Radiator and boiler Sizing

the_viper2kie

Hi all,

I am currently buying a house - new build and the radiators went in yesterday without the plumber asking me about sizes of the rads. I went up and measured them today and tried doing some calcs and it looks like they are way undersized - makes me think my calculator may be wrong. They are quinn rads and got their BTU/hr capability from the quinn website. It's a 3 bed terraced house, 1200 sq ft.


Type Size BTU Watt Room Size (m2)
main bedroom DC22 90 x 50 1498 5105 13
main bathroom SC11 60 x 50 531 1812 5.3
Ensuite SC11 50 x 50 443 1510 3.8
Bedroom 2 DC22 100 x 50 1662 672 12.9
Bedroom 3 SC11 100 x 50 885 3021 7.7
Sitting Room 2 x DC22 80 x 50 1330 x 2 4538 x 2 23.8
Hallway (combined) SC11 120 x 50 1239 4229 11.8
Downstair toilet SC11 50 x 50 443 1510 2.5
Kitchen Not in yet 19.3

Do these radiators sizes look correct? Also what output boiler would you recommend this needs?

Appreciate your help

listen to me now

The boiler should be no bigger than a 50/90 condensing..make sure its condensing. i dont undrestand ure measurments. give me a few rooms in feet and the size of rad gone in and is it a double or single panel

the_viper2kie

Sorry,

Can't seem to get formatting from Excel to come out correctly. All rads are 500mm high. First column is room size in ft2 second is length of rad and third is single or double.

Room Size ft2 Length
139.88 900 Double
57.028 600 Single
40.888 500 Single
138.804 1000 Double
82.852 1000 Single
256.088 2 x 800 double
126.968 1200 Single
26.9 500 Single

Thanks for the help,

H

listen to me now

i`n sorry maybe im a little slow tonight. if u could give me one room size ie 12ft x 10 ft x 8 ft(ceiling height) and rad size in there. the number of external walls in the room play a factor too

the_viper2kie

Sorry,

Example of one - the sitting room first.
It is 11 ft x 21ft x 9.3ft. There are 2 rads in there double paneled 500 x 800mm.
There is one external wall and has a window and a french door - both double glazed.

listen to me now

ye that seems a little small alrite. alot of plumbers these days tend to undersize to cut costs. me personally i like to oversize by one size usually. i havent my rad calculator with me now. if u call into any heat merchants branches, tell them ure BUILDING a house. give them the sizes with ceiling heights and external walls and they`ll tell u exactly what u need

the_viper2kie

Thanks a million,

I'll have to go back to him. He said I have to let him know first thing on Monday if I want them changed...Do you have a link to any good calculator?
What is the consequence of undersized rads? Takes too long to heat the room I guess, if undersized completely would it be possible the room would never reach temp?

H

listen to me now

ah no unlikely in a new well insulated house. probrbly a bit harder on your fuel bill is all that will happen cause boiler will have to work alot harder for longer to bring room up to temp. also make sure TRV`s are fitted on all rads( thermostats). good luck. sorry have no links. I use a calculator called a MEYERS(probably not spelt right). probably the same as heat merchants use. good luck

yoshytoshy

Personally ,I wouldn't buy heatmerchants radiators. They're one of the cheaper rads ,very lightweight.

Myson and Quinn radiators are superior quality and a better output aswell.

listen to me now

i agree but they do rad sizing free of charge. most of there stock is **** to be honest. i swear there fittings are only 10% brass and 90% ****

yoshytoshy

People are usually suprised at how well the newer rads heat up the house ,when it's properly insulated.

No point in having bigger rads if you don't need them aswell ,definetly worth getting it right.

the_viper2kie

Just realised I had mixed up the Watt and BTU columns on the quinn website. They are not that far off being right it seems now. There is one in a hallway that might be on the small side as there is quite a high roof.
Plumber is putting thermostatic valves on all rads for me - except in the rooms where there is a thermostat on the wall, guess that makes sense. Presume this only an extra few quid - he might not charge me.

Also, he is trying to source a boiler. It was a development that most of the houses were finished 3 years ago and the manufacturer they previously usd is gone bust he said. The boiler is mounted ouside on the back wall of the house so only a few available for use outside he said. Looking at Vokera i think. Anything I should look out for in a boiler put outside? I presume these all have frost protection.

listen to me now

not all so make sure frost stat is fitted inside boiler. trv`s are usually about 20 euro per pair for good ones. PEGLAR are a good make

JohnnieK

If you are renovating the house and bringing it up to current regs then more than likely the radiators are over sized which in theory you could run the boiler at a lower temp to keep it condensing more. The calculation you are using is the rule of thumb method and is not as accurate as the proper heatloss calculation that plumbers where thought in collage. The only thing about this method is that all u-values must be known in order to come up with the right result. If the house is been brought to current specs than this makes the calculation easier as u-values are taken from the current regs.

That's the proper way to do it.