Mini split auto restart and connecting an additional thermostat

First Name:  Don

Last Initial:  M

Problem: Our split system is controlled by a remote. Every time the power goes out the system has to be manually turned on.This is a problem because our power goes out quite frequently and we have pets and are not always home to turn the unit back on.Can a thermostat be hard wired or is there some other solution?  Thanks

Solution:  Most mini split air conditioners have an “auto restart” function that turns the evaporator back on after a power failure.  When power returns the indoor evaporator’s electric circuit board will restart the system to the last setting before the power failure.  If you had the unit set at 77 degrees before the power failure it will return to 77 degrees at restart.  Make sure your equipment has the “auto restart” feature.  If it does you probably need the indoor evaporator circuit board replaced.

Mini split air conditioners are not built to have an external thermostat.  In order to attach a thermostat they would need to have an extra wire built into the circuit board.  They do not, therefore it is not possible..

Can you convert a single mini split air conditioner to a dual air conditioner?

From:  Chris M

Problem:  Hi. Is it possible to add indoor units to a compressor initially set up for only one indoor unit? Or put a different way: Could I install a compressor with the capacity for more indoor units than initially installed? Thanks.

Solution:  I get asked this question on a weekly basis so it is probably a good idea to address it to the public.  Mini split air conditioner are manufactured as either a singe (1 evaporator to 1 condenser) or multi-head systems (1-4 evaporators to one condenser).  When a multi-head system is manufactured it is built with a larger compressor that can handle multiple evaporators.  Trying to add a second evaporator to a single condenser would drastically effect the output size.  An even larger problem with trying to add an extra evaporator is that all the wiring and circuit boards are only installed for a single system.  There is no place to wire in a second evaporator.  And lastly, you would have to add two more copper line sets into the condenser which it is not set up for.  In short, there is no way to add more evaporators to an existing single mini split air conditioner.

Mini Split Air Conditioner Remote Not Working.

First Name:  Phyllis

Last Initial:  B

Equipment Type:  Samsung AM18B109 KCV

Problem:  The remote control will not operate the unit.  The battery has been checked and the unit was shut off to try and reset.  I suspect lightning.  Can the sensor in the unit react this way and can it be reset?

Solution:  Usually with remote control problems it stems from a broken controller.  The mini split remotes just don’t hold up to a lot of abuse.  I would think that a new remote would be the first step in problem solving.  If that does not work than I would have the sensor replaced.  The sensor is the device that receives the remote control signal.  Also, make sure that all the wires are connected to the control board (circuit board).  Evaporator circuit boards are usually located under the cover below the temperature display.  Sometimes they are behind a separate panel.  Check this first.

High Efficient Ceiling Cassette Air Conditioner

Problem: I have a 3 season porch that is glass from ceiling to floor and is constructed with double pane low E glass windows. I live in the Kansas City area. It has a northern exposure and is 14 X 20  sq.ft.with 9.5 ceilings.  My goal is to install a heat pump with the evaporator section recessed into the ceiling. I do currently have a gas fire place that is rated for 30,000 btu/hr and I am able to heat the space, but would like to consider a heat pump if possible. I would be willing to pass on the heat pump if a cool only system would qualify for the energy credit.  Is there a manufacturer who makes a ceiling cassette model that qualifies for the energy tax credit?  I understand that the SEER must be a minimum of 15, the EER must meet 12.5 and the HSPS 8.5.  Do all three efficiency ratings need to be met in order to qualify for the 30 credit?   Thanks–Mark

Solution:  Hello Mark, searching around I see Friedrich has a 15 SEER cassette air conditioner with an HSPF of 8.5.  I am sure that other brands as well will follow with the inverter compressor ceiling cassette units.  Prices seem to start around $3100.00 for an 18,000 btu. ceiling cassette system.  You can probably find a lesser SEER rated unit for much less money.  Make sure to contact the manufacturer to make sure their system qualifies for the 30% tax credit.  Remember all three numbers must be obtained for the tax credit.  15 SEER, 12.5 EER, and 8.5 HSPF.

Replacing and Sizing an Air Conditioner for a Sunroom

First Name:  Chuck

Last Initial:  H

Friedrich 12,000 Through The Wall

Problem:  We have a 21′ x 14′ sunroom addition that sits between our basement and the first floor. A few years ago we had a Unico a/c system installed in our first floor. When they did it, they ran 3 outlets through the garage window into the sunroom. The 3 outlets don’t help much in the intense afternoon sun. The room is poorly insulated with big windows. My wife wants to tear it down completely and re-build, but I don’t think we can do that for another 5-7 years. The room also has an older model Freidrich through the wall air conditioner (12,000 BTUs). Of course more insulation would help, but for the next 5-7 years is it worth getting a split a/c system, replacing the Freidrich wall unit with another, more efficient through-the-wall unit, or just leave it alone until we do the room.

