Central Heating only comes on with Hot Water

[Skid Solo]

Hi, I have read through various posts on this site and cant find a solution, my CH will only work if the HW is turned on. Having read details on here I replaced the 3 way valve, but this has not made any difference, here are the system details :

• 3 Way Valve Danfoss HSA3D (New replaced today, same situation with both old and new)
• Room Thermostat Honeywell appears to be working as the 3 way valve will move as the thermostat is turned up and down
• Controller Honeywell
• Boiler Stelrad Ideal W

Synopsis :
Just moved house and haven’t had the heating on until now
Turned the heating on and when the hot water is on as well everything seems to work fine
If the heating is on and the hot water is off, the heating does not work (with the room thermostat on full) and the pump does not come on

Tested:
The three way valve moves to two different positions dependent upon the selection of the control and thermostat
The actual valve seems free and not seized, I can turn it with my fingers
The three way valve actuator seems to move the correct position (both old and new) and to my mind if the I test this not connected to the actual valve then when in the right position for heating only the pump should turn on, it doesn’t

Any ideas ?

 

[Agile]

So this is the first time at this house that you have ever tried to use the heating?

So its very possible that its designed/configured to only work that way.

Why would you even NOT want the HW to be on when the heating is on?

Once its up to temp the cylinder stat would turn it off anyway.

Try looking at the programmer settings ( or the wiring ).

Tony

 

[kevplumb]

could be programmer is set for gravity

 

[Skid Solo]

Thanks for the replies, My old heating system allowed CH and HW to work independently I assumed they always should, I thought that was why a 3 way valve was installed.

I don’t understand the comment ‘Programme Set for Gravity’ how can I check this and what difference would it make ?

 

[kevplumb]

I don’t understand the comment ‘Programme Set for Gravity’ how can I check this and what difference would it make ?

depending on the model some have switches(usually on the back) to set fully pumped or gravity hot water

if its set to gravity you cant have heating without water