what size of a boiler do I need please?

geordief

I have measured the radiators in the house and their surface area comes to 330,000 cm^2.
There are about 30 of these radiators and so an average size works out at 60cm X 160cm.

The overall dimensions of the house (as an approximation) are 20 metres x16 metres (and there are 2 floors -say 20 rooms all told)

The boiler I am replacing has dimensions of 73cm x77cm x 107cm or 601447 cm^3 which I also work out at a little over half a cubic metre.

So it would approximate to a boiler 1 metre in depth by 1 metre in width and ,say 60 cm in length(if that helps).

Obviously it is an antique but can I gauge from it the size and kilowatage of the new (efficient) boiler that I am going to replace it with (along with the size of the house itself)?

When I squint at what is written on the burner it seems to indicate a kw rating of either 58 or 120 (it seems to read 58 +120)

JohnnieK

geordief wrote: »

I have measured the radiators in the house and their surface area comes to 330,000 cm^2.
There are about 30 of these radiators and so an average size works out at 60cm X 160cm.

The overall dimensions of the house (as an approximation) are 20 metres x16 metres (and there are 2 floors -say 20 rooms all told)

The boiler I am replacing has dimensions of 73cm x77cm x 107cm or 601447 cm^3 which I also work out at a little over half a cubic metre.

So it would approximate to a boiler 1 metre in depth by 1 metre in width and ,say 60 cm in length(if that helps).

Obviously it is an antique but can I gauge from it the size and kilowatage of the new (efficient) boiler that I am going to replace it with (along with the size of the house itself)?

When I squint at what is written on the burner it seems to indicate a kw rating of either 58 or 120 (it seems to read 58 +120)

You cant go by the dimensions of the old boiler or indeed the radiators. Unless you knew the make of radiator and the output compared to surface area there is no way of knowing.

A heat loss calculation needs to be done for the building which appears to be large so I would think you would need a light commercial boiler. The plumber or Building services engineer would be able to do the calculations for you.

Did you say 30 radiators or was that a typo?

geordief

no typo.Yes it is a large house and fairly poorly insulated (draughty) although the walls are thick stone

JohnnieK

Not to do a proper heat loss calculation and take into account the poor insulation a draughts would be madness.

I think you should get it done.

pache

Id give it a 45kw boiler given ceiling heights of 3 meters.

This will heat the property whilst on but when its turned off the building will not retain any heat.

Best senareo would be change windows and reduce draughts,insulate attic and keep the old rads as the would work very well at a lower boiler flow temperature thus allowing your new condensing boiler to perform at max efficiency for longer.

geordief

well the ceilings are a bit lower -210 cm downstairs and 235 upstairs.
Also we have a large oil stove downstairs in the kitchen that runs 24 hours a day which I think must heat the house to a degree.

pache

pache wrote: »

Id give it a 45kw boiler given ceiling heights of 3 meters.

This will heat the property whilst on but when its turned off the building will not retain any heat.

Best senareo would be change windows and reduce draughts,insulate attic and keep the old rads as the would work very well at a lower boiler flow temperature thus allowing your new condensing boiler to perform at max efficiency for longer.

If the hot water is split like with the Viessmann.

pache

gary71 wrote: »

If the hot water is split like with the Viessmann.

Ya i couldnt agree more,the Viessmann is some bit of kit allright,dont think twill happen in this case.I wonder would it be more efficient to heat the how water electricall rather than bringing in the oil and leave the boiler for rads??...

Shoes34 with the lower ceiling heights the demand would drop by at least 4/5 kw so a reduced boiler output would do.
The stove i wouldnt take into account when doing the buildings heat demand but that does not mean when the stove is on that the heat demand is not reduced as the stove will, of course, make its own contribution.

shane0007

JohnnieK wrote: »

The plumber or Building services engineer would be able to do the calculations for you.

If asked nicely, Heinbloed might do the calculation for you!

pache

shane0007 wrote: »

If asked nicely, Heinbloed might do the calculation for you!

Good idea!!

pache

pache wrote: »

Ya i couldnt agree more,the Viessmann is some bit of kit allright,dont think twill happen in this case.I wonder would it be more efficient to heat the how water electricall rather than bringing in the oil and leave the boiler for rads??...

There is 200ltr cylinders on the market now with air to water heat pumps incorporated in the top that have COP of 3.7, 4.5 hour reheat time from cold, works down to -5 and under €2,500, I think there a good idea, but I'll shut up incase it sounds like a advert:o