Rv mini split insta..
Rv,erRick
| Posted in Expert Exchange Q&A on
Hi I am planning on installing a 2nd mini split in our 40′ coach.
I have one in the main bedroom it’s a wall hung 9k.
Works awesome.
But the second one I would like to use the existing ducts that run thru ceiling.
The older heat pump was installed in the basement, it has a cfm rating of 350.
Will a ducted unit mini split have enough cfm to achieve this install.
Also need to source a 12k unit that will work on 120v.
I did find wall hung units, but so far no luck with a ducted unit.
THANKS
RICK
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Replies
I don't think a ducted 120V mini split exists. Your best bet is to install an auto transformer and use a 240V unit.
As for the duct sizing, you have to check how much pressure your existing air handler is running at, all you need is a simple low pressure gauge (ie Dwyer Minihelic 2-5002). From there you can pick the right ducted unit that has similar pressure capability. Usually the mid static (ie Mitsubishi PEAD) ones are good enough for most jobs.
What does an auto transformer do?
I do know that my original heat pump puts out 350cfm.
Will a ducted mini put the same camper out or more?
Thanks
An autotransformer is a transformer with a single winding with multiple taps that can be used to raise or lower voltages. The downside is that the use of autotransformers is often limited by code, so it may not be permissible in your application. You can get "regular" transformers to convert between 120v and 240v, but they are relatively large and heavy for the capacity you'd probably need for a decent size minisplit.
Do you have any way to get 240v service to run these units? Could you use two smaller 120v units instead?
Bill
As stated, I am running allready a 9k in bedroom .
This unit would be for living area which potentially I could use another 9k unit, it would just work a bit harder.
If it can .move the the Air thru the duct work it could potentially be more efficient than the wall hung split.
Or I can hang another wall hung whi h I have found in a 12k pkg. That would run on 120 volt
Do you think this would be an advantage rather than
Using ducting that's goes thru a HOT roof area?
My preference would generally be to a void ducting when trying to condition a small space. If that wall hung unit gets around the issue with ducts that run through a hot area AND solves the issue with 120v only power, then that's the unit I'd install.
Bill
It's an area of 240 sq/ft but it's a motorhome , no insulation, very hot 85 plus outside.
I thought the same why
Would I be cooling the air vents b4 the space.
Will order a 12k copper & Hunter 120v tomorow.
Ductwork is generally for better air distribution not for efficiency. When you look at the SEER and HSPF numbers for different configurations, the best performance is always a wall mount mini split.
If the space you are trying to heat/cool is mostly open a single wall mount should work.
If you want to use your ductwork, check the data sheet of your exisiting air handler and compera it to a ducted unit.
For example take a look at P A-606 here:
https://mylinkdrive.com/viewPdf?srcUrl=http://s3.amazonaws.com/enter.mehvac.com/DAMRoot/Original/10006/M-Series_Technical%20Data%20Book_01-2021.pdf
The PEAD-A09AA7 can deliver up to 0.6" WG pressure at 350CFM. As long as your existing unit is rated for similar pressure, it can be a direct swap.
You would still need a pretty large transformer to get you from 120V to 240V.