Red90's Land Rover Defender Heater Upgrade - The Heater

The Heater!!
The heater I've chosen is
the Mobile Climate Control model 12-1203, This is available in Canada from Princess Auto, a nationwide chain, part number 9089533, There are quite a few other choices.  Some are meant as aftermarket car heaters, others as supplemental car heaters and some as heating in boats.  My second choice of heater was one made by Heater Craft, model 201HOR.  It is only $190 at Summit Racing.  The heat output is decent and it should work in both LHD and RHD.  The other plus is that it will be easier to duct the intake side.

Here is the heater as received getting ready for flow testing.

MCC 12-1203 Heater

And looking inside we see the monster matrix with 3 rows of 6 tubes each.  The fins ares 12.5" x 2.75" x 6.25".  The stock heater assembly is in the background.
MCC 12-1203 Heater Matrix

The Install!!

Here we see my engine bay with the stock heater.  I have a Webasto heater installed so the heater hose routing is not quite as per normal, but the rest of the install should be the same in any LHD Defender.
Stock Heater

the stock heater and you are faced with this.  The hole in the bulkhead is 4.5" wide by 3.25" high.  This is a bit small for the flowrate of the new heater.  I opened it up to 6" wide which allows re-fitting of the stock heater if desired.  I also reshaped the angled portion on the left (with a hammer) to allow clearance for the new heater before this photo.

Here is the opening widened to 6"
Bulkhead Widened

In order to fit the new heater I built a discharge duct and welded it to the outlet housing of the heater.  This could easily be made as a bolt on piece as well.  Here is a drawing showing the layout of the heater as well as a cutsheet for the duct pieces.
Heater Install Drawing Heater Install Duct Cutsheet

The outlet duct during test fitting for placement of the supports.
Outlet Duct

And here is the complete install for the first stage of the project.  You notice that in the coolant supply line to the heater is a valve.  This is needed to control the heat output of the heater.  In order to work in the correct direction with the stock lever, it needs to be a push to open, pull to close valve.  I used a MEI corporation model 2252 valve.
Outlet Duct

The table below shows the measurements for the heater as installed.
  1. I'm getting twice the heat output over stock with a much higher air temperature.
  2. Air temperature is much higher.  This means I'm getting warm air even before the temperature gauge has moved which is a huge benefit in in town driving.
  MCCI Stock Units
Low Medium High Low High  
Inlet Temperature 8 8 8 7.5 7.5 C
Outlet Temperature 70 68 67 50 49 C
Flow Rate (inlet) 62 95 119 37 71 l/s
Flow Rate (outlet) 75 115 143 42 81 l/s
Heat Produced 4208 6327 7673 1731 3260 W

  MCCI Stock Units
Low Medium High Low High  
Inlet Temperature 46 46 46 46 46 F
Outlet Temperature 157 155 152 122 120 F
Flow Rate (inlet) 131 201 251 78 149 cfm
Flow Rate (outlet) 159 244 303 89 172 cfm
Heat Produced 14359 21590 26182 5906 11122 btu-h
    1. Heater Install
    2. Intake Modification
    3. Outlet Modification