Advice / opinions on electric combi boilers

[Chalked]

On long lengths of flue there is an inner support. Sometimes these are not located on the correct place. This makes the inner flue joints sag. They then leak condensate water, which is extremely corrosive.

 

[DevsAd]

Not all dev some are metal

Also probably a flue seal had gone and started leaking condense liquid

You still get steel concentric flue for modern gas boilers? Jeepers.

 

[DevsAd]

@DevsAd Well, at least this time I was smarter and asked them do it in a screw-on boxing so theoretically it should be possible to take boxing off, and put in a new flue. But I'm really worried there is something wicked in the layout of this flat that makes it impossible to do it well. There are some pipes going down between boiler room and bathroom that somewhat limit the position of the flue (it didn't seem like it was in the way but... who knows). I really tried to check everything (according to my very limited layman's knowledge, of course) - so I double checked their drop calculations, and I know they installed quite a few support points. Whilst the first guy cut corners, with these guys I had a feeling they really tried to make it right.

The company that came today to give me quote for electric said they could do a new gas installation (well, technically they said they could fix the flue on this one, but then it would only be 1 year warranty, which, if it breaks at speed so far, will not be long enough to see if it's done well).
Is it possible that the problem was caused by a boiler that was not good enough for this length of flue (despite what manufacturer says)? Could replacing it with a new one potentially make it better, or is it just them trying to make more money? In any case, with all the leaks that were happening I suspect this boiler might be on its last legs anyway...
I'm really torn. I would much, much rather stay on gas for obvious reasons but I'm really scared I'll face this issue again (and even if this time they paid for fixing, that does not compensate for being weeks without hot water/heating!).
Sigh.

The actual flue run looks ok, and there's straight and consistent slope there.

The flue as it comes out the boiler does, however, have an extra elbow to 'crank' the flue away from the back wall a bit presumably to avoid something? Elbows certainly don't help flow, but I presume this was taken account of in the length calcs?

But the original question still remains - WHAT is wrong with that flue? WHERE is the exhaust gas getting back to the boiler?

And a new one - why will they only give a 1 year warranty on a new flue?! What's this great mystery? What are they expecting to happen again?!

I am clearly missing something pretty darned obvious here.

 

[ShaunCorbs]

You still get steel concentric flue for modern gas boilers? Jeepers.

Either steal, alu or plastic outer
And alu, plastic or ss inner

 

[Lili]

@DevsAd you have a very good eye even with these few details. The flue is pished away from the wall as between bathroom and boiler room there is space for for pipes and there is one (big one) going next to the wall. So the flue needs to fit in little space between that pipe and the bathroom wall. Still, max length of flue is 10m and the run is around 6.5 so that leaves some space for this extra bend, theoretically.
As for: what is leaking, I'd like to know that now. When the first guy came and said it I accepted it, but now I wonder if that's the case. He tried to show me that some gas/steam is coming from the flue into boiler but whether it indeed was or was it coming from somewhere else I couldn't tell.
I wonder if perhaps the only leaky bit is right next to elbow. Can something like that be replaced as a part or the whole flue needs to be put from scratch?

 

[DevsAd]

I don't know what the leaky bit ist, but I'd love to know. My guess, too, would be the connection to the boiler, or one of these first bends. And, yes, in theory only that part would need replacing - a dead easy and dead cheap job.

I must be missing something, tho' - the only other conclusion is that all the plumbers you have had out are 'trying it on' in some way, and that is extremely unlikely!

They have seemingly all come to the same conclusion - there is an inherent 'issue' with this setup that - for some bizarre reason - cannot be resolved by simply replacing a dodgy flue part with a good new one.

But I can't get my head around what that 'issue' could be.

For plumbers to go to the lengths of recommending a change to an electric combi (yuck...) for a 5-year old boiler (that's no age), or to offer only a 1 year warranty on a new flue does suggest there's something else going on, an 'issue' that I ain't getting.

Lili, you are now an 'informed' layperson - you have a good grasp of what's involved here - so if you could insist these plumbers explain, in laypeep's terms, what the 'ell the actual issue is, that would be great. And then folk on here could almost certainly advise further.

 

[Harvest Fields]

@DevsAd you have a very good eye even with these few details. The flue is pished away from the wall as between bathroom and boiler room there is space for for pipes and there is one (big one) going next to the wall. So the flue needs to fit in little space between that pipe and the bathroom wall. Still, max length of flue is 10m and the run is around 6.5 so that leaves some space for this extra bend, theoretically.
As for: what is leaking, I'd like to know that now. When the first guy came and said it I accepted it, but now I wonder if that's the case. He tried to show me that some gas/steam is coming from the flue into boiler but whether it indeed was or was it coming from somewhere else I couldn't tell.
I wonder if perhaps the only leaky bit is right next to elbow. Can something like that be replaced as a part or the whole flue needs to be put from scratch?

