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Hot water running hot then cold then hot...

Does what it says on the tin
OLTB
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Hot water running hot then cold then hot...

#436734

Postby OLTB » August 22nd, 2021, 9:24 pm

Evening all.

As above really - new combi-boiler fitted last year (Worcester) and when I run the hot tap, it takes an age for the water to heat and then it starts to run cold and then hot again. Any help appreciated and I’ll contact the heating engineers who installed it.

Many thanks, OLTB.

tacpot12
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Re: Hot water running hot then cold then hot...

#436744

Postby tacpot12 » August 22nd, 2021, 10:09 pm

Has it always done this or is this new?

AsleepInYorkshire
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Re: Hot water running hot then cold then hot...

#436750

Postby AsleepInYorkshire » August 22nd, 2021, 10:26 pm

Blockage in the hot water heat exchanger?

AiY

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Re: Hot water running hot then cold then hot...

#436757

Postby Mike4 » August 22nd, 2021, 11:11 pm

This is usually contamination of the domestic hot water heat exchanger.

It can be either water scale on the domestic water side or corrosion deposits on the primary water side. Did the installers of your new boiler carry out a thorough power flush of your heating system before fitting the new boiler? (This takes several hours or a short day, done properly.)

OLTB
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Re: Hot water running hot then cold then hot...

#436762

Postby OLTB » August 22nd, 2021, 11:25 pm

Thanks all - just started doing it the last few days and I think I remember them saying they were doing a full flush through - the dismantling of the old system and new location and installation of the new system took about 3 days last year. We live in a hard water area and they fitted some sort of filter to the pipes just under the boiler that I think helped with the hard water. Thanks for the advice about the heat exchanger and I’ll mention this when I book the appointment so they can bring a spare one if needed.

Cheers, OLTB.

bungeejumper
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Re: Hot water running hot then cold then hot...

#436783

Postby bungeejumper » August 23rd, 2021, 8:36 am

The filter ting below the boiler will have been a dirt trap (Worcester Bosch's equivalent of a Magnaclean), which catches iron deposits in the circulating water, so that they can be cleaned out once a year during the annual service. It doesn't have any contact with the actual domestic hot water flow, though.

You've got a ten year warranty with your boiler, so maybe you should just ask the installers?

BJ

Mike4
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Re: Hot water running hot then cold then hot...

#436949

Postby Mike4 » August 23rd, 2021, 11:59 pm

bungeejumper wrote:The filter ting below the boiler will have been a dirt trap (Worcester Bosch's equivalent of a Magnaclean), which catches iron deposits in the circulating water, so that they can be cleaned out once a year during the annual service. It doesn't have any contact with the actual domestic hot water flow, though.

You've got a ten year warranty with your boiler, so maybe you should just ask the installers?

BJ


Or better, ask the company (Worcester), giving the guarantee!


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