Boiler Recommendations (Not Keston Please!)

[James.Brown]

All,

I'm the unfortunate owner of a Keston 80 condensing gas boiler. It came installed new with our home in 1999 and lasted about 3 years before springing a leak, needing a new gas switch, plus heat exchanger swaps and various other disturbing problems.

For the last three months, we=92ve been without heat and 8 engineer visits later (6 from BG and 2 from Keston), our home still resembles Antarctica! The boiler will manage about 2hrs before the run lamp extinguishes, sometimes not firing at all when the timer kicks in. We=92re probably faring worse than our neighbours, who all have the same boiler, but everyone has had their nightmares with this awful product.

The Keston 80 model is apparently out of production now and the Keston engineer told me that it is almost impossible to get repair work done on any of their products during winter (unless you=92re within the 2 year guarantee period). If you live outside the M25, apparently their support is even worse.

Apart from grumbling about Keston, the real reason for my post was to find out if anyone could recommend a replacement boiler please? The current boiler is 80000btu and fits in a kitchen cupboard (resting on a surface) with dimensions 120cm x 55cm x 42cm. Serviceability and a reliability are what I=92d need and of course, similar level of efficiency. I=92m actually a complete newbie, so could anyone tell me if I have to continue using a condensing boiler, rather than say a combi? Also, how much should you pay for an installation and which boilers would British Gas be able to support? (evidently not Keston!)

Many thanks to anyone who responds.

James.

[Clot]

I know nothing about Keston boilers I might be pleased to relate from your experience and that of neighbours. I would be seriously concerned about using BG to support a replacement! I would be even more concerned to allow BG to install a new boiler - not the ability to do the job, but the timing of site visit, etc. and even more significant to me the ££££s for the job.

[Doki]

AFAIK all boilers must be of the condensing type these days. A friend's father has a business installing boilers and he put a Worcestor Bosch in her house, so I'd expect them to be amongst the best.

[Andy Hall]

So you've learnt that BG is inept at service. Ask them to quote for a replacement and also ask 3-4 local firms and individual installers and you will find that BG likes to enjoy a high margin as well. Frankly, you would be better off by far avoiding having further dealings with this company.

Combi and condensing are not descriptions on the same axis - i.e. they are not alternatives.

A condensing boiler has higher energy efficiency than a non condensing one and for a couple of years now it has been a requirement of the Bulding Regulations that condensing boiler is fitted unless there are specific circumstances that actually prevent that. Given that you have already had one, it is highly unlikely that you would meet the expemtion criteria even if it were desirable to do so.

A combi boiler attempts to heat the water as it passes through the boiler on an "instant" basis as opposed to the boiler heating a storage cylinder. Provided that the existing HW system is performing properly, there is no reason to change to a combi. It would give mains pressure hot water and with a large enough boiler and modest enough HW requirement may be adequate. A 23kW combi boiler is unlikely to be adequate other than in the smallest of dwellings. You can get up to 40kW or more models which will simply modulate down to your CH requirement. However, they may exceed your available space.

As far as manufacturers are concerned, you would not go far wrong with anything of German manufacture or design, including Vaillant, Viessman, MAN and Worcester Bosch.

[Ed Sirett]

Please read the Boiler Choice FAQ and the wiki.diyfaq.org.uk pages.

I have installed another Keston this week and have one in my own home. They are not my first choice for reliability but they are not in the same league as the low end manufacturers either.

They are the boiler of choice when there is a very difficult route for the flue. This may have been the case with your house; in fact you may not have easy access to outside walls from the current location of the boiler.

[Doctor Drivel]

Worcester Bosch, Valliant and Glow Worm are good. Atmos are better as are Viessmann, ACV, Buderus.

[Mark BR]

A 23kW combi boiler is

I keep reading 23kW is for small houses, but every calculator I try says I need about 20kW - for a 180sq metre detached house, not very small. Most reports also say don't over install as it is ineffieicent even with modulation.

Which is correct?

-- Mark BR

[John Rumm]

If you are buying a combi, then you can in effect ignore the space heating requirement and size it based on your hot water needs. 24kW will do a decent shower, but will be dismal for bath filling.

