boiler sizing

[billozz]

can someone tell me how to choose the right size boiler for my house please, i have a 3 bed semi
bedrooms 2off 12x12
1off 8x8
l/room 21x12
front room 12x12
i am after a condensing combi but not sure which one to go for
thanks
Bill

 

[Fluffster]

Your Corgi reg installer will work it out for you based on other factors such as your hot water requirements and water flow and pressure rates.What type of walls and windows you have etc.
Pete

 

[billozz]

yes i appreciate that the guy fitting it will know, i just want an idea myself so that i can do a bit of research into which boiler to have
thanks

 

[Fluffster]

Do a google on btu calculators then enter in your room sizes etc.
You never mentioned any of your hot water requirements which directly affect your boiler size.
I would guess a 28kw or 30kw
Pete

 

[mikej2005]

Most combis available will be powerful enough to provide adaquate central heating for a house of that size, so (as mentioned above) you'll need to decide on your hot water requirements.

These are the kinds of questions you need to answer :

How many outlets do you have (bathroom/kitchen etc) ?
How many hot taps would you ever be likely to have on at once ?
What kind of flowrate would you find acceptable for filling a bath ?

Also - bare in mind that a more powerful combi will use more gas (so distance from meter and size of gas supply pipe become very important) and will require a higher cold water pressure/flowrate.

 

[billozz]

not sure what my requirments would be its just me and the missus a bath shower so not loads i would nt have thought

 

[namsag]

24KW combi average 9 litres a minute hot water 28/30 kw combi 12.5 litres a min average... Combi is worked out on HW demand and they will usually take up to 15 rads easily,so they are usually oversized for CH load in standard size house

 

[billozz]

thanks guys for your help, i get the idea now jsut try to determine the h/w i need and then most of the combi's will be sufficient.

on a side issue but related if you see what i mean, my water pressure is not too good about 30 psi ( sister lives round the corner and gets 70psi) is there any way to increase it or not
thanks again

 

[corgiman]

not really about how much hot water you need but what flow rate you have through you main supply pipe

need to check that out before installing a combi

 

[kirkgas]

as other posts have said most combis will cover your heating requirements, it is your water requirements that count, choose a 28kw rather than 24kw, about £30-40 quid is the diff (depending on make) so well worth the extra to get better flow rate from the taps,

 

[billozz]

http://www.vhsdirect.co.uk/site/product.cfm?id=26D8594F-95AD-124F-D278BBBAB3A7F016

http://www.vhsdirect.co.uk/site/product.cfm?id=26DA1955-073D-C7B4-F1D7C86CC17CF219


would either of these be suitable for an average 3 bed semi
thanks again

 

[Fluffster]

As mentioned before they will both heat up your house adequately it is down to what your incoming flow and pressure rate which you have not provided. I would advise going for the higher flow rate model.
Pete

 

[sturharv]

How long is a piece of string with a combi !..... its all about the hot water.

I'd go for at least a 30kW version.