New gas supply needed to a boiler?

I've just had a new system boiler fitted (40cdi Greenstar Worchester). When I had quotes for the work all the installers were saying that the system needed a new gas supply pipe since the existing one was not large enough from the meter. The people we went for included a quote for a new supply pipe.

The existing supply was 3/4 inch (22mm) and supplied a Ideal Mexico boiler (v. old but worked find) and it also goes around to an 8 hob gas cooker.

When the firm came to do the work they installed the boiler first and said that it was working fine without any new pipework.

They upgraded half the pipework from the meter to the boiler (about 3 meters) and they left 5 meters without an upgrade and joined it to the old pipework. The new supply was 25mm. At this point the engineer said that he had redone his "calculations" and that the supply was sufficient for the new boiler.

I'm a bit confused on two grounds:

1) Did the pipework really need a upgrade or would 22mm be sufficient anyway for this new type of boiler. If the older boiler was running okay on the 22mm pipework and the new one is more efficient surely it will need less gas and not more? Was this just a way of padding out the quote anyway and so it was not necessary.

2) What possible benefit could a half-pipe upgrade have had? There will be more gas in the new wider section of pipe, but when it joined back to the old pipe surely the supply would go back to the previous levels and so we're not gaining anything by a half-upgrade.

I'm suspicious that the engineer might have just felt it was too much work to do the upgrade and so because the boiler is okay he left it. But it might not last as long or work as well because the pipework was not fully upgraded.

I also wonder if they're just trying to save a bit of money given copper prices!

Any help or thoughts would be very grateful as I've not got a good answer from the company and I would like to know a bit more before I get more assertive with them.

Thanks,

MS

Ask for a free Gas Safe Register inspection.
If there are any problems they will ask the installer to sort it out.

Thanks for the suggestion. I looked at this, but it looks like it might get an inspection, but it might not get one as well. If I don't get selected I still might not get one.

I'm wondering if the gas supply upgrade was necessary for the new boiler and whether I should insist on one.

Thanks.

MS

You can always pay someone to check the work your contractor did.

Without seeing the installation it is difficult to give an answer,given the size of your new boiler it is quite likely that your existing pipe work was undersized. It is possible that upgrading only half the pipe work is sufficient as its more about the resistance to flow than how much gas a particular section of pipe holds.It is important to check the inlet working pressure of the appliance and this would/should have been done at comissioning you can check the benchmark as the installer would have recorded his findings.

Most of the points you are mentioning demonstrate your lack of understanding of gas pipe sizing.

If you take the time to peruse all the relevant posts on this forum you will see everything you need,

Otherwise either trust your installer or make a complaint to Gas Safe!

Tony

Agile said:

Most of the points you are mentioning demonstrate your lack of understanding of gas pipe sizing.

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Then why not help him understand rather than criticise?

Domestic Gas Pipe Sizing

OP, there is a good chance the gas line needs to be upgraded the full run. If the Mexico needed 22mm gas line, you present boiler will need a lot more gas as it is possibly twice the power Mexico was.

It is best the get someone out to service/ check/ commission the boiler and see what the outcome is.

It is not a case of 'wet the digit and see what direction the wind is blowing'. The gas line bore and length is decided by the gas requirement for the appliance/ s, number of beds and tees and the length of pipe runs.

mseymour said:

I've just had a new system boiler fitted (40cdi Greenstar Worchester).
The existing supply was 3/4 inch (22mm) and supplied a Ideal Mexico boiler (v. old but worked find) and it also goes around to an 8 hob gas cooker.

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8 ring hob will be about 15 kW, if not more. Add 40 Kw for the boiler and you are looking at the best part of 60 kW in total.
Not a snowflake's chance in hell that it will meet the spec if that is partially fed by 22mm.

mseymour said:

The new supply was 25mm.

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Are you sure it is 25?
Copper comes in 22, 28 and 35 normally

The six burner plus wok cooker here takes about 16 kW.

However, the cooks here rarely have more than four burners on at a high power even when cooking for 20-30 people.

However the regs say that gas pipes should be sized for the MAXIMUM load!

Tony

its an 8m pipe run

mseymour said:

The people we went for included a quote for a new supply pipe. MS

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Based on that then one could say that they should refund 5/8 of the price quoted for upgrading the gas supply !

But you really need someone to check that the pressure loss from meter to boiler does not exceed 1.0 mB wwith every gas appliance on at full power.

I would expect that its well over that pressure loss.

Tony

Check the gas flow calcs yourself (give up 4 hours to read and try it yourself)

http://www.ukcopperboard.co.uk/lite...ion-Tips/Domestic-gas-planning-and-sizing.pdf

Learn via webcasting: http://www.ukcopperboard.co.uk/education/webcasts.shtml#gaspipesizing

Make yourself a spreadsheet. Draw a schematic of the pipe runs to each appliance. Measure them. Count how many bends/elbows/tees there are.

Every Gas engineer should supply the calculations to you. They can only be calculated on paper now, with larger boilers and larger hobs.


You can of course wait for a gassafe engineer to come visit, and if the work is incorrect, they can ASK the gas engineer to perform remedial work. That's all they can do.

Hope you like the info.

johnjohnscg said:

You can of course wait for a gassafe engineer to come visit, and if the work is incorrect, they can ASK the gas engineer to perform remedial work. That's all they can do.

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They can do more than ask. If unsafe work is not corrected, the rgi can have his license withdrawn.

Not in my experience. Complaint investigations outcome are withheld due to 'data protection act' reasons.