Time tracking operation on boiler OKOFEN
In order to understand the merits of the approach, I would like to make a small reminder from the "granules" file that I wrote for the forum :
The heating of a house is a system in constant balance between a heat flow that escapes from the house (losses, vmc, etc.), and an incoming heat flow (heating, sun, people inside ( do not laugh: each person brings about 100W).
Throughout the year the need to heat a house varies, but on a short scale of time (a few hours), there is a demand for heating that can be defined as practically fixed. This required heating value is always lower than the maximum power of the boiler. How does the boiler adapt to the power actually needed? By its regulation system but especially by operating INTERMITTENCE.
When the burner of your 30kW oil boiler is running, it delivers 30kW! If the need in the house is only 10kW, the burner stops 2 / 3 of the average time.
An oil or gas burner starts in a few seconds and stops instantly; a NON wood fire.
The "chopping" of power on / off is very poorly suited to burning wood. Manufacturers of pellet boilers have therefore sought ways to modulate the power of boilers by different devices more or less effective that I will not detail here. The important thing is to understand that modulation always has a minimum threshold, and that the efficiency is generally much better near full power than the minimum threshold.
So if your pellet boiler has a max power of 30kW, like your old oil boiler, it has a reduced modulation minimum power of maybe 8 or 9kW. When the heating requirement is 4 or 5 kW, it will have to stop 50% of the time. During each start-up phase, it will consume more electricity (to light the pellets), and will waste pellets that go badly or not burn; and she will have a deplorable return. During shutdown, she will also waste energy by sweeping the fireplace with a draft (for safety reasons), sending the calories in the chimney.
Conclusion: A well-dimensioned pellet boiler with well-regulated regulation must operate over long periods to be effective. To give an order of magnitude, I would say that periods of operation less than 30 or 40 mn are not favorable (whereas a fuel boiler sometimes runs 5mn). In addition, the shutdown period should be short, because in this case, the restart is better (presence of ember). It is better a pellet boiler that runs 40mn and stops 10mn than the reverse.
further down ....