Gas Flow

[alexbetts]

Hi

can some one explain simply why is it such a big problem and what will it do if the gas at the appliance working DHW mode is less than 18mbar as the appliance appears to be working fine

 

[simond]

Have you measured the gas rate, as you suggest the appliance is working normally?

Most gas appliances can run at 15mB because it is accepted that there will be;
- differences in supply pressure from the transporter
- tolerances in the regulator
- pressure loss across the meter
- pressure loss across the installation pipework

However, the rules (GSIUR) set strict criteria how much those pressure drops can be in each instance.

Failure to follow our industry mandated rules can lead to the production of dangerous odourless fumes which will kill. The rules are in place to enable a consistent and auditable approach across the UK to help reduce fatalities due to ignorance and cost cutting.

If you are dropping more than 1mB across your gas pipework from the meter test point to the boiler when in HW mode it has been incorrectly installed, it is as simple as that.

If you are on a network where your incoming pressure at the meter test point is 19mB, then there are circumstances where 18mB at the appliance inlet would be acceptable. If you want to know more, you should be taking a course, its not really the place to go into more detail.

 

[onlyfitidealboilers]

depends on the boiler manufacture how you deem the appliance ie, say for instance you have 19mlb at the gas meter working & 16mlb at the boiler this means that it does not comply wit the Gas regulations. as you have a full 3mlb drop between meter and boiler, I would deem this NTCS as long as the manufacture instructions say it will accept a minimum inlet working pressure on 16mlb, if not I would class it as at risk.