Annoying Gas Fire Problem

[Willum08]

Hi, I have a Kohlangaz Gosford HE gas fire. It has recently been serviced but when it is set to it's lowest heat output setting using the Remote control the heat output now seems excessive compared to that which we have become used to since it was installed in 2017. I contacted the firm who carried out the service and their engineer looked at the fire and said he could not see anything wrong. This is just NOT the case - we know from our fairly long experience of using the fire that the output on the lowest setting is excessive but we are getting nowhere with the firm in question. I believe there is a system where the heat output of a gas fire can be determined at different settings, by observing the Gas meter readings for a specific time and doing some calculations...... Gas Rating ?
I would really appreciate some guidance.....

Kind Regards and Thanks

 

[Deleted member 120897]

Yes it’s called gas rating, and this determines the heat input of an appliance. This is based on 2 meter readings, some known values and a calculation.

What do you mean by, it seems excessive? Too hot? using too much gas?

 

[SimonG]

When was it last serviced?

 

[Willum08]

Thank You for your replies... much appreciated. When I say 'seems excessive I mean that the heat output when set to its lowest setting, is much greater than it has been over the years since we had the fire. Sitting in the same positions in the room as we always do, we can feel that the heat being produced at the lowest setting is much greater than we have become used to over the years. The fire was last serviced in September 2021. Prior to the last service, the heat output on the lowest setting was just as it has been since its previous service in 2020 and since installation.
From the Manufacturer's data ... Maximum Heat Input=5kW. Minimum Heat Input=3.5kW. Efficiency is stated as 80%
as specified in BS 7977-1.
Would it be useful to carry out a gas rating test at the fire's maximum setting and then at the fire's minimum setting to determine if in fact it is using more gas than expected at the lowest setting and therefore producing more Heat output. If this proves to be the case, then surely there must be something wrong with the device which regulates the amount of gas being fed to the burner, when adjusted to different settings....
Where can I find a detailed procedure explaining how to carry out this 'Gas Rating test ? I am a retired engineer but not a Gas Engineer.

 

[EvilDrPorkChop]

Thank You for your replies... much appreciated. When I say 'seems excessive I mean that the heat output when set to its lowest setting, is much greater than it has been over the years since we had the fire. Sitting in the same positions in the room as we always do, we can feel that the heat being produced at the lowest setting is much greater than we have become used to over the years. The fire was last serviced in September 2021. Prior to the last service, the heat output on the lowest setting was just as it has been since its previous service in 2020 and since installation.
From the Manufacturer's data ... Maximum Heat Input=5kW. Minimum Heat Input=3.5kW. Efficiency is stated as 80%
as specified in BS 7977-1.
Would it be useful to carry out a gas rating test at the fire's maximum setting and then at the fire's minimum setting to determine if in fact it is using more gas than expected at the lowest setting and therefore producing more Heat output. If this proves to be the case, then surely there must be something wrong with the device which regulates the amount of gas being fed to the burner, when adjusted to different settings....
Where can I find a detailed procedure explaining how to carry out this 'Gas Rating test ? I am a retired engineer but not a Gas Engineer.

You can download an app on your phone that will work it out for you. To confirm if you are correct or not. It maybe that it was incorrect before.

 

[Willum08]

Thank you to all contributors... Happy 2022

 

[John.g]

Hi Willum,

Gas Rating calc.
Ensure no other gas appliances on.
Set your fire to max then min for a set period and take the meter readings exactly at the start and end of each monitoring period, 5 minutes should be sufficient?.
If your meter is in M3, multiply the 5 min consumption by ~ 10.8X0.8 which should equal the gas fire output for this 5 minute period, for example if your measured 5 min consumption is 0.0482M the the G.fire output is 0.0482*10.8*0.8*60/5, or 5kw.
If the measured 5 min consumption is 0.0337M3 then the G.fire output is., 0.03374^10.8*0.8*60/5, or 3.5kw.

If your gas meter is in FT3, multiply the 5 min consumption X 0.306X0.8X60/5 for G.fire output, for example if the 5 min consumption is 1.7Ft3 then the G.fire output is 1.7*0.306*0.8*60/5, 5.0kw.

I used 10.8kwh/M3 gas but this will vary, it may be shown on your gas bill, if so just use this number.

Edit: Your fire is rated on gas input so no 0.8 multiplier above, so 0.0386M3 = 5kw, 0.027M3 = 3.5kw or
1.36Ft3 = 5kw and 0.953FT3 = 3.5kw. if gas meter is in FT3.