Boiler sizing

[everflow09]

hi all.
what method does anyone use for boiler sizing?any hints or tips out there.

i have alwys used the whole house method - long winded

 

[dontknowitall]

Measure rooms individually. Times 45 divide by 1000 (or times 0.045). Add them all up. Add say 2Kw for hot water. Add a little more for luck. Then find a boiler to suit. Simples!!

2.5m long x 3.0m wide x 2.5m tall = 18.75 times 45 divided by 1000 = 0.844Kw. Should have a 0.844Kw (or say 1Kw) radiator.

Doesn't take too long to do this. Then when you get more experience you just stick to one make of boiler and know which model to install without having to measure all the rooms.

 

[everflow09]

thanks for advice

 

[kirkgas]

room size in ft, Lx B x H x 5/3412 = kw requirement for each room, 2-3 kw for a cylinder if req'd, not very accurate but close enough, who has time to do a 3hr quote for these kind of jobs

 

[doitmyself]

i have always used the whole house method - long winded

Say 10 minutes at the most; and much quicker than having to measure each room if all you are doing is sizing the boiler.

Where does the multiplier of 0.045 come from?

Depending on the construction of the house and the amount of insulation, the heating requirement for the room mentioned can range from 500W to nearly 2000W.

 

[fuzzy]

whole house method is supposed to be the quick way!

 

[doitmyself]

whole house method is supposed to be the quick way!

May be everflow09 is using the paper based version (CE54) published by the Energy Savings Trust.

There are web-based versions which give the same result. The Replacement Boiler Size Calculator is probably the easiest to use.

 

[dontknowitall]

No idea where 0.045 comes from. Was told that one and to use 0.040 for a warm/well insulated room/no outside walls etc or 0.050 for a cold room ie no insulation, large windows, outside walls etc. All I know it's a reasonably accurate formula.

 

[everflow09]

i used the paper version

 

[doitmyself]

i used the paper version

Are you a Luddite?