anyone know of a decent combi that only needs a 15mm gas feed?

[Marco]

hi - I'm looking to swop a boiler for a customer, current supply only 15mm for gas.
DHW out put around 23kw, tricky to put in a 22mm gas supply - anyone know of a decent condensing combi which would only need 15mm gas? I've not seen one, but thought I'd ask on the off chance!
Cheers

 

[gasmarc]

viessmann 24kw vitoden or a remeha or even better intergas never really had an issue putting a 24kw on a 15mm supply so long as it aint to long , only been doing it for around 20 years and never had a call back

 

[Marco]

viessmann 24kw vitoden or a remeha or even better intergas never really had an issue putting a 24kw on a 15mm supply so long as it aint to long , only been doing it for around 20 years and never had a call back

Thanks a lot gasmarc - I was expecting some abuse about correct pipe sizing etc - so good to hear you reply - will look into these. Boiler about 5m from meter so not excessive!

 

[fuzzy]

viessmann 24kw vitoden or a remeha or even better intergas never really had an issue putting a 24kw on a 15mm supply so long as it aint to long , only been doing it for around 20 years and never had a call back

theres chance yet then!
Dont you leave them a false number? lol just kiddin

isnt it asking a lot from 15mm?

 

[gasmarc]

people will argue the point if the pipe is not big enough and another appliance say like a huge range cooker is also on the supply it would not be big enough to serve both appliances on full power which is correct, the viessmann is 26kw from memory , i always tell the customer if there is any issue regarding performance then the pipe will need up grading at an extra charge

 

[Mrs Tara Plumbi]

people will argue the point if the pipe is not big enough and another appliance say like a huge range cooker is also on the supply it would not be big enough to serve both appliances on full power which is correct, the viessmann is 26kw from memory , i always tell the customer if there is any issue regarding performance then the pipe will need up grading at an extra charge

Good point.
We just had some negative feed back as a result of a quote which the recipient said was too high because we added unecessary work. Our quote included the cost of new pipework even though we had discussed it with him and explained the existing pipework was unlikely to be adaquate. We could have phrased our quote your way.

Mind you he was also annoyed that we told him we must recommend TRVs and he will have to sign a disclaimer as proof that we recommended and he doesn't want them.
O yes, he does all his own plumbing and would preper to fit his own boiler but he's not gsr..... you've all met him!

 

[GQuigley67]

I was away looking at a job today for some plumbing work, but while i was there i noticed that there was alot of 15mm gas pipe to the Vokera Compact, I would think it would be undergassed but haven't checked it yet, told customer if i get job i'll check it out. You'd struggle to get the required m3/hr with 15mm in long distances

 

[AWheating]

aslong as you have all the correct pressures and gas rate with 1mb drop or less then no problem with 15mm pipe. if its only a short run of 5m of 15mm from meter it would not take very long to do the calculations to be 100% sure you wont hit any problems before you start.

 

[tamz]

3m of 15mm will supply 2.9m3/hr, about enough for a 28kw.

 

[diamondgas]

If I may stick my peneth worth in ... Put a 30kW boiler in.... last 3m in 15mm. Boiler worked a treat! Registered it, Gas Safe got in touch with the custard, GS went and visited and I got a none conformation letter from gas safe! Wp at meter 20.5, WP at boiler 17. Mi's ask for 18 minimum regs state no more than 1 across the pipework! Only a bleed'n boiler and hob fitted! Held my hand up ... guilty as charged! Gas rate was spot on, bye-the-way!

Anyhoo's I went and removed as much of the 15 as i could everything else was under concrete!!! I was foamin!! LOL .... Boiler is an logic+

 

[AWheating]

trouble is many customers think you are trying to make work for yourself by insisting on installing the correct size pipework when a cowboy wont even think about it and stick it on what evers there.

 

[sweet]

Do your gas flow calculations, if these work out ok go for a 24kw Intergas, these combis have the potential to be the most reliable available, installed one last week and was very impressed & will be installing many more. I usually install Viessmann & Valliant brands but as a Combi the Intergas is where the smart money is being spent...

 

[tamz]

Worst one i saw for a while was a 29kw vokera fitted on a 24m run of 15mm + about 10 elbows on.
Customer had just bought the house and asked me to check the boiler as they didn't seem to be getting the same amount of hot water as their last house.:whatchutalkingabout
They got it fixed at the sellers expense.

 

[missplumb]

the ideals have a 1to1 gas valve which in the MI's says will run the boiler at full power with an inlet pressure of 14mbar. therefore if you can test the supply pressure at the boiler with all other appliances running and it is greater than 14 mbar then i understand that will be adequate. obviuosly it not the perfect situation and we recommend to our customers that the pipework is upgreaded if necessary but as has been said some people just think you are trying to con more money out of them. this is an easy way round it without contravening MI's

 

[mikegas]

But if your getting more than 1mbar drop to the boiler then your contravening gas regs so its still not allowed

 

[metaldust9]

gasmarc shorley you would run 22mm as near to a range cooker as you can, then go to 15mm ad feel very uncomfortable doing the whole lot in 15mm same applies to the boiler altho i can see were marco is coming from ive known people go in 15mm with no problems but its all down to the mi,s and most say go in 22mm then down to 15mm for the last meter because its the force of the gas behind, to fill the pipe thats being used, not the size of the pipe hence the length of the pipe is taken into account

 

[diamondgas]

the ideals have a 1to1 gas valve which in the MI's says will run the boiler at full power with an inlet pressure of 14mbar. therefore if you can test the supply pressure at the boiler with all other appliances running and it is greater than 14 mbar then i understand that will be adequate. obviuosly it not the perfect situation and we recommend to our customers that the pipework is upgreaded if necessary but as has been said some people just think you are trying to con more money out of them. this is an easy way round it without contravening MI's

Hi missplumb, what you say is not technically true unfortunatly, as I found out to my cost when Gas Safe inspected one of my installs. He clamped down on the "no more than 1mbar from meter to boiler" requirement. I had to go back and alter pipework! The inlet at the boiler I put in was actually just 1mbar under what the MI's asked for!!!

