When did building regs come into force for 22mm gas inlets

[romablade]

I'm in the process of obtaining quotes for a replacement combi boiler. The house is 13 years old (built 1999) and has 4 bedrooms. We currently have an Ideal SE Combi with 15mm gas inlet pipework that disappears into the wall directly behind the boiler.

So far, the quotes we have rightly state that we need to change the gas inlet pipework for 22mm type. BG wanted to replace the whole run, from the meter to the boiler (the whole length of the house) and even suggested putting the pipework on the outside wall (that would look nice I'm sure you'd agree!).

The current pipework goes into the garage behind the meter box, up into the ceiling void and runs across the house in the void. What I'm not sure of is at what point does the pipework switch to 15mm.

I don't really want to start lifting up floorboards until I really have to.

The Gas Fire pipe comes down about halfway across the ceiling void and is also 15mm. Would the pipe work for the boiler also change to 15mm at this junction?

I read on another thread that the building regs change stated that the last 1m of pipework into the boiler could be 15mm. I assume this was so the boiler manufacturers could sell off existing stock with 15mm connectors, now they've all gone and are all 22mm connectors.

When did the regs change? Can I assume the pipework is 15mm for only a meter and the joint from 22mm-15mm is somewhere in the ceiling void directly above the boiler?

I know the HE will discover this eventually, but I just want to get a feel for how complicated this job is going to be.. Any help appreciated.

 

[Dan Robinson]

It has nothing to do with building regs.

It is about the gas regs and boiler instructions.

 

[simond]

If you shop around you will find there are plenty of Gas Safe registered installers who will connect a new combi to that 15mm pipe. Just like the original installer did.

Some will do it out of ignorance, some knowing full well that the boiler will be under-gassed.

They will probably put in the cheapest quotes too.

But if you want the job done properly you need the gas pressure to be within 1mb of what it leaves the meter at, when the boiler is running full power. In the case of a combi, this usually equates to the hot water being used.

There is no gas regulation expressly saying a pipe inlet size; the installer is presumed to be competent in sizing the pipework appropriately for the route taken from the supply. Some commercial burners have 15mm inlets, but that doesn't mean you can run the supply to them in that gauge.

Many struggle with the pipe sizing calculation, which is why when Gas Safe Register look at an install, the working pressure is one of the first things they check (along with the flue).

 

[Gasguru]

The pipework may be perfectly ok. It could jump up to 22 or even 28mm directly behind the boiler wall. Is the boiler still working, if so the working pressure should be measured at the meter and boiler to determine if the pipework really is undersized.

Just be aware that plenty of cowboys will install a new boiler onto undersized pipework..it's illegal, can be dangerous especially for cookers/hobs/fires that are tee'd into the pipework and often voids any warranty on the boiler.

 

[bolshy]

The Gas Regulations are there to help ensure gas appliances and their gas supplies are installed correctly, and operate safely. This is to prevent as far as possible damage to property, injury and even death.
Manufacturers give minimum operating pressures for their appliances below which they will NOT guarantee it's safe operation.
Call in expert advice, and use that advice. If you are not happy with what one RGI says, call another to verify. And another. You should get 3 quotes anyway, if you are shrewd.
If the appliances can all be operated at full rate, the working pressure can be checked. If not, the information on the data plates can be used to calculate the volume of gas required for each appliance per hour at full rate. Pipework runs and minimum sizes can then be calculated based on the volume of gas your new boiler will need.
Do you have any other gas appliances connected to your supply (you mentioned a fire, is there a hob?) Your boiler is going to be installed at the other end of the house from the meter, where the current one is, I assume. It sounds like a long run to me and the minimum size I would expect to be required is 22mm. In many cases to provide sufficient gas from meter to appliance, I have upgraded the first 6m of the customers supply pipework to 28mm when needed. Your new boiler must achieve it's minimum working pressure (stated in Manufacturers' Instructions), at full rate with all other appliances on. Upgrading a gas supply is not an uncommon problem these days. Floorboards may need to come up. Do it right now, and you will never need do it again.