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I have issue with the Ideal Independent 30 - rated at 33.7kw gross (30.4 nett)
The working pressure at the meter is 21mbar, and at the test point on the isolation valve only 18mbar. Clearly over the 1mbar drop allowed in BS6891. The MI mentions a pressure drop between the external gas cock could further reduce the operating pressure when measured at its test point however as the test point is part of the cock, I cannot see how this can be that restrictive. Has anyone else found the gas test point under the ideals give a restricted reading?
I have gas rated the boiler and obtained a measurement of 2.91m3/hr. The MI show a gas rate of 3.13m3/hr (based on a lower cv of 38.7), so around 7% below MI but within a tolerance -10% / +5%
I have rechecked the pipework sizing, and calculate a 0.74mbar drop from the meter to the end of the 22mm. The final 0.4 metres is reduced to 15mm to supply the boiler with 1 elbow (effective length 0.7m) – This is outside the range of the chart which shows a max of 2.90m3/hr over 3m for 15mm – even at this rate it would cause a drop of 0.23 – total of 0.97 mbar over the system, which is within limits.
Without fitting a test point on the pipework, it not possible to confirm pressure loss over the pipework.
As I am achieving a gas rate within a -10% tolerance, and 18mbar pressure (within the MI specification), is the supply undersized, or are the readings some peculiarity of the ideal isolator test point? Would it be worth fitting a test point on the pipework to confirm? In this event, the final 0.4m of 15mm with elbow might as well be upgraded to 22mm - this will gain approx 0.2mbar.
If undersized, obviously, I want to try to avoid having to upgrade the 22 to 28mm, and I suspect that the final 0.4m of 15mm should be upgraded to 22mm with a 22mm elbow before the reducer. This should gain around 0.2mbar.
The working pressure at the meter is 21mbar, and at the test point on the isolation valve only 18mbar. Clearly over the 1mbar drop allowed in BS6891. The MI mentions a pressure drop between the external gas cock could further reduce the operating pressure when measured at its test point however as the test point is part of the cock, I cannot see how this can be that restrictive. Has anyone else found the gas test point under the ideals give a restricted reading?
I have gas rated the boiler and obtained a measurement of 2.91m3/hr. The MI show a gas rate of 3.13m3/hr (based on a lower cv of 38.7), so around 7% below MI but within a tolerance -10% / +5%
I have rechecked the pipework sizing, and calculate a 0.74mbar drop from the meter to the end of the 22mm. The final 0.4 metres is reduced to 15mm to supply the boiler with 1 elbow (effective length 0.7m) – This is outside the range of the chart which shows a max of 2.90m3/hr over 3m for 15mm – even at this rate it would cause a drop of 0.23 – total of 0.97 mbar over the system, which is within limits.
Without fitting a test point on the pipework, it not possible to confirm pressure loss over the pipework.
As I am achieving a gas rate within a -10% tolerance, and 18mbar pressure (within the MI specification), is the supply undersized, or are the readings some peculiarity of the ideal isolator test point? Would it be worth fitting a test point on the pipework to confirm? In this event, the final 0.4m of 15mm with elbow might as well be upgraded to 22mm - this will gain approx 0.2mbar.
If undersized, obviously, I want to try to avoid having to upgrade the 22 to 28mm, and I suspect that the final 0.4m of 15mm should be upgraded to 22mm with a 22mm elbow before the reducer. This should gain around 0.2mbar.
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