Just Installed a mini split in NH

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Rene T

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May 20, 2011
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Farmington NH
We just installed a Mitsubishi multi mini split here in NH. What a great set up. The condenser is a 24K unit and we have a 9K wall unit that takes care of the master bedroom and master bath and a 15K wall unit that takes care of our living room, kitchen/dining room open concept, a hallway and a small utility room.
I can’t get over how quiet this thing is. The condenser is so quiet, I have to get right in front of it and bend down to put my ear next to it in order to hear it running. The units in the house are the same. I have to hold a piece of tissue Paper in front of them to see if the fans are running when the speed is on low mode.
I did a lot of research before jumping in with both feet and thanks to TonyL and others, they really helped out. Mitsubishi IMHO is the way to go.
We go to fL next weeekend for the winter and my goal there is also to install a system. Thanks to everyone who participated in the decision to go this route. We should have done it long ago.
 

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Thanks Rene, I'm glad I was able to provide some useful information. I assume you had it professionally installed rather than DIY. The installation looks really tidy, so if you did do it yourself, top marks!
 
Lots of operational benefits but can't warm up to the box on the wall. I've seen some that fit in a wall or ceiling cavity which gets my attention. I know some have fitted mini splits into their RV's and I saw a utoob video where one was installed by the factory into a 5th wheel. Hard to beat the quiet compared to a window unit.

Mark B.
Albuquerque, NM
 
From what I've researched these are the standard in Europe. More efficient and less cost overall. Going to put one in the MH next summer. Just trying to figure out how to do it without mounting it to the exterior wall. Plenty of "cavities" under the chassis, especially by the wheels, but a blowout and road debris would be the concern there. Weight of the outside unit is about 60-70 pounds for most so bumper mounted id also an option with safety struts installed. It is very important to use flexible lines running from the outside unit to the inside unit, otherwise the copper tubing WILL eventually crack with all the vibrations.
 
If anyone is thinking of mounting a domestic air conditioning unit on any sort of RV that is mobile (that is, not permanently sited) they will definitely need to use some form of flexible tubing. Due to the very high pressures involved, I would think hydraulic hoses would suffice, so long as the material is compatible with the refrigerant. You would need to ensure the correct fittings.
 
There is a site that sells the tubes specifically designed for air conditioners. Don't remember what it was. I did not save it because the tubes were only available in 6 or 10 foot lengths right now and that is not long enough. I watched a YouTube video of a guy who installed flexible tubes on his mini split on an RV. I know there are places that manufacture them to be used with AC systems, however I figure with the popularity of tiny homes and the fact the RV AC's pretty much suck, mini splits will begin to become more common and the technology and available parts will be better every year.
 
Thanks Rene, I'm glad I was able to provide some useful information. I assume you had it professionally installed rather than DIY. The installation looks really tidy, so if you did do it yourself, top marks!
I had it professionally installed. I did do all the layout work, I installed the condensate piping and predrilled holes in the wall prior to the install. The techs did say that this install was the easiest install they’ve ever had.
One important thing is that if you notice behind the condenser the pipe is covered with a black foam. My installer told me that they’ve found that over time, piping wrapped with the white foam is causing a chemical reaction and is causing some pitting in the copper lines so they are now using this new black foam. So if anyone is thinking about installing a system you should look into this.
 
It is very important to use flexible lines running from the outside unit to the inside unit, otherwise the copper tubing WILL eventually crack with all the vibrations.
Copper tubing is used from the central propane manifold to all of the appliances in an RV and there has not been any issue with it cracking. Seems like it should also be acceptable as a refrigerant line as long as it's firmly fastened to the RV. Maybe use flexible line from the outside unit to the RV's body, then copper from there to the inside units?
 
Copper tubing is used from the central propane manifold to all of the appliances in an RV and there has not been any issue with it cracking. Seems like it should also be acceptable as a refrigerant line as long as it's firmly fastened to the RV. Maybe use flexible line from the outside unit to the RV's body, then copper from there to the inside units?
That makes perfect sense.
 
Looks good, Rene. We have hot water baseboard heat so this type of A/C system is what we'd have to use if we get rid of the window units (which I hate).
We have that same hot water baseboard and we had a 25000 BTU whole house window A/C and we also hated it. It was so loud. I’ve got that one on Craig’s List now. It probably won’t sell till next spring
 
Is hot water baseboard what we call underfloor heating?
 
Copper tubing is used from the central propane manifold to all of the appliances in an RV and there has not been any issue with it cracking.

That's a good point but then I have to wonder why cars don't use copper, it would be a lot cheaper and GMC doesn't usually pass up a cheaper solution so I have to believe there is some good reason.

One important difference is the pressure. Propane is less than 1psi and AC lines can be as much as 300psi. Maybe a small crack or leak in a propane line isn't enough to leak at 1psi but would at 300psi?
 
Is hot water baseboard what we call underfloor heating?
No. Baseboard heat is a radiator that runs around the perimeter of the room on the outside walls. Hot water runs through these baseboards giving off heat.
Under floor heating is plastic piping with hot water running through this piping that is either attached to the under side of the subfloor in a zig zag pattern or it can be fastened on top of the subfloor in a zig zag pattern then the finish flooring goes on top of that. This system, keeps the floor warm all the time when heat is called for
 
We call your baseboard heating radiant pipe and it sometimes has fins on it to increase surface area. The underfloor heating is exactly the same.
 
As Lou said, if refrigerant grade copper tubing is securely attached with hydrozorb clips around the RV so it moves in unison with the body, it should be fine. If the outdoor unit is bumper mounted, it could well flex and fracture rigid pipe. That's where some flexible pipes would be beneficial. Depending on what type of indoor unit is used and where it's located, will help to decide the correct way to connect.
Never be tempted to use pre-insulated pipes, they were always inferior grade tube.
 
That's a good point but then I have to wonder why cars don't use copper, it would be a lot cheaper and GMC doesn't usually pass up a cheaper solution so I have to believe there is some good reason.

One important difference is the pressure. Propane is less than 1psi and AC lines can be as much as 300psi. Maybe a small crack or leak in a propane line isn't enough to leak at 1psi but would at 300psi?
Brake pressure can go up to 900-1000 PSI, much higher than the air conditioner's 300 PSI. At those pressures you need a harder metal than relatively soft copper. Even things like tees have to be rated for the higher pressures, you can't use a standard brass plumbing tee in a brake line.
 

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