Which? Boiler test results

Maxie, you are a breath of fresh air.

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The discussion on boiler efficiency may be interesting but really is irrelevant if you accept that the difference of efficiency of modern boilers will fall within a 10% envelope. For most, I suggest this equates to something like £50-£60 in their annual gas bill. If we can agree that a call out charge for servicing is of the same order, more if it requires part replacement,cost of repair and servicing are the more important criteria. I know this has been raised by many but 'we' still persist with focusing on boiler efficiency.

Further, the cost to replace a boiler, non DIY, is what, something of the order of £1500 plus? If the reason is purely to benefit from gains in efficiency and we agree the efficiency of a non condensing boiler is 60%, repayment on cost will be 15 years plus, hardly worth considering.

In my judgement it is economically advantageous to keep a non condensing boiler in service for as long as economically possible. How long that is will obviously vary from case to case but to replace a boiler to benefit from gains in efficiency is not a factor.

I know there is nothing new here but I would really benefit from changing the focus of the discussion from efficiency to reliabilty and cost of ownership.

On the most recent models it's in about a 3% window allowing fo rmeasurement uncertainties and the difference in gas bill perhaps around £15.

As you suggest, in the scheme of things, almost negligible.

A call out charge for a service is probably closer to £100.

It depends on the point from which one is measuring and projecting and isn't a simple linear discussion.

On the one hand, if one has a an existing old boiler that is 15 -20 years old and has 60% efficiency then the capital cost is long written down and the discussion is about the cost in parts of keeping it running. That one is a fairly simple game of costing. If a failure is from a thermocouple or perhaps a thermostat, it is probably economic to continue with it. If a failure is from the heat exchanger or gas valve, probably not.

On the other hand, if the boiler is a more recent model, it may already have a 70-75% efficiency and may also not be written down. Then the replacement of even the more expensive parts may be viable.

One also has to factor in the increasing cost of gas (say 10-15% pa); although at this point that is still a second order factor - being a percentage of a percentage.

On that first level, I would agree with you. If a boiler is already running well and has some lifetime left, and remains servicable economically, there is no point on a purely financial basis to change it.

There can be other triggers for changing a boiler:

- Change in usage pattern - e.g. more people in the house, building of an extension

- Original was never up to the job

- Need to relocate the boiler

For me it was a mixture of criteria:

- The old boiler was > 15 years old and had had a new thermostat. There were signs of deterioration from the heat exchanger.

- It was a 65% efficient model and had been written down

- It was necessary to move it owing to a kitchen remodeling

- Additions were being made to the property in terms of a conservatory and heating for the workshop and it would not have been adequate.

On the basis of these, I felt that there was a fairly clear decision to replace. Having made that decision, the choice of replacement was based on build quality, test reports (in my case from Germany), research of different models and on servicability. I did not decide based on whether a product was 90 or 91% efficient. As it happened, the model chosen was at the top end of efficiency at the time (there are others than are more efficient now but only by about 1%). There was a 5 year parts and labour warranty.

All of that put the purchase price into the top decile of gas boiler prices among condensing models.

The other thing that I do is to maintain a slush fund for replacement of domestic equipment. My philosophy for that is to choose only high quality products - e.g. Miele for white goods and to write the cost down on a more aggressive basis than the likely lifetime. So for example, boiler, washing machine, tumble dryer is 10 years. I know that I am safe with the Miele appliances because the warranty is 10 years. I am taking a reasonable punt with the boiler. For each year's contribution to the slush fund, I put in an amount to replace with something from the top decile of products of the type and add 10% to that to compensate inflation. This works pretty well and always remains in "profit".

It would be very hard to find TCO for a boiler based on repair costs. Manufacturers know what they are funding in terms of spares during warranty. They also know what they are selling out in terms of spares after that, plus they know the size of the installed base. Of course, they won't tell you that. Then there is the issue of generic parts (although those are generally the low cost ones).

Given all of that, there is not much to go on, other than the common sense things of looking at build quality - a Viessmann or Vaillant is better built than a Ravenheat - something obvious to anybody taking the trouble to research.

Then you can talk to those who actually fix the things independently but don't have an axe to grind commercially.

In those senses, we do have several people here who give honest opinions based on their experiences.

I don't think that it gets more scientific than that.

Its so nice to see someone else applying ruthless cost benefit analysis to home economics.

