Combi v. Conventional Boiler

paulypost

We have an old (non-condensing) conventional boiler. It has performed well for nearly 20 years old, and we thought it might be the right time to replace it for energy efficiency and cost saving. But we are undecided - combi v conventional.
Looking for some guidance as well as maybe suggested models. Relevant details:- 4 bedroom detached, 2 bathrooms - one with mains shower pod, one with electric shower
Been advised by first visiting (quoting) gas engineer that combi maybe not ideal because of distance from utility room (current location of boiler) to furthest bathroom, which happens to be most used (master en-suite) and has the shower pod.
A straight swap is currently favoured based on just the one quote. British Gas rep coming next week so will be interesting to see what is suggested/quoted by them.
Grateful for any advice.
Thanks

captainhindsight_2

Stick to a straight swap, by keeping the hot water cylinder you can also fit additional technologies for hot water I.e solar t o help save on your gas bills

duncansby

We were in exactly the same position as yourself and went on plumbers recommendation for a conventional boiler.

Interestingly our next door neighbour got theirs done at the same time by British Gas who also went for a conventional boiler, but a smaller model than ours

Cardew

Loads of threads on this over the years and mixed opinions.


I would never consider a combi in a 4 bed 2 bathroom house. I would only consider one in a small property if space was at a premium.(for the HW tank).


The heat loss from a HW tank is small and in any case the 'lost' heat warms the fabric of the house - hence a HW tank is often in an airing cupboard.


The other important issue, depending on house configuration, is pipe runs.

Pincher

For engineer types who like their systems resilient, i.e. redundant/backup, in one house I have:

1. Ground floor bathroom and kitchen is supplied by a gas multipoint.
2. First floor bathroom is supplied by a DHW cylinder.


One system fails, the other one soldiers on.


In another house, which is the length of two normal houses,
there are two DHW cylinders. First cylinder supplies the kitchen and En-Suite, the second cylinder is located mid way, and supplies bathrooms number two and three, plus two more face basins. Boiler failure is backed up by immersion elements in the cylinders. To prevent leaving the elements on permanently, they are wired into countdown timers.


Obviously mains pressure cannot supply three showers simultaneously, so second half is supplied from a loft cold tank with 3 bar pump.

paulypost

Thanks to first three responders - and it's only 8.30 am!
We already have PV panels and one issue with a combi would have been the absence of an immersion heater to use up free elec power in the summer.
A straight swap looking liklier by the day. Any thoughts on boiler model - Worcester Bosch currently in the frame. Voted most reliable by Which? readers last Sept?

Pincher

Note that the 5/7/10 year warranties usually require proof of annual service (like a car) by approved engineers. So it works out like the old style car dealership service stitch-up.


Sometimes I think the boiler business is getting like selling printers, where they don't make much on selling the boiler, but make their money on service/maintenance/repair. With the old non-condensing boilers, there was not much to go wrong. If it did, you called the plumber and he swapped out the flame sensor, valve or pump, and the whole thing carries on for another five years.

macman

Expect your friendly BG rep to quote you around 40% more than an independent RGI for the same install.
But if your existing boiler is working well and spares are still available, why change it? It'll take you at least 10 years to recover the outlay in efficency savings-by which time your new boiler will most likely need replacing itself.

pendragon_arther

We've had both. Combi is cheaper to run but will only last maybe 10 years if you're lucky. Conventional can last forever.

paulypost

But if your existing boiler is working well and spares are still available, why change it? It'll take you at least 10 years to recover the outlay in efficency savings-by which time your new boiler will most likely need replacing itself.[/QUOTE]



Good point - have been quoted just under £2k and would expect to save maybe 30% of £1k pa plus about £150 pa on Br Gas Homecare for duration of warranty. So maybe payback will be more like 5 yrs? And the Ideal Mexico is getting on a bit!

Cardew

Good point - have been quoted just under £2k and would expect to save maybe 30% of £1k pa plus about £150 pa on Br Gas Homecare for duration of warranty. So maybe payback will be more like 5 yrs? And the Ideal Mexico is getting on a bit!

My Ideal Mexico is 26.5 years old and I will hang onto it as long as I can.

Your expectation of 30% saving is IMO highly ambitious. You can look up the efficiency of your model of Ideal Mexico on the SEDBUK tables - but I suspect it will be about 70%(my older model is 65%)

The quoted 90% efficiency of modern boilers is never achieved in practice - only in a laboratory.

The Royal InstitutionofChartered Surveyors stated recently :

The average cost of installing one of these modern boilers is £1,720, but saves on average just £95 off people's gas bills." See:

http://www.telegraph.co.uk/news/ukne...erts-warn.html

From the Guardian

But critics argue the switchover is unlikely to be plain sailing. The new systems cost upwards of £2,500 to buy and install - £500 more on average than conventional boilers. And if the many letters from Jobs & Money readers and heating engineers are anything to go by, the boilers come with a hidden surcharge, so high that it can wipe out all the gains for the homeowner and the environment.
Critics argue that condenser boilers malfunction easily and can cost hundreds of pounds a year to maintain. Many survive only half as long as their traditional counterparts. They are technically complex, with many more things that can go wrong than traditional boilers. It can add up to nightmarish bills.
One major independent firm of plumbers said that over the past three to four years it has made thousands of call-outs to mend condensing boilers, and that the greenhouse gas emissions from its vans were probably greater than the savings made by the shift to eco-conscious boilers.

There are literally hundreds of post on MSE along these lines.