Strange Central Heating Motorised/Actuator Valve behaviour Manual Mode

[fromage]

Hi there,

I have a Danfoss HSA3 3-port mid position actuator/motorised valve that has failed a few weeks ago which was no big deal as I have just been using the manual override switch on the side to set to either Central Heating or Hot Water as and when I need each until I got round to fitting the replacement.

The manual override has been working without issue until the other day (only the required mode when set manually would operate as expected) but now when I set the it to "Central Heating" it appears to also heat the hot water tank/cylinder which it didn't the previous weeks when setting it manually (it also ignores the thermostat on the tank and heats it to the radiator water temp). When I set it to "Hot Water" only mode then it functions correctly for that mode and just does the hot water and also shuts off as expected when the required temp is reached and noticed by the thermostat.

I was planning on replacing the motorised actuator/valve next week which seems a super simple job in itself but was wondering why my hot water tank is also being heating on central heating mode (when manually set to central heating) as I'm worrying that not only had the valve/actuator failed but there may be an issue with the actual pipe junction/valve. When I remove the motorised valve/actuator from the pipe I'm able to manually move the physical valve on the pipe without issue so its not stuck

 

[Deleted member 120897]

It’s a 3 port mid position valve, so it should have been heating the cylinder and the heating anyway if set to manual position. You need to get the head changed ASAP. Perhaps you were lucky in previous weeks that it didn’t do the 2?

 

[fromage]

aha that makes sense, maybe before it was half failing (unable to fully switch over to itself) but when I set it to manual it had enough power to to fully close off the rest of the circuit.

Thanks for the reply, appreciated will get a new one ordered.