Viessmann system boiler 100W or 200W

[JohnD]

I particularly wanted a stainless exchanger, so I bought a Viessmann, and I wanted a relatively simple boiler with not much in it to go wrong, so I bought a 100 conventional.

The cost of parts has never troubled me, since I've not needed any in 15 years.

I have no problem with spare parts being sold so rarely that they are not stocked in every high street. Quite the reverse.

Of course, YMMV.

If you put five gasmen in a room, you will get six opinions of the best boiler.

 

[Mojo12345]

Thanks JohnD think I’ll go for the Viessmann 100w 26W regular condensing boiler, the company is offering 12y parts and labour warranty included so seems good to me, plus the stainless steel heat exchanger is very good, I’ve asked the company if it’s hard to get parts they said not at all, I guess all the gas engineers have different opinions to each other

 

[Gasguru]

Awards mean absolutely nothing especially coming from magazines like Which...do not be guided by them.
Both stainless steel or an aluminum heat exchanger can be equally as reliable but it's all in the detail, even similar stainless tube arrangements can have different outcomes...Keston a disaster, Atag very reliable.
Your existing boiler has a French designed stainless heat exchanger and is used in many manufacturers models. However, the multiple coil bundles are in parallel, without spotless water they can block and the boiler gradually kettles (noisy).
A diyers view of boiler reliability is irelevant...but when you have 1000s of customers you get the real picture.

Read the small print very carefully regarding the warranty...especially anything to do with water quality (regular servicing) and voiding the policy.

 

[Mojo12345]

Gas guru you seem to be very knowledgeable which boiler do you recommend ?

 

[JohnD]

when you have 1000s of customers you get the real picture.

Very good point.

Like with car reliability, asking thousands of owners "what car do you drive, and how often has it broken down" is likely to show a pattern.

 

[Gasguru]

Gas guru you seem to be very knowledgeable which boiler do you recommend ?

Difficult one there's not a lot of choice...
I was trying to find a Worcester heat only with the original large rectangular aluminium heat exchanger introduced around 2002...a 20 year life is possible.
The only model now that has it is the 8000 Life heat only. It can be range rated (heat output turned down) and it modulates to a very low output.
For what it is it's an expensive boiler and Worcester are now screwing over customers on spares too. Shame.
If 24kW would be sufficient then the Worcester RI range has been around since 2005 and are pretty reliable.

 

[sxturbo]

More importantly if your settled on an installer go with what he recommended and make sure he services it every year. If there are any warranty issues his relationship with the local boiler rep will also aid in whether a warranty claim gets passed or not.

The 200 isn't worth the extra 500 notes imo

 

[Mojo12345]

Thanks all

 

[Mr.B]

Several years on.

I've re-read the above (and quite a bit of stuff elsewhere too) and STILL haven't fitted a new condensing boiler in place of my 28 year old heat only Ideal Classic 50,00 btu boiler in the garage - it had a fan a couple years ago and just keeps going.

I think I hold the record for sheer indecisiveness. It's still going so haven't HAD to swap it. And I'm sure most will say keep it until it DOES bite the dust.

BUT I still yearn to be able to know for sure what I'll replace it with.

Not a Combi. Not a System Boiler. I want a Heat Only to work with my current vented cylinder in the airing cupboard with the possibility of changing it one day for an unvented.

The names Worcester, Vaillant, Intergas, Ideal, Baxi, Viessmann, Vokera ... even Alpha (stainless HEX) have all been conjured with. I have honestly thought (over-thought) every conceivable angle and option.

I really would favour not having an aluminium HEX despite having clean well dosed water and a Spirotrap MB3 filter.

Tomorrow a local Viessmann approved installer of some repute is popping in on his way back from somewhere else and I'll see what he advises. Probably a Viessmann. But, on the face of it, the 100W 16kw heat only does have the stainless HEX and a ten year warranty, a very decent minimum 3.2kw ouput (I think the word is modulation) and a few local shops that stock parts and it's not much different in price than most of the other and when I rang the installer he rang back within the hour and when I rang Viessmann Customer Service they, too, answered the phone and also rang back when they said they would.

I'm still flummoxed by the controls that may or may not be available for it though. Opentherm ? Honeywell T6 ? Weather Compensation ? plus a million other factors. And to complicate the issue I see (somewhat unsettlingly) that Urban Plumbers on Youtube isn't keen (and I rather thought he had his head screwed on and was worth taking notice of.

But if anyone would like to add anything to the above I'd be glad to hear it it.

Ta.

 

[muggles]

The Heat Only version of the Viessmann 100-W is NOT OpenTherm - caught me out the first time I fitted one.

 

[Notch7]

I want a Heat Only to work with my current vented cylinder in the airing cupboard with the possibility of changing it one day for an unvented

I stayed with a vented cylinder, less to go wrong, less servicing cost.

Although I had a fast recovery cylinder fitted when getting a new boiler.

Worcester, Vaillant, Intergas, Ideal, Baxi, Viessmann, Vokera ... even Alpha (stainless HEX

The problem you will have is finding out which boilers will work properly with hot water priority and which smart controls work with which boiler.

