Filling redundant warm air heating ducting

[jimwiley]

Just after some advice, i have inherited my granddads house which has now got central heating but the old air vents for the warm air heating which has been removed are still there, just wondering how is best to fill and seal the ducting as it runs throughout the ground floor under concrete and lets be honest I'm not going to dig up all the flooring looking for the ducting.
can i just fill with rubble best i can and then concrete them shut, they are rectangular and do not contain aspestos as I've had a survey done the ducting is vented in grills in the foot of the walls.

thanks

 

[stem]

I helped a friend 'make good' after having his warm air system removed about 15 years ago. We simply removed all of the external grilles, cut off the end of the duct to allow space for the insertion of wooden battens and a piece of plasterboard to cover the hole so that it was flush with the existing plaster, then we packed some loft insulation material into the open end, and that was it. The main duct was left in place and apart from the 'plug' of insulation, empty.

 

[jimwiley]

Hi thanks, thats the sort of thing i was thinking of doing, the old system entry point for the air was through the ground under where the HVAC system originally sat so I'm left with a large hole in the floor in a cupboard, just wondering if you had the same and if you filled with concrete as i want to remove the cupboard?

 

[stem]

Seem to think that a timber floor went in the cupboard, it was certainly retained, but that was done before I got involved.