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Discussion Starter #1
Hello Everyone...
I bought a Duromax xp12000eh portable generator (Rated Gas-9500w/Surge Gas-12000w, Rated Propane-9025w/Surge Propane-11400w) in hopes of running my entire house if needed. 50amp inlet box was installed and wired to the main panel with a 50amp breaker and interlock kit. Not using a transfer switch. Several weeks ago my son and I went through the house and each breaker with a clamp meter to measure amps. After yesterdays test run with the generator and testing numerous appliances at the same time, I am happy with the generator to power my home.

Now comes the central AC. It is a 5 ton Amana ASX16 single speed scroll compressor that was installed June 2018 with a Goodman air handler. Clamp meter read 49amps on start during my testing with a LRA rating of 135. I installed a 5-2-1 hardstart kit which brought the startup down to roughly 34amps.

I tested the AC by itself under generator power using propane with every other breaker off. The generator stumbled slightly once but recovered rather quickly. I noticed the AC compressor sounded different at startup and the fan had roughly a 2 second delay to start VS starting almost instantly while running off normal power. Also, while running on generator power, it appears the fan was not running at fun speed and there was a vibration coming from the unit that would cause the grate to make a noise. You can hear all this in the videos.

I read elsewhere about testing the frequency but unfortunately that was after the fact. Im not really sure where to start troubleshooting. I don't want to keep forcing the AC to start while using the generator to diagnose the problem if I am putting unnecessary stress/wear on the compressor and/or fan motor.

Generator Start

Normal Start
 

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If I were you I would buy a frequency meter. (About $5 from Anazon) and set the speed to 60 Hertz.
You can install it permanently on the generator.
I put one on my Honda when I installed the NG-LP fuel supply.
You have to start some where and the meter is a begining.
Then one of the other guys may help you on the ailments of dirty power from the generator.
 

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you need a soft start unit. hard start helps a bit.. but the soft start is the way to go
EasyStart™ 368-X72 Soft Starter is the model number for the large air con unit.
it will support up to a 6 ton unit or 72k btu.
here is the link to the oem place to buy it direct from them

EasyStart™ 368-X72 Soft Starter
they are pricy $338.00 usd plus shipping.
but they are the best in class.
they sure work right!!
you get what you pay for..
these help reduce the load even when on normal grid power as well.

most folks when the go to replace the old style ac units get an inverter ac unit.
they cool so much more for less power.
just saying if you do replace the compressor unit in the future upgrade it.
 

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I'm wondering if something more problematic is at work?
Is that ac unit a variable speed or variable frequency type? If so you could be experiencing harmonics or more likely waveform distortion/ interactions/ feedback. An o-scope would show this but I realize that is not a common tool.
You might also catch some waveform issues by looking at the a/c duty cycle; usually duty cycle is a software function of most decent dvm's. (Example on Fluke 189: set to ac; toggle "Hz % ms"; duty cycle is the % toggle).
Good luck.
 

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Discussion Starter #5
If I were you I would buy a frequency meter. (About $5 from Anazon) and set the speed to 60 Hertz.
You can install it permanently on the generator.
I put one on my Honda when I installed the NG-LP fuel supply.
You have to start some where and the meter is a begining.
Then one of the other guys may help you on the ailments of dirty power from the generator.
I have a Kill a Watt meter somewhere. Even though it only has a 120 outlet, Ill throw an extension cord on there and see what I get

you need a soft start unit. hard start helps a bit.. but the soft start is the way to go
EasyStart™ 368-X72 Soft Starter is the model number for the large air con unit.
it will support up to a 6 ton unit or 72k btu.
here is the link to the oem place to buy it direct from them

EasyStart™ 368-X72 Soft Starter
they are pricy $338.00 usd plus shipping.
but they are the best in class.
they sure work right!!
you get what you pay for..
these help reduce the load even when on normal grid power as well.

most folks when the go to replace the old style ac units get an inverter ac unit.
they cool so much more for less power.
just saying if you do replace the compressor unit in the future upgrade it.
I read quite a bit on the hard start VS soft start kits a while back. Went with the hard start first for the simple fact that it was 30$ vs 300$. I have no problem buying the soft start If i knew it would solve the issue at hand. Just trying to troubleshoot a little more at this point

I'm wondering if something more problematic is at work?
Is that ac unit a variable speed or variable frequency type? If so you could be experiencing harmonics or more likely waveform distortion/ interactions/ feedback. An o-scope would show this but I realize that is not a common tool.
You might also catch some waveform issues by looking at the a/c duty cycle; usually duty cycle is a software function of most decent dvm's. (Example on Fluke 189: set to ac; toggle "Hz % ms"; duty cycle is the % toggle).
Good luck.
The AC is a single speed rated at 60hz. Appreciate the info on the Fluke. It may be the tool I need to get.
.
.
.

