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Discuss Is 22mm supply pipe always required for combi boilers? in the Gas Engineers Forum area at PlumbersForums.net

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Hi All,
I need your advise as I'm really concerned here. I only just had regular boiler replaced with combi (Vaillant ecoFIT Pure 25kw). I had few surveys done and everyone stated the gas supply pipe from the meter to the boiler must be changed from current 15mm to 22mm. The plumber I used said there is no need for that if the gas pressure meets boiler requirements (13-23mbar), and what he's done, he ran like 2m od 22mm pipe from the boiler and then connected to existing 15mm pipe. The distance from the meter to boiler (horiz +vert) approx 8-9m. Gas pressure test hasn't been done yet.

Can anyone please confirm if this is correct, safe and legal? All the regulations I've read were saying only about 22mm pipe and nothing about the minimum pressure.
Boiler works fine, and to be honest I wouldn't mind if that was ok and could stay like that (what could save me running the new pipe outside or stripping the floor).

Thank you very much.
 
It all depends on the amount of bends and or fittings used. I know the EcoTEC pro states it can be fed in 15mm pipework, not sure about the ecofit. Regulations and standards state that pipe sizing needs to be carried out, and I find it odd that the pipe has been upsized from the boiler back to the existing. If you’re genuinely concerned then put in a call to gas safe who should then visit and inspect the installers work and advise you better than we can on a forum.
 
I've assumed 6 elbows used as that is about the minimum for most installations and worked on the basis its 15mm the entire length

That number in the bottom right hand box has to be below 1.0, as you can see its miles above it.

This is only theory, his working pressure at the appliance will be the only way to confirm if what he has done is OK. I would presume not.
 

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Thank you for the answers Gents.
The pipe just at the meter is also 22mm it goes under the floor so not sure how long it stays before converting to 15mm. I would say it't about 7-8 elbows used at the moment.

With regards to gas safe, how much approx.is the inspection, and if they state the connection is wrong, will I be able to claim the proper installation from my current installer? My worry is if he signs the work off, that will be it.

Anyway, when he does his pressure checks and the gas pressure is between 13 -23mbars, will it mean all is good?

Regards
 
I would say it’s wrong need more than 2 m of 22mm

Gas safe inspection from gas safe is free

Meter should be 19 mbar and at the appliance is should be 18mbar tested from the pipe
 
You're allowed 1 mbar drop from meter outlet to appliance when running on max load.
The manufacturers do say there is a minimum (the 13mbar you mention) but they presume the outlet to the meter will not be less than 14mbar. i.e. the appliance will run safely at 13mbar but the rules with the installation side are still the same.
He will test the meter pressure with the appliance on full and test the appliance under the same conditions. If there's only 1mb drop, it is acceptable.
 
As above.

The minimum the meter should be under full load is 19mb. At the inlet to the appliance it can only be up to 1mb less.

Some boilers take there reading from the other side of the gas valve in the boiler. In the case of some Worcester boilers you allow a 1.5mb drop across the valve, totaling a maximum difference of 2.5mb.

Nothing ruins a relationship quicker than a customer telling you how to do your job while you're doing it. I would wait until he's finished then raise concerns. If he dismisses them then just mention you may call gas safe for a second opinion. You could withhold payment (or some of.) If deemed not safe then he would have to put it right or risk losing his registration which he would be stupid to do.
 
Thank you for the answers. The test will be done tomorrow, and as I said before I hope everything is ok.

Fowlerboi, I must disagree with you. The reason I asked the question is I had 3 independent surveys done, and everyone was saying the new 22mm pipe will be required. I choose the company who sent independent installer for the job, and who said 22mm pipe is not required. So I believe a customer paying 4k for the job has the right to wonder.
Also I believe your assumption is based on fact everyone is doing their job properly, but unfortunately it's not always like that (I'm sure you've witnessed that in your career), and I will give you the example of the roof flue that I had installed as a part of the same job, and it was leaning to one side (about 15 degrees) what looked horrible (especially that it was next to the ventilation pipe that was straight up). Why shouldn't I tell the installer I didn't like it ? I politely asked him and he amended that (although his first argument was it was still better then some of my neighbours flues).
 
Thank you for the answers. The test will be done tomorrow, and as I said before I hope everything is ok.

Fowlerboi, I must disagree with you. The reason I asked the question is I had 3 independent surveys done, and everyone was saying the new 22mm pipe will be required. I choose the company who sent independent installer for the job, and who said 22mm pipe is not required. So I believe a customer paying 4k for the job has the right to wonder.
Also I believe your assumption is based on fact everyone is doing their job properly, but unfortunately it's not always like that (I'm sure you've witnessed that in your career), and I will give you the example of the roof flue that I had installed as a part of the same job, and it was leaning to one side (about 15 degrees) what looked horrible (especially that it was next to the ventilation pipe that was straight up). Why shouldn't I tell the installer I didn't like it ? I politely asked him and he amended that (although his first argument was it was still better then some of my neighbours flues).
You definitely do get to ask the questions. My advice though is to do so at the end once the installer has had time to put things right, nobody knows 100% if the gas pipe is big enough until he does the test so lets not presume he's not going to put it right if he finds out it is. You're unlikely to convince any professional who thinks they're doing something right that they are in fact wrong if you your self are not qualified until you have facts to show them.
 
You definitely do get to ask the questions. My advice though is to do so at the end once the installer has had time to put things right, nobody knows 100% if the gas pipe is big enough until he does the test so lets not presume he's not going to put it right if he finds out it is. You're unlikely to convince any professional who thinks they're doing something right that they are in fact wrong if you your self are not qualified until you have facts to show them.
I totally get that. I stated in the beginning the test is still to be done, and also stated I would be over the moon if it is ok (that would save me running additional pipe (probably outside)).
I asked the question, because I didn't know if 22mm pipe is always required or not. Now, when I got the answers from the professionals on the forum I know it's not essential (or I know where to go if I'm concerned). This only proofs it's worth asking questions :)
 

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