Radiator Quality

[OnlyAsking...]

I was wondering if any of you had any preference on which brand of radiator you choose when replacing a radiator- there seems to be lots out there- I just want to choose on which is resonable quality and good value- and preferably want to buy it online.

I am about to change a rad in the box room which the original is just too small to heat the room quickly- so I was wondering if I simply swap the single for a double this should suffice????is there a calculation I should follow?
the original rad is 21" high and 33.5" wide (single)
room is around 7ft x 6ft x 8ft

I am finding it difficult to find the same size rad to replace, new ones seem to be 600mm high, which means the bottom of the rad is only a few inches off the floor...is this OK? ( I mean its under a window sill )

Any advice most welcome.

 

[oilman]

Ah, imperial radiators by the look of it, that means old, and that could mean sludge in system. The radiator seems a reasonable size for the room, so you need to check if the system is clean. Drain a sample of water from a drain cock. If its dirty, clean the system this will improve the efficiency. You might find the radiator does not heat evenly all over, definitely sludge. How quickly do you want to heat the room? any bigger rad will overheat it, and if yuo haven't got a thermostatic valve on it you'll need one, then it'll fail after a few years and you'll need another. A small supplementary heater (electric) would help and you can turn it off when the room's warm. If you're not going to be there when the heater needs turning off, why do you need fast heating?

First thing is check for sludge though.
Second thing is, does the box room have a loft above it? If so, before you do anything to increase the heat input, reduce the losses and add some insulation. If you ve got 10" of insulation, dont worry, otherwise put more in.

 

[OnlyAsking...]

Thanks for the reply...
I have a drain cock on the exterior of the house actually just behind the boiler itself, i think this is where you can drain the system- so im looking for something brown or black..and sludgey? How do I get rid of it? The house had a new water cylinder put in about 5 years ago, and a new rad in the bathroom..does this mean they would have had to drain the system anyway?

Other than that...the loft has insulation and has been boarded throughout.

I need fast/powerful heating because it the room has 2 exterior walls and a large window..

The rad does heat up, but as you said the bottom half is only a litte bit cooler than the rest, still i am not convinced that the rad is efficient, hence me wanting to change it...are the newer rads better than the old ones even if they are the same size..?

Tell me more about draing the system of this sludge stuff, and how can i be sure that the entire system is free of it and how do i stop it from comming back?

thanks again

 

[oilman]

See here for draining/refilling info. If your rad is noticably cooler at the bottom than the top it needs investigating. When you have drained the system, you can undo the joints on the radiator (put plastic sheeting and rags down first) and take it outside and hose it through. You may find quite a lot of black water comes out.

For efficiency, what is the temperature of the rad when it is hot? what are the temperatures of the other rads. You could perhaps increase the heat output by pening the fixed valve oo the rad by a little, but this will need doing if you change the radiator as well. What rate of temperature rise do you get now? with what outside temperature? and what are the losses through the walls and window. There is not much point in putting in a bigger radiator unless you know what the size needs to be. Otherwise will the new one provide the performance you want?

The temperature the room will reach will depend on the heat input, more heat means higher end temperature. How will you stop it overheating? What is the window frame made of? Is it double or single glased? What are the walls made of?

 

[OnlyAsking...]

Thanks for he link...

Seems like the draining of the system is a bigger job than I first thought, then you got to get the air out and stuff- hmm might need to look at getting someone else to look at it...

As for the rad it seems to function OK..not a great deal of difference in temp top to bottom, ( BTW all the other rads are the same temp wise)it just takes a little while for the room to get warm - also i just noticed there is a old element heater which was on the wall, which proves that the room has heating deficency previously. So bigger a Rad maybe the right thing to do. I was wondering if using this Hep20 stuff, might be easier to work with if i was going to replace the rad myself..? its only push fit stuff..should be OK with CH systems right?

Windows are newly UPVC double glazing. house is of standard 9" twin wall brick construction.

BTW what is "pening the fixed valve oo the rad by a little"???

 

[ChrisR]

Thinks like windy corners and north walls mess up heating calculations for small rooms. Did on our small bedroom so I doubled the rad - fine now. I added a TRV but it's always full open like the rest!

You will have no trouble getting a 20" (500mm) hi rad from a proper plumber's merchant, though 800mm (approx 32" ) long. Use telescopic radiator valve extensions - not a problem to fill the extra 20mm or so each end.

Radiators are always hotter at the top than the bottom! It depends how much...

It sounds like yor sludge problem, if you have one, isn't too bad, but add some Inhibitor (Sentinel X100 or Fernox MB-2) to the header tank. It'll get intothe system gradually.

Going over 4" insulation is in my opinion a loony thing to do. If you do the sums you find you're losing a tiny amount through that, so making a big mess in your loft to make it 8" saves you half a tiny amount. Sales nonsense. I daresay the EST want about a metre. You will be pouring heat through your 9" solid walls so where's the point in saving a couple of Watts?

 

[scook17]

I found installing the reflective and insulated panels you can get from B&Q immediately beind the radiator made quite a bit of difference to the room temperature. All our radiators are on external walls, which are old cavity ones with no insulation. I was a bit sceptical, but they certainly appeared to work for us anyway.

Kind Regards,
Shane Cook.