I want my basement back! Any pics of Mini-Splits?

[Seangie]

Hey all you cutting edge Mini-Split conversion elitists!

Do you all have any pictures of your Mini-Split installs?  I'd really like to see how you placed the Air Handler on the inside of the bus.  Ideally I think that one 18k unit with (2) 9k air-handlers (240v) and then possibly a 2nd  9 or 12k unit (120v) as a backup with a single air-handler.

I've been reading nothing but good things from those of you who use them - if you have some horror stories I'd love to hear those as well.

I am looking to re-arrange my basement and possibly get rid of the 2 coleman basement AC units.  A couple of reasons for this -   

1. They each have 2 compressors and put out 24k BTU's.  For 400sf of space it seems like an overkill, much less the power needed to run them (should that read "much more?"). 

2.  Duct work - In the existing space under the bus (already converted) I'd have to get creative as to where the duct-work should run and cut a bunch of holes in the floor to get the air to where I want it.  With the splits its 1 hole for each air-handler.

3. Intakes - There are (2) intakes in the floor (one for each unit) right where we'd like to put the bunks for the kids.  The intakes are pretty hefty (12" x 16") and take up space where we could put storage under the bunks. 

4. Size - Each of these units takes up about 2/3's of a bay with the intake and output duct work.  One bay has the AC unit raised up which creates a little bit of space underneath and the other unit is on the floor of another bay with plumbing over the top. 

I'd also like to opt for a smaller 8-10k generator at some point in the future. 

I think the challenge in the mini-splits is the placement of the air-handlers and getting good coverage without freezing out one person while the driver sweats to death.

As always - Your feedback is amazing...thanks!

-Sean

PS - My psychic ability predicts (2) Coleman Basement AC units and a 14k watt martin generator for sale about 3 to 6 months in the future...

[Ericbsc]

I would probably opt for the two or three unit system. I would also add a dash air. That is about the only way you will stay cool in the drivers seat. I have a 15k ducted directly over the drivers seat. Cools fine sitting still withe the shades down. On the road the windshields act like a betty crocker oven!!!!

[belfert]

240 volt is going to limit you to staying places with 50 amp connections, or running the generator.

[robertglines1]

go to prevostcommunity.com/forum/      visit hvac section look under mini-split I posted picture there before I had cabinets installed.   Also go down to updates   section look under ceiling led pic and you can see more.   Don't know why but did not have luck getting pic up here tonight.    Bob

[Sean]

240 volt is going to limit you to staying places with 50 amp connections, or running the generator.

I will add my voice to this by advising you to avoid a 240v system.  That will get expensive very, very quickly on the road.

If you have no choice but to use a 240v air handler, I would suggest a boost autotransformer to supply it from a 120v source.  Also spendy.

-Sean
http://OurOdyssey.BlogSpot.com

[Seangie]

I will add my voice to this by advising you to avoid a 240v system. 

Sean - My mistake - That should have been 208 single phase - not 240v (208ph-230 @ 60hz)  With 208 single phase I should be able to run it off a 30amp from a campground? (if that is all I am running?)

go to prevostcommunity.com/forum/     

Bob,

Thanks for the pics - Is your system (2) separate outside units?  Are they both 110v?

[robertglines1]

have 3 separate units    one in spare tire compartment. two located in old condenser bay.  Will try to get more picture later. heat side is great also  working in teens now 'one 9000 maintains coach after warmed up.   I have 2 9000 and a 12000 in front. all 120 volt system Inverter (410 refrigerant) .

[eagle19952]

30 amp pedestals in all camp grounds are 110v.
all 208v appliances are 220v
Depends on what your plans are, I am 220v AC and I am fine with it.
You can't take your $$$ with you....
there is no affordable inverter/battery bank that will run 110v AC.

I will add my voice to this by advising you to avoid a 240v system. 

Sean - My mistake - That should have been 208 single phase - not 240v (208ph-230 @ 60hz)  With 208 single phase I should be able to run it off a 30amp from a campground? (if that is all I am running?)

go to prevostcommunity.com/forum/     

Bob,

Thanks for the pics - Is your system (2) separate outside units?  Are they both 110v?

[Sean]

Sean - My mistake - That should have been 208 single phase - not 240v (208ph-230 @ 60hz)  With 208 single phase I should be able to run it off a 30amp from a campground? (if that is all I am running?)

No.  "30 amp service" is all 115-120v.  Appliances rated for 208 sometimes carry a dual rating to 230 or 240 but none will run on 120.  In order to run this type of unit you will need to be on true "50 amp service" (which is either 208 or 240), have your (240v) generator running, or use a transformer to convert 120 to 208.  This is why I recommend against 208-240v appliances in general.

-Sean
http://OurOdyssey.BlogSpot.com

[pvcces]

Seangie, you are planning on an awfully hefty system. 36,000 BTU will take care of a lot of full sized houses. Oversizing system will create headaches for you, just like undersizing a system.

Here in Ketchikan, we only use 18,000 BTU for apartments that are nearly 800 square feet. They carry the heating needs down to 15F.

The other thing that I didn't see mentioned is that these indoor units need some room to throw the air. For 18,000 BTU, I believe that they recommend a full 16 feet of unobstructed distance in front of them. The 12,000 BTU units need 12 feet clear.

The only way you can do that in a coach is if the indoor unit is mounted in one end and facing the other end. And, if you stick to 12,000 BTU units, 120 volt units are readily available.

The only place to mount the first unit that makes any sense to me is on the destination sign enclosure pointing aft.

If you only install one unit to start with, and use it for a while, you will have a lot better idea of what you want if you need an additional unit later.

Good luck with your project.

