Looking for a new rad for the lounge at Handyman Towers.

Wickes list a 60mm high x 700mm wide @ 4370btu/1280w and a 700mm high x
60mm wide @ 3952btu/1158w

Since they are exactly the same surface area, why is one 10% more
efficient than the other?


--
Dave - The Medway Handyman www.medwayhandyman.co.uk

On Sat, 09 Nov 2013 20:52:04 +0000, The Medway Handyman
wrote:

Looking for a new rad for the lounge at Handyman Towers.

Wickes list a 60mm high x 700mm wide @ 4370btu/1280w and a 700mm high x
60mm wide @ 3952btu/1158w

Since they are exactly the same surface area, why is one 10% more
efficient than the other?

Convection?


AB

On 09/11/2013 20:52, The Medway Handyman wrote:
Looking for a new rad for the lounge at Handyman Towers.

Wickes list a 60mm high x 700mm wide @ 4370btu/1280w and a 700mm high x
60mm wide @ 3952btu/1158w

Since they are exactly the same surface area, why is one 10% more
efficient than the other?

Do they have the same surface area though? The fins between the two
panels cover nearly the whole width, but stop well short of the full
height. I guess that means the two shapes have differing fin surface
areas. I can't be bothered to do the maths though.

Then there's the trade-off between many short fins and few tall ones...

Cheers,

Colin.

On 09/11/2013 20:52, The Medway Handyman wrote:
Looking for a new rad for the lounge at Handyman Towers.

Wickes list a 60mm high x 700mm wide @ 4370btu/1280w and a 700mm high x
60mm wide @ 3952btu/1158w

Since they are exactly the same surface area, why is one 10% more
efficient than the other?


But are they "exactly the same surface area"?

Is the pattern of waterways and between waterways identical?

Are the waterways the same diameter, shape length and volume?

Are they the same thickness?

If they have fins are the fins exactly the same size and number?

Is the spacing of the fins the same?

Anything else different that could effect the efficiency?


--
Old Codger
e-mail use reply to field

What matters in politics is not what happens, but what you can make
people believe has happened. [Janet Daley 27/8/2003]

---
This email is free from viruses and malware because avast! Antivirus protection is active.
http://www.avast.com

On 09/11/2013 21:10, Colin Stamp wrote:
On 09/11/2013 20:52, The Medway Handyman wrote:
Looking for a new rad for the lounge at Handyman Towers.

Wickes list a 60mm high x 700mm wide @ 4370btu/1280w and a 700mm high x
60mm wide @ 3952btu/1158w

Since they are exactly the same surface area, why is one 10% more
efficient than the other?

Do they have the same surface area though? The fins between the two
panels cover nearly the whole width, but stop well short of the full
height. I guess that means the two shapes have differing fin surface
areas. I can't be bothered to do the maths though.

Then there's the trade-off between many short fins and few tall ones...

Cheers,

Colin.


Even if they did they wouldn't match.
As the air rises next to the rad it gets hotter and the heat transfer
gets less as the temp difference is less.
So the extra 100 mm on the height will transfer less heat than the extra
100 mm on the width.

In article ,
The Medway Handyman writes:
Looking for a new rad for the lounge at Handyman Towers.

Wickes list a 60mm high x 700mm wide @ 4370btu/1280w and a 700mm high x
60mm wide @ 3952btu/1158w

Since they are exactly the same surface area, why is one 10% more
efficient than the other?

Height is more efficient than width, due to chimney effect.

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

On Saturday, November 9, 2013 8:52:04 PM UTC, The Medway Handyman wrote:
Looking for a new rad for the lounge at Handyman Towers.
Since they are exactly the same surface area, why is one 10% more
efficient than the other?

It's not any more efficient; it has a higher output.

It is possible that different specs are given for different water flow and return temperatures.

Mrs Handyman will probably prefer (a) the more expensive or (b) the one you didn't buy.

Owain

On 09/11/2013 23:03, Andrew Gabriel wrote:
In ,
The Medway writes:
Looking for a new rad for the lounge at Handyman Towers.

Wickes list a 60mm high x 700mm wide @ 4370btu/1280w and a 700mm high x
60mm wide @ 3952btu/1158w

Since they are exactly the same surface area, why is one 10% more
efficient than the other?

Height is more efficient than width, due to chimney effect.


Except that the higher narrower one claims to give out *less* heat!

[I'm assuming that the smaller dimension is 600 in each case, and not 60!]
--
Cheers,
Roger
____________
Please reply to Newsgroup. Whilst email address is valid, it is seldom
checked.

wrote in message
...
On Saturday, November 9, 2013 8:52:04 PM UTC, The Medway Handyman wrote:
Looking for a new rad for the lounge at Handyman Towers.
Since they are exactly the same surface area, why is one 10% more
efficient than the other?

It's not any more efficient; it has a higher output.

It is possible that different specs are given for different water flow and
return temperatures.

Mrs Handyman will probably prefer (a) the more expensive or (b) the one
you didn't buy.

I'm sure Mrs Handyman prefers the one that matches the
wallpaper/curtains/sofa/this weeks' choice of paper napkins

tim

On Sat, 09 Nov 2013 20:52:04 +0000, The Medway Handyman
wrote:

Looking for a new rad for the lounge at Handyman Towers.

