I'm in the process of renovating the last room in the house (thank
goodness!) and need to replace the 620mm x 1415mm single radiator as it
is 42 years old and looking a little dated. It may also be following its
friend from another room by developing a pinhole leak.

The room is 2.3M high, 3.33M wide and 4.11M long with a 2.43M2 double
glazed window. Two of the walls are external walls with cavity wall
insulation, the room underneath is heated and the loft above it has
~170mm of insulation. If I enter all that into the BTU calculator at
http://www.heatandplumb.com/radCalcs.html it would seem that I need a
radiator with an output of 2018BTUs. Single radiators of a similar size
(Stelrad K1 Compact, 600mm x 1400mm) to the one I am replacing are
listed at 4681BTU.

Has the insulation I have installed really reduced the heating I need to
provide to less than half? Or am I missing something?

TIA

--
F

In article ,
F news@nowhere writes:
I'm in the process of renovating the last room in the house (thank
goodness!) and need to replace the 620mm x 1415mm single radiator as it
is 42 years old and looking a little dated. It may also be following its
friend from another room by developing a pinhole leak.

The room is 2.3M high, 3.33M wide and 4.11M long with a 2.43M2 double
glazed window. Two of the walls are external walls with cavity wall
insulation, the room underneath is heated and the loft above it has
~170mm of insulation. If I enter all that into the BTU calculator at
http://www.heatandplumb.com/radCalcs.html it would seem that I need a
radiator with an output of 2018BTUs. Single radiators of a similar size
(Stelrad K1 Compact, 600mm x 1400mm) to the one I am replacing are
listed at 4681BTU.

Has the insulation I have installed really reduced the heating I need to
provide to less than half? Or am I missing something?

Possibly.
Do the same check on other rooms in the house.
If they are all similarly over-spec'ed, you really need to do the same.

Other factors are that radiator outputs are often given using unreasonably
high delta-T values. What delta-T is yours specified at, and what temp do
you actually run your boiler?

Have you got a condensing boiler? If so, oversized radiators can make for
more efficient operation (providing they're all similarly oversized).

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

On Oct 25, 6:39*pm, F news@nowhere wrote:
I'm in the process of renovating the last room in the house (thank
goodness!) and need to replace the 620mm x 1415mm single radiator as it
is 42 years old and looking a little dated. It may also be following its
friend from another room by developing a pinhole leak.

The room is 2.3M high, 3.33M wide and 4.11M long with a 2.43M2 double
glazed window. Two of the walls are external walls with cavity wall
insulation, the room underneath is heated and the loft above it has
~170mm of insulation. If I enter all that into the BTU calculator athttp://www.heatandplumb.com/radCalcs.htmlit would seem that I need a
radiator with an output of 2018BTUs. Single radiators of a similar size
(Stelrad K1 Compact, 600mm x 1400mm) to the one I am replacing are
listed at 4681BTU.

Has the insulation I have installed really reduced the heating I need to
provide to less than half? Or am I missing something?

TIA

--
F

Try toolstation

On 25/10/2009 19:51 Andrew Gabriel wrote:

Do the same check on other rooms in the house.
If they are all similarly over-spec'ed, you really need to do the same.

They're all based on the original 1967 installation (pre insulation)
sizing. We don't have any problems getting the house up to temperature
in good time on cold days.

Other factors are that radiator outputs are often given using unreasonably
high delta-T values. What delta-T is yours specified at, and what temp do
you actually run your boiler?

From the website: 'All radiator outputs are calculated @DT50°C inline
with European BS EN 442 testing standard'.

It's a Worcester Bosch 24(?) Ri and hasn't got a dial marked with the
temperature, just 'Reset' and 'max'. I just run it as low as it will go
without the house taking for ever to warm up. It's a little less than
half way between the minimum (35C) and maximum (82C), so say 50C?

Have you got a condensing boiler?

Yes.

If so, oversized radiators can make for
more efficient operation (providing they're all similarly oversized).

OK, so the radiators I've looked at are around 5% or 10% oversized
according to the calculator.

--
F

On 25/10/2009 19:51 spud wrote:

Try toolstation

For...

--
F

On Oct 25, 8:18*pm, F news@nowhere wrote:
On 25/10/2009 19:51 spud wrote:

Try toolstation

For...

--
F

Precisely

F wrote:
I'm in the process of renovating the last room in the house (thank
goodness!) and need to replace the 620mm x 1415mm single radiator as it
is 42 years old and looking a little dated. It may also be following its
friend from another room by developing a pinhole leak.

The room is 2.3M high, 3.33M wide and 4.11M long with a 2.43M2 double
glazed window. Two of the walls are external walls with cavity wall
insulation, the room underneath is heated and the loft above it has
~170mm of insulation. If I enter all that into the BTU calculator at
http://www.heatandplumb.com/radCalcs.html it would seem that I need a
radiator with an output of 2018BTUs. Single radiators of a similar size
(Stelrad K1 Compact, 600mm x 1400mm) to the one I am replacing are
listed at 4681BTU.

Has the insulation I have installed really reduced the heating I need to
provide to less than half? Or am I missing something?

TIA

Should be less than a third.

I'd say you are about right.

something like 100W/sq meter Just under a kilowatt probably.

On 26/10/2009 11:44 The Natural Philosopher wrote:

Should be less than a third.

Good news and, thinking about it, I've spent quite a lot on insulation
over the years: the house had no double glazing or cavity wall
insulation and had just 25mm of loft insulation when built so would have
needed fairly chunky radiators to cope with the heat loss.

I'd say you are about right.

I'll get the smaller (and cheaper) radiators ordered then.

Looks like a toss-up between OnPlumb and HeatAndPlumb, though OnPlumb
are cheaper with their free delivery for orders over £50 (ex-VAT).

Unless someone knows cheaper...

--
F

On 25 Oct, 20:17, F news@nowhere wrote:
On 25/10/2009 19:51 Andrew Gabriel wrote:

Do the same check on other rooms in the house.
If they are all similarly over-spec'ed, you really need to do the same.

They're all based on the original 1967 installation (pre insulation)
sizing. We don't have any problems getting the house up to temperature
in good time on cold days.

Other factors are that radiator outputs are often given using unreasonably
high delta-T values. What delta-T is yours specified at, and what temp do
you actually run your boiler?

*From the website: 'All radiator outputs are calculated @DT50°C inline
with European BS EN 442 testing standard'.

It's a Worcester Bosch 24(?) Ri and hasn't got a dial marked with the
temperature, just 'Reset' and 'max'. I just run it as low as it will go
without the house taking for ever to warm up. It's a little less than
half way between the minimum (35C) and maximum (82C), so say 50C?

Is this a conventional boiler? I have been told that they have to be
set at a minimum of 65C to get the hot water cylinder at the correct
temperature.


Have you got a condensing boiler?

Yes.

If so, oversized radiators can make for
more efficient operation (providing they're all similarly oversized).

OK, so the radiators I've looked at are around 5% or 10% oversized
according to the calculator.

--
F