Mini-split installation

[Sean]

OK, OK, so I know this is not a bus, but the issues are similar, and I thought some here might benefit from our experience. And I still own a bus (darn thing just refuses to sell, even at a fire-sale price), so they haven't thrown me off the board yet

I just finished installing a mini-split air conditioner in the pilothouse driver area of our boat water-bus. We did this because our main air conditioning will not run on the inverter either on batteries or while the main engine alternator is running, and we wanted air conditioning under way without running the generator.

Now that it's done and tested, I am extremely pleased with how effective and quiet it is, and also how easily it starts on our inverter. Our batteries alone will run it for a while, and under way it uses much less current than our 3kW alternator can produce, so the batteries still charge. If I were doing a bus conversion today I would seriously consider two or three of these rather than the roof units we used a dozen years ago, with the condenser units mounted in a bay (fans to the outside with the intakes ducted). At just $700 apiece they are way less expensive than CruiseAir or similar split units, but more importantly, they are much more efficient and easier to run on an inverter.

My write-up on the project is here:
http://ourodyssey.blogspot.com/2016/07/keeping-our-cool-under-way.html

I'm happy to answer questions about it for anyone interested.

We also have one of those roll-around portable units now, which we bought as sort of a proof-of-concept and which we plan to use elsewhere (the bedroom, specifically) so I can speak to those a little bit, too.

-Sean

[DoubleEagle]

There was a long recent thread about Mini-splits, so I am sure your experience will be valued. One of the problems noted with the stand-alone units is that room air is expelled through the discharge hose, which has an effect on the total cooling level, but apparently yours is doing alright despite that. It is hard to believe that your eBay buyer for the Neoplan did not go through with the purchase after you went through all the hassles of getting it going.

[Oonrahnjay]

... We also have one of those roll-around portable units now, which we bought as sort of a proof-of-concept and which we plan to use elsewhere (the bedroom, specifically) so I can speak to those a little bit, too.

-Sean 

     You commented a while back that the portables cool air and blow it into the room and then pull it back into the unit and exhaust it after it is used to cool the condenser -- obviously, outside air for this cooling purpose would be beneficial, leaving cooled air in the room.  I *had to* have something while my engine change is underway so I bought a mid-sized portable.  It just barely works in a small room inside a shop in 95 deg NC heat (pulls out about 3 gallons of water overnight and this might be its biggest contribution). Did you ever rig up an outside air feed for the intake of condenser cooling air?  Any other suggestions to make this anvil REALLY cool air?
     Many thanks, and always good to see your contributions to the board again.  BH

[sledhead]

I have used a split unit in the coach for 6 years now with zero problems and yes it is waaaaaaaaaaaaaay better then the crappy roof shaker + it works fine off the inverter

dave

[oldmansax]

And I still own a bus (darn thing just refuses to sell, even at a fire-sale price), so they haven't thrown me off the board yet

-Sean

It WANTS me, Sean! I'm trying to win the lottery, rob a bank or something. My money from Nigeria should be here any day now! I even had 2 of the grand kids say they would throw in all $15.66 they have in their piggy bank.   

I do wish you the best in selling it, but if you don't, I'm going to try to talk you into selling it to the grand kids once I get a little better.. 

TOM

[TomC]

If you use a portable A/C, always buy the two hose unit. With only one hose, the A/C is continuously pulling cold air out of the room that has to be replaced by the warm, humid air. With two hoses, the outside condenser air is separate from the inside room.
Sean-where did you mount the condenser?
Good Luck, TomC

[Tom Y]

Sean, Nice job. Can you tell me the sizes of both units? Thinking of this for the front driver area, not happy with what I have now. Thanks for the information.  Tom

[bevans6]

I've seen those portable AC/heatpump units with coaxial hoses.  The condenser air intake and exhaust is from the outside.  There was one in the century old (or older) apartment we rented in New Orleans in February a couple of years ago.  The temps were down in the low 30's at night, and it could not keep up heating the place.  After a couple of days we had found several space heaters, the breaker panel for when they blew the breakers, and we would turn on the electric oven and leave the door open.  NOLA is great, but it can throw temperature curve balls at you...

All of the details are in the blog post Sean linked.

[Oonrahnjay]

I've seen those portable AC/heatpump units with coaxial hoses.  The condenser air intake and exhaust is from the outside.  ,,,

      Since the unit I bought seems to work pretty well except that it exhausts so much of the cool air, I think I'll build a box around the inlet for the condenser air (they have an arrow pointing to in in the installation directions, almost in a "nudge, nudge - wink, wink" sort of way) and build in a hose made from clothes dryer parts.  That should make it work better, and it may reduce the amount of condensate water if it doesn't have to pull in so much outside air into the room to make up for the amount that it's wasted.  Mine is A/C only so the heating part is not applicable.

[robertglines1]

In the 89 used one with outside exhaust  air discharge. worked fine. had to put drain line on pan because it produced a lot of water.  prob 7 on ten scale. 300 dollar range. Strictly mini-split this time 2 ea 9,000 and 1 ea 12,000 over drivers side window.   they are zoned.    Bob

[robertglines1]

pic

[Sean]

Sorry for the delay... been a bit busy here.

