Is a 12kw boiler sufficient for a 3 bed semi?

[zj]

We are looking to change our old conventional G rated boiler.

It is currently a potterton prima 40f.

Looking to change it to a 12kw baxi solo A rated boiler.

Reason we are looking at 12kw is so that we can use the original gas line otherwise we would need to run a new gas line from the gas meter which is working out to be alot more.

Is 12kw sufficient for a 3 bed semi with a conventional heating system?

The house is pretty well insulated and going to be double glazed very soon.

 

[powell30]

Tight.

I assume it needs to heat up an indirect cylinder for your water? If so i would be looking at 15kw and you need to bite the bullet and upgrade the gas line.

 

[zj]

Yes does have a cylinder for heating water.

The potterton is 12kw at the moment which seems to do the job fine

However its getting old and making a few noises so thought it would be a good time to change it.

 

[D_Hailsham]

Use either Sedbuk Boiler Calculator or EST online boiler calculator to find out what size boiler you need.

 

[zj]

Any further views on this would be most appreciated.

 

[onlyfitidealboilers]

18,000 btu per 1kw i think what is your rad sizes

 

[zj]

9 rads in total and the sizes are:

1: 440mm x 530mm

2: 740mm x 530mm

3: 740mm x 530mm

4: 950mm x 530mm

5: 640mm x 670mm

6: 440mm x 530mm

7: 440mm x 530mm

8: 440mm x 530mm

9: 840mm x 530mm

 

[CharteredEngineer]

rather than quote in bedrooms, if you get a rough floor size, ceiling height and whether you have cavity wall/loft insulation would allow a better estimate.

Just off the top of my head 15kW seems low.

CE

 

[powell30]

No. 1 kw = 3414 btu's

Unless there is some unusual factors 15kw should be fine. Allow 2kw for water heating (as per sedbuk) this leaves 44k of btu's approx (13x3414).

Divide by 9 rads = 4400btu's per rad. From the sizes the op has posted (allowing a double or 2) that is more than sufficient.

That said the op seems reluctant to bother doing the research and filling the form in on sedbuk to definitively ping the right size boiler for his specific house

 

[muggles]

9 rads in total and the sizes are:

1: 440mm x 530mm

2: 740mm x 530mm

3: 740mm x 530mm

4: 950mm x 530mm

5: 640mm x 670mm

6: 440mm x 530mm

7: 440mm x 530mm

8: 440mm x 530mm

9: 840mm x 530mm

Single panel? Double panel? One or two sets of fins?

 

[onlyfitidealboilers]

No. 1 kw = 3414 btu's

Unless there is some unusual factors 15kw should be fine. Allow 2kw for water heating (as per sedbuk) this leaves 44k of btu's approx (13x3414).

Divide by 9 rads = 4400btu's per rad. From the sizes the op has posted (allowing a double or 2) that is more than sufficient.

That said the op seems reluctant to bother doing the research and filling the form in on sedbuk to definitively ping the right size boiler for his specific house

spot on sorry!

 

[D_Hailsham]

Any further views on this would be most appreciated.

Why haven't you used Sedbuk Boiler Calculator or EST online boiler calculator to find out what size boiler you need? They are officially approved calculators and will give identical results - one may be easier to use. It will stop all the arguments.

Boiler size is determined by heat loss, not by radiator sizes.

 

[powell30]

op prefers us to do the work for him free of charge of course

 

[mickyg]

This is hilarious! why the detective work? the OPs exisiting boiler is already 12kw, if that one heats the house ok then so will the new one!

 

[powell30]

Part L requirements?? Just a guess.