Answer:  Chuck you have a bad case scenario for an air conditioner.  A 300 square foot room with lots of windows and poor insulation will need an air conditioner with approximately 18,000 btu.’s.  I would recommend replacing the Freidrich 12,000 with a Unionaire 20,000 btu. through the wall air conditioner.  You will be able to use approximately the same size hole and reduce your utility cost with a 220 volt air conditioner.  A mini split air conditioner, although very efficient, will cost much more to install and purchase.  Here is a link to view the Unionaire specifications:

http://www.clearanceac.com/index.php?l=product_detail&p=16

What Size SlimDuct Do I Need for a 1/4″ x 3/8″ Line Set?

First Name: Joseph

Last Initial: E

Mitsubishi MXZ-4A36NA

36,000 btu. Heat Pump Mini Split

Problem:  What size SlimDuct line set cover do I need to hold a 1/4″ x 3/8″ refrigerant line set, wiring and condensation line?

Solution:  SlimDuct recommends that you use the SD-77 series for installation of line sets for single mini split systems.  The dimensions are 3″ x 2 1/2″ and is made for lines up to 3/8″ x 5/8″  

You can find SlimDuct equipment at the following link:

http://www.clearanceac.com/slimduct-line-set-covers/

Spacing of the Indoor Evaporator in Relation to the Ceiling

First Name: Joseph

Last Initial: E

Mitsubishi MXZ-4A36NA

36,000 btu. Heat Pump Mini Split

Problem:  What should the space between the indoor wall unit and the ceiling be?

Solution:  Ideally, you will want to leave approximately 10 inches between the ceiling and the indoor evaporator.  This leaves enough room for the indoor unit to draw in fresh air through the top and positions the unit high enough to maximize the cooling effectiveness throughout the room.  Cold air settles downward, so the higher the better.  You can mount the indoor evaporator at any level, but the best position is 10 inches below the ceiling. 

Dual Mini Split Air Conditioner Recommendation

First Name:  Vamsi

Last Initial:  O

Problem:  I don’t own any AC yet. I am planning to purchase one. I needed an advice on whether I can get any product that fits my requirement.  I have two rooms that need to be fitted with an AC. My initial analysis is that 1.5 ton would be sufficient for each. So I was wondering if I can purchase a split AC with one compressor (may be 2 tons or so) and two evaporators.  Is this possible? If so which is a good company to go with?  Are there any special considerations with such setup?

Solution:  You have a perfect scenario where a dual or multi split air conditioner should work great.  The ACDE12HP220 is a dual 12,000 btu. Inverter system with two indoor evaporators and one 2 ton condenser.  Each room can operate separately with its own remote controller.  Installation is the same as any other single wall mounted mini split air conditioner with the exception that you need to run two separate line sets to the indoor units instead of just one.  I would recommend either the ACDE12HP220 or the ACDE09HP220 which is a dual 9,000 btu. system.

You can view there specifications at ClearanceAC.com by clicking on this link:

http://www.clearanceac.com/index.php?l=product_detail&p=35

Window Unit vs. Mini Split Efficiency

Written by:  Jackie S.

Problem:  Not a problem.  I have a Whirlpool 15,600 btu. window unit through the wall.  It cools to 70 degrees at a reasonable cost.  My question is can I expect an 18,000 btu. mini ductless to perform equally to my Whirlpool or better?  The sizing is right, I just don’t want to get too large or too small of a mini split air conditioner.

Solution: A mini split air conditioner will be a much more economical system than a window through the wall air conditioner.  Older window units are at or below 10 SEER.  Ductless mini split systems start at 13 SEER and at the 18,000 btu. size reach up to 16 SEER.  A 13 SEER unit will save over 30% on your utility bill versus a 10 SEER unit.  Also, mini split systems are much more quiet than a window unit.

Replacing Just the Evaporator of a Mini Split.

Written by Megan A:

Problem:

My inside evaporator will not come on.  I have checked the power, checked the fuses inside the cover, changed the batteries in the remote. Can I use the same compressor and just buy the inside unit or do I have to buy the compressor and evaporator. I have looked everywhere and can not find just the inside unit. I hate to throw away the compressor.

Solution:  After checking that power is indeed reaching the indoor evaporator and the fuse is still intact you most likely have a circuit board failure.  Many manufacturers call it a “PCB Board” and it is a relatively easy repair.  Call your manufacturer to purchase the correct part.  Most manufacturers will have a one year warranty on the circuit board.

If you need to purchase a new evaporator there should not be a problem swapping it with the older unit.  Make sure the model number of the new evaporator matches the old evaporator.  A HVAC installer will be needed to vacuum the line set and recharge the entire system’s refrigeration.  The only difficulty I see is if you have an older 10 SEER evaporator and the only thing available is the newer 13 SEER evaporators.  The two systems will not be compatible.  You will also have to find a distributor that will sell only the evaporator.

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