Viessmann boilers

[F]

Anyone got any experience and opinion on Viessmann boilers with or without weather compensation?

We've currently got a seven year old Worcester Bosch boiler (not combi) and the heat exchanger seems to be starting to shed a grey (aluminium?) powder into the condensate stream. It's also locking out increasingly regularly due, we think, to overheating. There's some kettling to be heard...

Options when it finally fails are either replace the heat exchanger, or replace the boiler with one that doesn't eat its heat exchanger. Viessmann had been suggested as it's all stainless steel. Weather compensation would be nice, though not if it's £silly.

[Dave Plowman (News)]

I've got a Vitodens WB2 system boiler with storage hot water. Weather compensation. Been pretty reliable - but setting the software for it is a nightmare, even with the service manuals. It is several years old so modern ones may be better.

It certainly seems to be well built and hopefully will return the higher initial cost. I installed it myself, and their helpline was pretty good. But if getting one installed make sure you find someone who knows them well.

[Muddymike]

Anyone got any experience and opinion on Viessmann boilers with or

No personal experience but I see they are rated third best after Worcester and Vaillant in the latest Which report.

Mike

[F]

That's interesting.

I wonder what Which do to take aging into account? The plumbers I've been talking to have said that the WB is/was an excellent boiler and they have fitted them for years but, now the boilers are aging and they are servicing them regularly, they are starting to notice the aluminium depoits from the interior of the heat exchanger and are needing to replace the exchangers. The heat exchanger on ours has a rippled exterior and you can hear it kettling.

WB, apparently, deny there's a problem.

[Dave Plowman (News)]

I'd be surprised if Which had enough data on early Viessmann boilers to come to an accurate conclusion about life.

[Muddymike]

They claim the reports are based on sample size;

84% Worcester 1,911 83% Vaillant 903 80% Viessmann 103 76% Remeha 39 69% Glow Worm 446 This is the Top 5 by % satisfaction

Mike

[Andy Cap]

What concerns me is that increasingly people seen to feel 7 > 10 year life is acceptable for a boiler costing £2000 > £3000 + servicing and faults ! If you then add in the lost useful heat of an old boiler the savings are really exaggerated but of course there's now no choice.

Andy C

[ARW]

Who's satisfaction?

[The Other Mike]

The typical happily married Toyota driving 2.3 kids, 0.5 labrador family that buys Which. In reality the bloke, a plumber by trade is nipping to the local knocking shop 3 times a week, the wife is shagging the next door neighbours son, the kids are smoking skunk and the 0.5 of a labrador is the subscriber to Which.

[Dave Plowman (News)]

Which boiler costs 2000 - 3000 quid? Unless you are including very expensive installation.

[Andy Cap]

I am, as although this is DIY, it's usually done by pros. Am I wrong in thinking normal installation is in that range? So far I've avoided this change but not for much longer. I just find the expected lifetime, appalling.

[Bob Eager]

Our last boiler change (~ 3 years ago) included:

- removal and disposal of old boiler

- removal, flush and replacement of all radiators (about 11 of them)

- installation of a number of TRVs

- resulting pipework adjustments

- new boiler, including uprating of part of main feed

- new pump and 3 way valve

It excluded electrics work, which I did.

Cost was £1900 (local man). British Gas wanted £3800.

So your range is right-ish, but the lower end is more realistic.

[Muddymike]

I assume the 103 Viessmann owners who could be arsed to reply to a Which survey about boilers.

Mike

[F]

Ours is seven years old and, no, I don't think that (possible) replacement after seven years is acceptable. But that's the position we find ourselves in. What I'm looking to do is to make a judgement on repair v replacement with a superior and more reliable boiler with the addition of weather compensation.

As for £2000 - £3000, that's way over the top. A ball-park-off-the-top-of-his-head estimate from the plumber I was talking to for replacement with a Viessmann 100-W (I think that's the one) 26kW system boiler with weather compensation was ~£1500.

[charles]

The difference is probably because a like for like replacement will be much cheaper than replavcing am "old fashioned" boiler like mine with a condesing one.

[Dave Plowman (News)]

If it's a simple boiler change, sounds WOTT to me. It took me two easy days, and I'd expect a pro to be a deal faster. Boiler itself cost about

1200 including the weather compensation kit.

[F]

The WB we had installed seven years ago to replace a Baxi Bermuda 'fireback' boiler cost ~£1200 including relocation to the garage and a whole lot of new 22mm pipe runs.

[Scion]

The Other Mike put finger to keyboard:

That's cos each issue of Which has several pages of lab reports.

[F]

I'm (not for the first time!) confused.

Reading through the Viessmann weather compensation literature it explains that the boiler will set a lower flow temperature if the weather is warm, and a higher one in cold weather 'to adjust the radiator output, to maintain a constant temperature indoors'.

If the boiler is messing with radiator temperatures 'to maintain a constant temperature', how would my current programmable room thermostat be set?

[Dave Plowman (News)]

You don't have a room thermostat - programmable or otherwise. You set the software in the boiler to give the required temperature.