Micro Air EZ Start on Rec-Pro 3800 A/C

[Rocketman3]

Hello everyone,

I figured I would let you know about my latest project. 
 

About a year ago I replaced the rear A/C with a RecPro 3800. The old A/C had its own 4-button thermostat. The front A/C (and furnace) work on a different thermostat. It has worked well when we needed it to (we don’t usually travel to places we need it).  I also moved the incoming power for that A/C to the inverter breaker box - that way I could run the A/C on inverter. 
 

When I did that my inverter (Victron Multiplus 12/3000) would send me a warning saying low voltage and high ripple when the compressor started. 
 

I finally decided to put a soft start on that A/C. I put the MicroAir EZ start Bluetooth unit. It was a very easy install. 
 

Then it was time to do the 5 starts. The first start is without any EZ start help. It took 27.9amps (@120v) to start. No wonder the inverter was giving me the warnings. After finishing the starts - it now only takes 16.5amps (120v) to start the compressor. The inverter no longer complains!

Today (just for fun), I ran the A/C for several hours on battery (544ah lithium) and solar (1400w). The A/C slowly drains the battery-  ended my day at 90% full.

 

[1nolaguy]

Michael, I am very interested in your project on several levels. I have a 2005 Safari Cheetah w/ 12/3000 AIMS and two years ago I had the OEM Penguin II A/Cs replaced with RecPro 3800s. I have been thinking of changing one (the one in the bedroom) to the I/C so I can use it when boondocking. Unlike you, we spend a lot of time in the south so A/C is a need not a desire. Would you mind sharing or PMing me with details about how you rerouted the electric.

Also, you note that your furnace still runs runs on the thermostat. Since installing the RecPros (Haughton) A/C-Heat Pumps I get no power to the therm and the furnaces do not work. What do I need to do with the wiring to get the furnaces working again? We rarely use them but wen the outside temps drop below 40 the HP struggle.

[Rocketman3]

For my MotorHome to get the bedroom A/C to work on inverter, I moved the breaker from the “shore/generator “ panel to the “inverter” panel.  The shore panel has breakers going to the inverter for charging. 
 

Then either in pass-through mode or inverter mode the inverter supplies the inverter panel with power. Your electric system may be setup completely different.

For the heater… Your old thermostat that controlled the A/C’s also controlled the heater. The heater control wires go up to the A/C to a board that operates a relay that controls the heater. (which you removed when you took out the oem A/C).
 

My rig had two independent thermostats one for rear A/C and one for front A/C and heater (4-button). I did not replace the frontA/C because I wasn’t sure how to handle the heater at that time (we use the heater way more than the A/C’s). I figure I can put up a thermostat just for the heater  when I replace the front A/C.  I have not pursued that yet.
 

The furnace has two 12v control wires - if you connect them together- the furnace starts, break the connection and it stops.  If you don’t use it much you could literally just connect those wires to a manual switch or find a heater only RV thermostat. 
 

I want to figure out how to hook the Micro Air thermostat to run just the heater - but I haven’t taken the time yet to figure it out. 
 

Good Luck with the project 

[Tom Cherry]

23 minutes ago, Rocketman3 said:

For my MotorHome to get the bedroom A/C to work on inverter, I moved the breaker from the “shore/generator “ panel to the “inverter” panel.  The shore panel has breakers going to the inverter for charging. 
 

Then either in pass-through mode or inverter mode the inverter supplies the inverter panel with power. Your electric system may be setup completely different.

For the heater… Your old thermostat that controlled the A/C’s also controlled the heater. The heater control wires go up to the A/C to a board that operates a relay that controls the heater. (which you removed when you took out the oem A/C).
 

My rig had two independent thermostats one for rear A/C and one for front A/C and heater (4-button). I did not replace the frontA/C because I wasn’t sure how to handle the heater at that time (we use the heater way more than the A/C’s). I figure I can put up a thermostat just for the heater  when I replace the front A/C.  I have not pursued that yet.
 

The furnace has two 12v control wires - if you connect them together- the furnace starts, break the connection and it stops.  If you don’t use it much you could literally just connect those wires to a manual switch or find a heater only RV thermostat. 
 

I want to figure out how to hook the Micro Air thermostat to run just the heater - but I haven’t taken the time yet to figure it out. 
 

Good Luck with the project 

MY 2 cents….great job.  The MicroAir Thermostat will have to be “tested”.  It puts out a Multiplexed signal like the Dometic’s (4 or 5 or the new CC2).  That signal goes to a control board that has to “interpret” or know what to do.  There is NOT a pair of “bell wire” going to the roof. There is a data cable,  If there were bell or thermostat wires going from where the original thermostat was to the roof….you just hook them up.  You are correct on the furnaces, as well as the Aquahot’s.  You need to “close” or connect 2 wires.  Doesn’t matter if they are the original in the roof or if you go to the furnace.  It is just like a light switch,  if you have a MicroAir thermostat, it has NO direct DC (one that is designed for a Dometic system).  The DC power comes from the ceiling or the “control module”.  Use any thermostat like a generic Coleman 1w VDC….you gotta run DC to it.  Then, the Furnace OUT is a Positive 12 VDC on the terminal marked FURNACE.  That is a totally different system than Monaco put in,  You CAN put in a Bosch relay.  So, when the furnace signal goes out, it closes a relay.  BUT….there ain’t NO bell wire running up to the ceiling or down to the furnace,  YOU MIGHT be able to use the Data Cable….and use one or BOTH (called BiWiring) pairs….twisted so you had two phone wires (say back and yellow connected….and the other two colors…twisted) wires giving a signal to the furnace….  That MIGHT run it.  But the signals coming out of a MicroAir designed as a replacement for a .Dometic…..NOPE…NADA.  It needs a controller so, you have to have the original module to interpret it.

Hope that makes sense,  I talked to Dometic and MicroAir and Coleman.  That is I confirmed with them.  

[1nolaguy]

OK. So when the Rec Pro were installed the "brain" of the Penguins were left in the plenum under the belief by the installing tech that they would continue to operate the furnaces; our rig has two, one on each side. To further complicate things each OEM A/C and Heater have separate temperature sensors ( one near the powder room and one in the bed room and a central 5 button control, that I believe has two RH-11 phone cords to bring  data from the two ceiling units. The 5-button controller originally controlled the two A/Cs, two Heat Pumps and two furnaces. My guess is the systems were split to two zones , living and sleeping with an A/C-HP, Furnace for each zone.

I do not know if the controller get 12V from the ceiling "brains" or separately from a different source. I need to go back and pull this off the wall to see. I know I can spend hours tracing this all out. If anyone has a diagram for the wiring of this Cluster* I would appreciate you sharing it.