[folivier]

Since a few of you guys have installed mini splits in the last year or so how about an update?
How are they working, do you think you have enough BTU's? or feel like you need more?
How did they perform for heating over the winter?
Real world experience would be great!

[Jack Houpe]

Forest its like Mary Poppins practically perfect in every way. We did however overkill the one in the bedroom area, 1.5 tons is way to much for that space, if we leave the front two 1 ton units on it keeps the bedroom cool or warm dependent on if the sun is coming through the window. My suggestion to anyone is to buy the LG two ton unit and put 1 ton up front like we did and one over the refrigerator then put a 6k btu in the bedroom, I was told this happens all the time by LG engineer and the inverter compressor handles it well plus there are three ports for low and high pressure on the compressor. Another plus is we have solar panels from front to back of the coach this air gap between the panels and the roof that would normally be heat soaked by the sun.

If someone would like to not pull the lines and utilize the old ducting there might be a way that can happen but you'll have to use a home ducted HCAC air handler with the inverter compressor. The home ducted units supply a massive amount of CFM compared to the split units the beauty of the inverter compressor and ducted unit is they slow down when the reach the setpoint.

[Jonestead]

Forest, since Jack took Mary Poppins, then I suppose I'll have to identify as Goldy Locks then.

As a refresher, I replaced two 2ton SCS units with one 24k ducted mrcool, which was bought through a dealer, not as a DIY kit, so I also have a full 10year warranty. I sealed R2 at the under stair return plenum and vented the minisplits outside unit exactly like the SCS, intake air thru the floor near centerline and exhaust is thru the floor curbside in its own fabricated sealed duct. My original concern was air mixing under coach, but I have seen no difference in performance whether or not I separate that air or not.

L2 houses the ducted inside unit, like Jack installed midcoach above his fridge. The floor was sealed with new sheet metal and supplies return air thru entry stairs, again as originally designed. I had ductwork fabricated to connect the ducted minisplit directly to the original Newell ducts that supplies the entire coach. the only thing that I changed was to add one additional 5in hose into the salon. finally a condensate drain is plumbed thru the floor to just dump on the ground.

The one thing I overlooked was winter condensate/defrost drainage in R2, which has since been remedied by installing a fabricated drain pan. 

Would I do things differently if i were to do it again? A tiny tweek here and there, but overall, with 3 1/2 seasons and almost 1 year of use, I am quite simply thrilled. 
Our temperature has ranged from teens to very hummid 100+

Thank you again Jack and Tim for all of your patient help (aka. 40thousand pestering questions) while i was planning out our system.

[Richard]

Arch,

Thank you for the details. Jack has done a great job but not all Newell floor plans, aka mine, lend themselves to internal evap units.

Would you mind sharing the air flow and pressure details for the evap unit? It seems super critical to know that when utilizing the existing ductwork.

Second, you chose to fab the ductwork to both exhaust and intake the air from under the coach. I am not saying that was wrong. Would you mind sharing your logic with the group ?

You have a successful install of what would be the easiest path for those retrofitting SCS units utilizing the existing ducting. Thank you for allowing us to pick your brain on the details.

[Jonestead]

Arch,

Thank you for the details. Jack has done a great job but not all Newell floor plans, aka mine, lend themselves to internal evap units.
Agreed

Would you mind sharing the air flow and pressure details for the evap unit? It seems super critical to know that when utilizing the existing ductwork.
It would seem that I need to remind you with whom you are asking such details, lol!
How/Where would I find such information to share. Spec sheet of new equipment or airflow test?

Second, you chose to fab the ductwork to both exhaust and intake the air from under the coach. I am not saying that was wrong. Would you mind sharing your logic with the group ?
Our coach has solid bay doors and the original SCS was installed in such a manner, so the simple answer is Occam's razor
that combined with Jacks comment about the NASA level craftsmanship of the original duct work really drove our system design/install choice

You have a successful install of what would be the easiest path for those retrofitting SCS units utilizing the existing ducting. Thank you for allowing us to pick your brain on the details.
I have a rather large debt to repay considering all the time and energy that I have been given from yall!


