Probably no point circulating water other than frost protection. It won't heat up by much if circulating it all the time while not in use. It will be a waste of diesel.
The system is designed to shut on and off during use saving fuel rather then sending water back to tank.
No quite the opposite actually it is designed to run continually most people have a return to the tank with hot water mine will heat 1000 ltr by returning water to the tank by lunch time you can hardly bare to put your hand In the tank as the water is that hot , the last thing you want with a diesel heater is for it to be stop start all the time works far better if run all the time otherwise it will come up the screen causing premature failure
That’s what I was wondering.
We used to have a hot box when I worked for a company 10 years ago, and it was always failing, needing a new burner every few months and cost a fortune. That burner was set up so that every time you stopped the flow of water at the brush, it stopped the burner. In my head I always thought that it couldn’t be good for a burner constantly stopping and cooling down then firing back up again.
Will be interesting to see if grippatank set it with the recirculating.
With my old L5 gas heater if I recirculated my water, within half an hour of it recirculating the water in my tank went from cold, to warm. So I reckon with a webasto, it will easily be capable to run constant from say 8am to 12pm, then you’d have a tank of water well above 60 degrees to last you all afternoon. If not, you’d just fire up the burner again.
That should mean a healthier and longer life for the burner as it’s running constant for 3 or 4 hours a day, (rather than stop start) and also means your only using £5 or less of diesel.