22mm to combi boilers? 15mm no good?

[Mobileghod]

i know it says 22mm must be taken from the meter all the way to the boiler but obviously older boilers ive seen 15mm has been taken upto the boiler.

is it entirely incorrect say if you were doing a boiler swap combi for a combi to just extend the 15mm to the boiler or would i need to trace back and take 22mm all the way upto the boiler?

just a question as the boiler is n the landing and tge customer has new flooring down with the gas pipe going straight down under the boards???

cheers

 

[newbie1]

not an expert but i blve the newer boilers require a higher gas flow to operate so 15mm pipework will obv not flow enough gas and the boiler i guess will under perform..only solution is too take new 22mm suplly outside and back in again

 

[fatoftheland]

The pipe size depends on the Kw of the boiler, how far away the meter is, how many bends, other appliances on the same pipe. If the gas pipe inlet on the boiler is 22mm then 22mm pipe is required all the way.
If the boiler is running on 15mm pipe. Check the inlet pressure on the boiler when the boiler is working full bore and any other appliances on the same pipe are running.
The pressure should not drop more than 1mbar than the same test taken at the meter
Low inlet pressure can lead to incomplete combustion, a rise in carbon monoxide and any warranty from the boiler co. being void!
Best practice is to allow for the pipe size upgrade in your Quote

 

[Mobileghod]

i think the best bet is to have a proper look at the job and with a bit of luck 22mm isnt too far away.
sticking to the manufacturers instructions is number 1 priority i suppose.
think we best plan this out out thoroughly
the boiler will be 30kw only gas appliance in the house
cheers for the reply

 

[fatoftheland]

30kw may even mean 28mm pipe from the meter then reduced at the boiler. Measure the distance, count the elbows, bends etc, check what else is on the pipe run. 15mm is never enough for 30kw, even if the meter was within touching distance

 

[Mobileghod]

yeah thought as much. ill plan it out and trace pipework back to the meter. i havnt been round yet. the customer just mentioned that hes got the boiler looked at the instructions and found he needs 22mm to the boiler which i say is correct but theres only 15 on his old one...his main worry is obviously his flooring but im hoping his meter is outside and we can just run it up the wall and through to under the boiler..

so why would 15mm be ok for the older boiler, same kw? or wasnt it!?
half the time its the manfacturers covering there backs, but were best oversizing than undersizing for reasons u have mentioned.

 

[plumbnuts]

If you don't know the answers to your own questions you are obviously not a registered installer. Remember you vistors are restricted when in prison if you kill somebody by illegally fitting a gas appliance. Good luck

 

[Mobileghod]

If you don't know the answers to your own questions you are obviously not a registered installer. Remember you vistors are restricted when in prison if you kill somebody by illegally fitting a gas appliance. Good luck

what are you on mate get off your high horse, i was asking a valid question thats what this forum is all about... surely if you want to find out something you have to look into it and do a bit of research. i havnt installed anything and if i did it would be legal not illegal...... good luck pffft

 

[dan_merkel@msn.]

Modern gas boilers with a 1:1 gas valve to not need 20mbar pressure at the burner.
one manufacture states in there manual that there boiler will give full output down to 14mbar, and can run on 15mm pipe work, but this goes against british standars that state you can not have more than a 1mbar pressure drop accross the pipe work.
This british standard is now out of date when it come to modern boilers but still needs to be worked to as gas fires and cooker ect still require 20mbar at the burner.
On tests, one boiler manufacture has seen full output at single figure pressures!!
Dan

 

[plumbnuts]

The questions that you ask in relation to sizing gas pipes are as you state for a "Customers House". You dont have to be a "Pffft" to realise that you are on this forum to try to gain information to carry out illegal gas work. As I said good luck in prison if you kill somebody. Alternativly, just send me your CORGI number by private e-mail and I will appologise for being a "Pffft". I await no response.

 

[fatoftheland]

We are, whilst being Corgi registered, at the mercy of non registered installers. Unfortunately its cheaper to not be corgi registered and do no retraining, get caught, maybe pay a fine if Corgi can get there act together. Corgi registration and the traing involved is not cheap. Thats why I don't do bathrooms!
I imagine the new Gas safe Register will be rubbing there hands together with glee come April!
Its hard to be tested by an inspector who has little knowledge or experience! Its even harder to think that Corgi registration can be done in 13 weeks training (BG from street to engineer). I have been doing this for 30 years and Still dont know it all.
In Mobileghods defence, Thre is no pipe sizing training in ACS as there was in Acops
There was a watchdog programme a while ago where a young Corgi registered Engineer, couldnt even work out how to get the lid off the boiler. There was an outcry as to how his work was done. But and its a BIG BUT. There is no training on individual boilers in ACS, or Acops before, or any other college course Including NVQ.
The lad needed experience with a variety of boilers with an older and more experienced engineer. Corgi is not the be all and end all of gas safety. The PArt P electrical qualification is even worse. In my course of 5 days which I had to do to get Part P. There were gas installers who somehow got through the course, with no prior Knowledge of electrical installation. Thats Scary. I am a qualified electrical engineer, and had to sit for a week watching disasters in the making as A gas installer magically became an electrical installer. I can speak as a Gas installer as I have TEC certs in Gas, and HAve all elements on my Corgi ID card. As a self employed Gas and Electrical consultant (and installer sometimes but my knees are knackered) It has cost me a fortune.
I am getting off my high horse now and apologise for talking off topic.

 

[Mobileghod]

nice posts, like i say it was just a question, plumbnuts im still learning mate only been registered very recently it was just something i wanted to ask, simple as. ive not broken the law nor installed anything that will pose any risks, thats why im checking n questions like the above....awesome

 

[CharterGAS]

well then i suggest you reference your pipe sizing guide and that will tell you. im surprised you are asking that question if you are registered, more-so if you are newly registered!!

 

[plumbnuts]

Exactly my point CharterGas! I agree with your comments with the exception of learning gas pipe sizing on ACS. I agree that it is not included in a re assessment but it most definatly is included in the initial course/assessment. As I have said, I am willing to assist Mobileghod and explain the methods/reasoning behind gas pipe sizeing all he has to do is give me his CORGI number. I am not however, prepared to assist illegal gas workers who under cut RGI's due to no overheads, nor prepared to assist them with manslaughter.
Steve

 

[newbie1]

have to say i have to,agree my son has paid for his training and cost best part of 4 grand but corgi seems very reluctant to get out there and police the installation/mtce gas area and as such illegal fitters who havnt been trained and certified are out there doing gas work
hopefully the gas safe register(daft name)are going to crack down on illegal gas work and yes in his training my son had to do pipe sizing and flow rates etc