Hi Suzanne, I’m sorry but you are expecting a bit too much.
Wood is a difficult fuel to burn and to design burning systems for. It has different stages of combustion and requires a minimum temperature of 400C to burn properly. Then you want to put all the fuel in in one go and expect it to burn steadily. Imagine you put all the petrol into the engine and then asked it to burn just a little each time the engine revolves. It just isn’t going to happen!
Wood has a low calorific value, so even if you put 4 kg logs into a burner, that only about 10kW so from 10:30 to 7:30 that going to be about 800 Watts an hour, just warm.
Wood is good for ovens and space heating, and bad at heating water as the boiler reduces the combustion chamber temperature. This applies to all wood burning appliances.
Please consider a dry 3-oven cooker, which you can cook on and will keep the room it’s in nice and hot. With a wood burning stove in the sitting room, the oil boiler will heat the water and bedroom radiators for just a few £££s a year, or NZ$’s. 80% of the heating will be done by the wood burning cooker and stove.
Nowadays we use very little energy for hot water as we shower, and our washing machines and dishwasher are all cold fill.
Just an idea? Or as my mother used to say ‘food for thought’. Regards, Graham