Heating only works when HW is filling

[Monkey789]

Hi all

As per the title really. I need some advice if possible.

As most people seem to be turning on their heating around about now, we have recently done the same.

Turned the heating on and it's not working. It's not working independently without HW being on. It's only working when the hot water is active and filling up. If the hot water tank is full, the heating won't warm up. We have a 'normal' boiler, not combi. Sorry don't know what they're called!

I've looked in the airing cupboard and the valve appears to be working. I've had the wife turn each heating and hot water on in stages and the valve turns. I've held the pipe that feeds the radiators and when the heating is turned on with the hot water, you can feel the pipe suddenly go boiling hot, so to me, there's nothing wrong with the central heating itself. When the hot water is off, the heating is on, there's no hot water flow down this pipe. The boiler neither fires up when heating is switched on alone.

I'm at a loss! I'm no expert at all, just a little knowledge that I've read myself and what plumbers have said when we've had previous problems.

We have a Tower 3 port valve. This was replaced about two years ago by a plumber. The pump is also working, this is a DAB pump that's was also replaced about two years ago.

I thought there may just be an air lock so I've banged the pipes to no avail.

I would appreciate any advice! Hoping this will be a DIY job as opposed to calling someone out.

Many thanks in advance.

 

[picasso]

Looks like your 3 port valve has a fault , it's opening to c/heating so programmer and stat ok, I would guess one of the microswitches in the 3 port head has failed, I think you can just change the head on these.

 

[Monkey789]

Thanks for the reply.

Whats a micro switch and where could I get one from? Sorry if this is a dumb question.

I assume this is an easy job too.

 

[picasso]

You can replace the valve head for £35 .

 

[Madrab]

You want to check model numbers off of your valve but one of these is what you probably need. The microswitches are internal to the head.

http://www.heatingcontrolsonline.co.uk/tower-val322mp-val328mp-a3mid-powerhead-p-426.html

 

[Monkey789]

Ah ok so I just need to change the bit in the picture and not the pipe bit that's attached to it?

Seems easy enough to me, thanks for the advice will give it a go!

 

[Madrab]

Just remember a few points. This is not definitive. You really need to check the circuit to confirm that the switched live to the CH isn't being made when the valve switches, confirming that the microswitch is actually at fault and replacing the head will fix the issue.

• Isolate the mains before any electrical work
• make sure the type you buy is the same as the one you are replacing
• Ensure you are aware exactly how to remove the old one and replace with the new