Tom Caffrey

[robertglines1]

To add to Tom's post   my 12 is mounted in front of bus  pointing back 31 ft of free air space . 0ne 9 on side pointing across with about 7 feet of clear frontal space (it has swing feature so helps with circulation) and rear is again mounted in rear pointing back with about 12 ft of free air in front of it. I over sized on purpose to have a back up in case one failed. MY  test have proven any two will keep coach comfortable in teens  to 100 F: Would add when coach is cooled or warmed up one will maintain most of the time.       I'm cooling heating  45 ft coach with 29 ft slides and raised roof   so my cubic ft is up there.  another 72 sq ft of living space over reg 45ft coach (360)=432sqft  approx.  I know it's over kill.  Draw your own conclusions. by the math one 12000 would be good. but no back up. and air flow with our partitions might be a problem. I do prefer the inverter tech and minimun seer 15 units.  Bob

[Seangie]

Seangie, you are planning on an awfully hefty system. 36,000 BTU will take care of a lot of full sized houses. Oversizing system will create headaches for you, just like undersizing a system.

Here in Ketchikan, we only use 18,000 BTU for apartments that are nearly 800 square feet. They carry the heating needs down to 15F.

The other thing that I didn't see mentioned is that these indoor units need some room to throw the air. For 18,000 BTU, I believe that they recommend a full 16 feet of unobstructed distance in front of them. The 12,000 BTU units need 12 feet clear.

The only way you can do that in a coach is if the indoor unit is mounted in one end and facing the other end. And, if you stick to 12,000 BTU units, 120 volt units are readily available.

The only place to mount the first unit that makes any sense to me is on the destination sign enclosure pointing aft.

If you only install one unit to start with, and use it for a while, you will have a lot better idea of what you want if you need an additional unit later.

Good luck with your project.

Tom Caffrey

Tom - Initially I was thinking 2 systems primarily for redundancy and different use.  Neither system would be planned for use at the same time. 

The single 12k system would sit in the very front facing back, would run on 110v and would primarily be used while traveling and focus cooling on the front part of the coach. 

The 18k system would have 2 heads (airhandlers) and would be mounted in the bedroom facing forward to cool the bedroom and bunk area and the other in the Kitchen/Living area blowing forward to cool there.

The reasons for the 208v 18k dual zone system is because it's cheaper and it would be one less outside unit in the bay.  I'd actually use a dual zone 110v system if they make them.  I just haven't been able to find any.

Great suggestion on using one unit first.  I'll probably just use the 12k system see how well it works and go from there. 

Thanks again. 

- Sean

[Sean]

Seangie, you are planning on an awfully hefty system. 36,000 BTU will take care of a lot of full sized houses. ...

FWIW, I don't think this number is too high at all.  And one absolutely can not compare cooling requirements between a conventional house and a bus -- the heat loads in a bus are far greater.

We have 39,000 BTU/hr of capacity (not including the separate 20k in our weird driving area), in the form of three 13kBTU/h roof units.  On really hot days, we need all three running at once to keep the coach cool.  I will grant that you will not see that in Ketchikan, AK, but we've sure seen it in Las Vegas, Scottsdale, Tucson, McAllen, Orlando, Fort Lauderdale, and many other places around the US.

Beyond that, our 39kBTU/h is only being called upon to keep two humans and three very small pets cool, and we have a super well insulated coach.  Sean's units will be asked to keep six people and one pet comfortable, a much greater heat load.  So I would strongly advise him not to consider anything less than three tons (36kBTU/h) of cooling for the entire coach.

Again, FWIW.

-Sean
http://OurOdyssey.BlogSpot.com

[Uglydog56]

Read the fine print on those dual zone 18's.  I had looked at them as a possibility as well.  The outside unit is just two single zone outside units stacked.  Very tall, I don't think it will fit under the bus anywhere.  I will also wager if you figure the cost of two 9k's vs. an 18k and a transformer, you would be ahead moneywise to go with the two nine's and they will be much easier to fit.  I am going with two 9's and a 12 in the front in a 35ft bus.  I am putting the 12 in the parlor on the destination sign place as previously discussed.  

I also struggled with the 2 vs 3 unit question.  My bus is very well insulated and smaller than Bob's, but due to my layout, I don't think one unit in the bedroom will adequately cool the kitchen area during the day, even with a couple of fantastic fans to help out.  Conversely, one just in the kitchen won't get to the bedroom at night, so I'm installing 3 but probably only ever running the kitchen one during the day and the bedroom one only at night.  A better layout with the mini-splits in mind would probably have made three units unnecessary, but we all work with what we have.

I also believe that we need more btu's than an apartment because we aren't as airtight as an apartment and don't have the same levels of insulation in the walls/roof.  There's also a lot more window area in a bus than in an apartment - well, except for Scott Bennett's.  I don't believe you can use the same math.  There's a lot of rigs running around with 3 13.5K roof units that are just adequate cooling at best.

[buswarrior]

Also, to round out the thinking, we need to consider how fast or slow the temperature may be changed if the coach has been sitting hot soaked or cold soaked. Parked at an attraction or otherwise not running the life support systems.

There is the goal of efficient operation, (both in power consumption, as well as the cycling of the machinery) which encourages us to choose a smaller BTU number, but a smaller BTU capacity will take longer to get the coach to the temperature you are aiming for.

For instance, just about any small engined car can get to 100mph these days, but a big engined car will accelerate to that mark much faster.

Multiple smaller capacity units gives us the best of both worlds, just run them all to reach your desired temperature, and then shut off what isn't needed, at the added expense of acquiring and finding space for them all.

I do not recall a busnut complaining as hard that the coach had too much heating or cooling,

but sure have heard sad stories of not enough?

The joys of being a busnut, you get to do it your way!

happy coaching!
buswarrior