BTU/KW Sizing advise please

[back2space]

My friend bought a new house last year. He is doing the house up and redecorating it and wants air con installing (wall mounted units) here are the sizes etc.

The house is well insulated with Cavity Wall and lots of loft insulation. I said I would find out what he would need before he calls a company out so he has an idea of what he is looking at. I've used lots of calculators with differing results - ive put down below what the results are that I have got from websites.


Room sizes are as follows in meters.
Lounge
4.26(l) x 4.26(w) x 2.64(h)
Usual TV and sofa arrangement with seating for 4 people – 6 at a push. Usually only 2-3 people sat in here. This room is separated by the kitchen by a door. Off of the lounge is a small hallway with stairs to the landing. The window in this room faces South East. Gets the sun first thing in the morning which is gone by midday. Was thinking a 7000 btu unit?


Kitchen,
5.18(l) x 3.35(w) x 2.74(h)
Has a dining table that can seat 4 people and a breakfast bar that seats 2 people, usually 2 people through the week though. Gas hob with 5 rings along with a fan oven. Cooking is usually on weekends where we have all the hob fired up and oven. The kitchen is an entrance to the house from the garden and if having BBQ's or entertaining the kitchen external PVC door is left open. Kitchen window and door faces North West. Gets the sun from about 2pm until sunset if were lucky to have summer. - maybe a 3.5kw unit)


Main bedroom
4.26(l) x 4.26(w) x 2.64(h)
Faces South East, sun shines in on a morning. - possibly a 7000btu unit?


Second bedroom, Currently has a 7000btu unit (2.1kw)
3.35(l) x 3.35(w) x 2.64(h)
Smallest room in the house, this faces North West. - possibly a 5000btu unit?

[frank]

CIBSE 'Rule of Thumb' calcs are based on square metre floor space x 125w

i.e. for the Lounge, 4.26 x 4.26 x 125 = kW heat gain

[back2space]

CIBSE 'Rule of Thumb' calcs are based on square metre floor space x 125w

i.e. for the Lounge, 4.26 x 4.26 x 125 = kW heat gain

But what about ceiling height etc?

[al]

Unless the ceiling is over 3m I wouldn't factor it in. In a house trying to factor in solar gain (unless it's a conservatory) is going to lead to over sized units, plan for the 80/90% of conditions it will actually see, unless they have unlimited budget? I would if possible suggest upping the insulation, both wall and attic, money spent here pays bigger dividends, should also reduce required capacity on air con.

As frank suggests, CIBSE's rule of thumb is as good as any sizing program I've seen.

[back2space]

Unless the ceiling is over 3m I wouldn't factor it in. In a house trying to factor in solar gain (unless it's a conservatory) is going to lead to over sized units, plan for the 80/90% of conditions it will actually see, unless they have unlimited budget? I would if possible suggest upping the insulation, both wall and attic, money spent here pays bigger dividends, should also reduce required capacity on air con.

As frank suggests, CIBSE's rule of thumb is as good as any sizing program I've seen.

Ok seems reasonable.

So got the lounge and bedrooms sorted what would you put in the kitchen? A 3.5kw to cope with the heat from the oven and the hob when cooking?

[Brian_UK]

I'd be careful in the kitchen due to the potential for grease laden air and a 'domestic' split.

Very, very regular cleaning may be required.

[back2space]

For sure they will be kept clean, his kitchen extract also vents to the outside.

What would you advise for the KW for each room and I can check to see if this fits with my calculations?

Many thanks for your advise so far.

I was thinking a 9000btu for the kitchen to allow for cooking, (7000btu without the cooking) a 7000btu for the lounge, 7000 for the main bed and a 5000btu for the small bedroom. Or do I go for a 1200btu for the kitchen, cant work out the heat gain for kitchen as seen somewhere else that you add on 4000btu for kitchens but is this commercial?

[al]

Turn off the split in the kitchen when cooking, otherwise you'll be taking the indoor off the wall to degrease every few months, again this is not commercial so KISS. a 2.5 would do the kitchen.

[back2space]

Thank you for your input.

When cooking though he does no frying all is done in the oven or boiling things on the hob and he has the extractor running when he does to help clear the steam. There is no frying at all.

If you are using it when cooking what would you put in then?

Oh and what would you reccomend for the lounge and bedrooms?

[mikeref]

Guessing North East would be somewhere in England. Kitchens have a tendency to grease the filters and eventually clog the Evaporator... extraction fan or not. Comments above are spot on.

[back2space]

Yes this is in England. There is no grease in his kitchen, he does not fry etc only oven bake. The hob is only used to boil.

[mikeref]

Hob?... Sheet, I'll have to ask Wicki for a translation.:D

[back2space]

Hob?... Sheet, I'll have to ask Wicki for a translation.:D

Hob being the top part with the gas rings on lol.

[Josip]

Hi, mikeref :)

Hob?... Sheet, I'll have to ask Wicki for a translation.:D

if you have a problem with meaning of English words .... don't even try to imagine my problems sometime ...there is no Wiki or similar dictionary to help me to find a real meaning and to ask for explanation is not always "easy" ....

fortunately, this above (hob) is explained well with images ...

... for that reason it is nice to use as much as possible simple and known words ;), not only for me ...

Best regards, Josip :)

[Good^Man]

I would skip the kitchen, unless it is also a dining room.

If also a Dining room then locate the air-conditioner away from the cooking area (opposite wall?)

[back2space]

I would skip the kitchen, unless it is also a dining room.

yes a kitchen diner.