Vaillant or Viessmann?

Hi All,

After another failure of my Potterton Suprima and Boilermate 2000 we've decided to change both, especially as we're about to put a new kitchen in, and the boiler is located in the kitchen.

I've received 2 quotes from recommended installers. Both have quoted for the Vaillant ecoTEC 428 open vent boiler with a choice of unvented cylinders from Megaflo, Unistor, etc.

However, one installer speaks very highly of Viessmann boilers. He's suggesting the 26kW 100-W open vent model. I'd never heard of these previously. He thinks the build quality of the boiler, in particular it's heat exchanger is the best on the market. I live in a hard water area and he said the Viessmann would be particularly well suited. He also commented the after sales service was superior to Vaillant.

His quote for Viessmann is approx £200 cheaper than Vaillant.

Would appreciate any views on this as I can't find any recent posts on this.

Also, is it worth staying with an open vent boiler or are there any benefits moving over to a system boiler?

Many Thanks...

In the context of your post, hard water means nothing. The only water both boilers contact is what goes through your heating system. Hard water only affects the water you consume at the taps and outlets.

the viessmann is IMHO the better choice, if nothing else the 'one pipe' heat exchanger seems to be more tolerant of 'old systems' (one larger CSA waterway, not a bundle of 4 smaller ones)

System will still require cleansing, system water treatment, and I would suggest a magnetic filter/strainer to minimise debris build-up.

i am sure your preferred installer is clued up on all this.

DH

I've a veissmann 200w and chose this model over the 100 as I believe the 100 range was a cheaper model made especially for the UK market (says it all) and has experienced quite a few problems with quality. That may well be overcome by now as I'm told some of the problem components have been replaced by those from the 200 range.

I suggest you go for the weather compensated model since it sets its heat output in accordance with the outside temperature (the colder the weather the hotter the boiler runs)

As has been said it has a single large bore heat exchanger which comes with a 10year guarantee

To me the main advantage of the 200 range is a much more sophisticated weather comp control system.

But the 100 range compares very well with the Vaillant range.

Tony

as a homeowner, I went for the open Vitodens 100 because it is very simple, meaning it has not much to go wrong. It is also very small.

If the fancy takes me I can change the pump, 3-port valve and some controls without needing to be a gas-safe boiler man, or I can get any pro without needing Viessmann experience, as they are not within the boiler, and the parts might be cheaper too.

I like Viessmann's coiled stainless steel heat exchanger and long guarantee.

Any particular reason your installers have quoted for a 28kW boiler? There is no benefit in oversizing a boiler.

Vaillant over viessmann any day of the week.
Be better sealing the system and using a 600 series bunny!

Viessmans heat exhanger will block just as easy as the Vaillant....it's the tight bend connection that are susceptable.

Viessman parts are unbelievably expensive and often only available by courier...few stock them....and a warranty's worthless in many cases.

I've given up working on them...just too much trouble to deal with.


Have you considered the Worcester CDi Classic heat only range?

Had a spate of CDi heat exchangers leaking to condense.

British Gas quoted for a 40kW boiler!

My understanding with the Boilermate was that it allowed you to install a smaller boiler than you normally would for a given property. I think the Suprima 60 is around 18kW. With this in mind I expected the quotes to include a larger boiler as I'm going over to an unvented cylinder. So I wasn't surprised at the quotes I received. The British Gas quote did surprise me, and when I questioned it I never received a response.

I've had a third quote and that guy recommended the Worcester Bosch 27Ri and the same Vaillant. The Viessmann I've been quoted for is the 26kW unit.

The house we live in is a 4 bedroom town house, and it does seem to need a lot of heating. There are two en-suites with thermostatic showers and a family bathroom. 13 radiators in all.

40kW is insanse. they must have an overstocking and have put an extra bonus on the sales muppett.

You have to feel for their installers sometimes.


Wouldn't go for either of your choices, but a Vaillant over Viessmann if that was the only option. for the reasons Gasguru explained.

Although I wouldn't fit a Wooshitter Botch either.

how old is your town house? Was the 18kW boiler adequate for it? if so, then 18kW is what you place needs, which sounds about right.

My house is 4 beds and the boiler for that is technically running at 15kW, although I have tweaked things on it and can't remember precisely. Think it might boost to 20 for hot water.

I think around 24kw would be ample without obviously being there to work it out. You'd probably get away with another 18kw to be honest. But for quickest heat up time of hot water 24kw would be my choice since most unvented cylinder coils can absorb more than 20kw anyway (your heating requirement will almost certainly be lower than this though). If you don't mind waiting a few extra minutes for hot water and have no plans to extend and need extra heating then an 18kw would be more efficient than a 24 or above.

BG customer services called me earlier in the week to ask what I thought of the quote & salesman. So I told them. They've now kicked off a complaint/investigation. That came as a surprise.

I did email Viessmann to enquire about their products and reliability. They admitted there were reliability issues with their first products, but said the current range is rock solid. They commented their heat exchanger is superior, guaranteed for 10 years and portions of it won't block up as can happen with the Giannoni heat exchanger in the Vaillant. They also commented that the boiler can have its entire warranty extended for 10 years by paying an additional £200.

The house is about 13 years old. There are another 2 of the same design on my estate and the owners of those have also commented they are cold, especially on the ground floor.

It's difficult to judge whether the boiler is adequate as the system was never serviced prior to us moving in 3 years ago. As a result the BM2000 doesn't get to the store temperature it needs to and constantly calls the boiler for heat. When you put the heating on the rads start to come on. After a few mins the store temp drops way below 60, so the heating is turned off until the store temp gets back to 60. The heating pump re-starts, store temp drops again and the process repeats. As a result the house takes a long time to heat up. Showers are ok. You can just about run one bath before the DHW drops to a Luke warm temperature. We've had BG homecare out numerous times to deal with issues, mainly with the Suprima locking out. The latest board seems to have cured that. Nothing has improved the store temp which now never gets above 69C.

A long winded, non-scientific response I know, but about the best I can do!

Then upping it to 24kW might be necessary, btu I can't help think it is more an issue with the Boilermate rather than the boiler output.