One afterthought:   the original SCS units were both 2ton as stated.
What I failed to mention was that the salon air was supplied by the R2 unit via (2) 5in tube ducts venting thru the driver side columns flanking the salon window. An additional 5in tube was added to supply more air to the salon and vents fore and aft of the couch at floor level.
The second SCS, L2, was originally ducted via trunk towards the rear. This then discharges conditioned air thru (1) duct over the fridge, (1) duct in the mid bath, and (2) ducts to rear bedroom, hidden in columns on drivers side, one at the front bulkhead and the second in the rear.

[Richard]

Arch, spec sheet or link to the evap unit will do just fine.

I had forgotten you had solid doors.

[hbens]

I installed a Pioneer 240volt 20k system with 2 12k cassette evaporators. I used the original SCS ducting to the coach mounting the cassettes in the return air plenum.
I wasn't satisfied with the cooling when sitting in full sun which is what I have here in my parking pad behind our house.
I used the heater ducts that exit below the console in the salon for additional cooling ducts. These 4 small ducts weren't providing heat so I made them dedicated to the mini split. This provided 2-3 degrees of cooling relief.
I added 4" inline fans to the elephant trunks in the front salon. This also added 2-3 degrees of cooling relief.
I added additional 4" inline fans to 4 of the rear ducts. I did this in 2 steps. The first provided another 2-4 degrees of cooling. The last 2 inline fans I cannot tell you with data how much they added. 
My SWAG (Scientific Wild A$$ Guess) was comparing the before and after when I had 2 very similar weather days prior to and after the installations.
Richard gave me the suggestion to add the fans to the rear to increase airflow there. 
I believe each time airflow was increased through the cassettes the cooling performance increased.

I plan to hang a 12k 115 volt mini-split in the bedroom most likely sticking with Pioneer. This should make the coach cool enough for anyone and allow us to stay at parks with only 30amp service. Of course power management will be a concern at these parks. The 115v mini-split will run off my inverter as well. I have 2 Subzero fridges so I have 2 inverters and no room above them to install a cassette there.

I like the quiet operation of the mini splits compared to the SCS units. Still, I would have preferred to keep the SCS units but when my transfer switch died it took out the SCS units forcing my hand.

Thanks to Jack, Arch and Richard for their inputs for this project. All you others who have commented with your experience(s) on our posts have also helped me.

[folivier]

Thanks for your responses. So it sounds like either the SCS were overrated or the mini splits are underrated. From reading and researching it sounds like mini splits are underrated compared to other AC's.
Very interesting that increasing air flow helps so much with cooling.
BTW I started this not to get technical info, that is in yall excellent posts on installing these. Rather I want this to just be a quick rundown on your experiences and whether you think you sized your units correctly.
Thanks and hopefully this will help others who are thinking about these.

[Jonestead]

Forest,
In planning phase, I was very concerned that i would not get the sizing right, which is exactly why I hired the HVAC guy. I had always been told that sizing a HVAC system was critical, and too big was actually worse than too small. It is my understanding that these new systems kinda size themselves, as long as its big enough to do the job. Think of it kinda like a generator, too big is no longer as big of a problem as it used to be. Its still important, just perhaps not as critical to get all the numbers precisely right.
Thank you for prompting this follow-up discussion. I've actually been meaning to, just hadn't gotten too it yet.

Richard,
I think this is what you are looking for

Hi 550PSIG / 3.79MPa
Low 340 PSIG / 2.34MPa

CFM - 435.14/693.47/775.93

MRCOOL Olympus Hyper Heat (O-HH-24-HP-C-230 / DUCT-24HP-230)

[TJ Clark]

Thanks.

This helps a lot.