Advice on New Combi - variance in gas pipe sizes?

[Matt@staffs]

We are changing out an old Glow Worm Ultimate 60 FF (17.5Kw), for a new Combi that will be sited in the airing cupboard to save space. The boiler options that we have been given are WB 37 CDi or Vaillant ecoTEC 838. Very similar performance wise, however the WB requires a 22mm feed and the Vaillant states a 15mm gas feed. The difference means a 12 metre of new 22mm or re-use exiting 15mm pipe in the cupboard. This has an impact on the quotes that we have been given.

Most boilers of a similar output require 22mm gas feeds, is the Vaillant a typo or is this correct? Has anyone any installion experience, because it could potentially sway our decision on which boiler to go for.

The property is 4 bedroom, 1 bathroom with electric shower, 1 shower room with a power shower - As an alternative would a WB 30 Si or Vaillant 832 be upto the job?

Thanks

 

[tipintim]

The connection to the Vailant is 15mm but will still require at least 22mm from meter to airing cupboard.
I would look at the Ideal Logic +35 if your looking at costs. Not a bad boiler for the price.

 

[Blackcatgas]

a 12 meter run of 15mm pipe, then add on 0.5m for every elbow will not be sufficient to run a 38kw boiler wether its vaillant, worc ester, glowworm etc, a 38kw boiler is a 38 kw boiler, you may even need to run some of the feed in 28mm.
Any quotes youve had where they have said that 15mm will be ok should be put in the bin.

 

[Matt@staffs]

tipintim and Blackcatgas, thanks for your speedy replies.
Had a third and final quote today, the guy suggested that it might be a case of 28mm to the gas meter cupboard, and a 22mm tee to the boiler.
Regarding boilers he hinted towards 37Kw upwards (quote will be in the post).
It still amazes me that the output has doubled from the original Glow Worm at 17.5 Kw............

We really require a quiet boiler because the airing cupboard is between 2 kids bedrooms. Out of the 3 suggested, WB, Vaillant, Ideal, is one than the others?

Advice again, will be gratefully received.

Thanks

 

[tipintim]

WB and Vailant to me are getting to expensive. I have been fitting the Logic + with no problems as of yet.
But each to there own.

 

[armourer]

Those that mentioned the gas pipe will have to be upgraded are right, 15mm supply feed will be no where near enough.

As for the difference in rating, that's usual remember you are changing from a standard boiler (stored hot water in cylinder) to a combi system which heats cold mains on demand.

 

[Blackcatgas]

Out of those boilers Id go with the Vaillant. If I was quoting Id recomend a Viessmann, but every installer has his favourite manufacturer.