gas size off pipe

[joe1234]

Hi can some one please help me.I have just installed a 30kwatt combi boiler and all see to be ok.Got a corgi man to check and test it .But he said the gas supply was to small and needs to be run in 28mm pipe.I hae used 22mm pipe. i did my sums and worked out30kwatt boiller = 0,o3mwatts 0,03divided by 38.7mj/m3 =0,0007751m3/s and so max pipe runfrom charts =20mts .My pipe run is12mts +6fittings = 3.6 mts so a total off 15.6mts is this right and if i have to run a new 28mm run from the meter can the last 3.5mts be 22mm as this part is under the floor and tiled over. many thanks Joe

 

[Agile]

The sizing calculations should only be taken as a rough guide for a minimum.

Whats relevant is the measured pressure loss between the meter and the boiler. It should not be more than 1 mB !

Thats normally measured at the meter and at the inlet to the boiler gas valve. However on Vaillants there is significant pressure loss within the boiler itself so different critera apply.

What pressure loss did the CORGI measure?

Tony

 

[joe1234]

Thanks for the reply.I will find out as he did not say.Also the boiler is a glowworm betacom 30he combi.thanks again Joe

 

[ddraig]

Also are there any other appliances conected?? gas fire, cooker ect??

 

[Razor900]

Who is going to notify this boiler then?

 

[joe1234]

yes gas fire and gas hob both fed from 22mm ie output from meter split to two 22mmm feds one for boiler and one for fire and hob.

 

[corgiman]

Who is going to notify this boiler then?

Well he has got a moron RGI willing to put his name to his work and break the rules so I would suppose that the pillock woild not mind notifying it for him

Mind you he sounds more clued up than his tame RGI moron

 

[ddraig]

yes gas fire and gas hob both fed from 22mm ie output from meter split to two 22mmm feds one for boiler and one for fire and hob.

Well Its very possible that you need to upgrade to 28mm from the meter, BG are doing this on most installations of combi's now.
Re-do you calc's and add on the heat inputs for you cooker and fire, will prob find you need to upgrade.

 

[joe1234]

Thank for last reply.if i up grade to 28 mm will the last 4 mts to boiler be ok in 22mmas as i said before it runs under finished floor.once again thanks

 

[ddraig]

Again you need to work it out on the pipe calc's, but I would guess it will be ok, you may only need to run 1 or 2 lengths of 28mm from the meter.

 

[clf-gas]

yeah it will be ok.

 

[Agile]

yes gas fire and gas hob both fed from 22mm ie output from meter split to two 22mmm feds one for boiler and one for fire and hob.

Well Its very possible that you need to upgrade to 28mm from the meter, BG are doing this on most installations of combi's now.
Re-do you calc's and add on the heat inputs for you cooker and fire, will prob find you need to upgrade.

As the fire and hob have been seperately fed directly from the meter they do not need to be included in the boiler pipe sizing calculations.

Its most cost effective when every elbow is equivalent to 0.9m of tube to upgrade the bendy bits. Thats usually the pipework around the meter! Then any accessible straight lengths of tube.

But as I said before, its the measured pressure loss that matters and not reams of calculations!

Tony

 

[BigBurner]

Have dedicated pipe for the boiler only from the meter.

Look at here for gas pipe sizing: http://www.copperinfo.co.uk/webcasts/domestic-gas-pipework-pipe-sizing/player.html

 

[ChrisR]

Have dedicated pipe for the boiler only from the meter.

Not necessary, ignore that.

Look at the charts by all means, then get someone who knows what he's doing to size the gas pipe. The charts are wrong.

 

[BigBurner]

Have a dedicated pipe for the boiler only from the meter.

Not necessary, ignore that.

With sensitive pre-mix burners and poor quality slow reacting gas meter regulators, I emphasise once again, "Have a dedicated pipe for the boiler only from the meter".

The charts are wrong.

Will you tell us what is wrong?