Central Heating Motorised Valves

[diynoob]

Hi,

I'm trying to get to grips with the CH in a house I have recently moved in to. Firstly, the house has no gas. The HW is heated by an aga. If the aga is off, the HW can be heated by an immersion on the HW cylinder.

The CH is heated by an oil boiler. My assumption is that the HW and CH are therefore completely separate. So I am a bit confused to see 2 motorised valves off the boiler.

The one near the pump is for the CH I would think so would appreciate if someone could explain what the other valve might be doing.

Thanks

 

[ianmcd]

possibly separate circuits for upstairs and downstairs, cant really see much in your pics

 

[diynoob]

Sorry about the pics, will take some better ones. In terms of heating controls the radiators have TRVs and there is a thermostat in the hallway. I cannot find a programmer or second thermostat. When I turn the thermostat up the boiler fires up and all of the radiators get hot.

 

[diynoob]

It is meant to be a 2 zone system! A better photo is attached.

When I turn up the hallway thermostat, the valve on the right comes on and the pipes around it get hot. All but two of the radiators get hot.

If I then manually turn on the left hand valve, the two remaining radiators get hot. These two radiators are in bedrooms 2 and 3, which were not really used by the previous owner. So it looks like they tried to make a second zone for those 2 rooms.

So the remaining mystery is how I am meant to activate zone 2. Surely it wasnt designed to have to manually open the motorized valve? There should be a second thermostat near zone 2 I guess, but there isnt one. There does seem to be an extra wire coming from the wiring centre near the boiler.

 

[Nozzle]

Is your AGA solid fuel? If so, that's fairly telling as tI think they should be set up to work with natural circulation (though that's not to say can't ALSO be pumped). Perhaps the AGA was added later as a luxury but there was no need to get rid of the oil boiler. Then, once there are two heat sources (one which NEEDS a pump, the other which be able to function safely without one) they need connecting together somehow. Using the AGA to heat a tank of cold water makes sense, then the oil boiler to fire the radiators during winter.

With this in mind, you might find there is a circuit of large bore pipe from the AGA to the cylinder which is separate from the rest of the system?

Nozzle

 

[diynoob]

The aga is oil. Yes there will be a separate circuit from the aga to the HW cylinder. Haven't looked yet as I'm happy with how the HW is working. It's the above CH circuits that I'm confused about.

 

[Nozzle]

Then I agree with IANMCD - different circuits. You can feel and hear each motor operate when you force each channel of the timer to run. Do so, and go around and feel the radiators and you'll know which get hot and which do not.

Unless there's a UFH manifold hidden away somewhere? Hoa many pipes go into/out of your hot water cylinder?

 

[diynoob]

You can feel and hear each motor operate when you force each channel of the timer to run. Do so, and go around and feel the radiators and you'll know which get hot and which do not.

Hi, thanks. Yes I already did that as explained above:

When I turn up the hallway thermostat, the valve on the right comes on and the pipes around it get hot. All but two of the radiators get hot. If I then manually turn on the left hand valve, the two remaining radiators get hot. These two radiators are in bedrooms 2 and 3, which were not really used by the previous owner. So it looks like they tried to make a second zone for those 2 rooms.

So the remaining mystery is how I am meant to activate zone 2. Surely it wasnt designed to have to manually open the motorized valve? There should be a second thermostat near zone 2 I guess, but there isnt one. There does seem to be an extra wire coming from the wiring centre near the boiler.

So I know which rads are operated by which valve. It just seems odd that the only way to turn on zone 2 is to manually operate the valve. There is no thermostat or programmer in zone 2.

 

[Nozzle]

You could link the two valves in parallel (electrically) so when one operates, they both do - but only one set of Aux contacts is used to fire the boiler.

Nozzle

 

[diynoob]

Hi, thanks, I think I'll try that. I dont really know why they went to all expense of an extra zone rather then just turning the TRVs down in the 2 unsed rooms.

Before trying your suggesion though I'll try to trace the wire labelled ??? as I think that must have been a zone 2 thermostat at one point and perhaps got removed. If so I may be able to just put a thermostat on the end of that wire to get zone 2 functioning again.