MCI 12 Outside air vents on the sides near the front of the coach

[Jim Eh.]

When doing a conversion should these fresh air intakes be blocked off? I'm talking about the ones just aft of the front wheels on the side panels below the windows. Also the siphon tube ion the rear wall dusted to the air intake?

[Dave5Cs]

Are you talking about the Battery acid vents. Square area with little holes? If the batteries aren't there and have been moved you could block those but if they are still there those need to be left.

[RJ]

Are you talking about the Battery acid vents. Square area with little holes?

Dave -

You're talking about the vents on the battery bay door, Krank's talking about the fresh air intake vents in the billboard area under the windows - above the HVAC compartment.

Krank -

If you're keeping the big heater core in the HVAC compartment for coach heat while running down the road, then don't block off the fresh air vents.  The system is designed to duct approximately 25% fresh air into the coach when operating.  If you're not going to keep that big core, you could close them off, or get creative and figure out something to use them for.

The vent tube on the rear wall runs from the restroom holding tank into the engine air intake to help vent holding tank fumes while running.  You'll probably find, if you haven't already, a blower fan under the RR sink that the tubing is vented thru.  That fan is wired to come on with the master switch up front.

FWIW & HTH. . .

[Jim Eh.]

Thanks Dave,

I kind of understand how it works. Quite similar to present day building codes requiring an outside fresh air supply? What are the +/- to using the stock HVAC system vs a new system design and is a new design what is done most often? I live in a seasonal location so heating is a concern not that I am thinking of doing any winter camping exactly but I do not want to rule it out either.

Thanks for the reply

Jim

[shelled]

The plus and minus of the stock HVAC system on any intercity coach is (1) it's way overkill designed to handle comfort of 40 plus bodies and (2) it only works when engine is running.

e3

[lvmci]

Hi All, pictures always help, eliminate confusion and as the saying goes, they're worth a thousand words, lvmci...

[Jim Eh.]

The plus and minus of the stock HVAC system on any intercity coach is (1) it's way overkill designed to handle comfort of 40 plus bodies and (2) it only works when engine is running.

e3

Crazy notion of swapping out the A/C compressor and installing a belt driven generator, then using an electric motor to drive the OEM compressor. That way you could use the cooling side of the OEM HVAC to cool while connected to shore power.

[Jim Eh.]

Krank -

If you're keeping the big heater core in the HVAC compartment for coach heat while running down the road, then don't block off the fresh air vents.  The system is designed to duct approximately 25% fresh air into the coach when operating.  If you're not going to keep that big core, you could close them off, or get creative and figure out something to use them for.

The vent tube on the rear wall runs from the restroom holding tank into the engine air intake to help vent holding tank fumes while running.  You'll probably find, if you haven't already, a blower fan under the RR sink that the tubing is vented thru.  That fan is wired to come on with the master switch up front.

FWIW & HTH. . .

Actually there is (edit) no sink so no fan (ex US prison bus) just the engine air intake (it's plumbed into the plenum on the LH side) to provide the negative pressure for air movement inside the coach. The reason I question the need is that most of the time spent in the unit will be while parked and without engine intake providing suction, there would be no air transfer.

[Tony LEE]

I still have the OTR aircon working but I made big changes to the ducting including the fresh air makeup ducts.

However, because I have propane appliances in the house, our regulations require a certain area of fixed ventilation down near the floor (and up on the ceiling too) so I installed vent grills on the inside wall to match the ones on the outside wall.

[Jim Eh.]

Do you have a fan installed to ensure air transfer while parked?