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Mitsubishi FE-18 mini split heat pump

Solaris Showroom, Spring 2013

Primary heat source for our 1250+ sq ft showroom.  

Heat pump IMG 3905 blue wall, window, plant


Heat pumps are great for offices too.  They are very inexpensive to operate, nearly silent and improve indoor air quality.  The do a great job if you have rooms that are always too hot or too cold. 

In the spring of 2013 we installed this cold weather heat pump in our showroom.  It is rated to work  even with outdoor temps as low as -15.  The winter of 2013/2104 showed us that Portland can still get below -13, and our heat pump kept right on going.   Reports from northern Maine say the FE  line seems to shut down at around -22.  Although with the Mitsubishi's when you get below zero you do not get the full Btu output. Also with all heat pumps the unit will shut down for about 10 minutes and go into defrost mode more often when it is really cold.  Some of the heat pumps we sell are rated to 5 degrees, other's as low as -15.  In all cases the shut off point is not a hard number and is based on many factors including outdoor temp, wind, humidity, even how hard the unit is running to keep the home or office warm.   

Our office is poorly insulated and leaky.  We leave the door open to the other rooms so this unit is asked to heat more space than we expected it to handle.  Our unit had no problem keeping the office at 71 degrees.   We did find on the really cold days, if we set it back to 60 at night it took too long to come back up to 70.  Our solution, just leave it at 66 at night.  These units use so little electricity when maintaining the temp that leaving it on all night little impact on our bill..   Even on the very coldest days, with the unit running 24 hours, we spent about $250 a month.  Had we used the old propane furnace our bill would have been about $800.  

Normally we would center the wall evaporator over a window but in our case the siding outside, and the window framing, prevented this.  

Our foundation if poorly insulated.  In the summer the office stays very cool as the floor is always cold.  Even with the hot summer we had in 2013 we found we did not need to run the A/C but we did constantly run the unit in dehumidify mode.   This mode does provide some cooling but just taking the moisture out of the air made the entire office perfectly comfortable. 

We have been able to monitor the electric usage of our heat pump using an Efergy system.  The desk display shows current watts as well as lifetime and the last 24 hours.  I can monitor remotely using their web site.   Depending on options we sell  these units for about $125 and monitor anything, including your solar system output.  


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600 Riverside St.

Portland ME 04103

(207) 797-0979

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