I'm trying to put in perspective the sequence of events that occur from switching on the AC, into the delayed start, then eventually starting. Lets see if this makes sense....

1)Generator is running with no load
2)AC is switched on
3)Generator bogs down/drops RPMs for 1 second and catches itself returning to normal speed
4)At the same time the generator bogs down, the AC compressor/fan turn attempt to turn on
5)Instead of the normal loud click from the compressor while using grid power and instantly turning on, there is 1 click, followed by a second click which then starts to spin the fan

So, is it more likely the generator is under-powered to handle the initial load and when the generator regains its normal operating speed that is the cause of that second click from the AC which then makes it start?

However, if that's the case why wouldn't the fan be operating at full speed?

Just thinking out loud here
 

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I think its safe to say the generator is too small to start a 5 ton without a soft start. Even if the engine of the generator only momentarily bogs then recovers, the initial amp draw is likely causing too much voltage drop. The AVR will try to adjust back but it may not recover enough fast enough. Definitely confirm the frequency. The Hz is in direct correlation to engine speed. Low Hz will result in erratic voltages as the AVR struggles to maintain ~125 vac. I like to start at 62.5hz at no load then throw on the generators rated load (resistive) and look for no less then 58hz.

I remember reading somewhere that inductive loads run way more efficiently the cleaner the sine wave. The duromax likely has a quite a bit of THD. I'd love to see what the waveform looks like on an oscilloscope.

I'll be buying a soft start in a month or so. Going to run my 3.5 ton rheem with a scroll compressor off my Eu7000. Though I'm torn between the micro air and hyper engineering. Leaning toward the micro air, but its 60-70 bucks more.

 

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Discussion Starter #7
I think its safe to say the generator is too small to start a 5 ton without a soft start. Even if the engine of the generator only momentarily bogs then recovers, the initial amp draw is likely causing too much voltage drop. The AVR will try to adjust back but it may not recover enough fast enough. Definitely confirm the frequency. The Hz is in direct correlation to engine speed. Low Hz will result in erratic voltages as the AVR struggles to maintain ~125 vac. I like to start at 62.5hz at no load then throw on the generators rated load (resistive) and look for no less then 58hz.

I remember reading somewhere that inductive loads run way more efficiently the cleaner the sine wave. The duromax likely has a quite a bit of THD. I'd love to see what the waveform looks like on an oscilloscope.

I'll be buying a soft start in a month or so. Going to run my 3.5 ton rheem with a scroll compressor off my Eu7000. Though I'm torn between the micro air and hyper engineering. Leaning toward the micro air, but its 60-70 bucks more.

I tested the frequency with no load directly into the generator 120 outlet and also with a 100ft extension cord (if that matters). The frequency ranged from 62.2 - 62.9. No chance right now to shut off the main house breaker and try the AC at this moment. However, when I get the chance, will a frequency reading taken directly off the 120 generator outlet give me a correct reading when I attempt to start the AC? Or will measuring frequency at the AC itself with a clamp meter be the more accurate way?

"I think its safe to say the generator is too small to start a 5 ton without a soft start"....My gut is leaning towards this as well.

I have seen in other generator manuals where the THD is actually listed. Unfortunately not in the Duromax manual. Ill have to call Monday
 

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Doesn't matter where you get your frequency reading its all the same. Voltage on the other hand will differ based on gauge of wire, length of cable, and amps being drawn.

Definitely report back the THD.
 

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hey ant what gauge of wire are you running from the gen to the house??
is it at least 6 gauge??

I think the micro air is better.. at least in the larger EasyStart™ 368-X72 Soft Starter units.
it is all voodoo lol!! or secret sauce stuff!!
chuckle..
we have been using the stuff from them for a while now and they work ok!!

those videos have a lot of noise for sure!! inductance to the shell steel!!
check the rubber isolators for the mounts on the fan and compressor..
is the fan cap bad?? just a question.. might be worth the 20 - 30 bucks to try another fan cap..
watch the ratings close.
 

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Discussion Starter #10
hey ant what gauge of wire are you running from the gen to the house??
is it at least 6 gauge??

