New Baxi Neta-Tec 33 HE combi - Do I need 22mm or 28mm feed?

[powerbooksub]

Dear Forum

I have a question re. sizing of new gas pipe to feed new Baxi Neta-Tec 33 HE combi boiler. BG provided a quote this week (I nearly fell off my chair) which included an upgrade from 15mm to 22mm pipe. I am concerned whether 22mm will be large enough as the pipe run has many twists and turns.

I have therefore measured the run and would appreciate it if a gas guru could advise whether 28mm (or larger) is required as I not technicaly minded when it comes to calculations! Thanks.

90deg elbow (glanded to top of gas meter)
5cm
90deg elbow
20cm
90deg elbow
100cm
T-piece (enable connection to 4-burner gas hob)
87cm
90deg elbow (to avoid supporting wall)
30cm
90deg elbow (to avoid supporting wall)
28cm
90deg elbow (to avoid supporting wall)
30cm
90deg elbow (to avoid supporting wall)
185cm
90deg eblow
200cm
45deg elbow
180cm
45deg elbow
70cm
90deg elbow
0.3m
90deg elbow (pipework now in line with boiler connection)

Total length of pipe run is 8.5m to 9m.
1off T-connection piece
10off 90deg elbows
2off 45deg elbows

BG included the extra 22mm copper in the quote but the quote doesn't show any evidence of number of elbows. This could be because it is irrelevant or that it was not properly considered.

Thanks in advance guys and girls!

 

[ServiceNumpty]

Who else have you had out to quote and what were their recommendations. As you only mentioned BG.

 

[powerbooksub]

Hi

I haven't had anyone else round yet.

Do you think the 22mm sounds ok or should it be 28mm?

Thanks!

 

[muggles]

You've failed to mention the power of your gas hob...

 

[ianblue]

22mm is fine.

 

[powerbooksub]

Hi muggles

Hob is nothing special, 5.4KW

ie: http://www.appliance-world.co.uk/Bosch_PBP616B80E_60cm+Gas+Hob.html

Thanks again

 

[powerbooksub]

Hi ianblue

Thanks for the info.

Is 22mm just adequate or is it the correct size?

I may as well lay the proper one while I am ripping the kitchen out!

Thanks!

 

[Agile]

I have not done the calculation. However, its does sound rather borderline. Particularly as actual pressure loss always ends up less than the calculated. Probably because the calculation assumes the pipe ends are deburred and reamed. If pipe slices are used then there is a reduction at every pipe entry to a fitting.

My solution would probably to fit it in 28mm up to the cooker take off as thats more critical and is only a short distance. Of course every elbow has an effective length which means that section is equivalent to a much longer route.

Get some other quotes and see what they tell you about upgrading the gas supply. Be wary of those who are not very concerned about that aspect of the installation.

Tony