Sounds as if the five pounds a week is a rental payment - if the payment is fixed, then it works out at 2600 over a 10 year period.
So if the boiler has a 10 manufacturer's warranty and the supply and installation is based on 1600, there is a 1000 return over 10 years, being a 100 pound per year return on an investment of 1600.
What about defaulters? There will be legal costs and the cost of removing the boiler, and a second-hand boiler that is worth very little, plus a load of bad publicity, so it wouldn't be worth thinking about removing the boiler. Would it worth going to Court to get an order for 5 pounds a week, maybe, but if they argue the case and have no money, it could be an expensive nightmare.
Difficult to see how anyone can make money out of this, unless the weekly rental can be increased, or if some kind of grant is involved.
I reckon there has to be more to it.