Forum Discussion

js415's avatar
js415
Explorer
Jan 27, 2018

New AC install questions

This spring I plan on installing a second AC unit in my 2017 Heritage Glen 300BH.

This model was offered with a second AC, but the only one on the lot had only one unit, so we took it.

The second unit will be installed in the existing vent in the front bedroom. It is already wired for the unit, and I have installed units before, so it should be no problem.

My question is this:

My current unit is ducted and has one duct running forward to the bathroom and bedroom, and another duct running rearward to the living area and bunkhouse.

When I install the second unit in the bedroom, should I then block off the duct from the first unit going into the bedroom and bath?

The second unit will provide more than enough for those two rooms. Will blocking off those rooms force more air flow into the other rooms, or will it reduce the total overall airflow of the original unit, and cause icing problems?

For those that have ducted units and a second non-ducted unit, how are your ducts configured?

Thoughts or concerns are welcome.

Thanks,

Jerry
  • garyemunson's avatar
    garyemunson
    Explorer II
    Jan 28, 2018
    Ours has 2 units feeding 1 duct. In milder weather, the front unit keeps the entire rig cool, as it gets hotter, we add the rear unit to the mix. Two units sharing a common duct seems to work quite well. I'd worry about freezing up, too, plus then the front unit would not cool the rear as well.
  • westend's avatar
    westend
    Explorer
    Jan 28, 2018
    Control the air flow from the unneeded ducts at the opening with an adjustable diffuser would be my suggestion. You could also add in a duct or two along the trunks to better distribute from the ducted unit.
  • js415's avatar
    js415
    Explorer
    Jan 27, 2018
    You guys pretty much agreed on what I thought was going to happen. My first thought was to close the duct up and call it a day.

    After thinking about how easy they are to freeze up I started second guessing myself.

    I guess I was right!!!

    Thanks,

    Jerry
  • jerryjay11's avatar
    jerryjay11
    Explorer
    Jan 27, 2018
    ScottG wrote:
    Had second AC installed, left original ducts operational for when only 1 is needed.
    Closing off ducts may cause freeze-up.


    I would agree with this as these RV AC's have restricted airflow as it is being ducted. The more you restrict them the more likely they will frost up on you and the more noise they will produce. Take it from a retired HVAC/R tech.
  • shastagary's avatar
    shastagary
    Explorer
    Jan 27, 2018
    i would leave the main ac alone as altering the duct work could cause freeze ups you should only need to run the second ac on those +90 degree days otherwise just run the main ac and save energy. when running both the main ac will help circulate the air from the bedroom back out to the rest of the rv.
  • TakingThe5th's avatar
    TakingThe5th
    Explorer
    Jan 27, 2018
    My original ducted unit in the living room remained untouched and is able to service the entire RV. The non-ducted is upstairs in the bedroom and I set it to run much cooler then the living room unit. So during the day my 13,500 btu bedroom unit runs almost continuous, dumping it's cold air downstairs, while the 15,000 downstairs runs as needed to maintain temp and to distribute the air. At night I shut off the bedroom air and just run the living room unit. I use this setup to minimize noise and it also seems to work better for me when there is a fair amount of in-out foot traffic. Hope that helps.
  • ScottG's avatar
    ScottG
    Nomad
    Jan 27, 2018
    Had second AC installed, left original ducts operational for when only 1 is needed.
    Closing off ducts may cause freeze-up.

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