Radiator change on large pipework

[thegudge]

Hi, I have 1 radiator in the house where the radiator is on a different diameter pipework. The rest of the house is 15mm but this could be 22mm, I'm not sure. I want to replace this radiator with a new one and if possible I dont want to disturb the original parkay flooring. What do I need to change this radiator over for a regular modern radiator without changing the pipework? or is there no alternative and the copper pipework has to change ? I've only ever dealt with a 15mm pipe feed in the past. Apologies for the mess, I've just removed an old cover that was over it.

 

[ShaunCorbs]

Old imperial 22mm as it’s timber floor best to lift a few boards and reduce it down to 15mm

 

[steadyon]

1. I'm afraid a 50p coin isn't much use as a measure. We need an accurate diameter to advise properly. Clean the paint off down to bare copper and measure the diameter. Either use a vernier caliper if you have one, or measure the circumference and calculate the diameter. Wrap a strip of paper round the cleaned pipe, and fold it sharply at a single circumference. Measure the distance between the two folds, and divide by 3.142 to get the diameter. Likely to be 22 mm, or, if imperial 21.5 mm.
2. I can understand you not wanting to disturb the parquet.
3. Do be aware that a new radiator is likely to have:
3a. A different distance between the entry points for the pipe. The distance will normally be that given for the radiator's length. If you go for a slightly shorter radiator than the existing, you can get extenders to match fairly closely the existing pipe centres. Don't go for the adjustable extenders, they often leak. If you get a longer radiator than the existing, you will need some fancy (but visible) pipework to connect, unless you go under the floor.
3b. A different distance for the centre's of the entry points from the wall. If you are replacing like for like this may not be much. You could probably get a couple of millimetres play in the existing pipes. Any more, and you will again need some altered pipework to math to the new centres.
4. You can get adaptors to go from 3/4" imperial pipe (the 3/4" refers to the nominal internal diameter of the pipe, not its outside diameter). E.g BES 6791. You would then need a 22 to 15 reducer to get to 15 mm pipe to the new radiator valves. The foregoing are solder connectors, as I don't think you have the room for compression couplings, and they might also look quite ugly.

 

[Knappers]

As above.
You'll struggle to get valves to fit straight to the pipes but its possible, expect them to cost almost as much as getting a plumber in to change to 15mm and if old 3/4 then you'd need 3/4 olives too.
Not ideal but a much more do-able diy job.

 

[thegudge]

1. I'm afraid a 50p coin isn't much use as a measure. We need an accurate diameter to advise properly. Clean the paint off down to bare copper and measure the diameter. Either use a vernier caliper if you have one, or measure the circumference and calculate the diameter. Wrap a strip of paper round the cleaned pipe, and fold it sharply at a single circumference. Measure the distance between the two folds, and divide by 3.142 to get the diameter. Likely to be 22 mm, or, if imperial 21.5 mm.
2. I can understand you not wanting to disturb the parquet.
3. Do be aware that a new radiator is likely to have:
3a. A different distance between the entry points for the pipe. The distance will normally be that given for the radiator's length. If you go for a slightly shorter radiator than the existing, you can get extenders to match fairly closely the existing pipe centres. Don't go for the adjustable extenders, they often leak. If you get a longer radiator than the existing, you will need some fancy (but visible) pipework to connect, unless you go under the floor.
3b. A different distance for the centre's of the entry points from the wall. If you are replacing like for like this may not be much. You could probably get a couple of millimetres play in the existing pipes. Any more, and you will again need some altered pipework to math to the new centres.
4. You can get adaptors to go from 3/4" imperial pipe (the 3/4" refers to the nominal internal diameter of the pipe, not its outside diameter). E.g BES 6791. You would then need a 22 to 15 reducer to get to 15 mm pipe to the new radiator valves. The foregoing are solder connectors, as I don't think you have the room for compression couplings, and they might also look quite ugly.

Thanks for your detailed explanation. I have replaced another old radiator so understand the issues with a different sized radiator, although that was on 15mm pipework. I'll get it all cleaned up and get a proper size, I have some calipers. Lovely use of PI that I have used many times before because of my previous job. I'm guessing imperial size but will check and then look at getting a reducer for both sides. Interesting that you mentioned the telescopic extenders, I used these on the radiator I did last week, upstairs. Fingers crossed they will do as they are on now. . Lifting the parkay and floor boards to change the pipe would make this a much bigger job as I would not want to ruin it and it has been down probably since the house was built.. Thanks again

 

[Ric2013]

Think 3/4" copper tends to run at 21.7mm, not 21.5mm?

 

[Timmy D]

Cut exposed pipe at low level and add a imperial to 22mm metric coupling + 22mm to 15mm reducer and away you go.