Gas boiler not heating water

macinalli

Hi folks,
Have a gas boiler that's used for hot water & central heating but since this week it's not heating thei water. The water pressure is fine and the heating still works as normal - just no hot water! I've tried the immersion and that works fine, but I'd rather not use that as a way of heating the water. Any tips on possible problems/solutions? Cheers!

DEVEREUX

Have you got your cylinder stat up around 60 degrees, if so might be faulty? just one possibility!

macinalli

The stat was around 60 - 70; it hasn't changed at all though and was working fine until this week. Is there a way to check if the thermostat is working ok?

DEVEREUX

Well if your heating is ok it sounds like your motorised valve to coil in cylinder is fecked. If you knock your boiler on to heat water a light should come on (Depending on model) this valve, if not you should be able to hear the valve open as soon as boiler is firing.

macinalli

I've noticed that when I turn the heating on, I get a steady green light on as the boiler kicks in. However when I set it to heat the water I get a flashing green light. It heats the water a little (v slowly) and is really just enough heat to bring it from v cold to just cold.

At this stage I think that I'm convinced that I need to get someone in. Does this sounds like a plumber problem? I've also had some (unhelpful!) suggestions that it might be electrical or to do with the boiler. Call out charges aren't cheap so I want to make sure I get the right guy!

DEVEREUX

Sorry to be throwing guesses at you, flashing green light could mean that boiler is being told that required temp is being reached. The pcb (circuit board) could be faulty. What make is the boiler?

Micky Dolenz

Very unlikely that the boiler is at fault. As already suggested it is more than likely a motorised valve or a turned down balancing valve.

Is there a valve with a box on it in the hotpress? the box would have a cable running from it, some thing like this:

macinalli

Hi, no valve like that in the hotpress. Is there a chance that it could be pump-related? A neighbour was telling me that other apartments have had problems with pumps giving up...

JohnnieK

You have a heating controls problem. If the boiler is heating the rads and not the water the boiler is more than likely o.k. What make of boiler is it? Can you look around the boiler to see if there are any motorized valves around they will look similar to what Micky posted, they will have a brass body with a small box attached to it. If you have a cylinder stat you have to have a motorized valve.

macinalli

Hi folks, sorry for the slow reply. First, the make of the boiler is Vokera.
Second off, I found the motorised valve - not sure how I never noticed it before! It's a Siemens valve and looks quite similar to the pic posted by Micky Dolenz. Is there a way of identifying if the valve is working ok?

Red Alert

There should be a small lever on it that you can move by hand - that should open the valve and fire the boiler.

macinalli

Have had a go at moving this lever from Auto to Manual but it doesn't want to move. It's at an awkward angle so I can't really see it too clearly - are there any tricks for this?

Also, if this does need replacing, is that a job for a plumber? Not sure how comfortable I'd be taking this on myself!

Red Alert

Depends if the valve itself would move if the motor housing was removed. If you want to have a go at changing it just make sure the power is off to the entire system first - then you'll have a power and switch loop on the valve motor. If it's that awkward to get at maybe a plumber might be a good idea.

JohnnieK

The lever is probably locked in a groove and needs to be pulled forward or backwards before moving it. Get a little mirror and have a look if it's at an awkward angle.