Size of boiler - Smaller better?

abtmay

All

Had several quotes for a new boiler this week. For a standard 3 bedroom, 1 shower and 1 bath, most of them mentioned that a Vaillant 831 or equivalent is sufficient. Actually I wanted a Vaillant 837, but they said that it is an overkill. However there's a gassafe guy who recommended a smaller boiler, Vaillant 824, as it will be more efficient, i.e. more time in condensing mode.

Now should I get a smaller boiler (824) or stick with the 831? Any help is much appreciated.

ormus

an 837 is certainly overkill re the heat output. unless you plan to build a large extension.
but the DHW flow rate is nearly double (9-15) and that might be useful to you?

whats the difference in price?

abtmay

ormus wrote: »

an 837 is certainly overkill re the heat output. unless you plan to build a large extension.
but the DHW flow rate is nearly double (9-15) and that might be useful to you?

whats the difference in price?

From 831 to 837, its £360 more.

ormus

and the 824?

abtmay

ormus wrote: »

and the 824?

Same price as 831. Besides the price, is 824 a better deal, in terms of performance, if I can get it cheaper?

ormus

i have the 824. and the same house as yours. 3 bed semi. 1 bath. 1 shower. (we rarely use the bath).
8 x rads.

the 824 is fine. no problems.

(bath filling is very slow).

Razor

There is some truth in the 831 cycling a bit more than the 824 as it doesn't go quite as low on the heating side but in practical terms it doesn't matter.

The hot water performance is in a different league.

831 all the way

arfurrrr

get the 831 and range rate the heating down to suit the house load , think its D1 or D0 in programming and put weather comp on it if you can

Razor

D0 it is

heating-eng

abtmay wrote: »

All

Had several quotes for a new boiler this week. For a standard 3 bedroom, 1 shower and 1 bath, most of them mentioned that a Vaillant 831 or equivalent is sufficient. Actually I wanted a Vaillant 837, but they said that it is an overkill. However there's a gassafe guy who recommended a smaller boiler, Vaillant 824, as it will be more efficient, i.e. more time in condensing mode.

Now should I get a smaller boiler (824) or stick with the 831? Any help is much appreciated.

its all about how fast you want to fill a bath ..an 24kw will give you around 9L at a at 35de or 8L at 42 de rise

were as a

35kw will give you around
14L at 35de rise and 12 at 42de rise ..the bigger the boiler the faster the bath will fill ..(as long as you have water pressure and flow coming in)