Only have heat to rads when I drain the return line

[oldbutnotdead]

Excellent news, glad you've made progress on it. Once you've got all the air out, your existing pump should be ok (provided there aren't too many long legs of skinny tube feeding several rads). Another thing i'm surprised wasn't fitted with the woodburner is a loading valve- basically a posh thermostat, creates a short loop so the water in the boiler warms up quickly, once its up to temperature it blends in cooler water from the heating system (or thermal store in my case). It does reduce the on/off nonsense you're getting with the pump on pipe stats.
Has your burner got a grate in for burning coal? (Or have you been burning wood on the grate). Wood burns best on an ash bed....

 

[Yellosub]

There is a grate above the ash pan. Can I add in a loading valve?

 

[oldbutnotdead]

You can, look for Esbe or Laddomat. Not much point if you're switching to propane though....
EDIT Have a look at the instructions for your stove, the grate comes out of mine for woodburning

 

[Yellosub]

Thanks OBND. Your help has been invaluable. And I'm still alive to say so!! I guess now I'll finish the other projects I was working on and scroll around the other sections here. Thanks again!!