Did we get an answer as to why the case is off the boiler?

 

[Lili]

@DevsAd Thanks a lot for your input, it made me think, and question, and call another person in to try and fix it. I trusted the first guy and went on the assumption that the whole flue would have to be relaid, and that being a second problem with flue, I thought it cannot be done right and thus electric is the safer option. Therefore, the other visits I had were for a quote for new installation only (they didn't even start they boiler).
After your questions and input I decided to call another person in to try and fix it, or at least explain to me why it cannot be fixed. The result is that this guy actually decided to check WHY the flue is leaking, and it turns out it is a problem with installation right near the boiler entrance. Basically, the previous company hung it a little bit too low, and rather than correct their mistake, they fudged the connections on the flue right next to it (see new picture). So the flue (probably) never had a proper, tight fit and it's a bit of a miracle (not) that it worked so long. Not a miracle because if it failed earlier I would have called in the people who f..d it up to fix it but hey-ho.

Apparently the rest of the flue looks fine - supported in the right places, right drop etc. Hopefully they didn't fudge it anywhere else (but we didn't see any moisture anywhere else around the joints).
Anyway, he said he can fix it - he will lift the boiler to correct place, and replace these few parts with new ones, and seal it correctly.
Despite all that mess and leak, apparently the boiler survived (again - brave little fella!).

I don't want to jinx it, but hopefully by the end of the week I'll have it up and running again. I'll report here once it's done, but in any case - thank you SO MUCH for your help here, it's been invaluable.

 

[Harvest Fields]

And also glad to see he has put the case back on for you.

 

[DevsAd]

@DevsAd Thanks a lot for your input, it made me think, and question, and call another person in to try and fix it. I trusted the first guy and went on the assumption that the whole flue would have to be relaid, and that being a second problem with flue, I thought it cannot be done right and thus electric is the safer option. Therefore, the other visits I had were for a quote for new installation only (they didn't even start they boiler).
After your questions and input I decided to call another person in to try and fix it, or at least explain to me why it cannot be fixed. The result is that this guy actually decided to check WHY the flue is leaking, and it turns out it is a problem with installation right near the boiler entrance. Basically, the previous company hung it a little bit too low, and rather than correct their mistake, they fudged the connections on the flue right next to it (see new picture). So the flue (probably) never had a proper, tight fit and it's a bit of a miracle (not) that it worked so long. Not a miracle because if it failed earlier I would have called in the people who f..d it up to fix it but hey-ho.

Apparently the rest of the flue looks fine - supported in the right places, right drop etc. Hopefully they didn't fudge it anywhere else (but we didn't see any moisture anywhere else around the joints).
Anyway, he said he can fix it - he will lift the boiler to correct place, and replace these few parts with new ones, and seal it correctly.
Despite all that mess and leak, apparently the boiler survived (again - brave little fella!).

I don't want to jinx it, but hopefully by the end of the week I'll have it up and running again. I'll report here once it's done, but in any case - thank you SO MUCH for your help here, it's been invaluable.

View attachment 32157

That looks like a result!

You know what, I almost mentioned - after seeing your last photo in your post #24 - that the bottom collar on that flue immediately above the boiler was not sitting straight - you can see an uneven gap under it - and I wondered if that flue was being forced to that angle due to incorrect alignment.

But it's even better that a new plumber (at last a decent cove) went to the effort to ID this issue themelves.

And - wow - that's some mismatch!

I am incensed that so many so-called GasSafes have repeatedly botched up your install and have got away with it. The last company - the one that lowered your boiler too far - should be paying for this. In more ways than one.

In reality it's 'unlikely' it would have been 'dangerous' since the exhaust gases are sent out in the centre pipe which is surrounded by the intake sleeve, but to knowingly (and they sooo knew) force a flue connection to fit when it didn't want to would be a valid issue for reporting them to GasSafe (in fact should ideally still be done as the guy responsible might still be trading with a different group, or alone). You can picture their frustration when they realised they'd gone too far - a series of expletives followed by "what are we going to do about it?" They made the wrong decision.

But, good result and Happy New Working Boiler

 

[DevsAd]

(I would have thought an alternative to raising the boiler - in theory at least - would be to lower the straight length's boiler end by an inch or so, and thereby tweaking very slightly the overall 'fall' of the whole length, and then rotating that elbow to suit the angle would also have worked? The terminal end should cope easily with this microscopic tilt as it passes through a rubber diaphragm as it exits allowing such teeny tiny movement. It would probably mean altering the boxing around the pipe to accommodate the drop, tho'. But that's just layman 'theory', as I'm not a plumber, and best to let these guys get on with it...)