8mm to 15mm for radiators.

[jackplumb]

I need to inrease 8mm pipes up to 15mm for about 2 metres on one radiator, will this work ok considering that the velocity of the water will be reduced.

 

[stevetheplumber]

it will work

 

[brasso1981]

Why not use a reducing set in the valve?

 

[Dylan Nelson]

can be dodgy with 8mm micro

 

[Best]

May actually HELP the flow of water to the rad to increase the size from 8 to 15mm. You are shortening the pipe with more resistance surely?
I would only worry about reducing pipe bore anytime.

 

[b.lynch plum]

Ya just push 8mm into 15 and braze up

 

[Best]

Ya just push 8mm into 15 and braze up

I personally would use soldered 8 x 15mm connectors. Can't be much money for a couple of these, so why do anything else? Brass connectors would do, if accessible, but soft copper microbore is more likely to weep someday.

 

[b.lynch plum]

I always have brazing rods in van as I do a lot of air con and fridg work and I know it don't have to fit perfect but it still won't leak

 

[Best]

Yes, I have seen that done on heating systems, - 2 or three microbore pipes brazed into a 15mm pipe to simplify things & save using manifolds or tees. But the OP said for one rad, so in this case just a simple increase in size on the 8mm to a rad.

 

[Guest123]

I do this usually when fitting a towel rad in place of a standard rad. Most houses pre 1990 have 8mm microbore heating systems. I cut the the tails, fit a 8mm to 15mm soldered reducer and file the chrome from the new 15mm copper and solder this to the reducer. The soldered reducer is then hidden under the floor leaving the chrome pipe on view. Never had one single leak or problem, but I definitely would not recommend a compression fitting on microbore if it is to be concealed under the floor space. Neither would I recommend a pushfit either as I've seen these blow off microbore, perhaps due to the softness of the pipe.