DIYblonde is in BIG trouble!!!!! Can you help?

[diyblonde]

Thanks D_H I'll give that a shot tomorrow morning and get some final calculations done before I order the rads and boiler.
Hopefully it won't pickle my brain with complicated formulas!

 

[Andy165]

You can buy a "Mear's Calculator" for domestic heating in either imperial (btus) or metric (watts) from B E S mail order. www.bes.co.uk £40.00 each. Or you could try calculating k values , u values etc. etc. or just use the x 5 method . Better bigger than smaller, you can always turn the rad.down but you cant do bugger all about it when youve sized one too small. Have you tried getting a quote from British Gas for a full ch system and the type of boiler they recommend. Be prepared for a high price though!

 

[diyblonde]

Hey Andy, I think I've got a handle on it now thanks. And agreed you can do b****r all it you run out of heat, so I will be going bigger just in case.

 

[Bon]

Hi Bon ... do you have any specific boilers in mind?

Thanks Andy I'll check my calcs against that. Any things to think about re outside walls and other factors that will influence?

I usually specify Vokera stuff as it's pretty cheap and cheerful (I work for an M & E contractor!!) however for a domestic application I'd look at Worcestor Bosch stuff, think they do a unit called the Greenstar which is pretty good. Dearer than the Vokeras but worth it IMO.

As for the heat loss calc it's simpler than you might think. All you need are the areas of external walls, windows and floors in each room. Multiply these by the u-value and then the worst case diffenece in temp between outside and inside (24 deg C will be plenty).

Add all these together for each room, i.e. wall 1 + wall 2 + windows + floor/ceiling and then add 10% margin.

Size your rads to these figures (bearing in mind they may be over or under the exact figure) then total up all the rads. This gives you your boiler duty.

 

[D_Hailsham]

As for the heat loss calc it's simpler than you might think. All you need are the areas of external walls, windows and floors in each room. Multiply these by the u-value and then the worst case diffenece in temp between outside and inside (24 deg C will be plenty).

Add all these together for each room, i.e. wall 1 + wall 2 + windows + floor/ceiling and then add 10% margin.

Size your rads to these figures (bearing in mind they may be over or under the exact figure) then total up all the rads. This gives you your boiler duty.

So where do you think Diyblonde is going to obtain all the U-values etc?

The reason I suggested the Quinn calculator is that it includes all this info and adds on the 10% for intermittent heating etc etc. The Sedbuk whole house calculator does exactly the same; it even makes allowances for where you live.

Why try to reinvent the wheel?