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heating but no hot water

Can anyone please help. I am unable to get any hot water using my gas fired central heating boiler when it is in either the heating and hot water mode or in the hot water only mode. I have a service contract with British Gas but all they suggest is that I have the system flushed at a cost of =A3250 as the problem is due to sludge and this is not covered in the contract (suprise suprise!!) The engineer made no attempt to diagnose any other causes and I was wondering if anyone can suggest any as I am loath to pay out for a service that may not be necessary. Many thanks Elsie

Reply to
elsie
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It's most likely the motorised valve on the HW circuit failing to open - due either to a seized valve or failed actuator.

We'd need to know more about the configuration of your system - number and type (2-port, or 3-port) of motorised valves, etc. - to be able to provide a more accurate diagnosis.

Reply to
Roger Mills

Hi Elsie,

we had a similar problem at the beginning of the year. We too have an insurance contract with British Gas who promptly came out and did a thorough check then diagnosed the problem as 'air in the system'. They bled a few radiators then turned on all the taps in the house in a specific order (can't remember which) but it worked. The hot water returned straight away. I was a bit unsure that air could have been causing the problem, but they said that ours was an old-style system with the water tank set at the wrong height (or at not a very suitable height) which often causes air blockages. I explained that we often got a lot of spluttering from the tap in the bathroom sink and the guys told me to turn on the taps in that order I have now forgotten... and that would alleviate the problem. It did and we haven't had such a problem for a long time! Hope that helps, Jo

Reply to
Jo

I interpreted the original question to mean that the HW wasn't being heated - resulting in cold water - rather than nothing - coming out of the hot taps.

Perhaps the OP (Elsie) could clarify?

Reply to
Roger Mills

Stuck motorised valve.

Reply to
The Natural Philosopher

Is it a combi boiler, or have you a hot water storage tank?

Reply to
Dave Plowman (News)

THANKS FOR ALL THE REPLIES BRITISH GAS DID TURN UP TODAY AND STILL INSIST THAT A POWER FLUSH IS WHAT IS NEEDED. THE ENGINEER REFUSED TO CONSIDER ANY OTHER CAUSE OF THE PROBLEM. NEEDLESS TO SAY I AM NOT SATISFIED AND AM WAITING FOR A TECHNICAL SUPPORT PERSON TO CONTACT ME. THE SYSTEM IS A STANDARD BOILER (ie NOT COMBI OR CONDENSING) AND THE PROBLEM I HAVE IS THAT I DO HAVE WATER COMING OUT OF THE TAPS BUT THE BOILER IS NOT HEATING IT IN EITHER HOT WATER ONLY OR HEATING & HOT WATER MODE. HOPE THIS CLARIFIES MY PROBLEM. I LOOK FORWARD TO MORE REPLIES. THANKS ELSIE

Reply to
elsie

PLEASE TURN OFF YOUR CAPS LOCK!!!

Thanks for clarifying the problem - it is as I assumed.

But we still need more details about your system configuration - as per my earlier message.

Reply to
Roger Mills

  • *PARDON?* *
Reply to
Chris Bacon

The clue that tells me this is a combi is "either the heating and hot water mode or in the hot water only mode" That'll be the summer/winter switch on the combi.

If there is no HW when a tap is run then given that the heating is otherwise fine there are only so many possibilities:

1) Boiler makes no attempt to fire - something wrong with the DHW flow detector. 2) Boiler fires but rads get hot instead little or no HW - diverter valve problem. 3) Boiler fires but then shuts down very soon afterward and water is cool/cold - partially blocked secondary heat - just possibly the system needs flushing out. The underlying problem still needs sorting which in this case will be very likely be the expansion vessel - constant topping up and so forth.

Call me cynical if you must but I am always suspicious when 'flushing' is prescribed without other measures. Likewise PCB failure should be the last resort not the first (unless it's a Potty Suprima).

Reply to
Ed Sirett

Hi Ed Thanks for your reply but the boiler is not a combi. The settings referred to are on the timer switch. The boiler fires up fine in both modes.Radiators all get hot but the water coming out of the hot taps remains cool. When in the 'hot water only' setting, the boiler fires and runs OK but again fails to heat the hot water in the hot water cylinder. It does however heat up the bathroom radiator !! Maybe it's time to replace the whole system!!! Regards Elsie

Reply to
elsie

In message , " snipped-for-privacy@fish86.fsnet.co.uk" writes

Aas has been said, we need bit more info to help further. The likely reason as has been said is faulty motorised valve (this/they control the flow of water around the heating system/HW heating circuit)

Do you know if you have any such valves (they look like samll box attached to the pipe) probably either near the boiler/controls or near the tank?

Not at all, if the above is the problem it is pretty simple repair (the motorised bit can be replaced easily) BG are being supremely useless, if they continue in this vein, I'd get someone else to do the job, then take BG to the small claims court.

Reply to
chris French

As others have said, the likely cause is a stuck motorised valve. It's

*very* unlikely gunge would only effect the hot water, and have no effect on the CH.
Reply to
Dave Plowman (News)

Unless that radiator is off a separate circuit, that would seem to invalidate the motorised valve theory, and implicate a blocked DHW heating coil.

Reply to
The Natural Philosopher

I tend to agree. If it's an S-Plan system, and the HW valve isn't opening, the boiler shouldn't fire in HW-only mode, but apparently it does!

I'm beginning to wonder whether it's a gravity HW system with the bathroom radiator on the gravity circuit. If so, and if the radiator gets hot but the coil doesn't, it sounds like a blocked coil. I suppose there could be a partial air-lock which is allowing enough circulation to heat the radiator but not enough to heat the HW.

Elsie, in HW-only mode, with the boiler running, do any of the pipes around the HW cylinder get hot? Does the pump run in this mode, or is that only used for the CH?

In which part of the country do you live, in case someone fancies having a look at your CH system?

Reply to
Roger Mills

Once again thanks for all your comments. Whilst searching for the motorised valve, we discovered that the eddy tank was bone dry due to a stuck ballcock. This has now been freed and hey presto - plenty of hot water and silent pipes. Cost - zero. BG would probably have noticed this and rectified the problem whilst carrying out the =A3250 powerflush but would have kept quiet about it. Obviously I shall be advising BG what they can do with their HomeCare cover and their supposedly trained engineers. I shall be demanding a refund of all my premiums as the service they supply is totally useless. Many thanks to all who replied Elsie

Reply to
elsie

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