Strange Gas Consumption

[picasso]

put your central heating on , boiler thermostat on max , turn up hot water cylinder to max and then time in seconds for the pointer on the gas meter to do 1 revolution.
if its a metric meter take note of last 3 numbers, after 2 minutes note numbers again , post results in seconds or numbers

 

[D_Hailsham]

It took 65 seconds for one revolution of the dial. This works out at about 55 cu ft/hour. The manual says it should be using 62 cu ft/hr.

Does the consumption depend on the calorific value of the gas? In other words could the difference between 62 and 55 be due to the fact that the CV of gas was lower when the boiler was made. so more would be needed to produce the same amount of heat.

 

[D_Hailsham]

More Info (don't know if it is relevant)

The boiler is in on the kitchen wall and the cylinder pump 3-port vale and controls are upstairs in the airing cupboard. I reckon is about 8 metres of 22 mm pipe between the boiler and airing cupboard, that's 16 metres total. The visible pipe is uninsulated and there is no way of finding if the pipe under the floor is insulated. Assuming it is not, there must be a lot of heat lost in this pipework.

There is a valve on the return from the HW coil. There is no wheel, so I can't turn it. Is this just to shut down the flow or would have been installed to act as a flow regulator?

There is also a 15mm bypass, after the pump and before the MV, between flow and return. This also has a valve without a wheel. How do I know if the bypass is properly adjusted?

 

[scaby]

your boiler has an imput of just over 15kw, the consumption does depend on the cv of the gas, the valve on your hot water cylinder return is a flow regulator and the uninsulated copper pipes between boiler and cylinder are normal,your system sounds normal, god only knows why your gas readings are so odd ,sorry i cant help

 

[Eeejit]

how`s about you show us in detail precisely how you managed
to get these kwh figures in the first place.

 

[tonybhoy]

It took 65 seconds for one revolution of the dial. This works out at about 55 cu ft/hour. The manual says it should be using 62 cu ft/hr.

Does the consumption depend on the calorific value of the gas? In other words could the difference between 62 and 55 be due to the fact that the CV of gas was lower when the boiler was made. so more would be needed to produce the same amount of heat.

I get that to 16.8KW/pr input (+ or - 10%)which makes your more or less boiler spot on.

 

[D_Hailsham]

how`s about you show us in detail precisely how you managed to get these kwh figures in the first place.

Read the meter on day 1 (D1)
Read the meter on day 2 (D2)
Calculate D2 - D1 = V (This gives Hundeds of cubic ft used)

Calculate M = V x 2.83 to give cubic Meters
Multiply M by Correction Factor and Calorific Value and divide result by 3.6 to give kWH used.

Divide kWH used by number of days between Day 1 and Day 2 to give average daily consumption.

At least, that's what I thought I was doing. I have now looked again at the formula on my spreadsheet and found that I was actually using accumulated figures from the time I started keeping records. I have corrected this and now get the following results:

---From ---------To---------kWH/day
21/09/2006 14/01/2007 83.49
14/01/2007 18/04/2007 115.24
18/04/2007 17/05/2007 60.99
17/05/2007 20/06/2007 40.87
20/06/2007 18/07/2007 28.20
18/07/2007 14/09/2007 23.41
14/09/2007 02/01/2008 87.85
02/01/2008 07/04/2008 110.54

That's more like it. PANIC OVER


My apologies to all contributors for wasting their time on a non-existent problem.