I think the micro air is better.. at least in the larger EasyStart™ 368-X72 Soft Starter units.
it is all voodoo lol!! or secret sauce stuff!!
chuckle..
we have been using the stuff from them for a while now and they work ok!!

those videos have a lot of noise for sure!! inductance to the shell steel!!
check the rubber isolators for the mounts on the fan and compressor..
is the fan cap bad?? just a question.. might be worth the 20 - 30 bucks to try another fan cap..
watch the ratings close.
Im using the Conntek 1450ss2 50 amp 15ft cord which is 6 gauge. Also using 6 gauge from the inlet box to the main panel which is about 4ft.

Fan cap is good. I tested it when I installed the hard start several weeks ago.

Testing to continue later today or tomorrow. Ill check those items you mentioned
 

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I'm not familiar with that brand of generator but others have stated it doesn't provide the best electrical quality. That being said, we shouldn't point our finger at poor THD just yet; there's a lot of appliances out there that tolerate surprising electrical abuse and still perform.
So let's think about this.

From your description of engine sounds and the air cond contractor / relay noise we have a few clues:
-(clue) 'after one second it bogs then goes back to normal speed' = the engine is taking too long to react to a heavy load change.
-(assumption) If the air conditioner had tolerated the (generator's) voltage & frequency dip wouldn't that keep the engine staining under a heavy load? If we assume that then we would expect the engine to initially ' bog' but then recover only to some slightly higher rpm. But certainly it wouldn't return to a "normal" frequency, which I think you mentioned is 62.9 hz.
-(clue & guess) From the way the air conditioner is reacting (unusual "clicks; fan running slow) it seems that generator behavior is a real problem for the air conditioner's electronics (control board?).

At least you now know the engine isn't as robust as needed. Whether any further soft-start add-ons will help is impossible to say without looking at the air conditioner's SD and CD schematics (primarily), maybe the generator schematics (secondarily). If you can get a few diagnostic metrics (freq & voltage/time; waveform;) it would help point you in the right direction.
 

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Im using the Conntek 1450ss2 50 amp 15ft cord which is 6 gauge. Also using 6 gauge from the inlet box to the main panel which is about 4ft.

Fan cap is good. I tested it when I installed the hard start several weeks ago.

Testing to continue later today or tomorrow. Ill check those items you mentioned
ok cool on the cord and inlet, that should be good for 12kw.
yea I wish they made 75 amp inlet gear cheap...
I was looking for another project something hd...
looks like I will end up with the rv marine 50 amp 240/125 twist plugs and inlet..
they say 80% is the real rating.. so only 40 amps continues on a 50 amp plug cord setup..
ok on the wire for the short runs at 6 gauge.

if the math holds your should be 37.5 amps at rated 240vac.
hey I have a question!! and a idea??
is the outside fan motor 125 volt or 240 volt?
and your inside fan motor is 125 volt..
if the out side fan motor is on lets say L1 and the inside furnace 125 volt electronics is also on L1
that could the it!! over load on one leg!!
this is why I do the fancy meter setup to watch the loads on L1 and L2.. see the below link

that makes it so you can see the real loads, the red and black switches indicate black as L1 red as L2 and are the meter on off switch, and the 1/4 amp fused green led's are for L1 and L2 grid indicator before the main breaker.
and the 3rd meter is for the 125 volt generator inlet at 60 amps for the eu2200i gens on natural gas.
I have links for the parts on the poustusa site.
I need to do a diagram as well..
lol been too busy.. GRIN!!
nice day out today!
lots done.
I also worked on the over night last night before the wind picked up.

I have been thinking of doing a you tube channel..
it takes lots of time to do a good repair video...
you can have 50 hours in production time for a 1/2 hour video..
now days with all the good computer gear it should take less if you had 5 cameras shooting all at once..
so much of this stuff is hands on...
easy to show you, but hard to explain how to!! GRIN!!
 

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oh yea are you running this on LP or gasoline during the testing???
what are your lp hose sizes?? as well as the couplings??
natural gas vapor hose needs to be 3/4...
and depending on where the regulators and the pressures on lp there are some size things on lp too!!
that affects the recovery on the gen set!!
try the testing on gasoline and see if it is ok!!
that might be an important issue..
 

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I reread OP's first post and he stated "propane", which, as iowagold intimates, has a bunch of performance 'gotchas' you have to be aware of before it'll work out.
Even if the generator was the gasoline fed variety it seems borderline for powering the OP's full household loads.
 

