Help needed sizing a boiler please

[daveprice0]

Can anyone help me size a new gas boiler for my house please.

The boiler is ONLY for heating - we have a separate system for hot water.

The house is large detached Victorian property, with around 6" of insulation in the roof and uninsulated cavity walls and is on the Isle of Wight. Rooms have high ceilings - up to 3.3m. Total room volume including halls and landings is around 1,000m2

I've tried the online calculators and am getting results of between 35Kwh and 85kwh so something must be wrong.

The following figures are properly aligned as I post this - may need window resizing to read properly


Room Sizes

Length Width Height Volume
Sitting room 5.59 3.96 3.28 72.61
Lounge 7.21 4.88 3.28 115.41
Dining room 5.59 3.98 3.28 72.97
Kitchen 5.79 3.98 3.28 75.58
Study 4.29 4.22 3.28 59.38
Utility room 3.15 3.10 3.28 32.03
Hall (front) 4.57 2.59 3.28 38.82
Hall (middle) 3.65 2.60 3.28 31.13
Hall (rear) 3.70 3.27 3.28 39.68
Toilet 1.85 1.00 2.67 4.94


Bedroom 1 (main) 5.72 3.96 3.05 69.09
Bedroom 2 (yyy's study) 3.28 3.28 3.05 32.81
Bedroom 3 (yyy's) 5.10 2.97 3.05 46.20
Bedroom 4 (pink) 4.22 4.20 3.05 54.06
Bedroom 5 (spare) 5.69 4.12 3.05 71.50
Bedroom 6 (xxx's study) 2.97 2.21 3.05 20.02
Bedroom 7 (xxx's) 4.12 2.95 3.05 37.07
Main bathroom 3.10 3.10 3.05 29.31
Ensuite 2.90 2.69 3.05 23.79
Landing 9.50 2.62 3.05 75.91
Laundry cupboard 1.80 1.00 3.05 5.49


Radiator Sizes
Rad 1 L Rad 1 H Rad 2 L Rad 2 H Rad 3 L Rad 3 H
Sitting room 1.00 0.60 1.00 0.60
Lounge 0.90 0.60 0.90 0.60 0.70 0.60
Dining room 1.00 0.60 0.80 0.60
Kitchen 1.40 0.60
Study 1.00 0.60 0.90 0.60
Utility room 1.10 0.60
Hall (front) 0.39 0.90 0.39 0.90 column style rads
Hall (middle)
Hall (rear) 0.39 0.91 0.33 0.91 column style rads
Toilet


Bedroom 1 (main) 0.90 0.60 0.90 0.60
Bedroom 2 yyy's study) 0.80 0.60
Bedroom 3 yyyy's) 0.80 0.60 0.80 0.60
Bedroom 4 (pink) 0.90 0.60 0.80 0.60
Bedroom 5 (spare) 0.90 0.60 0.90 0.60
Bedroom 6 (xxx's study) 0.90 0.60
Bedroom 7 (xxx's) 0.90 0.60 0.90 0.60
Main bathroom 0.80 0.60 0.80 0.60
Ensuite 0.80 0.60
Landing 0.90 0.60 0.90 0.60
Laundry cupboard 0.50 0.60


Many thanks

Dave

 

[gremlin16]

Try here.

http://www.energysavingtrust.org.uk...eractive-tools/Domestic-heating-sizing-wizard

 

[expertgasman]

http://www.radcalcs.com/

or similiar

 

[picasso]

The whole house calculators only go up to approx 25kw so fairly useless for big houses.

 

[D_Hailsham]

The following figures are properly aligned as I post this - may need window resizing to read properly

That's interesting! The data was just a string of numbers, with one space between each. But now I have "quoted" it, it is displayed below as correctly spaced columns of figures.

How did you do it?

Room Sizes

This info if not very helpful as there is no information about window (size and type) or about which are external walls.

Rad sizes

We need to know which type of rad they are - see Stelrad Elite Catalogue

Are the "column rads" the old fashioned cast iron type? If so, can you say how many sections they are?

Do the existing rads provide more than sufficient heat in very cold weather?

 

[Agile]

The first thing to do is to reduce the heat loss. Adding cavity wall insulations will probably reduce the heat loss by 20-30%.

Then decide how many live there and turn off rads in unoccupied rooms.

A 35 kW boiler is probably whats needed but calc first.

The gas bill for that would be about £4000pa. Is that what you have been paying?

Tony

 

[bengasman]

Why don't you leave the calcualtion to the installer? He's got to do it anyway unluss you are willing to take responsibility if you get it wrong.

 

[Agile]

I would agree that it should be left to the installer but only IF the installer is chosen for his expertise and not because he is the cheapest and doesn't speak English!

Its also a feature of many installers to oversize boilers. The inpression that I get is that 90% of installers dont even bother to make any calculation at all. Either make a guess or copy the existing boiler.

I would also say why should they at the quote stage? If someone asks for 3-6 quotes then why on earth should all of them waste 2 hours measuring and calculating the requirement when they are not getting paid for it and only one of them will get the job.

Sadly the one who gets the job is probably going to be the least interested/capable of even doing the calculations.

Tony Glazier

 

[mickyg]

just tryin to imagine the house from the room sizes, your probably looking at 40-50kw with poor insulation levels and big windows, might get away with less if its better than it sounds. Might be worth seeing if you can download and use stelrad stars.

 

[bengasman]

I would agree that it should be left to the installer but only IF the installer is chosen for his expertise and not because he is the cheapest and doesn't speak English!

Especially in that case should it be left to the installer.