Changing heating pipes from 15mm to 10mm All aspects of plumbing questions and answers, help, tips and information

[oscarbrindle]

Hello,
I am re routing some central heating pipes which feed my rads, and I am considering using 10mm instead of the 15mm which are there at present. i have a convetional boiler and a pumped system. i am only changing the downstairs pipes, so about maybe 50% of the systems pipes.
Is this possible, and does anyone have any opinions or comments, like will the system be as efficient.
thanks and God Bless

Frankie

[Oliver_murphy]

dont do it!!!! 10mm pipework, although easier to install, and smaller by appearance, will block up quicker, and cause you more problems.

I wouldnt, and DONT install as standard to any of my customers,

[ALDA]

FRANKIE,

IN MY OPINION ONLY, I CAN’T SEE WHY NOT.

IT ALL DEPENDS ON THE NUMBER OF RADS INVOLVED AND THE LENGTH OF THE PIPE RUNS ETC.

YOU WILL BE REDUCING THE FLOW DOWNSTAIRS BY APPROX. 1/3rd.

IF YOU ARE KEEPING SAME RADS : -

YOU MIGHT NEED TO ALTER PUMP SETTING.
YOU WILL NEED TO RE-BALANCE THE SYSTEM AS A WHOLE.
EXPECT A REDUCED HEAT OUTPUT FROM EXISTING RADS DOWNSTAIRS. (DEPENDS ON SIZE AND QUANTITY OF RADS)

IF YOU CAN‘T LIVE WITH THE IDEA OF SLIGHTLY COLDER ROOMS, YOU COULD REPLACE OLD RADS WITH MORE BUT SMALLER RADS EVENLY DISTRIBUTED IN THE ROOMS DOWNSTAIRS.

REGUARDS, ALDA.

[htg engineer]

Don't do it, either have 15mm to the whole system or 10mm, mixing pipe sizes can cause problesm, especially as the system gets older. You will find upstairs radiators will steal the heat.

I install 10mm and 15mm heating systems, I prefer 15mm but 10mm is spot on for new installations and if looked after, if flushed properly and inhibitors added after every drain down they will last as long as 15mm without sludging or becoming blocked.

[Perry525]

I have 10mm pipes to all my radiators.
They all work perfectly!
However, while a 15mm copper pipe will carry 13,620 Btu or 4.25 K watts
an 8mm pipe is about one third the size.
The advantages of 8mm pipe are easy to fit, can be cabled, few or no joints,
important much lower heat loss per meter.
This means that when starting from cold there is less pipe to heat up before the heat gets through. And when turning off, there is less heated water in the pipes, heat that you have paid for.