New Extension heating

[regsmyth]

I am planning the heating in our new extension and wondered if there is a rule of thumb about sizing the pipework.
The oil boiler is in the extension (downstairs).
It's a sealed S plan system.
The valves are located where the extension joins the main bungalow.
The flow and return are 22mm at that point.
The new run would be about 10m to the first rad, the other three rads will all be fairly close to that.

 

[squowse]

you should use 22mm if you're supplying 4 rads, then 15mm tees off to each rad is what i would use. some people like the microbore 8 and 10mm. i don't.
i would also be concerned that your pump may not be strong enough to cope with the 10m run even in 22mm. depends on the size of the rest of the system and the strength of the pump.

 

[regsmyth]

Thanks squowse, I was hoping to get away with 15mm all the way, but I guess not.
As for the strength of the pump, a plumber looked at what I was doing and recommended this boiler, it seems to cope fine with the existing system, and pump and boiler stat are both on middle settings. I guess I will just have to wait and see.

 

[squowse]

Thanks squowse, I was hoping to get away with 15mm all the way, but I guess not.
As for the strength of the pump, a plumber looked at what I was doing and recommended this boiler, it seems to cope fine with the existing system, and pump and boiler stat are both on middle settings. I guess I will just have to wait and see.

only a few quid in it. i was surprised by the price of 22mm when i bought it a couple of weeks a go. 7+vat each i think.