Water running hot-cold-hot-cold (shower & taps)

[Mr. Clueless]

Boiler = Worcester Greenstar 30Si

Noticed this a while ago & it got progressively worse. At first we thought it was the shower that needed to be replaced. So one night after my wife was cursing in the shower i thought i'd be the smart one & run the bath instead ... but it kept going hot-cold-hot-cold (i say hot, i mean warm). Maybe 30 seconds warm by a minute cold or something.

The flame light on the boiler would go out & then shortly thereafter the water would begin to run cold.

The pressure settles at 1bar but after the water had been running a while it was at 1.5 bar but then it'd be at say about 0.50-0.75bar.

My wife ran the water while i stayed watching the boiler & when it ran cold it would make surging noises like it was trying to kick in but couldn't. Then it'd make click-click-click noises. The pressure was under 1bar at this point.

The boiler was installed August 2012, i've been in touch with Worcester who say it's out of warranty. They responded with the following:

The boiler warranty has now expired,we have two payment options for a Worcester engineer to attend and repair your boiler.
The first is a repair only charge of £275.00. This will cover your Worcester boiler and its Worcester controls for labour, VAT and most parts however, should the boiler require a significant part, (such as a shell, a tank or back plate) or if the boiler is beyond economical repair, then the engineer will quote a revised charge on the day. Any parts fitted will be guaranteed for a period of 12 months and payment for the appointment is reserved, by credit or debit card, at the time of booking and then debited after the appointment has been completed.
The second option will cover the cost of this repair and will also provide a further 12 months breakdown protection at a cost of £300.00, which is payable via direct debit in 12 monthly instalments and administered for Worcester, by Domestic and General.
The charge includes labour parts and VAT, however if we find that we are unable to repair the boiler, or that it is uneconomical to repair, then you will be given a full refund. Only your Worcester boiler and its Worcester controls are covered and full terms and conditions will be sent to you within 14 days of taking out the cover.

As the name suggests i'm clueless at this & just wondering what the best course of action is here.

In this position would you guys get back in touch with Worcester and ask them to send someone to repair at a cost of £275 or £300 as quoted

or would you hit the yellow pages, find someone who can repair boilers & ask them to do it? Would you expect them to be much cheaper than Worcester? The guy Worcester sends out you would expect to know the boiler inside out whereas the yellow pages guy may not (although should be able to figure their way around it surely). Question is would you expect the yellow pages guy to be much cheaper as if not then i would guess it'd just make more sense to leave it all to Worcester.

Advice very much welcome.

 

[picasso]

The central heating system needs cleaning (the hot water heat exchanger is blocked) and I doubt wb would do that on a fixed price repair, find your self a good independent.

 

[Mr. Clueless]

The central heating system needs cleaning (the hot water heat exchanger is blocked) and I doubt wb would do that on a fixed price repair, find your self a good independent.

Thanks. I did think an independent would be cheaper but then i also thought Worcester MAY be a better option so figured i'd just ask those in more know than I.


Are you pretty confident that that is the cause?

2 questions then...

1) What causes this?
2) What's involved in sorting it - the process?

And actually for a 3) Any idea on what cost i should be expecting, approximately?

 

[picasso]

Everything points to blocked heat exchanger but never say never , if you clean the dhw heat exchanger without cleaning the system you will be in the same position in 6 months, hate to say it but a powerflush and a system filter fitted and the plate cleaned would solve your problem, no idea on costs as quality of plumbers can be variable.

 

[mcmoby69]

1. Dirt from the 1ch system lodging in the boiler.
2. Full system clean (powerfush?) A decent filter fitted. Replace or clean the plate heat exchanger
3. Cost? How long is a piece of string?
System size, access, location etc etc

Forget yellow pages, ask friends or relatives for recommendations.

(Edit. Wot he said)⬆

 

[Mr. Clueless]

Problem with asking friends - they only know of plumbers, not people qualified to be dealing with boilers. We've asked a few of them & it's a case of sorry i can't do that. Do they have to be gas registered or something?

The chap who fitted our log burner is gas registered plumber also & advertises as boiler servicing etc. He was a top bloke when fitting our log burner but i understand that may not include his plumbing work. His Facebook page seems to focus more on his log burner installs though.

Do they need special equipment for powerflushing i assume?

This filter - is it located within the boiler?


My system size is listed in my other thread https://www.diynot.com/diy/threads/...-screwfix-how-much-inhibitor-required.492653/ Would appreciate if anyone could clue me as to how much inhibitor this system needs as well. One plumber that came out put none in, one plumber just chucked a 1ltr bottle in. After a system drain i put in i think it was 2litre because i didn't know if 1litre was enough & i was told you can't put too much in (well if you put in 50 litre it may be too much but 2 litre i was told would be ok). Would just be good to know what's correct.


Oh & for some finer detail we're on 10mm piping, not 15mm :-/