Noisy Dometic AC - Event Date: 14 Jul 2018 - 21 Jul 2018

See page 1, the 2nd post. While inspecting for loose, dirty parts is always a good idea, with the small space of the RPods and the fact that they are direct and not ducted vent means that the AC will be loud. Step outside and listen. I think you will find that the AC unit itself is pretty quiet. That means the sound problem is noisy, turbulent airflow inside the shroud. Making sure the pathway for the air to flow is clear of anything that could vibrate is good. Doing as I did and putting some closed-cell foam on the inside of the shroud also will help. The biggest thing that helps is closing that big main vent and letting the air flow through the ends and sides. I for one have appreciated the AC at night when we were in areas where the nighttime temperatures did not drop below 80 degrees, especially if there were any significant degree of humidity. In that case, setting the fan to run on low speed to have a constant cover noise helps.

When I measured things a couple of years ago the 9000 btu/he Pioneer mini split evaporator would fit on the side wall above the bed on the driver's side of my 179. I wouldn't try to mount one to the curved wall. The most efficient minisplits are 240Vac, and it's difficult to find an inverter in the 2kw range at that voltage, so there are limited options in high efficiency minisplits available at 120Vac.

The condensing unit could indeed go on the tongue where the battery boxes are. Some kind of removable cover would be needed to protect it from road debris. The propane tank would need to move forward a couple inches and would just clear the manual tongue jack. The batteries would be replaced by Li ones under the bed area. The refrigerant lines would extend forward from the evaporator and run down along the front left corner wall. There is a kit available to conceal them.

Overall removal of the roof mounted a/c and lead acid batteries and installation of 5kw of Li batteries, the minisplit, and a 2kw inverter to run it resulted in a sightly lower weight, with a significant tongue weight reduction, which is good in a 179. The entire roof area is freed up for solar as well if you take the opportunity to remove the TV antenna and spoiler. You can get about 1.5kw of solar up there which when combined with 5kwh batteries should give you around half a day a/c operation every 24 hours. The solar array would result in a net increase in trailer weight of around 200 lbs or so for the whole project.

I would suggest configuring the DC system at 24V and using a small DC to DC converter to operate the 12V loads. There is a significant efficiency gain and copper weight reduction at 24V.

The biggest concern I had with this project and what stopped me from proceeding was the risk of line leakage due to over the road vibration. The minisplits aren't designed for use in RV's and there are mixed reports on how well they hold up to vibration. There are fine details in how the line sets are installed that can reduce those stresses, and a good HVAC tech (which I'm not) will know what those are.

So I just stuck with the crappy Dometic roof a/c which is much better at making decibels than btu's but if someone with access to a good HVAC tech with minisplit experience wants to try it I'd be happy to help with the design as I'd really like to know how well a mini split will hold up long term on a TT.

You can have vibration damage internally in the evaporator or condenser as well as in the line sets. Also, the flex connectors can have leakage problems of their own. So it's worth making the connection details as vibration proof as possible but that is no guarantee of long term success.

As for getting rid of the furnace, that would only make sense if you weren't boondocking. There wouldn't be enough energy available for the heat pump. But if you're not boondocking an electric space heater would also work fine. There's not a compelling reason to change to a minisplit if you have shore power, at least not to me.