15mm flow/return straight out of boiler

[JayneKelly]

Isit ok 2 plumb in a new boiler in 15mm flow and return pipes? Boiler is a 30 kkilowat glow worm betacom. thanks

 

[D_Hailsham]

It all depends on the total wattage of the radiators

 

[JayneKelly]

It all depends on the total wattage of the radiators

its abedsit 3 rads under window, tiny ones & one in kitchen & hall, far too small for a 30kilowatt i would have thought ( the total must only be around about 7-10 kilowatts)

 

[D_Hailsham]

It all depends on the total wattage of the radiators

its abedsit 3 rads under window, tiny ones & one in kitchen & hall, far too small for a 30kilowatt i would have thought ( the total must only be around about 7-10 kilowatts)

Don't forget that the Betacom is a combi, so the size of the boiler is determined by the hot water requirement not the heating. You say it is a bed- sit, what hot water outlets do you have? A 30kW boiler seems excessive. Who suggested it?

 

[JayneKelly]

quote="D_Hailsham";p="752732"]

It all depends on the total wattage of the radiators :!

Don't forget that the Betacom is a combi, so the size of the boiler is determined by the hot water requirement not the heating. You say it is a bed- sit, what hot water outlets do you have? A 30kW boiler seems excessive. Who suggested it?

i was under the impression that boiler sizing was a result of calculating the total kilowatt of all radiators?

 

[hi-spec plumbing heating]

do a heat loss calculation

 

[chrishutt]

It might help if you actually read what has already been posted -

the Betacom is a combi, so the size of the boiler is determined by the hot water requirement not the heating.

 

[JayneKelly]

do a heat loss calculation

not that clever to be honest, i know it has things to do with u values & north facing windows etc, will this give me the correct pipe size from boiler? thanks

 

[hi-spec plumbing heating]

do a heat loss calculation

not that clever to be honest, i know it has things to do with u values & north facing windows etc, will this give me the correct pipe size from boiler? thanks

well whos doing the boiler then ?

 

[Bahco]

Think you will be okay for 4 small rads in 15 mm.

I have seen 8 rads supplied in 15 mm and it has worked but not good practice.

 

[JayneKelly]

It might help if you actually read what has already been posted -

the Betacom is a combi, so the size of the boiler is determined by the hot water requirement not the heating.

i have but i`m obviously not getting it, so a combi boiler`s total size in kilowatts has nothing to do with the radiators?

 

[hi-spec plumbing heating]

yes it does

 

[JayneKelly]

yes it does

thanks, could you explain alittle further? because at first i was advised it depended on the total wattage of all rads by first poster, (D.hailsham, thanks) it`s left me a little confused.

 

[chrishutt]

Combi boilers require an output of at least 24 kW, preferably more, to deliver hot water to the taps. The heating load is unlikely to be anywhere near as much unless you have a very big and drafty house. Your heating load is probably no more than 5 kW (easily carried by 15mm tube).

Hailsham was referring to the sizing of flow and return pipes, not the sizing of the boiler!

 

[JayneKelly]

Combi boilers require an output of at least 24 kW, preferably more, to deliver hot water to the taps. The heating load is unlikely to be anywhere near as much unless you have a very big and drafty house. Your heating load is probably no more than 5 kW (easily carried by 15mm tube).

Hailsham was referring to the sizing of flow and return pipes, not the sizing of the boiler!

Ah haaa, thanks Chris so rule of thumb is 24kw or more for water then tot up kilowatts for rads and add them on for total boiler size?

Why do most plumbers install lengths and lengths of 22mm pipe then in modest houses?