Hello,

I was asking about radiators on the "CH pipe size" thread but the
discussion has moved on to radiator sizes rather than pipe sizes, so I
thought a new thread would be useful.

I just wanted to ask two last questions:

Is 300W a noticeable difference in heat output: I have found two
radiators for sale and their outputs differ by 300W, would I notice
the difference?

Is there a big difference between makes on panel radiator regarding
their outputs? Sorry to switch units but I was looking for a rad about
7000BTU and I see some makes I can use a 500x1300, others require
500x1400 and others 500x1600. Different makes of 500x1400 have
different outputs (hence question one above).

Thanks in advance.
Stephen.

In an earlier contribution to this discussion,
Stephen wrote:

Hello,

I was asking about radiators on the "CH pipe size" thread but the
discussion has moved on to radiator sizes rather than pipe sizes, so I
thought a new thread would be useful.

I just wanted to ask two last questions:

Is 300W a noticeable difference in heat output: I have found two
radiators for sale and their outputs differ by 300W, would I notice
the difference?

It depends on what percentage change this represents! You'd be more likely
to notice the difference between 300 and 600 than between 2300 and 2600.

Is there a big difference between makes on panel radiator regarding
their outputs? Sorry to switch units but I was looking for a rad about
7000BTU and I see some makes I can use a 500x1300, others require
500x1400 and others 500x1600. Different makes of 500x1400 have
different outputs (hence question one above).


To at least a first order of approximation, all radiators of a given size
and construction should give the same output under the same (Delta-T)
operating conditions. The output depends on:
* surface area of the panels and fins
* emmissivity of the surface finish
* mean surface temperature

None of those things are going vary all that much from make to make. There
may be slight variations depending on the spacing and depth of the fins -
which could have an effect on the amount of convected heat entering the
room.

There are rules of thumb for watts per square metre for each basic type -
single panel without fins, single panel with fins, double panel without
fins, double panel with single fins, double panel with double fins, etc.
Most manufacturers' published data fit in with the rules of thumb fairly
well - although some manufacturers do quote different outputs for different
shapes[1] even though the areas may be the same.

Are you sure that all the examples which you cite are specified at the same
dT?

[1] e.g. 2000 x 300 vs 1000 x 600
--
Cheers,
Roger
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On Thu, 6 Aug 2009 10:19:40 +0100, "Roger Mills"
wrote:

It depends on what percentage change this represents! You'd be more likely
to notice the difference between 300 and 600 than between 2300 and 2600.

Very true! I shall have to calculate the percentage difference.

To at least a first order of approximation, all radiators of a given size
and construction should give the same output under the same (Delta-T)

The output depends on:
* surface area of the panels and fins
* emmissivity of the surface finish
* mean surface temperature

None of those things are going vary all that much from make to make.

That's what I thought, which is why I was surprised that the outputs
differed. Perhaps some marketing departments "tweak" their figures
more than others?

I am currently looking at a Quinn Barlo 500x1400 double (2.3kW, 7900
BTU IIRC). Is Quinn barlo a good make? I think it's the least I can
do, since Barlo were kind enough to provide the calculator

I have looked at other makes 500mm high and double width to produce
the same output; one required 500x1600 but another managed with just
500x1300. I am surprised that 160mm in one outputs as much as 1300mm
in another; I would have thought a foot difference in length would
have made a big difference to output.

Are you sure that all the examples which you cite are specified at the same
dT?

Yes, after all your previous help with factors, I checked, double
checked and checked again! Only Toolstation and 4bathrooms quote
dT=60, everyone else is using dT=50

Thanks again.
Stephen.

On 6 Aug, 11:35, Stephen wrote:
On Thu, 6 Aug 2009 10:19:40 +0100, "Roger Mills"

wrote:
It depends on what percentage change this represents! You'd be more likely
to notice the difference between 300 and 600 than between 2300 and 2600.

Very true! I shall have to calculate the percentage difference.

