Very useful information Andy. Thanks.

I wonder if a bit more info will narrow it down then...

Our house has a mixture of new and old steel rads. The new ones are
fine (not as hot as they could be but they heat up more or less
evenly), but the steel rads are heating very badly (only the top 2
inches)- despite us removing them last year and cleaning them
thoroughly (and cleaning the system with Fernox etc).

So, we were recommended to buy new rads to replace these old ones,
which we have done - I must admit the plumber who told us the sizes to
buy did guestimate. Looking at the B&G catalogue, the output of these
4 new rads ranges from 4500 to 6200. 3 of them are currently on 8mm,
and the smallest is on 6mm.

From your figures Andy if the general rule of thumb applies, it looks
like we will have to replace most of the pipes (as 8mm generally deals
with up to 4500w). Have I interpreted this correct?

The plumber that recommended changing all the pipes to 15mm (but did
not recommend changing the rads) was the only one which was
recommended to us.

Your opinion with this extra bit of info would be much appreciated!

Changing tac slightly 0 another plumber told us that we would have to
change the pipes coming form the boiler (some sort of Potterton) from
22mm to 28mm and that is why the circulation is bad. This sounds dodgy
to me...we had about 6 plumbers round and no-one mentioned this. What
do you think?

Thanks
Rebecca


(Rebecca) wrote in message . com...
OK, I am so fed up with different plumbers and all their different
opinions. Can any of you help?

I have a very simple question and I hope its a straight forward
answer. I will miss out on the problem and suggested solutions and
hope this can be answered without the details.

Q Would you be happy keeping 8mm microbore thoughout your house (with
flow problems) or would you upgrade all to 15mm?

I realise that you may want more details but I'm not gonna give them.
This is the most basic difference 3 plumbers have told me.

No. 1 wants to change all pipes to 15mm
No. 2 wants to change only the 6mm pipe to 15mm
No. 3 wants to keep the 8mm

Please help. Its doing my head in!

Many thanks
Rebecca