changing normal boiler to combi

[ChrisR]

OK forget about the water pipe diameter and just put up with the extra seconds it'll take.
ANY combi can supply 8 or 9 average sized rads. The flow rate of HW is the variable to consider.
Bigger boiler doesn't necessarily mean your hw will arrive faster - you wouldn't want 20 litres per minute coming out of a bathroom basin tap! SOme combis keep themselves hot in summer so the HW is a bit quicker - look for one of those.


What is your CW main pressure and flow - we're going to be questioning your decision to have a combi at all. How many showers? Baths?

 

[Big_T]

well i was happy with the boiler, had new kitchen fitted etc....

boiler went wrong (maybe i should have got it serviced in the last 6 years)

cost of parts they THINK it needs, nearly £400, so i thought i would be better off getting a new boiler

 

[Bahco]

Onto a loser here mate.

Can you not disconnect the old 22 supply to your hot taps upstairs and run new 15 mm to them. The old pipe will be out of sight anyway as you have buried them.

If you can live with the reduced flow, lower temp of hot water, and energy waste, leave the pipe as it is.

 

[ChrisR]

Forgot to mention - if you go for a good combi you WILL need a new fatter gas pipe unless you current boiler is huge. Only good point is they can go on the wall outside.

 

[Big_T]

What is your CW main pressure and flow - we're going to be questioning your decision to have a combi at all. How many showers? Baths?

Im not sure, all i know is that that tap is only just open and i have lots of pressure, if i open the tap to any where near 90deg the water pushes past the seals on the ball valves in both toilets.

I only have one bath and one shower

 

[chrishutt]

big-T, if you happen to have a 15mm mains cold water pipe running in parallel with your 22mm hot pipe, you can resolve your problem by swapping functions over, so 15mm becomes hot and 22mm cold. Just make sure 22mm joints don't leak under higher pressure.

 

[Big_T]

big-T, if you happen to have a 15mm mains cold water pipe running in parallel with your 22mm hot pipe, you can resolve your problem by swapping functions over, so 15mm becomes hot and 22mm cold. Just make sure 22mm joints don't leak under higher pressure.

great idea, didnt think of that,

thank you for all the help