Vent from air conditioning?

[Flowergarden]

Hi. I am redoing a Ford E450 shuttle bus with the V10 gas engine that has an Air-con system that looks rather like a split system (condenser on roof, air handler over big back window). It appears to be factory installed, not aftermarket. When I removed the back seats, I discovered this vented box under them. It appears to exhaust hot air into the bus, as it gets very hot when the engine is running and the air-con is on. There was a metal plate installed on the underside of the upholstered seats, presumably to keep them from scorching.

Venting hot air into the bus seems counterproductive. Can I box this thing in? How do I protect my bed, which I was planning to install across the back, also under the big window? I’m assuming I cannot remove it. It has hoses that go under the bus and then appear to lead to the air-con.

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[DeMac]

The under seat vented box, as described above, matches the description of the under seat Heater (radiator). It's heated by the engine coolant system. Look in the engine bay, you should find the lines lead to two plumbing valves. Turn them both off, until cool weather arrives. The radiator & lines can be moved or removed.

[Flowergarden]

Originally Posted by DeMac

The under seat vented box, as described above, matches the description of the under seat Heater (radiator). It's heated by the engine coolant system. Look in the engine bay, you should find the lines lead to two plumbing valves. Turn them both off, until cool weather arrives. The radiator & lines can be moved or removed.

Thank you! So, the heater is on in error? I assume when the weather gets cold I turn the two valves back on? How do I then stop it from blowing cold air? Or, will it know not to blow cold air because I have it set to heat on the dashboard? Sorry for asking such elementary questions—I only know about cars, not buses. In terms of safety, do I need to protect my bed from the heat? Use insulation under that section of the bed board/mattress? I certainly don’t want to scorch the wood or set my mattress on fire.

[skoontz]

To relate this to cars, this under seat heater works just like the heater core in a car's dash board.

The heater uses engine coolant in a radiator, coupled with electric fans to move air over them. As mentioned, there should be 2 valves to shut off the flow of coolant to the heater. This loop of coolant is separate from the engine radiator, so you can close the valves and the engine should be fine. There should also be a switch by the driver's seat to turn on the electric fans. There may (or may not, I don't know if all busses have this) also be a switch for a booster pump that will help push coolant in the heater loop. In warm weather, the valves should be closed, preventing hot coolant from entering the heater. If you turn on the fans with the valves closed, the fans will just blow air around with no change in temperature.
On the other hand, if you open the valves, then it depends on how warm the engine is. If the engine is hot, you will have hot coolant running through the heater. When I drove school busses in Utah, the kids would always complain about the heaters moving cold air, but it was because the engine never got warm.
As far as protecting the bed, that is up to you. A quick search, it appears that your engine coolant shouldn't exceed 212 F. I don't think this will harm wood, but adhesives and plastics may be a problem.

[Flowergarden]

Thank you! This is super helpful.