Question About Harman SF-260 Coal boiler hot water issue

Hello I have a Harman SF-260 Wood/Coal Boiler that i burn only nut coal in. The boiler is connected to my primary oil boiler but the oil burner is not on just the controls so when it calls for a zone on the board the coal boiler handles it. I also have a stor-all tank that holds all of my hot water. Every 2 weeks or so, we won't have hot water when running the coal boiler so when i go downstairs and turn the switch off then on for the controls on the oil boiler the Taco valve will open and the pipe will then get hot and heat go to the stor all tank. This never happens when we use the oil boiler only in the summer, just happens intermittently when we use the coal boiler. I had an electrician look at it and they can't figure it out. but the only fix is to turn the main board on the oil boiler off then on then it starts to heat up the tank and open the valve. Looking for any ideas, electrician said i prob have a bad board but if it was bad why does it work great with the oil only. I also do not have the hot water coil for the harman boiler in the unit due to owning a stor all tank

Thanks Ryan L