Zone control valve playing up

[gcoco]

Please can somebody help.

About 6 months ago my boiler stopped producing hot water. The central heating worked fine, though unfortunately it was the middle of Summer.

I called in a gas engineer who had been recommended. I'd already figured out that if you moved the lever on the back of the zone control valve you could get hot water, but had to set the central heating as well to get it to switch on. Therefore, I turned all the radiators off until he came round to look at it.

The helpful chap replaced the rectangular metal box, saying that the pipe section didn't need replacing. It worked fine after that. Push the button, hear a whirring noise, then the boiler started heating up.

However, now it's packed in again. Basically it works some days and doesn't on others. Doesn't seem to be any logic behind its choice of days either.

So, I called the nice man back in. He had the cheek to stand next to me and lie. "I don't fit that brand" he said, "but I will replace it if you want." At a nice price too I'm sure.

Trading Standards will be hearing shortly. In the meantime, can anyone tell me if I can get away with just replacing the metal box or if it would be best to get the pipe bit replaced too (I understand there's a rubber ball in there that can corrode too).

The box says "Terrier" on it at the moment. The one on the central heating pipe just above it is a Honeywell.

Any help gratefully appreciated (unless you happen to be a Scottish gas engineer living on the Chantry estate in Ipswich).

 

[bengasman]

All depends on why it is not working.
Can be the head has packed up again, or the actual valve might be stuck. Can’t tell for sure unless you take the head off.
Must admit I am not familiar with terrier 3port valve.

 

[gcoco]

Thanks for that. It came on no problem this morning, but it's going to need fixing sometime.

I reckon I can change the head myself quite easily, it looks exactly like the Honeywell 2 port valve just above it. I'm not going to attack the pipe though.

Can anyone tell me what I'm looking for in the head to see if it is that that's stuffed?

Thanks

 

[bengasman]

2port valve abovde a 3port valve?
sounds very dodgy, put some pics on

 

[gcoco]

It's a normal 2 port zone valve/motorised valve directly below an identical valve that controls the heating flow. Don't think there is a 3 port valve nearby.

Anyone got any idea how I can tell if the whole thing is stuffed up, or should I just replace the metal box and hope that does the trick (mind you, that may be what the engineer did in the first place?)

Thanks