Hi.

Can anyone suggest a simple way to test if my heat meter is giving accurate readings?

I've got a 40kw log gasification boiler with a thermal store. It has a heat meter installed because of a backup oil boiler. My meter readings are much lower than expected. The meter didn't work properly at first as the return probe was incorrectly installed but since then it's still giving lower readings than I had hoped - about 15% of what I expected from the heating requirement calculation for the deemed rate.
The house is tenented and the tenents tell me they have been using wood almost constantly and have hardly used the oil boiler at all.

The boiler burn chamber has a capacity of 185 litres and is located in an enclosed boiler room and the is in the adjacent room, inside the insulated envelope. the heat meter probes are fitted close to the thermal store on the flow and return. The water in the tank has inhibitor in it. The wood fuel is dry and mainly norway spruce.

Any advice would be very welcome.

Cheers

Jwd

Timber has around 4.1 kWh/kg. (http://www.fao.org/3/a-i4441e.pdf)
Your boiler will have an efficiency of somewhere between 30 and 80%, depending on the length of burn and the relative temperature differences.

I would think that if you could start with a cold system, read the meter, burn 5 kg of timber, take meter readings every ten minutes while it burns, then take meter readings while it cools (if you can be bothered).
The meter should show something like half the energy content of the fuel, so around 10 kWh.

If your store can take a couple of decent burns then that is the better way.
You could make your own meter with a 10 quid raspberry pi, a temp sensor and a relay to sense when the pump is on.