One point that should be made,and that is the ratio of energy usage to capital cost.

If energy usage is very high, quite expensive solutions that only increase efficiency a smidegeun are economically effective.

Another one is reliability: consistently unreliable kit costs money in terms of the time needed to deal with the problems ..

There is an old axiom of production engineering: What leads to low productivity is largely *wasted time*. Instead of worrying about making people work harder, or more effectively,simply watch how often they are standing idle waiting for something to happen etc, then work out why thats so and fix it.

If you have to take a day off work to fix a boiler, thats maybe £300 of holiday time you lost.

Regular servicing is not about the lowest cost of ownership directly, its about spending fixed predictable sums of money to achieve 100% uptime :-)

I second all that Andy has said.

I would also like to point out that the external controls to a heating system are as significant as the boiler itself. Very often the guiled claims (there one out from BG at the moment claiming upto 30%) are incorporating the control system improvements together with the new boiler. The controls can be upgraded for a fraction of the cost and are often with the scope of d-i-y for many people. Although the worst case controls will also require plumbing improvements as well.

I think for many modern flats (small, well insulated), whole life COO is better for electric heating. For a landlord it is also better (as the LL does not pick up the energy bills, but does pick up the inspection/service/repair costs).

I used to laugh at marketing people saying that new flats are '"so well insulated you don't need central heating" as the same thing was said 30 years ago. But actually I am coming around to that POV. CH is just too complicated.

- Hide quoted text -

If you buy the electricity from nuclear power stations it's infinitely less COO

Sadly its still expensive. If carbon trading came in, it would instantly become hugely profitable..Or British Energy could give its carbon coupons to its shareholders, so they could have big fuckoff 4WD's ;-)

Which is flawed.

You have the assumption that all condensing boilers brake down./ Wrong!! They do not. Buy a cheapo and they may. Buy quality and they don't.

The difference between the condensing boiler and a non-condensing is minimal.

In message , Doctor Drivel writes

As in break, you mean (the tablets must be wearing off)

I don't think so ...

you mean the "non-" bit ?

The message from The Natural Philosopher contains these words:

That would be logical but governments in general, and our present sorry example in particular, don't do logic. If the did they would not have the face to impose the carbon levy on nuclear as well as on carbon based fuels.

Maxie, you have been on the pop again!!!!

Maxie, you have been on the pop again!!!!

Maxie, you have been on the pop again!!!!

Merry Christmas Maxie. ..and leave the dogs alone!

Which is interesting.

The Baxi & the Potterton are made by the same company.

Looking at the installation manuals, the Baxi and the Potterton mentioned above seem to be the same boiler. Spot the difference;

Anyone (excluding Drivel) know more?

Baxi, Potterton and Main are the same company.

Vaillant and Glow-worm are

Of course they don't.

...

There was a post-mortem of one of these on Gas News earlier this year, which criticised some aspects of its design such as the potential for a vertically mounted coil of tube to accumulate sediment at the bottom of the turns, and the impossibility of flushing out a blockage in one passageway plumbed in parallel with others:

Even Heatline, BIASI and Ravenheat have models using this heat exchanger. They work OK indeed and have been around for quite a while. They are a horizontal coil of stainless steel with the burner horizontal too. I prefer the Keston vertically coiled heat exchangers with the burner on the top and the flue outlet at the bottom. The condensate washes down the heat exchanger cleaning it as it burns. The Keston Qudos is now a highly cost effective well designed boiler offering high functionality too. This Qudos boiler must be assessed when buying a boiler. Reliability is not yet proven though, although most parts are taken from reliable Keston models, so should be fine

I personally like the Atmos heat exchangers. It is whole of the boilers back panel. The height and width of the boiler. This design uses all space available and makes for a smaller boiler too. They are also very well made of thick gauge copper too. The combi version just has a coil of copper tube run through the heat exchanger and acts like a conventional multi-point water heater when generating DHW. Have a look:

Look at the space inside the Atmos Intergas boiler for burner and pump. Amazing!

This shows the inside of the Atmos heat exchanger:

The Giannoni heat exchangers:

Dunno about Heatline but saying "even" BIASI and Ravenheat use this HX is like saying even Poundshop and Costcutter stock a product: it says cheap tat not high quality.

criticisms raised in the GN article.