Hot water but no central heating

[NickMidlands]

Hi All

I'm hoping to get some much needed help please!

I have an issue with my heating. I have an Ideal boiler which feeds the central heating and also a storage tank in the upstairs airing cupboard which supplies hot water to the taps and shower.

The hot water works fine from the controller but no central heating.

I have read that there should be 240 volts at pin 2 of the connector block of the boiler when the system demands hot water for either heating or water. This is the case for hot water, but there is never demand at this pin for heating.

The controller (also in the airing cupboard) has a junction box below it and I have found the terminals for both heating and hot water and everything seems fine here as they both change state when the controller requests it.

Also in the airing cupboard are 2 honeywell control valves. One is connected to the storage tank and I assume the other is for the heating. They are both electrically connected to the junction box. Unfortunately I cant get inside the control box for what I think is the heating valve because it has been installed too close to the floor boards and I can't get to the screw so I'll need to spend time taking the whole thing out perhaps.

I'm wondering whether a faulty valve will prevent the boiler from receiving a demand signal? Does the signal from the controller in effect pass through the control valve?

Out of interest if I connect pins 1 and 2 at the boiler it is constantly on demand, but I have to manually overide the heating valve (small lever) in order to get flow through the radiators. I'm currently using the heating this way to get me by.

Am I right in thinking the Honeywell control valve is the most likley problem and If so is there something I can try to fix it, or am I able to replace just part of it once diagnosed i.e. just the electronic control box if this is the issue?


Thanks in advance


Nick

 

[HERTS P&D]

There should be a lever on the valve that you can 'latch' open.


Andy

 

[K4Gas]

The heating side Honeywell 2port valve will need replacing
You can change just the head if you get the same model so no need to drain down.
Power off. Change head. Wire up the same. Power on. Heating

 

[stem]

I'm wondering whether a faulty valve will prevent the boiler from receiving a demand signal? Does the signal from the controller in effect pass through the control valve?

Yes, inside the motorised valve is a small microswitch that is operated when the valve opens, this switch is connected to the boiler and turns it on. Either failure of the microswitch, or the valve motor which would prevent the valve opening would cause the symptoms you describe. Either way, as the others have said, a new valve, or powerhead should see you right.

 

[NickMidlands]

Thanks everyone this is really helpful.

I'll report back once fixed.