Plumbing issue in new build

[Dan Le Moignan]

Evening all,

Hope everyone had a good Christmas and new year!

Random place to ask but always used to be some plumbers/ gas fitter in here!

Unfortunately since the previous cold spell we have had heating issues in our new build.

Its been fine from August to start of December (albeit slight whistling type noise from the cylinder at times)

We have a Worcester system boiler with Gledhill stainless es cylinder (unvented).

Issue started in December when a bath was run, no issues but then run out hot water when bath was topped up (never ran out of hot water before)

Assumed the wife had just emptied the cylinder and no issues.

From that point on hot water is hit and miss (Occasionally using Emerson)

Central heating seems lethargic, downstairs is UFH, the stats hit there set points but takes longer than before and floor is only warm in random areas (was not like this before)

Upstairs rads barely get warm at all.

Cylinder area seems to have gotten noisier also.

With this in mind I thought it was an air issue or problem with the 2 port valves.

Had the builder back out, everything bled and checked valves and was told no issues.

He mentioned the boiler pump would run for a few mins then stop, then cut back in again so said I needed to get Bosch engineer out as boiler fault.

Engineer came out just before Christmas which was great and thought it maybe a software or pump fault so replaced both items.
This unfortunately made no difference.

The Bosch engineer is saying the boiler return is only ever warm at best which points towards a partial blockage in the circuit.

Is this common on a new build?

Awaiting a reply from the builder now as Engineer saying a hot flush needs to be done.

I will try and upload two videos of the noise

Many thanks for any input, sorry for the essay!

Just don’t want to get fobbed off by thebuilder/plumber next visit!

[Dan Le Moignan]

When I think back the upstairs heating circuit was always switched off when first moved in and there were no issues
The problem was a couple of weeks after putting upstairs heating to timed, wonder if it’s dislodged something which is caught up by the 2 way valve causing the whistling as water pushes past?

Although if this was the case I’d expect the downstairs circuit to function fine.

[Dan Le Moignan]

https://youtu.be/5bJVycSpQ_U

Video of whistling noise, think this is whilst boiler is heating the cylinder, from the video the noise goes as I turn the upstairs heating stat up

[Dan Le Moignan]

Another random noise!

https://youtube.com/shorts/ytPQ40rtsfo?feature=share

[Svenb]

Is there a expansion vessel next to the unvented cylinder?
that needs to be pressurised

[Dan Le Moignan]

Yes there is an expansion vessel above, although no gauge so not sure what pressure it is

[Svenb]

Should be 3 psi

[Svenb]

Should be 3 psi

[Dan Le Moignan]

Thank you.
Plumber out yesterday and blew down the flow and return which all seem clear
Leaning towards the boiler being at fault so Bosch coming back out today

[Dan Le Moignan]

Turned out to be the heat exchanger in the boiler!
First one the Bosch engineer has had to do.
Fingers crossed I’m all sorted

[AJC]

That's a good result. Having completed a new build myself and having some niggling issues, they're very frustrating.

[Darrenaf]

Dan, there is a known problem with these boilers and the heat exchangers, Worcester/Bosch know about the issue, but are not doing a recall, if they have changed the heat exchanger they should also have done a software update as well.

[Dan Le Moignan]

Cheers guys, starting to go fed up with it!
Yes Darren they also changed the PCB/ software update.
Seems to be working ok but now get a drowning/ low frequency type noise for a minute or so when the boiler kicks in.
This is quite noticeable when sat in the lounge and once you hear it once really starts to irritate you
Im sure it never did this before so going to get them back out yet again!