condensing boilers

henryj

Has anyone had a condensing boiler fitted,my old oil boiler (29yrs) is still reliable,but there is a grant to change to a condensing, but would it be sensible to change it to a boiler I know nothing about ?

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any thoughts?

Old_Git

a condensing boiler uses around 40% less oil .
A condensing boiler costs around £1500 .
There is grant of £400 or £700 depending on your income .
If I could afford it now I would get one.

saverbuyer

You should probably get your bum in gear. The grant end on 31st March 2015.

CEON44

Old_Git wrote: »

a condensing boiler uses around 40% less oil .
A condensing boiler costs around £1500 .
There is grant of £400 or £700 depending on your income .
If I could afford it now I would get one.

Grant vortex condensers seem to cost about £825 ish.. Been told they are the best to buy. Of course there will be some changes needed to pipework etc etc plus labour cost of installation

Mistral001

CEON44 wrote: »

Grant vortex condensers seem to cost about £825 ish.. Been told they are the best to buy. Of course there will be some changes needed to pipework etc etc plus labour cost of installation

Old Git says that it cost £1500 and you can get a £700 grant. That is £800 which is not far from £825.


I once got cavity wall insulation installed the grant was £150. I think the cost was £645 less £150 grant ie. £495 cost to me. That was with a grant approved contractor. I remember that I also got a quote from a non-grant-approved contractor of about £500! Is this the same situation? Or am I just a cynic.

[Deleted User]

I set up a spreadsheet to answer this question, they just don't pay their way if you take into account gas consumption, inflation on gas and labour, interest on capital, servicing and repairs, guarantee period, depreciation etc.

In order just to break even the total cost including boiler labour and any cashback would have to drop to about £1200 based on a boiler life of 10yr. The figures I seen bandied around are £2k-£4k. Based on an installation cost of £2300, you would need a boiler life of 17 years just to break even. The economics are even worse if you have cavity insulation, the less gas you use the less gas the new boiler saves.

warmhands.coldheart

Mistral001 wrote: »

..... Is this the same situation? Or am I just a cynic.

I have had this happen on 2 occasions,
Once with Loft Insulation. Exact same scenario as you described..

Once with oil to gas conversion.... Plumber who was not registered with Phoenix Gas (He was Firmus registered as did most of his work outside Belfast) so could not claim back on the grant through Phoenix. Grant was £800. He was over £1000 cheaper than every other Phoenix approved plumber who would make use of the grant.

You're not the only Cynic here........

Stuarty1984

Remember, for a boiler to actually condense and for you to get the benefits of that, the flow and return temperatures need to be lower than your conventional boiler, so you will find that if say you living room needs a 2kw radiator to heat it now, you will need a 3kw radiator with the lesser flow temperatures to fulfil the heatloss from your room, your pipework will also be undersized. So condensing boilers aren't always a great idea for retrofit, unless you run them at the more standard temperatures, but then you don't get the condensing benefits.

CEON44

Sturty1984 wrote: »

Remember, for a boiler to actually condense and for you to get the benefits of that, the flow and return temperatures need to be lower than your conventional boiler, so you will find that if say you living room needs a 2kw radiator to heat it now, you will need a 3kw radiator with the lesser flow temperatures to fulfil the heatloss from your room, your pipework will also be undersized. So condensing boilers aren't always a great idea for retrofit, unless you run them at the more standard temperatures, but then you don't get the condensing benefits.

Interesting post and not something I was aware of. Do you speak from experience or are a plumber?

malc_b

Wikipedia will tell you the same thing. You need a return water temperature of ~55C for condensing. So assuming 65C that 60C average on the rads which are thus at 60% of their rated value.

What you need to look at is what is the current efficiency of your old boiler and compare that with the new, less say 10% if you can't achieve condensing. Old boilers were very inefficient so maybe the numbers work out even if you don't get condensing. Of course you will get some condensing at the start up so it wouldn't be as bad as 10% less.

Also, you might get some benefit from better controls and longer running at lower temperatures rather than turning up the temperature as the weather gets colder. I done some maths here to show how to understand the process.

martin57

This is a very interesting thread as I have been thinking of a condensing boiler myself, but got the efficiency of my old boiler (which is probably 25 years old) checked by a local plumber last year. It is made of cast iron it seems and since I came to this house a few plumbers have remarked on it, said it would be the kind of boiler that was found in a guest house or something like that

Anyway the plumber rated the efficiency of it to be over 90% So I am at a bit of a loss what to do, would I save on oil by having a condenser boiler, though the same plumber says they are not all what they are cracked up to be and can break down easy enough. I have an inkling that it probably the smaller pipes in central heating as well.
Thanks
Martin57