I've got a Beckett oil heat water on demand furnace that heats through baseboards. Since this past weekend the furnace hasn't been kicking on when the temperature drops below my set temp of 68 degrees. I have to go down to the furnace and simply touch the top of the reset box for it to kick on. After a shower for example, the furnace will kick on to reheat more water for use... sometimes it won't though. I am thinking I should replace the thermostat... is this the best option or would this point to another part needing replacing? Maybe a relay switch?

Thanks,
Shane

On demand tells me no storage tank.
So it only runs when there is water running.

Normal operation in my opinion