Looking to put a rad in a new conservatory which is 3m x 3m ceiling height
about 2.4m. Three outside walls.

One wall is double skin brick block with insulation, two walls are double
glazed floor to ceiling. Ceiling is transparent plastic - apparently with a
high insulation factor (but its not the triple wall stuff - its smooth).
Floor is chipboard - don't know whats underneath.

Tried this site http://www.radcalcs.com/ which reckons about 6,000 btu's -
but it doesn't have a pull down option for 'conservatory'.

Assuming this is right, its gonna need a 900 long x 620 high double or there
abouts.

Does this sound about right? I'd prefer to err on the side of caution & fit
a TRV.

TIA



--
Dave - The Medway Handyman
www.medwayhandyman.co.uk
01634 717930
07850 597257

In an earlier contribution to this discussion,
The Medway Handyman wrote:

Looking to put a rad in a new conservatory which is 3m x 3m ceiling
height about 2.4m. Three outside walls.

One wall is double skin brick block with insulation, two walls are
double glazed floor to ceiling. Ceiling is transparent plastic -
apparently with a high insulation factor (but its not the triple wall
stuff - its smooth). Floor is chipboard - don't know whats underneath.

Tried this site http://www.radcalcs.com/ which reckons about 6,000
btu's - but it doesn't have a pull down option for 'conservatory'.

Assuming this is right, its gonna need a 900 long x 620 high double
or there abouts.

Does this sound about right? I'd prefer to err on the side of
caution & fit a TRV.

TIA

I haven't seen the calculations - but I would be very dubious about the
result. Bearing in mind that 6000 BTU/Hr is somewhat less than 2kW, I doubt
whether that's enough[1]. I assume this is for a customer, 'cos if it was
yours, you'd know what was under the floor? Can you recover the cost of
doing the calcs, as well as of supplying and fitting the rad? If so, I'd try
to get hold of a better heatloss program (such as those available from Barlo
or Myson)[2] which allow you to specify U-values and other factors, and
which provide a breakdown of the calc rather than a single result.

[1] You could try putting a couple of 1kW oil-filled radiators in there on a
cold day to see how 'toasty' they make it.

[2] You can download the Barlo program from
http://www.barlo.co.uk/downloads_heatloss.php and, if you speak nicely to
Andy Hall, he'll email you a copy of the Myson program
--
Cheers,
Roger
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On 2007-12-31 14:05:07 +0000, "The Medway Handyman"
said:

Looking to put a rad in a new conservatory which is 3m x 3m ceiling height
about 2.4m. Three outside walls.

One wall is double skin brick block with insulation, two walls are double
glazed floor to ceiling. Ceiling is transparent plastic - apparently with a
high insulation factor (but its not the triple wall stuff - its smooth).
Floor is chipboard - don't know whats underneath.

Tried this site http://www.radcalcs.com/ which reckons about 6,000 btu's -
but it doesn't have a pull down option for 'conservatory'.

Assuming this is right, its gonna need a 900 long x 620 high double or there
abouts.

Does this sound about right? I'd prefer to err on the side of caution & fit
a TRV.

TIA

I don't trust any of the web site calculators and certainly not any
that work in BTUs, particularly if they don't say BTU/hr.

That aside, 6000 of the deprecated units comes to 1.75kW.

I always use the tables of U values and a calculator for each surface
or one of the radiator manufacturer's calculators - the Myson one is
the best IME.

You can look up the U values of each surface, multiply by the area and
the temperature difference. That gives the loss for that surface.
Then simply add the losses together. There is a similar calculation
for air changes based on volumetric measurement and air changes.

Assuming that the rear wall is against a heated room, you can
effectively ignore that.

Without doing the sums, based on my conservatory, which is quite a bit
larger and has a glass roof, and scaling to the size of this one,
1.75kW is rather light. 2.5kW is nearer to the mark on this basis,
assuming -3 outside and 21 inside.

I would tend to oversize for this application anyway. According to
building control rules, a TRV is needed anyway, so given that, it's a
reasonable approach.

The Medway Handyman wrote:
Looking to put a rad in a new conservatory which is 3m x 3m ceiling height
about 2.4m. Three outside walls.

One wall is double skin brick block with insulation, two walls are double
glazed floor to ceiling. Ceiling is transparent plastic - apparently with a
high insulation factor (but its not the triple wall stuff - its smooth).
Floor is chipboard - don't know whats underneath.

Tried this site http://www.radcalcs.com/ which reckons about 6,000 btu's -
but it doesn't have a pull down option for 'conservatory'.

Assuming this is right, its gonna need a 900 long x 620 high double or there
abouts.


Another option here would be one of the Myson fan assisted rads. These
will very much faster warm up times which can be handy for a
conservatory if it is not used as full time living space.


--
Cheers,

John.

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