     You commented a while back that the portables cool air and blow it into the room and then pull it back into the unit and exhaust it after it is used to cool the condenser -- obviously, outside air for this cooling purpose would be beneficial, leaving cooled air in the room... Did you ever rig up an outside air feed for the intake of condenser cooling air?  Any other suggestions to make this anvil REALLY cool air?

The portable unit was really a proof-of-concept for the split, so, no, I did not worry about ducting the condenser intake. Neither did we bother to shop for a model that has that ability built-in -- we had limited time and a borrowed ride, so we went straight to Home Depot. If I were trying to use this unit for serious cooling I think I would open it up and find some way to duct the condenser air.

What we did do, however, after a very short time, was to insulate the exhaust hose, which itself was dumping more heat into the room. You can buy 6" tubular duct insulation at the big-box store.

...
Sean-where did you mount the condenser?

It's bolted to the deck in the flybridge area. We found a spot that was out of the way but still had most of the required intake and exhaust clearances. It's well-positioned to set a cocktail on it if you are sitting on the forward end of the setee up there 

... Can you tell me the sizes of both units? Thinking of this for the front driver area, not happy with what I have now. Thanks for the information.  Tom

I don't have them handy, but if you follow the link to the Amazon page, there's a chart on there with the dimensions. I want to say the inside unit is about 26" wide by 10" tall and 7" deep. The outside unit is maybe 25x18x10 or thereabouts.

... I think I'll build a box around the inlet for the condenser air (they have an arrow pointing to in in the installation directions, almost in a "nudge, nudge - wink, wink" sort of way) and build in a hose made from clothes dryer parts.

Just make sure to have enough cross-section for the air flow; remember, it's designed for almost no restriction. Increase the cross section a bit for longer ducts or more bends.

-Sean

[Oonrahnjay]

Sorry for the delay... been a bit busy here.

The portable unit was really a proof-of-concept for the split, so, no, I did not worry about ducting the condenser intake. Neither did we bother to shop for a model that has that ability built-in -- we had limited time and a borrowed ride, so we went straight to Home Depot. If I were trying to use this unit for serious cooling I think I would open it up and find some way to duct the condenser air.

What we did do, however, after a very short time, was to insulate the exhaust hose, which itself was dumping more heat into the room. You can buy 6" tubular duct insulation at the big-box store.

    Thanks for taking time to pass along this information.  It is exactly what I need to know and I'll find it helpful.  After considering things -- and sweltering in a "98 degree every day North Carolina summer week" -- I'm thinking that for my temp setup, it would be best to put the unit outside and just pipe in the cool air.  That way it can darw in air from the Great Outside and dump the warm air there, too.  After all, since I'm in the middle of an engine change, I'm not going anywhere for a bit!

It's bolted to the deck in the flybridge area. We found a spot that was out of the way but still had most of the required intake and exhaust clearances. It's well-positioned to set a cocktail on it if you are sitting on the forward end of the setee up there 

I don't have them handy, but if you follow the link to the Amazon page, there's a chart on there with the dimensions. I want to say the inside unit is about 26" wide by 10" tall and 7" deep. The outside unit is maybe 25x18x10 or thereabouts.

Just make sure to have enough cross-section for the air flow; remember, it's designed for almost no restriction. Increase the cross section a bit for longer ducts or more bends.
-Sean

     I found this.  The guy seems to have a good setup.  Whether it will stand the harsh life on a trailer, I don't know but he seems to love it and seems to be getting great performance for low watt useage.  But is he nuts for mounting the outside-unit so close?  https://www.youtube.com/watch?v=IHDT5ZEpKkw

     I think I have an existing super place for outside unit(s) (240V central unit with two evaporators -- thanks Art Gill -- or two 120V units for the two evaps) in an existing box right below the "windshield" for my upper deck; it's the area where some old-fashioned GPS equipment was, an emergency radio (both removed) and the destination sign (gone now, leaked like a sieve).  I can put the upstairs evap unit just above the windshield (I'm pretty sure that there's room where it wouldn't block any sight lines) or on the "dashboard") and downstairs on above the driver's windshield; in both cases the copper high and low pressure lines could be a couple of feet long or less.  Inlet air grills will be easy and I think the exhaust should be straight-forward with the right ducting to move air out to side grilles.

     I look at wattage draws for roof units (which I can't use anyway since I'm at 13'6" already), basement units (ditto, got no basement), window units etc. and I have to say that if mini-splits will live in a bus conversion environment, then they have to be the way to go for me.

     Thanks for the help, Sean.

[luvrbus]

We had friends here on Friday ( temp 119F) their 2 Samsung 9000 Btu units in a 35ft insulated spray foam bus would only muster 98 degrees best.I let them in the shop with the evp cooler running they got down to 78. 
Did they ever have a stream of water coming from the units looked like a garden hose turned on.
Everyone needs units you can control with your Samsung smart phone  I have to admit it was neat though but I would prefer cold not the gadget so do they     

[TomC]

I'll be curious to see how Sean's mini-split does near salt water. Dometic makes marine versions of their roof top and ducted units-but are very expensive (like 3 times what Sean paid). Good Luck, TomC