Measuring gas pressure under load

[akist]

Hi,

I jad a boiler fitted a few weeks ago. The installer said that gas pressure is marginal.

I have another gas pipe outlet quite far from boiler I was hoping to use for a combi and/or maybe a gas hob. This is currently capped off. Can another gas fitter measure gas pressure at those remote points while the main boiler is full on, to see what pressure we have?

The SGN man said I had 65kW available and my boiler is 40kW so am hoping there will be something left.

Alternatively would I be able to get a larger gas meter?

 

[Madrab]

All about pipe sizing, not so much about pressure per sé., though there is an absolute limit as far as the meter size is concerned. Need to talk to your gas transporter as the supply may need to be upgraded as well as a larger meter, wouldn't be cheap.

 

[polesapart]

Can another gas fitter measure gas pressure at those remote points while the main boiler is full on, to see what pressure we have?

He can, but it won't tell you anything useful.

The issue is the pressure drop when both appliances -existing and proposed- are running at full chat.

 

[akist]

The issue is the pressure drop when both appliances -existing and proposed- are running at full chat.

How will I know whether there is enough pressure for a gas hob for my new kitchen before I order it?

 

[denso13]

How will I know whether there is enough pressure for a gas hob for my new kitchen before I order it?

A gas safe person can measure and advise.

 

[ianmcd]

Already have another gas outlet off of the same pipe run, it is capped off. I am thinking of buying a pressure gauge and attaching it to it so as to see what pressure we have under varying conditions. All I will need is the gauge up to say 100mbar and a gas safe plumber to fit it.

The gas safe engineer will have their own guage

 

[DP]

You could also extend the gas connection from boiler to another heat source to test if it has enough pressure to provide gas to two sources.

If the pressure at the boiler is marginal, fat chance of extending the gas line is going to work. The appliances will run but not as intended

Get the gas engineer to look at the gas run. Good chance the pipe run to 40kw boiler is undersized. At a minimum, get the installer to upgrade the gas line meter to point where the hob branch is taking into regard the boiler. Boiler supply will improve and hob will have its feed at correct level too

 

[DP]

Already have another gas outlet off of the same pipe run, it is capped off. I am thinking of buying a pressure gauge and attaching it to it so as to see what pressure we have under varying conditions. All I will need is the gauge up to say 100mbar and a gas safe plumber to fit it.

That would be waste of time. Once the job is done, what purpose other than give you visual, is that going to achieve

 

[fixitflav]

Already have another gas outlet off of the same pipe run, it is capped off. I am thinking of buying a pressure gauge and attaching it to it so as to see what pressure we have under varying conditions. All I will need is the gauge up to say 100mbar and a gas safe plumber to fit it.

It depends on the pipe diameter, length and layout. The meter rated for 6 m3/h (65 kW) doesn't mean it can deliver that flow with acceptable pressure drop.

 

[denso13]

I know it has a pressure reduction thingy, is that adjustable?

No.

 

[fixitflav]

Assuming the pressure at the meter is the 21mb I calculate a 4-5mb drop.

According to the regs the pressure at the meter outlet should be 21+-2 mb, so if it's 17 mb at the boiler, the drop could be anything from 2 to 6 mb. If it's 16 mb at the boiler, 3 to 7 mb.
From the calcs, I'd guess something like the 2 mb is more likely, but more careful measurement might be in order.

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We're closing the thread because we can't give gas advice.
There is more to do than put a pressure gauge here or there. A Gas Registered operative will be considering things that untrained people wouldn't think of, so we do not help DIY work.
Some posts have been deleted.
Mod
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