Help needed in sizing a Radiator

[RussellMrgn]

Please could I ask for someone to help me with sizing a rad for my living room. I have tried about 7 online sites so far, and have results ranging from 4379 to 6918 BTU's, which I find confusing as the same details are entered for each.

To give a bit of detail, I live in a bungalow that was built in the early 80's in Hythe Southampton.
The room has one exterior wall (on it's length) (brick, cavity insulated) with a double glazed upvc patio door and faces south. The 3 remaining internal walls are of block plastered construction, with the 2 width walls having a bedroom and the kitchen on the other side. The last remaining (length) wall divides the living room from the hallway.
The floor is carpeted over solid concrete and a pitched roof loft space above above the ceiling, which is 100 mm+ insulated.

The size of the room is:-

Length - 4.97m
Width - 3.58m
Height - 2.40m

The patio door is 4.99m2 (2.46mx2.03m).

At the moment, the room is heated by one old single panel rad which is roughly 600 x 1750.

I'm looking to replace it with a type 21 rad with TRV and hopefully by doing so can get away with a smaller length rad.

I'd be grateful if someone could please advise which size (BTU's) rad is required.

 

[AWheating]

Is the current radiator good enough?

 

[RussellMrgn]

Hi,

The current rad is looking pretty tired, and i'm guessing has been there since the place was built.
One of the tails has also got a bit of a dent in it, and I was going to take the opportunity to replace it before the room is carpeted. I have no problem with digging the floor up to do this, and having a slightly smaller rad on the wall would be a bonus.

 

[jonnyswamp]

What heating system do you have, is it a two pipe, or a single pipe running around the bungalow with tails going to either side of the rad
If single, you need the same length rad to replace with or excavate floor and alter pipework to suit new rad length
The rad may not work as good if pipes aren't altered, search on here for the difference between single pipe systems and two pipe

 

[RussellMrgn]

Hi jonnyswamp,

It's a two pipe system. I intend to dig the floor anyway to replace the tails, because of what I said earlier, one of the tails has a good dent in it, and the other comes out at a bit of an angle, (poorly laid from day one).

All of the rads in the bungalow are of the old imperial size, so digging up the floor to replace the tails and alter the pipe lengths to fit a metric sized rad saves me having to use extension tails on the new rad.

As I said in the original post, the rad fitted at the moment is a many times painted single panel steel rad. I'm hoping that by going for a type 21, I'll be able to shorten the length a little bit.

 

[Ray Stafford]

Hi Russell

I think that AW Heating's question above was not about the physical condition of the radiator, but whether it adequately heated the room. That could serve as a useful reference point.

Another useful piece of information is the location of the current radiator. Thats quite a large room, and the ideal site for a rad in such a room is the centre of one of the long wall. if you tuck it away in a corner, particularly a corner near the door, then it will be less effective, and you might be better to take the time to put two rads in.

For what its worth, I would stick about 6000 BTU of rads in that room. Don't ask me to justify that with science, because my simple calculation method would embarrass me in front of all the techy whizzkids on here. But I bet you it will be fine.

 

[Best]

As it is in your own house I would go a little higher on the output as I am sure you are not worried about an extra few pounds. If it looks well, go plenty of heat as you are using a trv.
Best to use an output that the rad heats the room in minus 10 temperatures IMO and also remember if you have a modern condensing boiler it is better to have rads oversized. Ideally 2 rads opposite ends of room that size would be good but you probably want to just use original position which as Ray says is hopefully central

 

[jtsplumbing]

1. is the rad you have now a convector type ? (fins at rear) or just the old type radiator,
You have approx. 5500 btu on currant rad, does this get the room to the temperature you want ? if so a 600 x 1000 double convector will give you around the same output

 

[RussellMrgn]

Hi Russell

I think that AW Heating's question above was not about the physical condition of the radiator, but whether it adequately heated the room. That could serve as a useful reference point.

