BTU : Advice

2012paddy2012

I’m just using different BTU CALCULATORS getting quite different results !! An apprentice plumber ( good lad) reckoned 1460. 1500 a guy who priced job thought with thermostat on rad!

I got a mad figure altogether on the btu calculator I tried....
Anyone any idea what output rad ( approx) this room would need.
Kitchen - width 11 feet height 8 feet length 15.5 feet.
Window timber double glazed - 4x4 feet
Wooden patio doors ( double glazed) 7 ft x 5 feet
Upstairs over it , heated bedrooms
Brickwork think ordinary block work ( house 15 years old)
2 outside walls ....

Thanks lads

Ginger83

Hi i have always went with length x width x height x 6 and you are well covered so 8184 btu's required.
Remember you can turn a radiator down but undersize and you are fecked

2012paddy2012

Ginger83 wrote: »

Hi i have always went with length x width x height x 6 and you are well covered so 8184 btu's required.
Remember you can turn a radiator down but undersize and you are fecked

Oh gosh that’s very interesting plumber mentioned I think 1500 or so , that’s well below what you say ...I agree undersized not good . He had say around 1500 figure ..-also an apprentice plunber , a good bit of stuff , thought just under the 1500 figure. Both seem way out ...
I have a single rad there and he is going to replace it with a double just to bring the heat up a bit ,,,
Thanks for this I’ll have to get onto the plunber to double check
Cheers

Ginger83

2012paddy2012 wrote: »

Oh gosh that’s very interesting plumber mentioned I think 1500 or so , that’s well below what you say ...I agree undersized not good . He had say around 1500 figure ..-also an apprentice plunber , a good bit of stuff , thought just under the 1500 figure. Both seem way out ...
I have a single rad there and he is going to replace it with a double just to bring the heat up a bit ,,,
Thanks for this I’ll have to get onto the plunber to double check
Cheers

Double check with them. Maybe 1500 was watts or length of radiator but definitely not Btu's. Different plumbers have different ways of working it out as insulation improves etc,I know some that multiply by 5.5 depending on the room.

2012paddy2012

Ginger83 wrote: »

Double check with them. Maybe 1500 was watts or length of radiator but definitely not Btu's. Different plumbers have different ways of working it out as insulation improves etc,I know some that multiply by 5.5 depending on the room.

Thanks a mill

John.G

This calculator may not be the best but its not bad.
For most of us I would think the rad output in KW is the easiest to grasp because every one can relate to a 1 kw electric fire?.
The trend now is to give the output in watts, just divide the watts by 1000 to get KW, so 1500 watts is 1.5kw, divide BTUs by 3412 to get KW, so 6824 Btus equals 2 Kw (or 2000 watts)

https://www.bestheating.ie/btu-calculator

2012paddy2012

John.G wrote: »

This calculator may not be the best but its not bad.
For most of us I would think the rad output in KW is the easiest to grasp because every one can relate to a 1 kw electric fire?.
The trend now is to give the output in watts, just divide the watts by 1000 to get KW, so 1500 watts is 1.5kw, divide BTUs by 3412 to get KW, so 6824 Btus equals 2 Kw (or 2000 watts)

https://www.bestheating.ie/btu-calculator

Maths not good !

Can you work it out !!

Kitchen - width 11 feet height 8 feet length 15.5 feet.
Window timber double glazed - 4x4 feet
Wooden patio doors ( double glazed) 7 ft x 5 feet
Upstairs over it , heated bedrooms
Brickwork think ordinary block work ( house 15 years old)
2 outside walls ....

John.G

Inputting your numbers above I come up with a figure of 825 watts = 0.825kw = 2815 Btu. Even if this figure is accurate one should be very very careful for two reasons, one is that the actual room heat up time would take possibly up to 2 hours without making a allowance for this, the other is potentially far more important....... all modern rad outputs are based on a "50 deg" standard which is the mean rad temperature minus the required room temperature, often taken as 20C. Before the advent of condensing boilers which require very low return temperature to attain some condensing benefits then quite easy to meet this 50 deg, ie boiler/rad flow/return temps of 75/65C (gives mean of 70C) minus 20C gives a full output from a 50 deg rad, condensing boilers run very efficiently with flow/return temps of 65/45C so your rad runs like this then you now only have a 35 deg rad or 63% of its output, so to compensate for this you should multiply your rad requirement by a factor of, at least, 1.6, and preferrably 2.0 so your above requirement is for a minimum 1320 watts = 1.32kw = 4505 Btu which was what your plumber more or less suggested.

Personally, I would advise installing a 2 to 2.5kw rad (6824/8530Btu) with a TRV (thermostatic rad valve) which will ensure a fast kitchen warm up time but the TRV will then cut back the rad output when it reaches temperature and cut it back even further when the cooker etc is being used.
I have a similar kitchen like you but less insulation also with cavity block walls and I estimate my theoretical heating requirement at 1.4kw but I installed a 3kw rad with a TRV which results in perfect temperature control at 20C.

What are the dimensions of your single panel rad?.

