The Outlet Modifications!!
The outlet vents are quite restrictive, even with the stock heater. These need to be openned up in order to get more flow from the larger (or even stock) heater.
The stock lower vents are 1-3/4" x 2-1/4" each. The defrost vents are about 1/4" x 12" with 1-1/2" ducting. This gives a total duct area of around 11.5 square inches. The stock fan inlet area is 14 square inches and the fan I've installed has an intake area of 28 square inches. The stock bulkhead opening is 14.6 square inches and the modified one is 19.5 square inches.
The first step on adding outlet area was to widen the lower vents to 4" and building larger deflectors. For the time being the closure flaps have not been changed.
Here are the new deflectors next to a stock one.
And installed.
I then added a rectangular adjustable vent above these. These vents are around 1" x 2-1/4". This brings the outlet area up to around 24 square inches.
I still need to get my lazy ass around to retesting the flow rate and heat output with the larger vents. Regardless of the numbers, there is a lot of air flow and heat into the cab. More than needed!!
- Heater Install
- Intake Modification
- Outlet Modification