likely heat output for 2 old radiators

[disconotdisco]

Hi all,

What is the heat output likely to be for these two old double radiators, neither have convection fins:
A) 1840x300mm
B) 710x600mm


A bit of background...

I am currently sourcing rads for my 1970s built ex council flat. I've got BTU calculations to give me an idea what output to go for in each room. Of course I want to be able to get more output that I need in each room but I dont want to go over the top. My lounge presents a bit of a problem.

In the lounge I have one long, not very high radiator under the windows (1840x300 mm) next to where i usually sit and a smaller one at the other end. Both are basic double radiators installed in the early 80s or late 70s with no heat fins to increase heating area and effectiveness.

I'd like to swap the one under the window for a smaller one if possible as it looks big for the space and while I know I can do this and achieve my target BTU, I'd like an idea of the output in the current radiator so I dont make it feel any colder for me when I'm sat in my armchair next to it. As the room isnt huge I dont want the rads taking up more space than I need.

So how do I do this?
Are any non heat finned double radiators available anymore?
I know what the BTU output is of similar sized radiators are today but they have heat fins - is there a standard % I could assume is the improvement since fins became the technology?

Any other ideas?

Thanks in advance

B

 

[Aire]

If you know the btu/h required to heat the room then buy your new radiators based on that requirement. The size of your existing rads is basically irrelevant. If your concerned about the room been cooler I would buy radiators that are one or two sizes bigger than what your calculation require. you should be fitting a trv anyway so you will be able to regulate the temperature of your room even if the rads are oversized.

 

[disconotdisco]

Thanks for your reply @Craig Watson .

I appreciate the usual advice is to go over the recommendation and turn things down if it gets hot. I got BTU recommendation ages ago last year for between 4700 and 5700 for the room.

It's a small flat though and I don't want to put in huge radiators if I don't need to as they will seriously affect choice and placement of furniture and decoration once I'm ready. I'll be spending a lot of money on designer radiators and want to get a bit more data to help me make a more informed choice.

Any further suggestions?

 

[Aire]

A 600x900 double radiator would cover that output nicely which is not specifically a big radiators. If you want designer and your limited on space then I'd recommend something verticle like this one.
1780 x 490mm Anthracite Double Flat Panel Vertical Radiator
It's only 500mm wide so will take up minimal wall space, has more than enough output looks good too.

 

[Ric2013]

Would others say this formula is accurate?

If it is, the two radiators would have 1160W and 750W outputs @ a Delta T of 50 (I'm guessing the 'factor' for a double panel without fins is around 0.15 as the formula below gives no such factor). Does that sound halfway reasonable?

Radiator output formula (from diyfaq.org.uk)
From the specifications of Myson's standard (seam-top) and compact radiators, Barlo round-top and Kudox compact rads, it is possible to derive a formula to calculate the heat output of any given sized-radiator of these types. This formula should be applicable to other manufacturers' radiators of similar types.

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

or

Heat Output = (Height + 120) * Length * FACTOR / 100
(Watts) (mm) (mm)

where FACTOR is (for Delta-T 50°C)

• 0.09 for SP single panel (no convector fins)
• 0.13 for SC single convector
• 0.19 for DX double: 1 panel with convectors + 1 without
• 0.24 for DC double convector

In other words:

• add 12cm to height (in cm) of radiator
• multiply by length (width) of rad
• multiply by FACTOR above