2012paddy2012

John.G wrote: »

Inputting your numbers above I come up with a figure of 825 watts = 0.825kw = 2815 Btu. Even if this figure is accurate one should be very very careful for two reasons, one is that the actual room heat up time would take possibly up to 2 hours without making a allowance for this, the other is potentially far more important....... all modern rad outputs are based on a "50 deg" standard which is the mean rad temperature minus the required room temperature, often taken as 20C. Before the advent of condensing boilers which require very low return temperature to attain some condensing benefits then quite easy to meet this 50 deg, ie boiler/rad flow/return temps of 75/65C (gives mean of 70C) minus 20C gives a full output from a 50 deg rad, condensing boilers run very efficiently with flow/return temps of 65/45C so your rad runs like this then you now only have a 35 deg rad or 63% of its output, so to compensate for this you should multiply your rad requirement by a factor of, at least, 1.6, and preferrably 2.0 so your above requirement is for a minimum 1320 watts = 1.32kw = 4505 Btu which was what your plumber more or less suggested.

Personally, I would advise installing a 2 to 2.5kw rad (6824/8530Btu) with a TRV (thermostatic rad valve) which will ensure a fast kitchen warm up time but the TRV will then cut back the rad output when it reaches temperature and cut it back even further when the cooker etc is being used.
I have a similar kitchen like you but less insulation also with cavity block walls and I estimate my theoretical heating requirement at 1.4kw but I installed a 3kw rad with a TRV which results in perfect temperature control at 20C.

What are the dimensions of your single panel rad?.

Thanks so much for going to all that effort .
There is a TRV on the single rad. He said he would put that on the double. I never use it , it’s on full , as it never got too warm ! The dimensions of the single rad is : 160 x 60. It has “‘fins” on the back . Thanks

Ps he mentioned it was last on the line so that it takes longer to heat fully tho it will heat fully !

John.G

That single is ~ 1.4kw so if replaced with the same size double ~ 2.3kw or effectively a 1.6kw rad if you have a condensing boiler set to 60/65C.

2012paddy2012

John.G wrote: »

That single is ~ 1.4kw so if replaced with the same size double ~ 2.3kw or effectively a 1.6kw rad if you have a condensing boiler set to 60/65C.

Would that do the trick so ? Cheers

John.G

Like the Carlsberg adv.....probably, you might ask your plumber to see if he can increase the circ pump speed/head to give a little faster circulation as well.

2012paddy2012

John.G wrote: »

Like the Carlsberg adv.....probably, you might ask your plumber to see if he can increase the circ pump speed/head to give a little faster circulation as well.

390 to supply /ft - for same size rad . Except it will be a double ! No idea. Seems a bit on the high side !?
Just wondered - no pipe work involved .

With exact same size of rad , from you tube , seems handy enough , once rad is isolated and drained properly , is it “doable” with reasonable diy skills !!! Half thinking I’ll give it a bash as there is no additional pipe work !

wiz569

2012paddy2012 wrote: »

390 to supply /ft - for same size rad . Except it will be a double ! No idea. Seems a bit on the high side !?
Just wondered - no pipe work involved .

With exact same size of rad , from you tube , seems handy enough , once rad is isolated and drained properly , is it “doable” with reasonable diy skills !!! Half thinking I’ll give it a bash as there is no additional pipe work !

If that's not a cash job then its a fair price, as for no pipe work I would be surprised if there is not any as the valves will be a bit further out from the wall on a double rad.

2012paddy2012

wiz569 wrote: »

If that's not a cash job then its a fair price, as for no pipe work I would be surprised if there is not any as the valves will be a bit further out from the wall on a double rad.

Fair enough , I’ll give it some thought thanks

Ginger83

2012paddy2012 wrote: »

390 to supply /ft - for same size rad . Except it will be a double ! No idea. Seems a bit on the high side !?
Just wondered - no pipe work involved .

With exact same size of rad , from you tube , seems handy enough , once rad is isolated and drained properly , is it “doable” with reasonable diy skills !!! Half thinking I’ll give it a bash as there is no additional pipe work !

Sticking a rad on the wall is only part of your needs but an experienced plumber will know how to have your system running efficiently. By all means have a go but you may be calling a plumber anyway.

I enjoy a bit of diy but I use a trusted plumber and electrician for the important stuff.

2012paddy2012

Ginger83 wrote: »

Sticking a rad on the wall is only part of your needs but an experienced plumber will know how to have your system running efficiently. By all means have a go but you may be calling a plumber anyway.

I enjoy a bit of diy but I use a trusted plumber and electrician for the important stuff.

True enough indeed. I’m mulling it over . I added one years ago but spent weeks balancing to get max heat onto it ! Bit unsure

John.G

Don't forget, the hanging brackets will more than likely be different as well, which I found to be the most tedious when changing a relations single to a double.

2012paddy2012

John.G wrote: »

Don't forget, the hanging brackets will more than likely be different as well, which I found to be the most tedious when changing a relations single to a double.

Funnily enough that’s the biggest concern !
Thanks for all the advice