I opted for an Ideal boiler because the plumber I used knows them well and parts are readily available in the U.K. Given a boiler is something you want to keep for 15 years plus, I wanted a common brand so stand a good chance of long term support

 

[Mr.B]

I'm not surprised about the absence of Opentherm as I believe it was mentioned in one of Urban Plumbers YouTube's . But, as I mentioned, I'm in no way familiar with it, or any other Smart Controls. I believe it was said he installed an accessory to facilitate OT.

I've not discounted other makes - Ideal and Intergas for example but hope tomorrow will be helpful but I can't say the simplicity of, say, the Ideal Logic doesn't have an appeal .... everyone knows how to fit and service them and spares must, presumably, be available everywhere. However it's not got a S/Steel HEX and only modulates down to around 5kw - and half of my radiators aren't in use as it's such a warm house so that might be a consideration. I don't know what controls are available for it but ideally they would be simple to understand and operate as neither my Mrs. or I are IT specialists.... I read that it IS OT compatible though (if that's an advantage).

 

[sxturbo]

I thought the atag boiler was like the intergas where you could buy 1 boiler and change the setting for system or combi boiler. But looking again it doesn't seem like it.

That said, atag boilers are worth a look at, 12 year warranty and stainless steel heat exchanger.

A friend has one and it's been fine for the past 5 years quiet etc,

I still think the intergas suits your needs perfectly and I wouldn't get too hung up on the aluminium heat exchanger, they've been producing them for a very long time and they have a very long warranty.

I've had a pump fail in the past 5 years, but was painless to deal with warranty wise,

 

[Notch7]

I've not discounted other makes - Ideal and Intergas for example but hope tomorrow will be helpful but I can't say the simplicity of, say, the Ideal Logic doesn't have an appeal .... everyone knows how to fit and service them and spares must, presumably, be available everywhere. However it's not got a S/Steel HEX and only modulates down to around 5kw

The ideal vogue has both stainless hex and modulates down to about 3.6kw

Personally I would prefer to choose a fully pumped pressurised system boiler

 

[Mr.B]

The ideal vogue has both stainless hex and modulates down to about 3.6kw

Personally I would prefer to choose a fully pumped pressurised system boiler

But it's not a heat only is it? Vogues are either System or Combi and I've said I want a heat only. But see below for my acceptance of the second paragraph regarding pressurizing. .... I'm sure you're right in what you say there.

BUT, if I was to go pressurized you might well say "get a Vogue System boiler" and you'd be partly right except I prefer to have separate pump and expansion vessel (rightly or wrongly)

Today a local (7 or 8 miles away) Viessmann accredited installer spent an hour with me. I was impressed and reassured on all counts. Too soon to receive his quote yet (obviously enough).

We spoke about pretty much every aspect of the installation - and there was much to cover ..... change of position in garage including changing wall flue to vertical, gas suppliy, controls for a heat only boiler using existing vented cylinder, pros and cons of changing from open vent to sealed using an expansion vessel and filling loop. To be honest he had a sensible answer to all the points raised. We spoke about a future possible change from existing (28 year old) cylinder to an unvented ... not to mention whether Viesmann, as a manufacturer, is advantageous over the likes of Worcester, Vaillant, Ideal etc etc etc.

I was very aware that the 100-W heat only boiler is different from most other heat onlys insofar as it has a stainless steel HEX and also the boiler modulates down to 3.2kw. Alpha has S/S and I Rightly or wrongly both those points were important to me. The warranty is 10 years if registered on the installer's portal and that is not dependant on fitting their own magnetic filter. A 12 year is available on payment of a fee. Don't know how much.

The boiler doesn't incorporate Opentherm from the factory and so he fits whatever controls are suited to the installation. I'll be honest I'm in the dark regarding modern controls and would be in his hands. Simplicity for us oldies is as important as economy to the nth degree. He did mentiuon Weather Compensation though.

Of course, the fact remains the existing 28 year old Ideal Classic 50,000 btu boiler (with electronic ignition, not pilot light) is still working and has had a new fan exactly one year ago ( £44 inc VAT and postage !!!! isn't that amazing? ) . But the debate regarding when to replace is acknowledged.

My main doubt concerns pressurizing the system and the possible leaks thereafter. He said it's very rare, and it may well be, but it still scares me.

If I did pressurize the heating circuit and there was no leak then fine. If, at some point in the future, the 28 yr old cylinder did start to leak then I'd almost certainly swap to an unvented cylinder.

The installer recommeded fitting a 19kw boiler to take into account the possibility of a new unvented cylinder in the future. My Mears Calculator tells me the (14) radiators are rated at a total of 15kw plus 2kw for the existing cylinder so that would suggest a 16 kw boiler may well suffice but his preference for a 19kw may well be prudent. I gather it can be range rated and it does have that very low modulation figure.

In fact the more I consider advice from most quarters and the more I think about the benefits the more I'm inclined to pressurize it by means of a vessel sited above the boiler's new position in the garage. But I will be fearfully scanning the ceilings downstairs hoping not to see a wet patch forming.

Ta for ongoing thoughts .... appreciated.