Off-Grid Home, need to overcome LRA of 141 on 5 ton Air Cond

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Off-Grid Home, need to overcome LRA of 141 on 5 ton Air Cond

Post by suleman » Wed Jan 11, 2017 1:36 pm

Hello Everybody, :smile:

I have an off-grid solar home and I'm limited to the amount of surge amperage I can provide to sufficiently run my air conditioning unit.

I have one Heil Air Conditioning 5 ton unit made by International Comfort products. I want to use 1 Outback Radian inverter (GS8048A), which I have not purchased yet. But I was told I would need use 3 outback Radians to be able to start the compressor motor to overcome the Lock Rotary Amps LRA of 141.

Is there a VSD (Variable Sequence Drive) or a VFD (Variable Frequency Device) to overcome my AC compressor LRA of 141 so I only have to use 1 outback Radian. If yes to this question, which one do you recommend? :grin: :grin: :grin:

The manufacturer of the AC unit is International Comfort Products Corp. (ICP) | airconditioners and furnaces, the brand name is HEIL

The model number

The serial number

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Re: Off-Grid Home, need to overcome LRA of 141 on 5 ton Air

Post by blackswan555 » Wed Jan 11, 2017 2:37 pm

is there a VSD (Variable Sequence Drive) or a VFD (Variable Frequency Device) to overcome my AC compressor LRA of 141 so I only have to use 1 outback Radian. If yes to this question, which one do you recommend? :grin: :grin: :grin:
There will be :grin: Need to know more details on the motor to be driven ph, kw etc, on the plate of the motor or in the manual ?
Also possibly worth trying the manufacturer ? They probably have already done it

My comments are based on my experience and research, They are not endorsed or checked by Outback.I am an independent British electrician living in Spain, So please take this into account when reading /acting on my post`s.

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Re: Off-Grid Home, need to overcome LRA of 141 on 5 ton Air

Post by bezalel » Thu Jan 12, 2017 8:25 pm

The cost of 3 Radians + batteries to supply them is going to be large.

Instead of looking at a separate VSD or VFD for the present 5 ton compressor you should look at replacing the present HVAC unit with a high efficiency one that has the VSD built into it. In off-grid situations is usually cheaper and better to decrease the supported load than add more solar. Have the building tested and modeled to see what the real required AC tonnage is. Improve the insulation and air sealing as indicated by the survey. You may be able to go with a smaller tonnage new unit that will use compressor and fan VSD to start at low amps and only run as hard as it has to. LCR doesn't really apply to this approach. Most systems rarely require the full capacity and if so only for a short time. The top end units have integral humidistats to further improve air quality and comfort and use less power when properly set.

Have set up systems in which a single Radian starts 3-4 ton VSD high efficiency units slowly with plenty of reserve to spare.
Have also had clients refuse to upgrade HVAC and seen 2 ganged Radians max out and shut down trying to start 4 ton single speed systems with 23,000 W start surge. Have also installed smaller solar battery systems that start a generator when the HVAC system calls for AC compressor start using a transfer switch to put power to the single speed compressor when the gen is up and ready.

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Re: Off-Grid Home, need to overcome LRA of 141 on 5 ton Air

Post by Yuba » Fri Jan 13, 2017 2:30 am

Wow 4 and 5 tons off solar?. I think bezalel has the right idea with running it off of a generator.
I'm new so I might be wrong but even if the inverter can do it, what kind of crazy battery bank and field of solar would you need? A proper sized ac should be cycled on a good part of the day. If it was me and I had to run central ac, I would run it off a proper sized gen. Dyed red diesel in a gen running at full load is cheaper then kwh from the power company.
A neighbor of mine has a central ac in his mcmansion. He has the biggest off grid house I have seen. He has a 48v 4 inverter system (Think it all adds up to around 14k of inverter). 3200ah of battery (4 24v forklift batteries). He only uses the central ac maybe once a year and when he does it's off his propane genny. The rest of the time he does what everyone else does : runs a window ac or mini split in a single small room.
I am not sure where you live but where I live in northern California it's VERRY hot and dry in the summer. evaporative coolers work really well. Our summers are brutal. average July high of 92.3F and my swamp cooler keeps my entire 2000sq ft house around 70 on a few hundred watts and no large start up draw.

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Re: Off-Grid Home, need to overcome LRA of 141 on 5 ton Air

Post by SwDoctor » Fri Aug 04, 2017 10:20 pm

Another option is using Mini-Splits, either to supplement or instead of the central unit (which may run from gen)
I have good luck running 3 of them at a time, total 2.5tons. I am willing to bet you can get two 2ton units to do rather well, assuming you have good insulation! - for "most" weather conditions.
I have over 2000ah battery, and >10kw system, but offgrid. And wife sleeps with TV's on, it still works.

You are not going to beat up the inverter with 141a inrush and want to live like that however...

China manufacturers are now making (up to) 24,000 btu (2ton) inverter controlled mini split heatpump units that operate DIRECTLY off 48vDC.... They internally boost the supply voltage of 48v up to 300vdc and use a VFD to run the compressor at soft start to any speed. VERY effective. And the nice part: YOU DONT NEED ANY INVERTER POWER!
(Just a big-a$$-battery!) <--you would need anyway...
Save the Power Inverter for running the TV... Make wife happy..


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Re: Off-Grid Home, need to overcome LRA of 141 on 5 ton Air

Post by gpearce52 » Tue Jul 02, 2019 8:15 am

Try a Hyper Engineering Sure Start. Installed with a 2.5 ton SEER 16 central air conditioner. no start issues with a Radian 8048A

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Re: Off-Grid Home, need to overcome LRA of 141 on 5 ton Air

Post by pss » Tue Jul 02, 2019 8:57 am

I have a single Radian 8048A. It has no problem starting my Delta Unisaw with a 5 HP motor which Delta told me the surge watts were over 32,000! It also easily starts my Rheem central AC unit which is 2-2.5 tons while it is running my pool pump and pond pump already where the load is 2600 watts. Yesterday, we were 92 degrees temperature. From 5PM to 9 PM I ran off grid with a 900 amp battery bank. Starting with SOC 100, by 9 PM I was at SOC=75%. This was with central AC set at 78 degrees, with a base load of 2,400 watts. When the AC comes on, load is 4,700 watts.

What I see is your problem is that you will need such a large battery bank to power the AC unit that it simply does not make sense. With the current solar system you have listed in the right panel, you would be lucky to run the AC unit for 2 hours before depleting the batteries. Your battery bank is 400 amp hours. Discharging to 50% is 200 amp hours. At a draw of 50V, your power output assuming you began at 100% SOC is 10,000 watts. 10,000 watts /240V = 41 amps. Being generous, lets say your running AC amps after startup is 30 on a 5 ton unit. That adds up to about 84 minutes of run time for your AC unit while nothing else is running. And yes, we did not take in account the power required by the air handler for the blower and you are probably not living in the dark. So you are in a bad predicament for your goals.
Your AC unit is 13 SEER. The best thing you can do, in my opinion, it to make certain your home, especially the attic is heavily insulated, like R40 in the walls, R50 or more in attic. Then upgrade to a 20 SEER unit, install a large diesel tank, 500-1000 gallons and a diesel generator. It makes much more economic sense than what you are trying to do.
But if you insist on going solar, then just be prepared to up your panels to about 24,000 watts, your battery bank to about 3,000 amp hours, install 2 Radians at a minimum, several charge controllers and hope climate change stops.

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