It's not just that its not financially viable but also a question of the overall quality of the installation and system design.
There is a lot more to it than people think.
Calculating the right size rads, choosing the best pipe runs, location of rads,choosing the best programmers/thermostats to suit your needs.
All these things come into the equation to ensure you have an efficient/cost effective system.
What are you talking about? A customer wants a commission on gas, flue, ventilation, safety etc. Nothing to do with efficiency or effective system.
They've chose to plump it, let them deal with it.
I can see that a responsible installer would want all aspects of the system to be correct, professionalism showing !
However I would like to say I agree with Gas2Air it's my choice to think I can do it and live with an expensive under achieving system, so long as no-one else is blown up. i'd have to live with the green issues too, wasting fuel.