To at least a first order of approximation, all radiators of a given size
and construction should give the same output under the same (Delta-T)
The output depends on:
* surface area of the panels and fins
* emmissivity of the surface finish
* mean surface temperature

None of those things are going vary all that much from make to make.

That's what I thought, which is why I was surprised that the outputs
differed. Perhaps some marketing departments "tweak" their figures
more than others?

I am currently looking at a Quinn Barlo 500x1400 double (2.3kW, 7900
BTU IIRC). Is Quinn barlo a good make? I think it's the least I can
do, since Barlo were kind enough to provide the calculator

Quinn Barlo are good, we have had one of their radiators for 6 years,
very well made and solid.


I have looked at other makes 500mm high and double width to produce
the same output; one required 500x1600 but another managed with just
500x1300. I am surprised that 160mm in one outputs as much as 1300mm
in another; I would have thought a foot difference in length would
have made a big difference to output.

Are you sure that all the examples which you cite are specified at the same
dT?

Yes, after all your previous help with factors, I checked, double
checked and checked again! Only Toolstation and 4bathrooms quote
dT=60, everyone else is using dT=50

Thanks again.
Stephen.

In an earlier contribution to this discussion,
David wrote:


I am currently looking at a Quinn Barlo 500x1400 double (2.3kW, 7900
BTU IIRC). Is Quinn barlo a good make? I think it's the least I can
do, since Barlo were kind enough to provide the calculator

Quinn Barlo are good, we have had one of their radiators for 6 years,
very well made and solid.

I'm sure they're as good as anyone else's. I tend to regard radiators as a
'commodity' purchase - they're all much of a muchness - so unless you're
prepared to pay through the nose for a pretty looking 'designer' jobby, go
for the cheapest. Whatever you go for, there are some good on-line deals
which are a lot cheaper than anything you'll get at the sheds.
--
Cheers,
Roger
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On 6 Aug, 16:46, "Roger Mills" wrote:
In an earlier contribution to this discussion,

David *wrote:

I am currently looking at a Quinn Barlo 500x1400 double (2.3kW, 7900
BTU IIRC). Is Quinn barlo a good make? I think it's the least I can
do, since Barlo were kind enough to provide the calculator

Quinn Barlo are good, we have had one of their radiators for 6 years,
very well made and solid.

I'm sure they're as good as anyone else's. I tend to regard radiators as a
'commodity' purchase - they're all much of a muchness - so unless you're
prepared to pay through the nose for a pretty looking 'designer' jobby, go
for the cheapest. Whatever you go for, there are some good on-line deals
which are a lot cheaper than anything you'll get at the sheds.
--
Cheers,
Roger
______
Email address maintained for newsgroup use only, and not regularly
monitored.. Messages sent to it may not be read for several weeks.
PLEASE REPLY TO NEWSGROUP!

The Altech ones from Graham are poorly made.

On Thu, 6 Aug 2009 16:46:02 +0100, "Roger Mills"
wrote:

I tend to regard radiators as a
'commodity' purchase - they're all much of a muchness - so unless you're
prepared to pay through the nose for a pretty looking 'designer' jobby, go
for the cheapest.

Thanks. That's what I thought, as I said in an earlier post, the
standard panel; ones all look the same to me.

The ones I had looked at were all double radiators with double fins
and all 500mm high.

The web sites all list output in BTUs, I have divided by 3.413 to
calculate the Watts.

Kudox (at B&Q) 500m x 1400mm has a 7053 BTU (2.07kW) at dt=50
Quinn 500 x 1400 is 7941 BTU (2.33 kW)
Myson 500 x 1400 is 7094 BTU (2.08 kW)

I cannot understand why the Quinn is so much higher than the other
two.

The Biasi from 4 bathrooms is the only one rated at dT=60. At dT=60
the output is 8505, which by my calculations (divide by 1.27) equates
to 6697 BTU (1.96 kW), which seems a little lower than the others.
Why?

