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[Taxi_Driver]

Im thinking about getting one of these

http://www.viessmann.co.uk/en/flats_apartments/Product/Gas_condensing_boilers/vitodens_100-w_compact.html

Plumber has told me he will have to replace the 15mm gas pipe going to my old boiler with 22mm....which is quite a bit of work involved.....ie ripping up floorboards...

My question is having looked at the install instructions on the boiler it says the gas connection is 1/2in male iron ?? Now that is 12.summat mm ..... so should the 15mm gas pipe i already have be ok  Im probably missing something here 

[martin42]

Its just a standard 1/2 " iron to copper fitting thats used 
Gas run is normally run in 22mm until about the last 1.5 m away from the boiler

[Taxi_Driver]

Its just a standard 1/2 " iron to copper fitting thats used 
Gas run is normally run in 22mm until about the last 1.5 m away from the boiler

Ah ok...thanks for that.....even tho the plumber couldnt see under the floorboards....he reckons the 22mm pipe that comes into the house goes down to 15mm somewhere halfway thro the house which is about 8m short of the boiler......so he's correct then 

[I_want_an_Omega]

Its just a standard 1/2 " iron to copper fitting thats used 
Gas run is normally run in 22mm until about the last 1.5 m away from the boiler

Ah ok...thanks for that.....even tho the plumber couldnt see under the floorboards....he reckons the 22mm pipe that comes into the house goes down to 15mm somewhere halfway thro the house which is about 8m short of the boiler......so he's correct then 

He should have done a test at the boiler location to determine that - you can't get as "much gas" though 15mm compared to 22mm pipes. Think of it as the really thick wires going to a starter motor .........

[Vamps]

Its just a standard 1/2 " iron to copper fitting thats used 
Gas run is normally run in 22mm until about the last 1.5 m away from the boiler

Ah ok...thanks for that.....even tho the plumber couldnt see under the floorboards....he reckons the 22mm pipe that comes into the house goes down to 15mm somewhere halfway thro the house which is about 8m short of the boiler......so he's correct then 

He should have done a test at the boiler location to determine that - you can't get as "much gas" though 15mm compared to 22mm pipes. Think of it as the really thick wires going to a starter motor .........

At low (relative) pressure...........

[zirk]

He should have done a test at the boiler location to determine that - you can't get as "much gas" though 15mm compared to 22mm pipes. Think of it as the really thick wires going to a starter motor .........

Or drinking the contents of your Home Brew Container through a Straw. 

[Marks DTM Calib]

So can somebody explain how any length of the pipe being 15mm is allowed....(assuming no other device is T-d off the pipe), or are we in the world of gas fitters logic 

As an example, do you think you could drink your home brew easier through a long thin straw or a pipe of the same length which was f-large for 3/4 of the run with the remaining 1/4 being the same thin straw size....

[Kevin Wood]

So can somebody explain how any length of the pipe being 15mm is allowed....(assuming no other device is T-d off the pipe), or are we in the world of gas fitters logic 

As an example, do you think you could drink your home brew easier through a long thin straw or a pipe of the same length which was f-large for 3/4 of the run with the remaining 1/4 being the same thin straw size....

Indeed. you could run the gas main directly up to the fitting on the boiler, but if it's only 1/2 in. guess where the restriction will be...

I'd be downloading the installation manual for the boiler and checking that, TBH. Then you can get the gas fitter to explain the logic behind ignoring what it recommends. Oh, and ask him how he's going to stop the condensate drain from freezing too, if you fancy a laugh.

[Sir Tigger KC]

I'd look at getting rid of all the old iron gas supply pipe while your at it, and get your fitter to run 22mm copper back to the meter.  Last year my Mum had a nasty gas leak where a joint in the old iron pipe had rusted and failed. 

[zirk]

As an example, do you think you could drink your home brew easier through a long thin straw or a pipe of the same length which was f-large for 3/4 of the run with the remaining 1/4 being the same thin straw size....

No idea Mark, but if its someone else's Beer and its free, Im up for the test experiment. 

[Marks DTM Calib]

As an example, do you think you could drink your home brew easier through a long thin straw or a pipe of the same length which was f-large for 3/4 of the run with the remaining 1/4 being the same thin straw size....

No idea Mark, but if its someone else's Beer and its free, Im up for the test experiment. 

[Sir Tigger KC]

Oh, and ask him how he's going to stop the condensate drain from freezing too, if you fancy a laugh.

I think they fit a little electric blanket around them these days.   

[Kevin Wood]

Oh, and ask him how he's going to stop the condensate drain from freezing too, if you fancy a laugh.

I think they fit a little electric blanket around them these days.   

Ahh.  anything to avoid Please read the manual!

[I_want_an_Omega]

When we wanted our new boiler installed BG gave us a quote  . After I'd got off the floor I went through it with the guy and sought explanations for some of the nonsense that was included.

The new boiler was to be about 15m further away from the meter than the old one, but on the other hand, the main gas run went onto feed 2 x 5Kw gas fires - which were to be removed at the same time

Part of the quote was to increase the size of this main pipe from 22mm to 35mm  . They point blank refused to take into account the fact that the two fires were being removed.

A local guy got the contract, he took the fire removal into account and was more than happy with the pressure & flow rate of the 22mm pipework which then ran all the way through to the boiler location.

[Ever Ready]

BG do tend to extract the Michael   I have always seen 22mm used to the boiler on new builds or upgrades from old 'vintage' boilers to more modern ones, although the manual that comes with your new boiler should give you some guidance.

As far as I remember the problem is often gas flow rather than gas pressure which is normally 20 millibar