New boiler has resulted in increased Gas usage

Joined
18 Oct 2007
Messages
10,587
Reaction score
1,352
Location
Kent
Country
United Kingdom
the fabric of the building won't get up to temperature in one hour
the temperature of the building fabric cools much much slower ... this obviously excludes the outside walls
1. The time for the fabric to get up to temperature and the cooling rate will depend on the thermal mass of the fabric and its heat retention capacity.

2. The internal fabric is not so important as the outside walls.
 
Joined
19 Nov 2008
Messages
26
Reaction score
0
Location
London
Country
United Kingdom
at least the post author has done the sensible idea of fitting a decent quality boiler with a high enough output for his future extensions.
cavity wall insulation will cut his energy usage by approx 25% if done correctly.
i had a detached 2 bunglow when living in hastings,winter was cold very cold even with a 28kw boiler at full pelt the place was cold not to mention the gas bills,lpg.
some elderly neighbours were having cavity wall insulation done as they qualified for a grant,i asked the guys doing the work for a quote and they did a private job for me,including loft and draught stopping,now the place is let out to students and gas usage has halved.
 
Joined
28 Jan 2005
Messages
34,181
Reaction score
3,139
Location
London
Country
United Kingdom
Which just goes to show that keeping your heating on 24 hours/day is more economical that just a few hours once or twice a day when the boiler spends all it's time getting the house up to temperature rather than just keeping it there.

This is really first year physics.
Heat transfer is the product of temperature and conduction plus radiation.
Higher inside, bigger difference, more gas use.

Following your reasoning, you would use less petrol if you did 100 miles at 100mph, than 20 at 100, 50 at 50, and another 30 at 100.

How many heating systems have you designed?
 
Joined
1 Dec 2008
Messages
1,145
Reaction score
103
Location
Devon
Country
United Kingdom
Yes but all heating systems designed if that's the word are based on the premise that you over size the boiler for the simple reason that you need more heat to get a cold object up to a desired temperature than you do maintaining that temperature. Otherwise your house would be instantly hot which is just not possible. If this is not so then why do all the latest boilers have modulating burners??

Please don't be critical of others if you don't know their background, qualifications and experience!
 
Joined
15 Jan 2008
Messages
12,264
Reaction score
3,006
Location
Glasgow
Country
United Kingdom
[quote="D_Hailsham.
See http://www.diynot.com/forums/viewtopic.php?t=158935 for a discussion on the need to range-rate an oversized modulating boiler. The OP had a 38kW boiler with an overheating problem, which disappeared when the boiler was turned down to provide the required 24kW max output.[/quote]

Not much different from what I wrote really and from what you edited from my original reply. Micky's instructions regarding downgrading the boiler's output is more or less what I said. Anyway with the 37CDi combi the heating load is only 30KW but you can enter the installer menu on the boiler to make the boiler start with a lower output then it modulates down from there.
 
Joined
28 Jan 2005
Messages
34,181
Reaction score
3,139
Location
London
Country
United Kingdom
Please don't be critical of others if you don't know their background, qualifications and experience!

That is why I asked how many heating systems you have designed.
If the answer is about none, there is little point in discussing it with you anymore than that I will argue with my dentist whether or not to stick a filling in.
 
Top