Hi all,
I have a single radiator (central heating type) of size 70cm*75cm, circa
1976, that I need to replace. It is in a small bathroom and was wondering
what wattage output it was likely to give. Does anyone know or know a
formula to calculate it?

Many thanks

Ferret

DUMBO wrote:
Hi all,
I have a single radiator (central heating type) of size 70cm*75cm,
circa 1976, that I need to replace. It is in a small bathroom and was
wondering what wattage output it was likely to give. Does anyone know or
know a formula to calculate it?

Many thanks

Ferret

Couple of hundred watts or so.

No more than 500W anyway.

In article , DUMBO
dumbo@home.? writes
Hi all,
I have a single radiator (central heating type) of size 70cm*75cm, circa
1976, that I need to replace. It is in a small bathroom and was wondering
what wattage output it was likely to give. Does anyone know or know a
formula to calculate it?

Courtesy of John Stumbles 17 Jan, 00:32

Q
Subject: Radiator output formula and finless rad specs

After a bit of firkling around with Myson & Kudox radiator output specs
I
found a formula which gives a reasonable approximation so one can
calculate output from dimensions (and v.v.)

Heat Output = (Height + 12) * Length * FACTOR
(Watts) (cm) (cm)

where FACTOR is (for Delta-T 50°C)

* 0.13 for SC
* 0.19 for DP
* 0.24 for DC

See
http://wiki.diyfaq.org.uk/index.php?...ting_Radiators

It might be useful[1] to be able to calculate the output of
old-fashioned
radiators without convection fins. Anyone have any data sheets on these?


[1] or at least, marginally interesting :-)
/Q
--
fred
Plusnet - I hope you like vanilla

DUMBO wrote:
Hi all,
I have a single radiator (central heating type) of size 70cm*75cm,
circa 1976, that I need to replace. It is in a small bathroom and was
wondering what wattage output it was likely to give. Does anyone know
or know a formula to calculate it?

According to the Wickes Good Ideas Leaflet a 800w x 620h single rad (roughly
similar area) is 2,552 BTU's/Hr which is about 750W IMCAC.


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

"DUMBO" dumbo@home wrote in message
...
Hi all,
I have a single radiator (central heating type) of size 70cm*75cm,
circa 1976, that I need to replace. It is in a small bathroom and was
wondering what wattage output it was likely to give. Does anyone know
or know a formula to calculate it?

The Stelrad catalogue from the late 70s says 605W for one 740h x 640
long, and 756W for 740h x 800 long. Interpolation is left as an
exercise for the reader. Other makes won't be very different.


--
Kevin Poole
**Use current month and year to reply (e.g. )***

In article ,
"Autolycus" writes:

"DUMBO" dumbo@home wrote in message
...
Hi all,
I have a single radiator (central heating type) of size 70cm*75cm,
circa 1976, that I need to replace. It is in a small bathroom and was
wondering what wattage output it was likely to give. Does anyone know
or know a formula to calculate it?

The Stelrad catalogue from the late 70s says 605W for one 740h x 640
long, and 756W for 740h x 800 long. Interpolation is left as an
exercise for the reader. Other makes won't be very different.

You need to watch out for the average temperature which is claimed
to generate the specified power, and then correct for real values
(or if comparing, ensure the two datasheets are using the same value
for average temperature). When I was designing my system, some of
the manufacturer data sheets had small print saying values were at
80C average temperature. Not even a conventional system is likely
to ever reach that, as that's typically the maximum flow temperature.
(They're usually given as the delta, i.e. difference between room
temperature and average radiator temperature, so a delta of 60C
would typically be a room temperature of 20C + 60C delta = 80C
average radiator temperature, which just isn't realistic.)

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

Andrew Gabriel wrote:
In article ,
"Autolycus" writes:
"DUMBO" dumbo@home wrote in message
...
Hi all,
I have a single radiator (central heating type) of size 70cm*75cm,
circa 1976, that I need to replace. It is in a small bathroom and was
wondering what wattage output it was likely to give. Does anyone know
or know a formula to calculate it?

The Stelrad catalogue from the late 70s says 605W for one 740h x 640
long, and 756W for 740h x 800 long. Interpolation is left as an
exercise for the reader. Other makes won't be very different.

You need to watch out for the average temperature which is claimed
to generate the specified power, and then correct for real values
(or if comparing, ensure the two datasheets are using the same value
for average temperature). When I was designing my system, some of
the manufacturer data sheets had small print saying values were at
80C average temperature. Not even a conventional system is likely
to ever reach that, as that's typically the maximum flow temperature.
(They're usually given as the delta, i.e. difference between room
temperature and average radiator temperature, so a delta of 60C
would typically be a room temperature of 20C + 60C delta = 80C
average radiator temperature, which just isn't realistic.)

Exactly. Which is why my gut feel is it would be in the 200W - 500W
range, depending on boiler temps.

"Andrew Gabriel" wrote in message
...
In article ,
"Autolycus" writes:

"DUMBO" dumbo@home wrote in message
...
Hi all,
I have a single radiator (central heating type) of size
70cm*75cm,
circa 1976, that I need to replace. It is in a small bathroom and
was
wondering what wattage output it was likely to give. Does anyone
know
or know a formula to calculate it?

The Stelrad catalogue from the late 70s says 605W for one 740h x 640
long, and 756W for 740h x 800 long. Interpolation is left as an
exercise for the reader. Other makes won't be very different.

You need to watch out for the average temperature which is claimed
to generate the specified power, and then correct for real values

Yes - I should have added that these are for average radiator
temperature of 170F and room temp of 70F, so delta T of 55.6C. The
correction factor to delta T=50C is given as 0.87 +/- 0.02.


--
Kevin Poole
**Use current month and year to reply (e.g. )***

In an earlier contribution to this discussion,
DUMBO dumbo@home wrote:

Hi all,
I have a single radiator (central heating type) of size 70cm*75cm,
circa 1976, that I need to replace. It is in a small bathroom and was
wondering what wattage output it was likely to give. Does anyone know
or know a formula to calculate it?

Many thanks

Ferret

Assuming it has no fins on the back, a reasonable rule of thumb would be
1280 watts /M^2 at a Delta-T of 60 degC.

For the size quoted, this would equate to about 670 watts.

If your system is running at a lower Delta-T than this, the output will need
to be downrated. For example, at a Delta-T of 50 degC it would be about 530
watts.
--
Cheers,
Roger
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