Dribble seems back with us and in at least two posts has stated that changing from a boiler with a cast iron heat exchanger to a condensing one will result in a 40% saving in gas bills.
Can anyone here who has actually done this and kept a record of gas usage confirm or refute this?
My figures show an average reduction in gas consumption of approx 25% in the 4 years I've had a condensing boiler. Not taking into account this winter.
=A0 London SW
I got around 20-25%
John
What boiler is he recommending this week?
Most people I know that have had a new boiler also have upgraded controls fitted at the same time so a straight boiler swap comparison is not readily available.
The only person I know that had a boiler swapped with very few other modifications done is my brother. He is claiming about a 10% saving but the modifiction was an extra bedroom extension and to be fair the last two winters have meant the heating is on for longer than previous winters.
I replaced an Ideal Mexico (20 yr old cast iron lump with pilot light) with a Worcester-Bosch 24i in 1995. I have records of Gas and Electric consumption going back 10 yrs. Direct comparison before and after is however difficult. The motivation for changing a perfectly functional boiler was not efficiency but a desire to improve the bathroom and replace a 8kW electric shower with something more comfortable. The biggest change in a before and after comparison is therefore a switch from electricity to gas.
Jul04-Jul05 Electricity 1849kWh, Gas 6756kWh totalE&G 8605 kWh
Jun07-Jun08 Electricity 878kWh Gas 5413kWh totalE&G 6291 kWh
There are also changes in the pattern of life to consider, I no longer have a server running 24/7 at home, I work at home less etc. And I changed suppliers from BG and EDF to Equigas/Equipower.
Overall I used to use 30% electric 70% gas, it is now less than 20% electric (by kWh), pricewise it was over 60% of the energy cost was electric now Electricity accounts for 40% of the bill. Prior to 2005 I was using (averaged over a year) between 20-25 kWh per day, it is now down to
15 kWh per day.There certainly was a saving on Gas, not least from no longer having a pilot light burning away all day. And heating a shower from Gas rather than Electric made a big difference to energy consumption, the cost, and not least, comfort. So any efficiency gain from the boiler was magnified by my using more of the cheaper source.
In conclusion I would say there may have been a 20-25% saving on Gas consumption as a result of installing a new boiler. But as a single person, in a small flat, out all day, my bills are not that large and the savings will never cover the cost of installation. It is justified because the new bathroom and better shower is more comfortable.
I still have a 19 or 20 year old boiler that was rated at 75% so I am not going to be changing boiler any time soon unless it fails very badly.
As far as Dribble's comment is concerned (like much of his output) what he claims as a general truth is only valid at an extreme limit. 92% is about as high an efficiency that can be realistically claimed for a condensing boiler but to achieve a saving of 40% my back of an envelope calculation suggests that the replaced boiler would have to have had an efficiency of 55%. Not many of such dinosaurs still around I would have thought.
At the end of March I changed my Potterton Prima 80F with steel heat exchanger (IIRC SEDBUK band E, ~ 75% efficiency) for a VAILLANT Ecotec plus 428 (band A, ~90% efficiency)
I appear to be using about 25% less gas than I was. Will know more accurately in 3 months.
Problem is I also installed a thermal store so like for like comparison is impossible....what I can say is that my installation assures that the boiler operates with "long burns" and (almost) always condenses. I believe 25% saving in this circumstance is completely plausible.
Dunno. What is top of Google today?
The only change I made to mine with the boiler change was to use weather compensation.
When I change mine, the winters either side were about the same. As, I think, were the summers. And my hot water use would be pretty constant.
Dave Plowman (News) ( snipped-for-privacy@davenoise.co.uk) wibbled on Monday 03 January 2011
00:17:
Surely: "which manufacturer of boilers gave the place he's tea boy at, the calendar with the best collection of totty?"
Why bother? Dribble is..dribble.
Sounds better than I would expect,.
The Oct-Dec 2010 period shows a 16% decrease - but I had a rad fitted in the hall at the same time (April 2010) as the boiler, so comparison is difficult.
June-Sept time, though, seems much lower - 40-50%. Average consumption this year was 0.28ft3/day, compared to 0.46 2009, 0.55 in 2008, 0.45 in
2007 and 0.47 in 2006. These figures aren't especially tight - but do seem to indicate water heating may be cheaper. Not sure what cooking contributes here.I use much more gas in the winter, obviously - so money savings won't be much if this trend continues.
Rob
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