gas pipe size and combi boiler failures.

SallyG

We've had endless trouble with our 6 year old combi boiler - I've now got quotes for a new "regulation" /no choice condensing boiler.
All the quotes specify replacing the existing 6 metres of 15mm diameter copper pipe from the meter to the current boiler with a 22mm dia. pipe; could the 15mm pipe size be the cause of fairly regular combi boiler shut downs?
The only other gas appliance we have is a gas cooker - the burner flames sometimes seem low/fluctuating.
The existing combi boiler when it works works perfectly well but seems to shut down randomly.
Is it possible that the boiler isn't getting enough gas to work properly?
I'm wondering if installing a 22mm dia pipe will fix the problem and I won't have to get the boiler replaced.

caveat_emptor

You don't say what your boiler rating in Kw is but it is possible that the 15mm pipe is the problem. As a boiler is an expensive item why don't you get a 22mm pipe installed before you change the boiler as you'll need it if you need to replace. Other thing to check is the gas pressure at the boiler when the gas cooker is on.

SallyG

I want to avoid needlessly paying for a new boiler if I can get this one to be reliable for much less outlay - the condensing ones seem to need all sorts of fancy stuff e.g. "condensate trace heater" to stop the outside pipe freezing - lots of things to go wrong.......
I've dug out the installation instructions the corgi installer left with us - word for word/sic :
"Pipework from the meter to the boiler must be of adequate size [22mm] min.To within at least 3 metres of the boiler [15mm] min. can then be used for remaining pipework to the appliance"
I think " 22mm min.To " is a typo? The only way it makes sense is :
"Pipework from the meter to the boiler must be of adequate size [22mm] min. to within at least 3 metres of the boiler [15mm] min. can then be used for remaining pipework to the appliance" i.e for a 6m. long gas pipe from meter to boiler at least the first 3m. should be at least 22mm dia ?
Later in the installation instructions - next to "Check with the local gas supplier if the pressure differs significantly from 20 mbar" the corgi installer has written "19 mB "
British Gas Homecare have repaired the combi boiler for the past 2 years and not mentioned the 15mm pipe as a possible cause of failure.
British Gas quote after a survey includes installing "3m" length of 22mm copper gas pipe work £191.91
Does that seem reasonable?
Seems a bit steep for a pipe clipped to a garage wall - but in any case the gas meter's at the front of the garage just inside the door and the boiler's on the back wall - at least 6m away.
I think I'll get quotes from elsewhere for replacing the meter to boiler pipework and see if that works.

Canucklehead

Hi...what is the make and model of your current boiler?

GSR

ihateyes

SallyG wrote: »

the condensing ones seem to need all sorts of fancy stuff e.g. "condensate trace heater" to stop the outside pipe freezing -

condensate tracer is a absolte need if you so with a new boiler....
so many boilers switch off when pipe freezes during the winter...
imagine waking up evey morning when it freezing with no boiler

macman

You should start by getting a quote/survey from a local independent RGI, they can advise on the required pipework. If your price is based on BG then you can expect to pay at least 30% more.
What do you mean by a 'no choice' combi? Of course you have a choice, you can specify whatever make/model you want.
You'll pay exactly the same to install a 'cheap' boiler as a decent one, so don't skimp on the brand, go for something decent.

Gman0365

Have the pipework upgraded to 22mm. This may solve your problem. By the sounds of it when the boiler is coming on for heating or hot water it's drawing gas away from the cooker causing the flames to fluctuate.

The pressure at the outlet of the gas meter should be 21mb + or - 2mb so between 19mb and 23mb is fine. What's most important is the pressure at the inlet to the gas valve on the boiler. There should be no more that 1mb difference between the pressure at the meter and the pressure at the appliance. If there is then the pipework is undersized.

If you need to change the boiler then the gas pipework is definately going to need to be at least 22mb so you would be aswell changing this first. You could also have the meter regulator checked out by the gas emergency service if you feel you have pressure problems. They will confirm there is sufficient gas pressure coming into the meter. Call them on 0800 111 999 for a visit.

Hope this helps.

DVardysShadow

My inclination on this is to have the gas pressures read at the meter and at the appliances, with boiler and cooker running and also with them off.

Given that the cooker is fluctuating, you could have pipework problems or a faulty regulator. I think I would have that looked into before considering a new boiler. And as a new boiler requires 22mm gas supply pipe, I would be upgrading the pipe to see if that made a difference before considering a new boiler

lemontart

has the gas safe registered installer said you have gas pressure problems? has he check the meter and said this, was your boiler working normally before and why was he looking at the boiler? what led up to him saying you need either new pipes or boiler - all questions that would need asking before you call the gas emergency service..............if you are changing your boiler the installer should advise you on any up grades to internal pipework and this is not a job for the gas emergency service.

If they are saying there is low pressure at the meter or low working pressure yes call 0800 111999 make sure the meter is turned off as you will be asked to do in this case - better still get the gas safe registered installer to call when on site.

bengasman

Just to clear up a few urban myths.

There is no legal obligation to feed any boiler with 22mm.
There is a legal requirement to supply enough gas to an appliance for it to work at a pressure that is less than 1 mb below the pressure at the meter. This leads to the need for 22 or 28 mm gaspipe to most boilers.

Condensate pipe heating is only necessary in rare cases in the region of 1-2%; the common freezing problems stem most of the time from faulty installation.

CORGI have nothing to do with gas safety, Gas Safe Register is in charge of that.

What the op needs, is a good RGI to find out what the problem is, rather than just throw the boiler away.

gas4you

Have to agree with above, except it is now being said/proved that trace heaters on condensate pipes are a total waste of time.