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Replacing Old Single with New Double. 10mm width difference + inlet/outlet question?

Discussion in 'Plumbing and Central Heating' started by Grinnders, 25 Sep 2019.

  1. Grinnders


    7 Apr 2006
    Thanks Received:
    United Kingdom
    I've got an existing Single radiator in a reasonably large bedroom that is 740mm wide and 620mm high. It doesn't really put out enough heat and is on an external wall. It has a TRV right side and normal valve left. Pipe centres are 820mm. I want to replace it with a double and plan to reuse existing valves/copper pipes.

    I cannot find the exact size as a replacement, only 750mm wide x 600mm high https://www.amazon.co.uk/Horizontal...0+x+750+white&qid=1569411682&s=gateway&sr=8-7 in a fancier design.

    1. Do I need to worry about the 10mm width difference? I am hoping there will be 5mm of pipe bend within each existing pipe/valve assembly to flex out a little.
    2. If I am using the same valves so I am presuming it does not technically matter which side may be indicated as inlet and outlet, or am I wrong?
    Apologies if these are dumb questions but amazon questions made be consider inlet when it maybe a red herring.
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  3. oldbuffer


    6 May 2010
    Thanks Received:
    United Kingdom
    1. You can probably make up the 5 mm each side difference by adjusting (hacksaw and deburr) the tails on the valves once you remove them from the old radiator.
    2. Some designer radiators do require flow and return to be on specific sides, and won't work properly if flow and return are reversed. The one you are thinking of buying looks as if it shouldn't matter, and also looks as if it could be fitted either way round to avoid the problem anyway.
    3. You also need to measure the centre distance of the existing pipes from the wall. The new ones appear to be 51 mm off the wall. If your old ones are different you'll need to alter the pipe work to suit. Not always easy unless you have access below the floor level and can move the pipes.
    4. Can't tell without knowing make and model, but I'd guess your existing radiator gives off about 700 to 900 watts (at delta T 50). The new one will give about 1,100 watts, not really a huge increase. Might be worth doing a heat loss calculation for the room to see what wattage is really needed before committing. Note that your boiler / system is an input to the calculation, particularly if you have a condensing boiler with a lower (75 degree) flow temperature.
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    United Kingdom

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