Gas pipe length

[garryb59]

I'm currently doing some work around the flat [at long last] and have just replaced the shower. It's powered by a Brittany Gas Water heater, which does the job just fine, but I'm wondering if I'm getting the optimal heat from this water heater - the gas meter is about 15m from the Brittany and is connected via 15mm pipe, along which run of pipe there are about 5-6 elbows. Would it be worth replacing the15mm pipe with 22mm?

There is also a gas hob and two wall-mounted gas heaters.

All appliances run fine, but my thoughts are as to whether I'm losing any gas pressure at the Brittany with this length of 15mm pipe.

Thanks Garry

[IMM]

Should be 22mm all the way.

Have these on a separate run from the meter.

It will not be operating to full efficiency for sure.

[garryb59]

Yeah, I suspect this may well be the case. I've lived with this layout of pipework every since I got the place, which is years now! I'll get a quote sorted.

Many Thanks Garry

[Alan]

In message , garryb59 wrote

See

[IMM]

The gas fires and cooker run. It is best to have 22mm to the first and second appliance and 15mm after. A separate dedicate 22mm run will do the multi-point.

[Andy Hall]

It really depends on the rating of the water heater.

Do you mean Britony as the model?

If so, the books are at

can do a theoretical check by obtaining the rating of the appliance and then using the method at

can do a practical test measurement at the heater using a manometer (obtainable for about £15 from a heating merchant). There should be a test point on the input side of the gas valve or on the pipe (not the burner). With everything including the water heater turned on, the pressure should not be less than 20mBar - strictly the pressure drop from meter to appliance should not be more than 1mB.

It's worth looking at Ed Sirett's gas fitting FAQ for more information.

THe regulator inside the appliance reduces the pressure down to the correct level for the burner and you can easily check that as well.

I suspect that the 15m length of 15mm pipe will cause the pressure to be out of spec. - these are 28-30kW heaters.....

.andy

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[IMM]

Suspect? He must fill a bath in about a week. See my other post for real advise.

[Andy Hall]

Your usual style you mean. Shoot from the hip without checking the details first or offering a proper explanation.

.andy

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[IMM]

I saw what he had and suggested the best solution. Very simple.

[Andy Hall]

Mind yourself with those spurs.

.andy

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[IMM]

You are right. Those spurs are terrible football fans. I prefer the Gooners myself.

[Ed Sirett]

I go along with that. You need some leak detection fluid (approved soap solution) to make sure that the test point is gas tight after use.

Typically multipoint heaters are well over 24kW and it is almost certain that the 18m (equivalent straight length) of 15mm is way insufficient. In fact a dedicated 18m x 22mm would not have 'slack'.

I suspect that existing 15mm pipe was installed for the heaters and may be cooker for which it is probably just about sufficient. The multi-point was then mis-installed as an add on.

FAQ below.