Wickes list a 60mm high x 700mm wide @ 4370btu/1280w and a 700mm high x
60mm wide @ 3952btu/1158w

Since they are exactly the same surface area, why is one 10% more
efficient than the other?


How many fin things do they have?

There's a number coding something like
11 - having one panel and one fin
12 one panel and 2 fins
21 having two panels and one fin
22 two panels and 2 fins.

They might not be called fins.. but you know the things I mean.
--
http://www.voucherfreebies.co.uk

In article ,
mogga writes:

How many fin things do they have?

There's a number coding something like
11 - having one panel and one fin
12 one panel and 2 fins

Never seen one of those!

21 having two panels and one fin
22 two panels and 2 fins.

Four of mine have 3 panels 3 fins.

They might not be called fins.. but you know the things I mean.

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

On Sun, 10 Nov 2013 16:53:46 +0000 (UTC),
(Andrew Gabriel) wrote:

In article ,
mogga writes:

How many fin things do they have?

There's a number coding something like
11 - having one panel and one fin
12 one panel and 2 fins

Never seen one of those!

21 having two panels and one fin
22 two panels and 2 fins.

Four of mine have 3 panels 3 fins.

They might not be called fins.. but you know the things I mean.

However the fins are arranged, the unit that stands taller will not
radiate heat as efficiently. By the time the convection current
carries the air from bottom to the top of the radiator, it will hotter
than that of the wider, lower unit. So assuming that the surface area
including fins is the same, then the heat tranfer would be limited by
the reduced temperature gradient as the increasingly warmer air
ascends.

AB

However the fins are arranged, the unit that stands taller will not
radiate heat as efficiently. By the time the convection current
carries the air from bottom to the top of the radiator, it will hotter
than that of the wider, lower unit. So assuming that the surface area
including fins is the same, then the heat tranfer would be limited by
the reduced temperature gradient as the increasingly warmer air
ascends.



I'm not sure it's so simple. I can't do the sums but as others have
pointed out there is eg the way that the velocity of air flow increases
with the height of the radiator. (Hence eg one book states "a long, low
radiator will therefore give lower convective output than a short tall
radiator of the same area"[1]). I'm inclined then to think that the
radiator manufacturers' figures are realisitic - not least as there'd be
open to prosecution if they are demonstrably wrong.


[1]Heat and Mass Transfer in Buildings (Hardback) By (author) Keith Moss

--
Robin
reply to address is (meant to be) valid

On Sun, 10 Nov 2013 16:53:46 +0000 (UTC), Andrew Gabriel wrote:

There's a number coding something like
11 - having one panel and one fin
12 one panel and 2 fins

Never seen one of those!

Neither have I! Unless always covered, there'd be fins sticking out at the
front - bit sharp for domestic use.
--
Peter.
The gods will stay away
whilst religions hold sway

On Mon, 11 Nov 2013 08:48:39 +0000, PeterC
wrote:

On Sun, 10 Nov 2013 16:53:46 +0000 (UTC), Andrew Gabriel wrote:

There's a number coding something like
11 - having one panel and one fin
12 one panel and 2 fins

Never seen one of those!

Neither have I! Unless always covered, there'd be fins sticking out at the
front - bit sharp for domestic use.

I only said it was something like...
Couldn't find the document I'd read it on the other week...

That's a 12 but apparently not as I remembered...
http://www.soakology.co.uk/Kermi-Hea...120612W02#zoom
--
http://www.voucherfreebies.co.uk

On Mon, 11 Nov 2013 09:17:44 +0000, mogga wrote:

On Mon, 11 Nov 2013 08:48:39 +0000, PeterC
wrote:

On Sun, 10 Nov 2013 16:53:46 +0000 (UTC), Andrew Gabriel wrote:

There's a number coding something like
11 - having one panel and one fin
12 one panel and 2 fins

Never seen one of those!

Neither have I! Unless always covered, there'd be fins sticking out at the
front - bit sharp for domestic use.

I only said it was something like...
Couldn't find the document I'd read it on the other week...

That's a 12 but apparently not as I remembered...
http://www.soakology.co.uk/Kermi-Hea...120612W02#zoom

The photo shows that it is 'covered'; the diagram looks like half a 22 and
half a 21.
--
Peter.
The gods will stay away
whilst religions hold sway

The Medway Handyman wrote:

why is one 10% more efficient than the other?

While we're on radiators ... most rads you see nowadays are plumbed
BBOE, is there any reason not to plumb them TBSE? Providing support to
the tall vertical pipe I can see being one possible issue.

In article ,
Andy Burns writes:
The Medway Handyman wrote:

why is one 10% more efficient than the other?

While we're on radiators ... most rads you see nowadays are plumbed
BBOE, is there any reason not to plumb them TBSE? Providing support to
the tall vertical pipe I can see being one possible issue.

The important thing is that the outlet is at the bottom.
On a gravity system, the inlet must be at the top.
On a pumped system, inlet can be top or bottom.
When inlet is connected to the bottom, if you look at the
radiator with an IR camera, you can see the hot water all
rises directly to the top in the first channel, and piping
it to the top instead makes no difference.

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