Using a boiler with a minimum output that is significantly in excess of the typical heat loss rate of the house will be less efficient than one which is better matched, but this is not as big an issue as it used to be with high water content cast iron heat exchangers etc. If you choose boiler carefully you can find some that will modulate quite low to just a few kW... once you subtract the house heatloss of even a well insulated place from that you should still get reasonably long efficient burns from it and relatively little cycling.

[Doctor Drivel]

The lowest is around 3 kW and is not cheap!

[Doctor Drivel]

Matt, attempts? Do you mean it doesn't heat the water. Not all combis heat water instantly, many use stored water using integral unvented cylinders or thermal stores. Many are two stage in heating DHW using stored water and reverting to infinitely continuous water after.

[Doctor Drivel]

It depends on the modulating control system. The cheaper boilers tend to modulate on the flow temp setpoint - maintaining a flow setpoint. The clever ones sense the flow and return temps. They also use outside weather compensation trimmed off bu te roomtemperatures.

Best have a boiler with OpenTherm room temp protocols and outside weather compensation. E.g.'s are Ethos

and Atmos.

[Andy Hall]

I chose the words carefully. It increases the temperature of the water. The question is whether it does so by a sufficient amount and at a sufficient rate for the user requirement.

That we know. We are also talking about a small installation space so such options are limited.

At a lower flow rate.

[James.Brown]

Andy/All,

Thank you very much for the great response, your input is really appreciated. I've had a read around your suggestions and have a few more questions...

Does anyone have any experience with a Worcester-Bosch Greenstar

30CDi? These can be had for =A3800 (inc.VAT) and I've heard they won the CORGI Boiler of the year award last year.

I also looked at the Viessmann Vitodens 200-W, which is twice the price for the same 30kW output. The warranty also seems to be the same (2 years), so I'm unsure what the advantage of spending this extra money would be?

Ed - What is it about the flue that might make a Keston the most suitable choice?

We actually already have a hot water tank (but no attic storage), so that rules out a combi and looking at the Wiki, a System boiler seems to be the correct type. Is that right?

Many thanks

James.

[Doctor Drivel]

Thank you very much for the great response, your input is really appreciated. I've had a read around your suggestions and have a few more questions...

Does anyone have any experience with a Worcester-Bosch Greenstar

30CDi? These can be had for £800 (inc.VAT) and I've heard they won the CORGI Boiler of the year award last year.

I also looked at the Viessmann Vitodens 200-W, which is twice the price for the same 30kW output. The warranty also seems to be the same (2 years), so I'm unsure what the advantage of spending this extra money would be?

Ed - What is it about the flue that might make a Keston the most suitable choice?

We actually already have a hot water tank (but no attic storage), so that rules out a combi and looking at the Wiki, a System boiler seems to be the correct type. Is that right?

[John Rumm]

Most houses will leak heat faster than that. So even 8kW is still quite useful once you knock off the rate of loss from the house.

[John Rumm]

then heat them electrically with no thermostatic control. So not relevant in this case.

[Ed Sirett]

Firstly, if you are using a stored hot water system then the boiler should be sized according to the needs of the space heating. Typically

24kW is reasonable for a large terrace house, average large semi, average detached house +/- for construction methods, materials and size. This raises the question of whether the original unit was correctly chosen...

Some manufacturers offer an option to use high quality MUPVC plastic pipe for the flue (and air intake). This is relatively low cost and even a long/complex flue won't come to more than £150 of materials. However Keston boilers only use this type of flue. Other manufacturers may offer an adaptor but costing an amount comparable to the rest of the flue materials.

Adding extra extensions, bends and offsets using the proprietary co-ax flue/duct systems use by nearly all the makes can be prohibitively expensive. E.g. Even one pair of 45deg bends will set you back most of £100.

For the above reasons when the flue route is awkward plastic flues need to be considered. Since you have lost all confidence in Keston you'll have to use another make and may be sort out the flue route at some additional expense.

[Owain]

But very relevant in Dribble's case.

Owain

[Doctor Drivel]

They can.

[Doctor Drivel]

Ethos use plastic flues, but no off the shelf drain pipes.