RADIATOR BTU PER ROOM SIZE?

[Bobbins29]

Hi. I'm looking for some information regarding radiator size/btu/quantity. In a new build, should the builder provide the radiator size/btu on the room size only or, the room size (3×4mt), ceiling hieght, how many windows and how many outside walls? I'm in a new build with the lounge the depth of the house. One triple payne window at one end and a double payne at the opposite side. Three outside walls. The builders have put 1 radiator under the three payne window only. The back of the room never gets warm, only the first 3rd of the lounge infront of the radiator. I worked it out with the full measurements. I would need over the btu of the one radiator, should the builder have know this and added a second radiator at the other end of the room to add up to the btu required? Any building regulations regarding this please? Any advice gratefully appreciated.

 

[Bonni]

Just use one of the many calculators on the internet -

Here's one

What I always advise is, if the calculator suggests xx Btu size, get the next sized up radiator. You can always turn radiators down, but in adverse cold weather, you can't turn them above their maximum. And obviously, the boiler should be rated to supply all the Btu requirements.

 

[JohnD]

Modernise and move forward go the 1980s.

Kw.

 

[oldbuffer]

1. Doing the full heat loss calculation for a property is a time consuming task. Key data are room heights and widths, ceiling widths and lengths, window areas, door areas, the expected temperature on each side of each wall, floor and ceiling. Plus thermal emissivity of each surface, which requires knowing what each surface is made of.
2. The on-line calculators can only make very broad assumptions about these things, and in my experience tend to produce very broad-brush figures, which can vary quite widely from one calculator to another.
3. I would expect developers to carry out a full calculation rather than relying on an on-line calculator of unknown accuracy.
4. Perhaps you could ask the developers for sight of their calculations.
5. It might also be worth checking (but not easy) whether specified insulation has actually been installed.

 

[Andy165]

You are now required to specify radiator size and output for lower flow temperatures so you are prepared for a future heat pump install. Builders are often ****s who work to a "price" . They screw the subby down on price and add their mark up on. Probabley should have put another radiator in, but what did you agree on? Just reread "new build". Probabley best getting your own heating engineer in to add another radiator. You have bought "as seen"

 

[Johntheo5]

You are now required to specify radiator size and output for lower flow temperatures so you are prepared for a future heat pump install. Builders are often ****s who work to a "price" . They screw the subby down on price and add their mark up on. Probabley should have put another radiator in, but what did you agree on? Just reread "new build". Probabley best getting your own heating engineer in to add another radiator. You have bought "as seen"

I think all rads must now be designed to give the required output with a flow temp of 50C, with Heat Pumps in mind.
I did these calcs for someone whose present rads require a flow temp of 81C to give a room temp of 21C at a OT of -5C. and intended to install a condensing boiler with WC and intended to install new rads downstairs based on a "T30 rad" (double the size of the existing rads).
It can be seen below that even doubling the rad sizes will only give a output of 68% at 50C so if 100% output is required at -5C, the rad would/will have to be oversized by a factor of ~ 2.9, almost X a factor of 3 or as stated above, install 2 rads, a bit messy, its easy to see why UFH is, by far, the preferred choice for new installs.

 

[fixitflav]

Modernise and move forward go the 1980s.

Kw.

kW