 

[stevetheplumber]

no wonder i cant get work when theres cowboys out there who fit anything they want on 15mm disregard gas regs and cut corners

 

[GQuigley67]

the one i seen the other day was under the house in the basement so had a look at the whole gas pipe, came off in 22mm to the fire reducing down to 10, then another tee in 15mm which fed a vokera compact he and a gas cooker, in quite long distances aswell, think customer though i was trying to get work though when i explained it didnt look right as "its worked fine"

 

[gasmarc]

i would always run pipe work in 22mm just to cover myself. i had a mate who put a boiler in with a rerun of 22mm ,his customer got a new range cooker to replace their existing electric one , the customer complained that there was an issue and my mate ended up footing the bill for a re run ,which was wrong

 

[tamz]

He shouldn't have backed down to it. It was the clown who fitted the range that was responsible.

 

[desrob]

boilers have run off 15 mm for years with no problems, it was the new regs that insisted on pipe work to boilers having a pressure drop off less than 1mbar hence 22mm.

 

[GQuigley67]

I wouldn't want to be leaving an installation which isn't done to regs anyway since your name is on it afterall and I know of someone who has been dug up for it

 

[emerald]

i have fitted an Ideal independent onto a 15mm gas supply as in the book it said it works fine with 14mbar at the inlet, it turned out i had 19.5 mbar anyway, but the performance seemed pretty good, and the flow rate was better then i thought it would be.

 

[arran197]

If the MI states it needs it, it should have it. I had to repipe a Duo Tec because it had been installed on 15mm copper and didn't meet the standard. It was a long run though tbh.

 

[andyplumber]

I always run 28mm to boilers as i like to cover myself for future installations, your bound to get a cowboy who will fit a 8 ring range cooker and a gas fire and not bother to check the pipework and gas pressure/pressure loss and just fit it and not leave any proof that the cowboy fitted it and when things go wrong i will be the one getting the phone call.. but always check the MI

 

[gasmarc]

that is the proper way to do it Andy ,as a mate ran it in 22mm only for a customer to change from electric to a rang cooker and blamed him for not putting the right pipe in

 

[GQuigley67]

I disagree, he's not at fault then. Its the guy that fitted the range cooker, he's the last gas engineer on the job, so the responsibility lies with him.

 

[Gray0689]

I disagree, he's not at fault then. Its the guy that fitted the range cooker, he's the last gas engineer on the job, so the responsibility lies with him.

I agree with GQ where not clairvoyant if they intend to add at a later date then should tell fitter at the time

 

[AWheating]

time and time again i have tried to explain to customers that have brought huge double cookers that there will be a chance that the exsisting pipework will not be correct for the new appliance.... you tend not to hear back from them unless the cowboy that fitted it left it unsafe and they want you to take a look cus they have realised that you knew what you was talking about. then you tell them to jump!!

on most new builds i have done in recent years we would always fit 22mm to cooker position to cover the new tennant bringing with them a huge appliance.

 

[Marco]

Update - we fitted the boiler last week and went for 22mm back to the meter, as I like to sleep at nite! Even at 5 meteres, with other appliances 15mm was not going to cut it on the pipe sizing.The issue (that I was trying to get round) was that most the gas pipework was lead, with copper tails to the appliances in a confined crawlspace. In the end we replaced the lead pipework with copper back to the meter, as neither of us are up to speed with copper to lead jointing on gas pipe. Do many of you do this jointing, or is it just us who struggle!?

 

[stevetheplumber]

22mm minimum gas carcase 28mm if higher than first floor in house

 

[gasmarc]

i dont thing lead to copper is legal to do nowadays ?

 

[AWheating]

you can not adapt/reconnect a lead pipe to a new gas carcus. if its exsisting then fine but a new joint to lead is no longer allowed as far as im aware .

 

[tamz]

You are allowed to connect to existing lead pipe but few now have the skills to do so therefore it is usually easier and safer to replace.

From BS6891

COMMENTARY AND RECOMMENDATIONS ON 6.1
When selecting materials for use as installation pipes, consideration should be given to strength,
appearance, cost and the need for protection against corrosion (see Clause 9). The Gas Safety (Installation
and Use) Regulations 1998 [1] state that lead or lead alloy pipes supplying gas are not to be installed.
However, historically, lead pipes were used to install gas meters and lead alloy pipes (known as lead
composition pipes) were installed as installation pipes and can still be found in old housing stock. Providing
this material is in good condition, sound, well supported and is of adequate size, connection may be made to
steel or copper pipework using appropriate fittings (see Clause 7).

8.3.3 Connecting lead composition pipes
When lead composition pipes are encountered and any connection joint has to be made, then only a soldered
cup joint onto copper pipe or a suitable brass union fitting shall be made. Compression fittings designed for
jointing water weight lead pipework shall not be used.
COMMENTARY AND RECOMMENDATIONS ON 8.3.3
It is essential that care be taken when soldering a joint onto lead composition pipework as blow lamps might
provide too much heat at the joint.
Lead solder should be used for this purpose. It is essential that joints be mechanically strong and gas tight.