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More Central Heating Woes

Community Veteran
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Registered: ‎04-08-2009

Re: More Central Heating Woes

@Mook

I'll lay you 10 to 1 that you have a zone valve somewhere that's stuck in the on position. The thermostats for room and tank temperature drive the zone valves for heating and hot water. These have a set of contacts in the head of the valve and a micro-motor. When the thermostat calls for no heat, the appropriate valve is supposed to lose it's control signal and run shut, and in doing this the butterfly flap in the pipe closes and the power goes off the boiler.

If the valve sticks, even though the signal to the valve motor has gone, the valve is still in the same physical position and still puts power to the boiler. The butterfly flap stays open and you get continuous heat, regardless of the thermostat position.

Inside the valve head is a manual lever. This can be pushed closed and will turn off everything, but it won't work on auto. You need a new zone valve. About £35 from Screwfix, Toolstation etc..

Community Veteran
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Registered: ‎16-10-2014

Re: More Central Heating Woes

@nozzer, I have what I think are two of these zone valves in the cupboard where the hot water tank is, I saw them when I went looking for the stolen water pump! They are fitted to the pipes and both have power supplies and toggling the manual switch has no resistance on either. So that looks promising I think.

 

Community Veteran
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Re: More Central Heating Woes

@Mook

You might have to raise or lower the lever slightly to get it to engage, depends on Manufacture. You should also be able to take the head cover off and have a look at the innards. MIND THE MAINS THOUGH!

The valve position should be indicated by a line or arrow somewhere on the valve body. There's not much else it can be. If you're getting continuous heat the boiler has a continuous call on it from somewhere, and the zone valve is the only thing it could be, assuming your thermostat is performing ok.

The heads are replaceable on their own, and the motors burn out as well and can be bought separately, but if the valve is physically stuck you need to exercise it manually or replace it.

Community Veteran
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Re: More Central Heating Woes

@Mook

I might be slightly out of touch with prices though! £80 looks more like it nowadays. If the whole valve needs replacing you'll need to drain the system.

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Re: More Central Heating Woes

@nozzer old bean I owe you several beers. :thumbsup: I went back the the cupboard and the valve marked C/H had no resistance but the one marked H/W does now. So using some applied logic I clunked the C/H valve with my stethoscope screwdriver and it made some weird noises and the resistance on the lever has now returned and the screaming in the control radiator has stopped and is now losing heat.

I'm know it's only a temp fix but all the same I now know what the tell the Plumber / Gas man.

 

 

Marksfish
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Re: More Central Heating Woes


@nozzer wrote:

If the whole valve needs replacing you'll need to drain the system.


We had some valves replaced in our system recently. System wasn't drained, the plumber froze the pipe instead and did the job. 

Community Veteran
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Re: More Central Heating Woes

In bed this morning when I was woken to a sound like an electric toothbrush running inside a glass. So I get up and I realised what it was as soon as I pulled the quilt off of myself. It was the heating trying to come back on from yesterday and the zone value was working overtime.

It wouldn’t stop with a clunk so I had no choice but to turn the heating down again and that stopped it. So it looks like I need to get a plumber in as soon as possible so that’s another job for today.

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Re: More Central Heating Woes

@Mook

It keeps you on your toes! :wink:

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Re: More Central Heating Woes

Yep sadly @Mook I think that's what you're going to have to do.

It will cost of course, and all you can hope it is an easy fix. Let us know how it goes and what the problem was.
You don't of course want a semi-functioning house with the heating of course, if the weather gets bad this time of year.

I can't really help with any useful advice as this topic is way out of my league.

I've had a boiler break and had to have the whole thing replaced, which all I can say it hit my wallet hard.

JayG
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Re: More Central Heating Woes

Before she had her boiler replaced a friend of mine had several call-outs for motorised valve problems, none of which involved draining the system, so the work might not be too labour intensive with any luck.

On the subject of new boilers, I had mine replaced 2 years ago, at which time the major players, including Worcester-Bosch, Vaillant and Ideal were engaged in a 'warranty war' with extended parts and labour guarantees of up to 10 years (subject to an 'approved' annual service.)

Worth checking that out if you conclude you've reached the point where you might be chucking good money after bad @Mook.

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Re: More Central Heating Woes

My sister called someone out locally from a website called topratedpeople (don't know if it still exists). Sorry don't tell me off mods that is a bit of cheeky advertising. :tongue:

The guy who replaced the boiler was very good, and of course it was around £1500. Cash, otherwise I will have to charge you VAT on top.

Of course you go for the cash option, so I jumped the bus to my nearest bank (10 minutes) and had to withdraw it one go. I bank with Barclays, (sorry another bit of cheeky advertising), but I didn't know this but their internal cash machines will let you withdraw £2000 a day so a bit more than the external ones.

Useful to know in case and I don't know if other banks do this.

Mind you I suspect you'd be hard pushed to find a someone in the building industry who declares all their income on their tax return.

I've got a Valliant, the broken one I had was a Ferroli which I was informed are not that good.

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Re: More Central Heating Woes

@JayG, I had given thoughts to this back in 2015 when I had the expansion tank fitted, the current boiler was fitted in 2009 so it may well be showing it's age and may not be the most efficient, but having said the the boiler for now works. Replacing it does appeal to me but how long would it take to return my investment on any savings gained on installing a newer more efficient one.

Now where's my bit of string...

 

Marksfish
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Re: More Central Heating Woes


@Mook wrote:

Replacing it does appeal to me but how long would it take to return my investment on any savings gained on installing a newer more efficient one.


And of course, new boilers have to be the condensing type, which bring their own set of problems at this time of year. The one I keep hearing is the vent pipe freezing, therefore rendering the boiler non functional until it thaws out. Handy mid winter, not!!

Mark

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Anonymous
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Re: More Central Heating Woes


@Marksfish wrote:

The one I keep hearing is the vent pipe freezing, therefore rendering the boiler non functional until it thaws out. Handy mid winter, not!!

Mark


 

Ensure the vent pipe when installed is on a downwards incline, so that the water flows all the time, and not static.

 

Community Veteran
Posts: 2,984
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Registered: ‎04-08-2009

Re: More Central Heating Woes


@Marksfish wrote:

@Mook wrote:

Replacing it does appeal to me but how long would it take to return my investment on any savings gained on installing a newer more efficient one.


And of course, new boilers have to be the condensing type, which bring their own set of problems at this time of year. The one I keep hearing is the vent pipe freezing, therefore rendering the boiler non functional until it thaws out. Handy mid winter, not!!

Mark


 

If it's installed properly it's physically impossible for that to cause a problem. There should be an air break in the condensate drain to stop water backing up from a frozen pipe and into the boiler, which then causes it to trip out. All you would get is a drop of water on the floor or into a bucket. The problem is that many installers don't know how to install them in compliance with the regs! Some types use a Syphon that drops a lot of water at a time. They don't need an air break because they tend not to freeze up.