Improving MG heating and insulating the heater box.

11-11-2008
Since I’ll be using my MG as a daily driver starting next year, I’m trying to think of ways to get maximum efficiency out of the heating system. The cockpit will, of course, have sound and thermal insulation on the floors, tranny tunnel and firewall and I’ll be redoing the heater valve by either modifying the flow of the original one or replacing it all together with a ball valve assembly.

I’ll also have a fully carpeted interior and I’ll be making an insulated headliner insert for the convertible top. But one other area I’m looking at is insulating is the heater box itself.

I figure that if this box remains warmer, the air passing through it will have to be heated less than if it was passing through the cold steel of the box. I had considered using something like the stick on Dyna-mat but I’m thinking that the heat in the box will cause it to break loose and sag into the box, possibly blocking the core or interfering with the blower fan.

What I think I will try is to apply several layers of 3-M spray-on rubberized undercoating to the insides of the box and then sticking a layer of heavy aluminum foil to it while it is still tacky. This undercoating material has stuck well to the harsh environment on the underside of the car and has been subjected to high heat in the area of the exhaust system without coming off so it should hold up well inside the heater box.

The aluminum will provide a thermal reflective barrier and will leave a smooth surface so as not to increase the drag on the airflow through the box like the rough surface of the undercoating by itself would.

I think this should greatly improve the thermal characteristics of the box and increase the amount of heat entering the cockpit.

Of course, the best improvements would be a 3-speed blower motor and a hardtop…but one thing at a time as my budget allows.