Whatever you go for, there are some good on-line deals
which are a lot cheaper than anything you'll get at the sheds.

Any offer/merchant you recommend in particular?

Thanks again.
Stephen.

Sorry, I should have added that the Barlo calculator says I need 2.2kW
or 7473 BTUs, so this is why I am anxious about the outputs of the
rads. The Kudox and Myson would be below this but the Quinn would be
ideal for my requirements. However, is the rating for the Quinn too
good to be true? I could buy a 1600mm rad just to be sure, but I would
like to keep the length and cost of the rad as small as possible!

Thanks.

In an earlier contribution to this discussion,
Stephen wrote:


I am currently looking at a Quinn Barlo 500x1400 double (2.3kW, 7900
BTU IIRC). Is Quinn barlo a good make? I think it's the least I can
do, since Barlo were kind enough to provide the calculator

I have looked at other makes 500mm high and double width to produce
the same output; one required 500x1600 but another managed with just
500x1300. I am surprised that 160mm in one outputs as much as 1300mm
in another; I would have thought a foot difference in length would
have made a big difference to output.


Would you care to define "double"? Some doubles have *two* sets of fins -
back to back on both panels - (K2 in Stelrad parlance) and some have just
one set (P+) - and it makes quite a difference to the output. Just looking
at a Stelrad data sheet, a 1200 x 450 K2 has a very similar output to a 1600
x 450 P+.

Are you sure that you're comparing apples with apples?
--
Cheers,
Roger
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On Thu, 06 Aug 2009 09:10:09 +0100, Stephen wrote:

Is there a big difference between makes on panel radiator regarding
their outputs? Sorry to switch units but I was looking for a rad about
7000BTU and I see some makes I can use a 500x1300, others require
500x1400 and others 500x1600. Different makes of 500x1400 have
different outputs (hence question one above).

suggest you check the article on radiators in the wiki - it has a formula
for working out the output of any standard rad given its sizes and
configuration



--
John Stumbles -- http://yaph.co.uk

"I used to think correlation implied causation.
Then I took a statistics course and now I don't."
"Sounds as if the statistics course helped."
"Well, maybe."

On 6 Aug 2009 19:13:28 GMT, YAPH wrote:

suggest you check the article on radiators in the wiki - it has a formula
for working out the output of any standard rad given its sizes and
configuration

But that was my question. If all radiators that are the same height,
same width, and all double finned, why should one make have a higher
output. If they are all constructed the same and obey the same
formula, should all outputs be equal?

Stephen wrote:
On 6 Aug 2009 19:13:28 GMT, YAPH wrote:

suggest you check the article on radiators in the wiki - it has a formula
for working out the output of any standard rad given its sizes and
configuration

But that was my question. If all radiators that are the same height,
same width, and all double finned, why should one make have a higher
output. If they are all constructed the same and obey the same
formula, should all outputs be equal?

The heat output of a radiator is also critically dependent on its
working temperature and the ambient temperature. So the same rad can
have many different outputs depending on how its measured.

If it was red hot, it would output a fair but more..

In an earlier contribution to this discussion,
The Natural Philosopher wrote:

Stephen wrote:
On 6 Aug 2009 19:13:28 GMT, YAPH wrote:

suggest you check the article on radiators in the wiki - it has a
formula for working out the output of any standard rad given its
sizes and configuration

But that was my question. If all radiators that are the same height,
same width, and all double finned, why should one make have a higher
output. If they are all constructed the same and obey the same
formula, should all outputs be equal?

The heat output of a radiator is also critically dependent on its
working temperature and the ambient temperature. So the same rad can
have many different outputs depending on how its measured.

If it was red hot, it would output a fair but more..

Yes, we *know* that - but manufactuers' published data should surely all be
based on measurements made under the *same* operating conditions - certainly
when they quote the same delta-T.
--
Cheers,
Roger
______
Email address maintained for newsgroup use only, and not regularly
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