Another useful piece of information is the location of the current radiator. Thats quite a large room, and the ideal site for a rad in such a room is the centre of one of the long wall. if you tuck it away in a corner, particularly a corner near the door, then it will be less effective, and you might be better to take the time to put two rads in.

For what its worth, I would stick about 6000 BTU of rads in that room. Don't ask me to justify that with science, because my simple calculation method would embarrass me in front of all the techy whizzkids on here. But I bet you it will be fine.

Hi Ray,

Yes, upon re reading AW Heating's post, I thought he may have been referring to that afterwards, but by that time I'd already posted my reply....

The patio doors are in the middle of the outside long wall, and the radiator is on the opposite internal long wall; This wall also has the internal connecting door to the hallway in the far corner of the room, and the rad is placed in the middle of the remaining wall if this makes sense...

 

[RussellMrgn]

As it is in your own house I would go a little higher on the output as I am sure you are not worried about an extra few pounds. If it looks well, go plenty of heat as you are using a trv.
Best to use an output that the rad heats the room in minus 10 temperatures IMO and also remember if you have a modern condensing boiler it is better to have rads oversized. Ideally 2 rads opposite ends of room that size would be good but you probably want to just use original position which as Ray says is hopefully central

Hi Best,

yes I agree it's better to oversize as you can always adjust lower via the trv as opposed to having a smaller unit that may not be able to supply the heat.
Unfortunately having 2 smaller rads on the opposite small wall is a no go as one end has the sofa, and the other the tv and hifi.

The Boiler is a British Gas 330, I have no idea how old it is as we only moved into the property in August 2014.

 

[RussellMrgn]

1. is the rad you have now a convector type ? (fins at rear) or just the old type radiator,
You have approx. 5500 btu on currant rad, does this get the room to the temperature you want ? if so a 600 x 1000 double convector will give you around the same output

Hi jtsplumbing,

Yes the rad at the moment is a single panel convector type with fins.
Bit hard to say if it gets the room to a comfortable temp, as the bungalow was like an ice box after we moved in as we were having so much work done at the time improving the property, ie new bathroom, megaflow tank, kitchen, utility room and second toilet.

Ive just been looking at the Kudox type 21 rads, a 600x1200 has a BTU of 5687 and the next size up, a 600x1400 has a BTU of 6635.

 

[AWheating]

1.8kw rad

 

[RussellMrgn]

1.8kw rad

Thanks AWheating,

1.8kw equates to 6141 BTU's, so on that basis the rad I need would be the Kudox type 21 600x1400, as the 600x1200 falls just short of that amount.

Do any of you guy's have a preference to the make of rad i.e. either a Steelrad P+ or Kudox type 21, or are they pretty much the same?
The TRVs I'll be using are Danfoss Ras-C's.

And one final question to you all - The last time I put rads in was around 21 years ago when I installed 15 faral aluminium radiators in my old place in Jersey, at that time my ex brother in Law who was a plumber / college teacher and then working for WRAS taught me how to use pipe benders etc. But one tip he had then was when hanging rads was to make them ever so slightly off level with the rad bleed end being higher to aid with bleeding - Is that something you've heard of before?

 

[ShaunCorbs]

Thanks AWheating,

1.8kw equates to 6141 BTU's, so on that basis the rad I need would be the Kudox type 21 600x1400, as the 600x1200 falls just short of that amount.

Do any of you guy's have a preference to the make of rad i.e. either a Steelrad P+ or Kudox type 21, or are they pretty much the same?
The TRVs I'll be using are Danfoss Ras-C's.

And one final question to you all - The last time I put rads in was around 21 years ago when I installed 15 faral aluminium radiators in my old place in Jersey, at that time my ex brother in Law who was a plumber / college teacher and then working for WRAS taught me how to use pipe benders etc. But one tip he had then was when hanging rads was to make them ever so slightly off level with the rad bleed end being higher to aid with bleeding - Is that something you've heard of before?

yes slightly out eg edge of bubble and depends on what rads you have already if matching

 

[solutions]

Should not be necessary on a modern convector.