replacing an imperi...
 

replacing an imperial sized radiator

Posts: 2134
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My house is a 90's "new build" that we've recently added an extension to. over the past 10 years I've replaced most of the radiators as I've renovated room by room. my next job is the living room and I'd like to double check my logic with you folks!

current radiator in that room is an imperial 69" x 21" type 11 and it has microbore into the wall. the rad has no TRV - this rad and another in the downstairs loo are the only ones without. the other 14 rads all have TRVs. boiler is a new WorsterBosch non-combi

my thinking is that as replacing with a new imperial sized rad from Myson will be £600!! I might as well bite the bullet, cut out the Microbore back to the 15mm I expect ill find in the wall, and re do it in 15mm to a new rad and put the biggest Type22 in that I can fit - its under a window so 500x1800 would fit no problem and give me double the BTUs

so

  1. any downside to using a much larger rad in that room?

  2. any issues from the fact that this position is currently where the always on rad is (all be it, theres another in the downstairs loo)

  3. where's good to buy rads from? what brand should I be looking for

  4. is eliminating a bit of microbore worth the effort?

  5. any other gotchas ive not thought of


 
Posted : 24/03/2026 5:13 pm
Posts: 12867
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There isn't much point in having a massive radiator of the room size doesn't merit it. All you are doing is reducing the useful range. Whats do the calculators say.

Some systems need to have an always on radiator to dump heat through and keep the feed and return connected. Often a bathroom so downstairs toilet would be normal. 

 

The microbore could be all the way back to the manifold 

 


 
Posted : 24/03/2026 6:32 pm
Posts: 3583
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From my limited experience with our previous 80s Barratt home,, I suspect the microbore will go most of the way to the boiler :/ because cheap and bendy.


 
Posted : 24/03/2026 8:11 pm
Posts: 6573
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Do you need a larger rad?

Similar metric-sized (1800x450) Myson type 11 is £200

Flomasta 1800 x 500 type 11 is <£100


 
Posted : 25/03/2026 11:34 am