I won't be able to look at it all again for a week or so. but from memory, both sides of the valve get hot at the same rate. I don't remember if this is the case if I put it to heating only. I will need to check. I will try to sketch out the circuit when I am there next.

 

[fixitflav]

but from memory, both sides of the valve get hot at the same rate.

If that's the case, when CH or HW, but not both are calling, it sounds like a problem with the valve