Help! Engineer doesn't know what's wrong with boiler says replace it

[Dottierichardson]

Have a 6-year-old Worcester Bosch condensing boiler Greenstar Junior 28i Mk1v. Was working fine but the pressure was starting to drop a little and needed repressurizing more than normal. Had a guy in to service it. Gas Safe, seems very decent.

Came to service boiler and said needed a deep clean. Broke the seals and cleaned it, but pressure still dropping when heating off and climbing up to 2.2, dropping again and then climbing to well over 3 in the red zone. Guy thought it was an expansion vessel problem. Came back again and re-pressurised the expansion vessel, checked the PRV and the Schrader valve and anything else on/in it that might affect pressure.

Says readings all normal but fault still there and doesn't know what's wrong with it so can only suggest new boiler! Obviously that's drastic and expensive...any advice? Worried about having no heating but don't want to replace a boiler if don't absolutely have to do it. Says can use hot water in the meantime just not the heating, but think pressure too low to safely run hot water. Rang WB but they charge over 300 just to come and look at it and could offer no advice. Don't know what to do next, do I just cave and agree to buy no boiler and find cash to do so or is there another option? I've never heard of anyone not knowing what's actually wrong, is this common?

Thanks Dobbin how do people find your DH? Is there something to look out for in selecting someone?

It's recommendations mostly, he doesn't really advertise (though have a FB page and a website, think they're still in the Yellow Pages), not on any of those trust a trader things or anything like that. Because his dad set up the company so long ago their registration number is 3 digits. So if it's a low number the company has been around a while, but that doesn't necessarily tell you anything of the quality of the engineers. He always tries to help people over the phone first, or at least tries to get as much detail of the fault as possible.

I'm obviously biased, but I do think he is good at what he does and he is working crazy hours struggling to fit everyone in atm. But there's still been the odd poor rating on social media etc from an unhappy customer.

OP, we have been having a very similar issue. Plumber has ordered us a new expansion vessel as he said its likely the pipe is clogged with a tiny bit of dirt. He's also going to do a clean though he's not a fan generally of doing that as he believes the chemicals rot the boiler from the inside out but he said it should give us another winter at least (ours is a 15 year old Potterton).

Hi All, Just to say thanks again. Contacted one of the recommended engineers who got back to me earlier today, first thing he asked was if the last engineer had tried draining a radiator to check what impact that had and he also said he thinks it's likely an expansion vessel. And said that it was necessary to check out things thoroughly and if absolutely necessary might have to fit an external expansion vessel. So based on what Dobbin and JohnD2 said he sounds like he’s the sort of guy we need. I told him the other guy said not worth draining a radiator and that no-one does that anymore, and he said you have to do things like that to find out what’s going on!

But if you all hadn't confirmed that it was worth getting a second opinion and what ought to happen I wouldn't have had the confidence to go elsewhere or the knowledge to know what to ask the new engineer - who sounds really upbeat - about what to do or how to get a sense of whether he was more hands-on.

Also re-pressurized the boiler myself and then did a reset and managed to get the hot water running. So feeling quite chuffed.

Excellent, pleased to read this!

Glad you've found someone who knows a bit more! Keep us posted!

That's brilliant - hope you've got it back to fully functioning soon.

With some of the money being talked about on here i think i need to go self employed !

Hi op as many have said this sounds like a classic expansion vessel failure with he pressure rising so high when system is on (I used to work in heating industry) you should be able to temporarily keep topping boiler up to enable you have heating and hot water but it will continue to fail. A new exp vessel should cost in the region of £80-£150ish depending on model and where it's sourced from plus any labour to fit. Should not take longer then an hour to fit.

Well it all depends on the make and model of the boiler. For some models it simply isnt a viable and cost effective proposition to strip it and fit a new EV. In those situations an EV could be fitted elsewhere on the outlet pipework of the boiler/system.

I bloody love mumsnet for its esoteric knowledge and the fact there is generally a really knowledgeable person on any subject, including expansion valves. Hail the nest of bikers

Haha.. not bikers, VIPERS!

Thanks again, the new plumber's coming next week so will let you know the outcome...The original guy has completely disappeared into the ether...May have to fit an external expansion vessel, but hoping not to...anyway a lot less than a new boiler!

Katiethecarrot using the hot water, topped that up a week ago and has stayed at level. Haven't tried the heating though...

Just to update, new guy came today. He checked out the boiler, said that the expansion valve (EV) was not at the right pressure. He also thought that when the last guy pumped it up, he failed/forgot to drain the water out of the boiler first. So new guy drained the boiler, repressurized the EV to the right level, and everything is now running fine. It cost under a 100 quid. So in my opinion best case scenario previous guy not that good/worst case scenario it was a possible scam to try to get me to buy a new boiler. Anyway seems to be running okay now so hope that's finally sorted. Can't help wondering how many poor souls ended up forking out for boilers they didn't need, and probably could ill-afford.