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/1158wSince they are exactly the same surface area, why is one 10% more efficient than the other?
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/1158wSince they are exactly the same surface area, why is one 10% more efficient than the other?
Convection?
AB
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.
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?
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.
Height is more efficient than width, due to chimney effect.
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
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!]
I'm sure Mrs Handyman prefers the one that matches the wallpaper/curtains/sofa/this weeks' choice of paper napkins
tim
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.
Never seen one of those!
Four of mine have 3 panels 3 fins.
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
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
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...
The photo shows that it is 'covered'; the diagram looks like half a 22 and half a 21.
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.
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