combi versus conventional boilers

[Doctor Drivel]

Chav, you an idiot, whose total experience consists of you fitting your own combi. You are one of the know-it-alls who people should be weary of.

[Ed Sirett]

Having read other posts. I have these additional comments.

The choice of plumbing for flats will depend on a number of factors. Including whether there is any provision for gas (which may well be the case for the lower end of the market).

Costs for new build will depend on a number of factors but when you start form a clean slate the cost of the smaller boiler+small store may well stack up fairly well against a mid-range combi, whilst working better.

A modern combi boiler will be microprocessor controlled, so will the plain heating boiler. The only other PCBs used in a stored system would be for a time-clock and perhaps a programmable thermostat.

A (new = empty) vented copper water cylinder can be picked up with one hand. It is easy to carry one two handed up the stairs.

Two guys can easily handle even a largish unvented/thermal-store in it box.

You remove the water from them when you take them out!

Many unvented cylinder/stores you see are often for the larger houses and will be 150-250 litre units. For medium quality new build with GCH and two beds+bathrooms the unit would be a more typically 80-120.

[Doctor Drivel]

I have seen an number of Gledhill Eletramate thermal stores about in flats, precisely for this reason.

I have seen some flats being told to fit smaller kW boilers as the mains pipes further down the line could not cope. Transco said it would be updated - within 5 years. So, replacement combis in 15 years time is a real option.

I good quality high flowrate combi serving one bathroom is hard to beat.

Gledhill thermal stores have microprocessor pcbs. Read my recent post on the Systemate to see what it does.

[whitely525]

Gledhill does. Roughly 1.5 metre tall and 0.5m square.

Fair enough, you could toss the old one over the balcony.

=A0 =A0 London SW =A0 =A0 =A0

=A0 London SW

ide quoted text -

[Dave Plowman (News)]

I'd guess you're talking about a thermal store. Is that what Gledhill calls it?

[whitely525]

Exactly.

=A0 London SW

[Doctor Drivel]

Exactly.

[Dave Plowman (News)]

Then it's a thermal store and not a hot water cylinder.

Are you related to dribble who, like Humpty Dumpty, thinks words mean whatever he wants them to?

[Doctor Drivel]

It is a cylinder. In fact twin cylinders inside the heavily insulated casing; a fine peice of kit indeed. Boy are some people dumb!

[Dave Plowman (News)]

Especially those who can't spell 'piece'. 'I' before 'E' apart from after 'C' works for most things. There - you've learned something new.

But I refer you to the bit you snipped.

Thanks for confirming this on your very next post.

[Doctor Drivel]

Please eff off as you are a plantpot.

[whitely525]

I am just an average Joe worried he is lumbered with something over specced, over-complicated and expensive in the long term. Beggin' your pardon for not knowing the preferred nomenclature...

IMO there is too much emphasis on fuel efficiency, rather than total cost of ownership, simplicity and servicability. Next time I look for a new flat I will probably look for one without any central heating as I think it makes much more sense.. especially for a landlord.

=A0 London SW

[David Hansen]

On Thu, 3 Jan 2008 11:09:44 -0800 (PST) someone who may be [e-mail] wrote this:-

Fuel efficiency is the major influence on the total cost of ownership of a boiler and associated systems.

[Roger]

The message from David Hansen contains these words:

Over the life of the average boiler fuel is probably the largest single cost but fuel efficiency is not *the* major factor, replacement cost is, and if the boiler being replaced isn't unreliable it is hard to justify replacement on economic grounds.

So how long will your shiny new condensing boiler last? 5 years? 10 years? 15 years? And how much would it have cost to install a condensing boiler that many years ago.

I have an old and leaky house and a somewhat less old Potterton Prima boiler with a sedbuk rating of 75% which is still going strong (touch wood) with less maintenance than a condenser would have required. Since March 1995 (when I started running Microshit Money) I have paid some £6217 for my gas. Assuming I could have installed a condenser in February 1995 with a sedbuk rating of 93.75% I could have saved 20% of that gas bill - £1243, or rather less if you factor in the interest I would have lost on the money the condenser cost, net say £1000. Could I have had a condenser for that sort of money? - Only if I had installed it myself. Would it have lasted those 13 years or so? Don't be silly, I would be on my second or perhaps even my third by now.

I can't remember exactly when I installed the Potterton but it could have been December 1991 (it was certainly December) and the irony is that I wanted to install a condensing boiler but couldn't find one. The previously advertised Trisave had disappeared (company went bust?) and there didn't seem to be anything else around.

[Dave Plowman (News)]

One would hope so, but many condensing boilers cost more in repairs each year than they save in fuel. Unless you were wasting money on a service contract in both cases.

I've just replaced a 30 year old Potterton Kingfisher with a Viessmann Vitodens. It's too early to say how reliable it will be - but I'm pretty sure it won't beat the Potterton which only needed a couple of thermocouples and some new heat exchanger O rings in its entire life. Again it's too early to be accurate, but it looks to use just under 20% less gas.

[geoff]

In message , "Dave Plowman (News)" writes

Ah, you might have hit the nail on the head there

They prolly put a bit of skunk in his cocoa last thing at night to pacify him

... which would explain the reason he lives in a different universe

[Doctor Drivel]

Maxie, you are a breath of fresh air.

[Edward W. Thompson]

If all other factors are equal then you are no doubt correct, however, it appears that efficiency comes at a cost of 'reliability'. As I understand it, the older style of boiler (non-condensing=more reliable) is not an option other than in very special cases so it appears that when a boiler must be replaced, the older and arguably the more reliable type of boiler, is not available therefore fuel efficiency is the dominant factor. It seems that the spread in 'rated' fuel efficiency of modern boilers is no greater than 10% (someone previously suggested 3%), in which case servicing cost (reliability) is likely the major influence on cost of ownership when fitting a new boiler.

I don't know what the 'spread' is for capital cost of a new boiler but I suspect on a like for like basis it is not more than £200, that is two call out calls for servicing. It would be my opinion that capital cost is not the dominant factor in overall cost of ownership, relability must be predominant.

Now comes the obvious question which is which manufacturer has the most reliable boiler?

[The Natural Philosopher]

Here I probably spend as much *each year* on oil, as the combined cost of the boiler and PHW tank (uninstalled).

[Tony Bryer]

We have had a number of users of our SuperHeat software asking about how to treat new-build flats with electric heating and communal gas hot water. This combination is not covered by the current SAP2005, though this will change very shortly. A key attraction is not having to pipe gas to individual flats; for owner-occupiers the heating is maintenance-free and probably cheaper to run than a gas boiler + service contract; for BTL buyers it cuts out the safety check cost and hassle.