pellet stoves

I've not got one - we went for an heatpump instead.

I suggest you investigate the cost of the stove, the supply of pellets where you live(they became a bit scarce about a year ago).

The cost of pellets as they have to be purchased from a certified source if you want to claim the RHI.

Have you got somewhere nice and dry and large enough to store the pellets and can you manage to lift the bags and fill the boiler.

Last but not least check the reliability and servicing costs together with availability of spare parts

They aren't everso common so you might find that getting one serviced or repaired might be a problem if you cant get it sorted out.