22mm to combi boilers? 15mm no good?

[Blackcatgas]

without even looking what the gas rate would need i would say at least part of that would have to be 22mm due to amount of bends and length especially with a gas oven and hob coming off it.

go for the worcestor....

I concur with q-plumb, its a bit late at night now to calculate it + Iam full of strong lager, either way, Halstead or worcester your going to need to uprate the gas pipe size, (cant this be run outside? etc) so you may aswell go for the worcester out of the 2 boilers.

 

[BlakesHeaven]

BlackCatGas / Q-Plumb, Thank you both very much. It is appreciated.

To answer your question, “cant this be run outside? Etc” – Unfortunately a run out side is almost impossible given that everything is on the side of the house next to the other half of the Semi-Detached. There is a possible run under the kitchen units and up a duct next to the soil pipe, but the oven is on the other side of the kitchen.

Just thinking aloud, I suppose the current pipe could be retained to supply the oven (& gas fire that I just remembered about) and break the new run off immediately after the meter. The only other option I can think of is to move the location of the boiler to the kitchen, but that would mean an equally long 14-15m run to the hot water tank, not to mention linking it into the radiator system.

Thanks again – I’ll most probably go with an upgrade to the pipe.

Cheers, David

 

[moony]

get a decent installer and he will calculate the easiest and cost effective solution, you may need 28mm and then 22, may come up outside drill through and run under floor boards and drop down to outlets. may find it easier that way - without seeing it i cant possibly say but any decent installer will let you know easiest and cheapest route.

 

[td1947]

I have seen these 22mm copper pipes appearing on the outside of relatively new houses. Personally I think it is an ugly way of doing it, but I suppose other methods are costly. My main reason for posting, is that PLUMBNUTS seems to be unhappy with DIY types asking questions on this forum. My undertanding is, that according to the LOGO on this site, that DIY questions ARE allowed,as well as from professional installers. The "going to prison" thing was mentioned twice, rather over the top I thought. My understanding is, that if a company, does unregistered GAS INSTALLATION work, AND CHARGES FOR IT, without being GAS SAFE REGISTERED, Is against the law. Perhaps someone can quote the law, that prevents someone installing their own boiler, then getting it checked/certified by a GAS SAFE registered person? TD

 

[newbie1]

in your own house you can do what you like BUT getting a gsr engineer to sign it off is not allowed as how can he possibly sign off something he hasnt installed and for what gain??? 50.00 notes in his pocket for leaving him liable for the whole install if theres a problem as in court the defence of
i didnt install it guv i just took a backhander to do the paperwork
its real simple if you want gas work done get a gas safe engineer

 

[kirkgas]

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

everything you have said is correct but i would add there is a distinct possibility of gas starvation to another appliance if you run a combi on 15mm pipe, eg cooker (which doesnt have FSD) is on and working, someone opens hot tap and combi fires up on full gas, depending on layout the cooker gets starved of gas and goes out, tap is shut boiler goes off and supply is reinstated to cooker which now has 3-4 rings passing full rate gas with no ignition

 

[td1947]

Well newbei1, I did not mention a backhander, OR £50. Are you saying that when GS engineers are asked for Landlord Safety certificates, the requestin LANDLORD ALWAYS knows the appliances have been professionally installed?? A landlord could have just bought several properties, and would not have personal, or even easily verifyable knowledge, about who installed what. I was talking about the GS CERT offered for about £40, on a legitimate basis. Is it not the duty or right, of any GS registered person, to report, via the GIUSP rules, the ID, AR, or NCS state of an installation?? I would have thought than these inspections potentially create MORE business, if a DIY'er does it badly. I beleive that some keen DIY'ers do the main install/plumbing grunt-work, but leave the actual gas connection and commissioning/testing to the proper GS registered person (a sensible thing to do I would have thought). In these economic times, would this sort of work be refused then?

