I'd love to know more about your heater upgrade. Where did you get the unit? Does it retain the original heater matrix?
It's this one:
https://www.carbuilder.com/uk/lightweight-compact-car-heaterI then researched the make (Kalori )and found they did a double vent front panel which was an additional £60. I wanted the ability to direct/close off heat if needed.
My Mog had the 'Smiths Fug stirrer' heater in the footwell. I completely removed this and associated 'plumbing'. Re plumbed in the new heater in the location pictured (I made the bracket from a chunk of aluminium I had in the shed - it is fixed with a couple of rivnuts to the gearbox cover).
Used one of
these for the pipes through the bulkhead.
And fitted a bowden controlled
bypass switch so I can turn off the heat flow if it gets too hot.
And a
Bleed ValveThe fan is a three speed and I made a bracket on the steering column (opposite side to the choke, which has the rotary speed switch, and the bowden cable)
I think it would be possible to run it in series with an original heater (I did this once with a Land Rover, and fitted a second heater from a Mini in between the front seats). My main issue at the moment is getting enough heat into the matrix itself, as soon as I put the heater fan on, it's so efficient on the lowest setting it takes a lot of heat out of the engine - I'm going to get a higher degree setting thermostat, and hopefully the electric radiator fan will allow me to run at a slightly hotter temperature.