Broken zone valve for downstairs heating?

[Flemingjp]

Hi all,

Hoping to check if I have a genuine fault, or something I've overlooked.

I've just moved into a my first house with a conventional boiler and hot water tank. The heating system has two heating zones (upstairs / downstair).

Currently with both thermostats up high and the heating zones active on the boiler controller, the downstairs radiators do not heat up.

If only the downstairs heating zone is on, then the boiler doesn't to run. Upstairs heating and hot water work just fine.

Is this most likely a broken zone valve stuck at "off"?

Any ideas on cost of repairs if this is the case? The boiler is a Potterton Promax SL 15kW and I am in the North East of England.

Thanks for any advice.

 

[Chuck]

What sort (make, model, wired/wireless) of thermostat do you have?

Does the suspect zone valve make a noise when its thermostat is moved from high to low?

Try opening the downstairs zone valve using its 'manual lever' and latch it into its 'open' position. (This won't normally fire the boiler.) Then move the upstairs thermostat to 'high' so the boiler fires up. Does the downstairs zone come on now? Compare the force need to operate the zone valves manually, is the suspect valve significantly different from the working ones?

 

[Flemingjp]

Hi Chuck, thank you for your response

The thermostat for the downstairs heating zone is a Honeywell DT92E which appears to be a wireless thermostat despite ours being fixed to the wall.

The suspect valve made no noise when turning the downstairs thermostat from high to low.

Trying the manual lever, with the heating off at the thermostat and event programmer, fired the boiler and the radiators heated up. This was without the upstairs heating being on.

With the upstairs heating on, and the suspect valve opened manually, the radiators downstairs did heat up.

The force to use the manual lever compared to the other two is comparable when the heating is off.

However when the heating is on, the upstairs value manual leaver is free moving (I assume as the valve is already open). Where the downstairs zone valve still has the original resistance. (Suggesting the valve has remains closed?)

Hope this helps - thank you again

 

[Chuck]

Find the receiver box for the zone valve and have a look at the lights on it. Try pushing the button, which should operate the zone valve. (One push to open, another push to close, etc.) Also have a look at the thermostat display, are there any symbols displaying. E.g. A flame icon should appear when you increase the set point and disappear when you reduce it.

 

[Flemingjp]

Hi Chuck,

I was unable to find such control for the valves either near or on the water tank, or the floor directly below around the boiler.

All the zone valves are wired into the white box in the top right of the image.

The thermostat displays the flame icon when the temperature setpoint is above the current temperature

 

[Chuck]

I was unable to find such control for the valves either near or on the water tank, or the floor directly below around the boiler.

Seems odd, if you have a wireless thermostat there is surely a (BDR91) receiver to control the valve somewhere. Perhaps you are mistaken about the thermostat model or the receiver is boxed in somewhere. Either way, the next step is to check the voltages at the suspect valve. Unless you are competent to undertake live mains-voltage testing you should leave this to a qualified heating engineer.

I don't know what people charge in your part of the world but it'll probably be a minimum charge (e.g. couple of hours labour) and parts. Say £150 give or take. Seems a lot for a simple job but it's what people need to stay in business and they ain't going to get rich if they only charge that!

Good news is that you can latch the ground floor valve open and run the house a s single zone using the upstairs thermostat for a few days so it's not an 'emergency' call.