Yes that question again I have just about finished the refurbishment of my house the utility room being the last which houses the Boiler. I have replaced all the rads and a new quick recovery cylinder I have done all the work myself which together with the water pressure being abysmal here I have stuck with a vented system. The original boiler is an old Glow-worm space saver it still works ok but has a limited like expectancy so im going to have it replaced as the utility room is being redone.
I know zilch about boilers, ;( I am specifically looking for a heatonly boiler thee seems to be 18 or more manufactures to choose from. All I am looking for is reliability and efficiency as almost all seem to be A rated and the price difference between models is not that large I could really really do with some impartial advice so I don't end up with a potty supreme type experience.
I had almost decided on buying a Worcester-Bosch but having read your comments re Aluminium heat exchangers I was again perplexed as to the best choice. You don't name Names which for someone with zero knowledge of boilers or how the many makes are constructed doesn't realty help in making an informed choice. I do however realise that recommending a specific boiler would be impossible, but a hint as to which makers spare parts are unrealistically expensive would be helpful, I found a 24v timer for one model priced at £230. The only info I have found on the net regarding reliability is this
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seems BG only fit Vaillant and Worcester Bosch and Baxi/Potterton and Ideal. From my own research Ideal does not seem to be a highly regarded boiler at all; I would not buy a Baxi/pot on principle after the Suprima ripoff. You have cast doubts over WB heat exchanger, if BG have got it that wrong on 3 out of their 4 choices were does the leave Vaillant, which was my second choice after WB. BTW the rest of your article on Choosing a Boiler was very informative as to the different systems available, but a few of the links are 404.
This has me puzzled, too, particularly the reference in Ed's FAQ to Silicon coated aluminium. It seems a very unlikely concept to me, though various makers do seem to highlight the existence of silicon in their aluminium alloys. I assume this is to give a faint aura of high technology, as none mention other, equally common and important, alloying elements.
The counter argument I have come across is that stainless steel is an intrinsically unsuitable material for heat exchangers due to its poor thermal conductivity. Most designs therefore compromise by reducing the size of water passages, increasing the probability of blockages. Some use a spiral of stainless steel tube with a horizontal axis, each turn therefore providing a place for air bubbles to become trapped. Another design fault which I've seen mentioned, though I couldn't tell whether it referred to stainless steel or cast aluminium heat exchangers, was that multiple parallel paths are provided for the water. If one becomes blocked, there is no means of rodding it out, or even forcing water or cleanser through it, since it will always take the easier parallel path.
Worcester Bosch, Vokera, and Ideal use cast aluminium and Vaillant, Potterton, and Baxi uses stainless steel for their SEDBUK A boilers. Glow worm use aluminium for their Flexicom, but stainless for their Ultracom. Apparently many makers, from budget brand to Vaillant, use Giannoni heat exchangers.
I suggested in a previous post that more emphasis should be placed on the minimum output a boiler can be modulated to, which varies widely from type to type. A Flexicom 30cx goes down to 9.3kW, an Ecotec 831 goes to 8.7, but an Ultracom 30cx goes to 4.95. Shouldn't a low minimum help part-load efficiency? 6kW must surely be plenty of output for many houses for most of the time, so is there much point to clever controls which talk to the boiler, only to get an "on-off" answer?
So I've not made my mind up yet. Worcester Bosch may win for the next installation - for my in-laws - since my mother-in-law has a thing about Bosch. And on the "no-one was ever sacked for buying an IBM" principle...
I think any of the makes with stainless heat exchangers should last a very long time, if correctly installed and operated. It's quite possible that Silicon coated Alloy is fine I just am not 100% sure. So That would add WB and Boulter Bruderus.
I'd be happy to fit WB, Vaillant, Glow-Worm (based on experience) and Eco Hometec, Viessman based on their spec. and other peoples comments.
Bottom of the market (probably not possible to say who's the lowest) Vokera, Biasi, Heatline, Ravenheat, (rebadged boilers sold in Sheds), Chaffoteaux, Saunier Duval.
Mid Market are Ideal, Baxi/Main/Potterton, Ariston,
Unsure: Alpha used to be crap but may be they have moved up market. F & P are new to me but the spec looks poor.
very interesting post thank you, I can now see why most manufactures insist on a power flush.
Ahhh googling this I found
and they are plastic outer cased
I think I will do the same, the new Vaillant looks nice but the electronics seem to be OTT and I can't say I was impressed at all by the Giannoni heat exchanger.
thanks for that now at least anyone googling this subject on here with no previous purchasing experience of boilers will know where the Mercedes and Lada of the boiler world lie.
Would seem to fit in with modern boiler reliability though. Ive got an older S class which has been faultless in over 245K, Much googling on this subject, it seem even Viessman are making a cheap down to a price boiler for the UK only market, with a corresponding reliability question mark re its electronics.
Perhaps it's because we remember the cast iron lumps that ran for decades, virtually maintenance free, without any of the unnecessary, yet extremely lucrative electronic paraphernalia. It's a con I tell you ! ;-)
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