 

[newbie1]

in a word yes
i am sick and tired of people who think its ok to do the work and then expect a gas engineer to pop in and sign the work off
i would not sign off any work i havent completed
doing a landlords cert and signing of an install are 2 completely different things
let me guess just a wild stab in the dark td1947 you are not a gas safe registered engineer
and if a diyer does it badly people can die and as such i dont want any tom dick or hary doing a bit of diy gas work no

 

[heatserve]

Halstead Eden *snigger*

 

[spudulike]

I'm looking for some advice and help - I have just had a combi boiler installed by a Gassafe registered fitter. All neat and tidy and it looks a good job.

But - the boiler is connected to the old 15mm pipe from the meter and is then taken up to 22mm for the last few inches at the boiler. Even though there was lots of discussion before starting the job about how to get under the floor and replace the pipes not a single floorboard was lifted. He is telling me that the pressure at the boiler is sufficient (although I do not think he has tested it with gas cooker and fire on at the same time.)

The boiler is about 5 metres from the meter in a straight line but the pipe is under the floor so probably has a few turns.

I am now worried that the boiler will underperform, be uneconomical and possible unsafe ?

Is the wider pipe a legal requirement ? Or if he proves that there is still adequate pressure even when all other appliances are running is the narrow pipe still okay ?

All advice appreciated.

 

[kirkgas]

safety is paramount, the MI's take the appliance requirments as paramount and might ask for 22mm pipe, if so easy peasy he is wrong, if the MI ask for a specific pressure then a test according to the gas regs and BS6891 needs to be carried out to determine what is required, if the pipe is wrong thew boiler under performing is the least of your worries more likely to create a prob at the fire or cooker, post the make and model of the boiler and also a distance/route as best you can for the 3 appliances

 

[Billy Bob Bob]

everything you have said is correct but i would add there is a distinct possibility of gas starvation to another appliance if you run a combi on 15mm pipe, eg cooker (which doesnt have FSD) is on and working, someone opens hot tap and combi fires up on full gas, depending on layout the cooker gets starved of gas and goes out, tap is shut boiler goes off and supply is reinstated to cooker which now has 3-4 rings passing full rate gas with no ignition

and this is exactly why we have pipe sizing,because this situation can and does happen

 

[spudulike]

safety is paramount, the MI's take the appliance requirments as paramount and might ask for 22mm pipe, if so easy peasy he is wrong, if the MI ask for a specific pressure then a test according to the gas regs and BS6891 needs to be carried out to determine what is required, if the pipe is wrong thew boiler under performing is the least of your worries more likely to create a prob at the fire or cooker, post the make and model of the boiler and also a distance/route as best you can for the 3 appliances

The boiler is a Worcester Bosch Greenstar 30Cdi combi. Distance from meter I guess at 5 metres. Gas hob is probably 3.5 metres. Gas fire is about 5 metres. These are straight line distances and as the pipes are all under the floor I don't know whether they have any turns.

The fitter is coming back to the house early next week - what should I be asking him to test or prove ? If he still insists this is a proper install can I get it checked independently somehow ?

Thanks for the advice - much appreciated.

 

[tamz]

A 30CDi requires 3.4 cubic metres of gas per hour to operate correctly. A 6m length of 15mm pipe (which is what you will have when adding in fittings) can only pass 1.9 cubic meters of gas so your boiler is working at just over half capacity at around 18kw.
The situation is made even worse as you have a fire and cooker and could lead to a situation as Kirk said where the other appliances are starved of gas.
Get him to do a gas rate of the boiler whereby you turn the boiler on to high rate (hold the chimney sweep button for about 10 secs) and time it at the meter.
Eg. A rough (but near enough) guide is
Metric meter (m3) time it for 2 minutes then multiply by 321 = kw
Imperial (ft3) 1092 divided by the time for 1 revolution of needle = kw.
You will need a 22mm pipe from meter to the boiler (22mm is stated in the manufactures instructions).

 

[fuzzy]

work out the gas requirement then you know!

wouldnt someone who had done their acs know this?