Over size rad?

[festive]

Ok i used an online BTU Calc on my room

3.3x3.8x2.4height concrete floor one wall ext and insulated bungalow roof.

Calculated i need a 2700btu rad, the one i removed was a ****ty very old twin rad, weighs a ton 1600x600

I checked and most of these are 4000BTU upwards using the same dimension for a new version!

Is that because the old rads were far less efficient? The pipes come out the floor in concrete, and i was thinking of fitting a smaller rad.

A) what if i fit a 1600x600 new rad which 'pulls' 4000btu will it load boiler more?
B) What if i fit a smaller rad around the 2700btu mark i guess the only way to make pipes tidy is to chase into floor?

TIA for thoughts!

 

[Terrywookfit]

2700 Btu hr?? What room temp was that.?
As a quick calc 12 ft x 11 ft x 8 ft 1 o/w at 70 ° I would guess at 5-6000 btu/hr.

 

[JohnD]

It's time to move forward into the 1960's, and quote kW.

 

[Terrywookfit]

It's time to move forward into the 1960's, and quote kW.

As most houses I work on are imperial and my Mears is also I will continue to use Btu/hr. (Until such a time when manus stop quoting in btu) !!!

 

[Doggit]

If the pipes are coming out of the floor in concrete, the hot water will be losing a lot of heat travelling through it, (until it's up to temp) so I think I'd be inclined to refit what was there. With a TRV fitted, and oversized rad will be okay, but an undersized one won't. An old rad wouldn't be inefficient, but having more metal, it would take longer to heat up, but it's the heat output rating that's more important. If the rads the same size, then it shouldn't affect the boiler, and if you were going to change the rad for a smaller one, then see if you can get a single rad of the same size to keep the pipes about the same position.

 

[oilboffin]

Well said big T I've a mears that's imperial I think btus are more accurate too,I think 5-6000 too.Bob

 

[Doggit]

BTU's, BHP, some things shouldn't be messed with. But I prefer Metres to feet and inches.

5,100 Btu's by my calculation, and just going on screwfixes rads, a 1600x600 single convector type 11 rad is 5603Btus.

 

[festive]

Ok first of all thank you all for your input and time most appreciated.

Link I used to calc but ws here

http://www.bestheating.com/btu-calculator

I includes 2m2 window one next facing wall.

 

[Doggit]

You didn't give us all the info for the calculator, but I found another site, and that gave 4359Btus. So it's pretty much up to you.

 

[oilboffin]

I always go a little bigger you can always turn a rad down if they are too hot.Bob

 

[Nige F]

Surely with modern boilers oversized is good for condensing mode ?

 

[Terrywookfit]

I always go a little bigger you can always turn a rad down if they are too hot.Bob

Exactly !!
You will rarely hear a complaint of "Being too warm" !!!!

I size all rads as a living area these days to avoid problems.
If someone leaves a room heated to 70° F and goes into an area heated to 65° it will feel cool........ (Fahrenheight used to pi$$ off pedants).
Most kids bedrooms are used as living areas these days.

Oh how I long for my youth when the only heated room was the Kitchen.