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yea I agree it is close on current.. I just thought if it was on gasoline that is the max output for the generator,
just for test..

I stand by my check on the L1 and L2 current on the fans on the hvac..
see if both the fans are on the same 125volt leg...
he can turn off the breakers for everything else in the house for the test only...
and see if it starts with just the furnace and the ac compressor..
I think the soft start will help on the heavy current run up..
then look at the current when running after the start...
I would build and put on the main breaker box the meter set like on this page
but set it for split phase or a meter for L1 and another meter for L2 on the generator input.
it will give you multi line data,
 

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Discussion Starter #16
I'm not familiar with that brand of generator but others have stated it doesn't provide the best electrical quality. That being said, we shouldn't point our finger at poor THD just yet; there's a lot of appliances out there that tolerate surprising electrical abuse and still perform.
So let's think about this.

From your description of engine sounds and the air cond contractor / relay noise we have a few clues:
-(clue) 'after one second it bogs then goes back to normal speed' = the engine is taking too long to react to a heavy load change.
-(assumption) If the air conditioner had tolerated the (generator's) voltage & frequency dip wouldn't that keep the engine staining under a heavy load? If we assume that then we would expect the engine to initially ' bog' but then recover only to some slightly higher rpm. But certainly it wouldn't return to a "normal" frequency, which I think you mentioned is 62.9 hz.
-(clue & guess) From the way the air conditioner is reacting (unusual "clicks; fan running slow) it seems that generator behavior is a real problem for the air conditioner's electronics (control board?).

At least you now know the engine isn't as robust as needed. Whether any further soft-start add-ons will help is impossible to say without looking at the air conditioner's SD and CD schematics (primarily), maybe the generator schematics (secondarily). If you can get a few diagnostic metrics (freq & voltage/time; waveform;) it would help point you in the right direction.
Manufacturer specs on the Duromax are 10-12% THD

My knowledge is limited in regards to reading schematics. If you care to thumb through those pages I can likely find them. Weather is nice today so I will hook the gen back up and get some numbers

My AC is model # ASX160601FC

7728


if the math holds your should be 37.5 amps at rated 240vac.
hey I have a question!! and a idea??
is the outside fan motor 125 volt or 240 volt?
and your inside fan motor is 125 volt..
if the out side fan motor is on lets say L1 and the inside furnace 125 volt electronics is also on L1
that could the it!! over load on one leg!!
this is why I do the fancy meter setup to watch the loads on L1 and L2.. see the below link

Im assuming the outside fan is 240. AC has a 50amp breaker
Inside fan is 240. Air handler has a dual 20amp breaker. Pulls 6amps at start and 3amps running
Im reading the spec sheet and the air handler has a has a "electronic blower time delay relay", that provides power to the blower motor with a delay of 7 seconds after voltage is applied. Wouldnt that delay negate the idea of overload?

Yes, I saw your meter setup and I like it. I will defineitly look into these parts
 

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Discussion Starter #17
oh yea are you running this on LP or gasoline during the testing???
what are your lp hose sizes?? as well as the couplings??
natural gas vapor hose needs to be 3/4...
and depending on where the regulators and the pressures on lp there are some size things on lp too!!
that affects the recovery on the gen set!!
try the testing on gasoline and see if it is ok!!
that might be an important issue..
Propane was used for testing. For testing i was using a 3/8 house with 3/8 fittings that came with the generator. I used a 20lb bbq tank. I just installed the fittings to my 200lb tank with 1/2" 24 foot hose on order. I need 20 feet of length.

I thought about using gas. Gen specs state...
Gas - Rated 9500w
Gas - Surge 12000w
Propane - Rated 9025w
Propane - Surge 11400w

Wishful thinking but maybe that small amount of extra wattage on gas would rid the problem :LOL:
 

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@anthony21078: "maybe that small amount of extra wattage on gas would ride the problem"...

Perhaps. A bigger factor is that when running on gasoline you're more-or-less guaranteed a foolproof fueling system, which can be problematic for backyard mechanics to size for and pipe adequately for propane. In other words, there's more planning and upfront costs for propane vs gas.
 

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Discussion Starter #20
Did a little testing today. No load on the generator and all breakers were off besides the AC and air handler.

On Propane
Frequency dropped to 58.5hz on AC startup. 61hz while AC running
28amps on startup measured from one leg before the contactor
Voltage dropped to 180 measured at the contactor when the AC started
Voltage stable at 241 measured at the contactor while AC is running

On Gas
Frequency the same as propane
Startup amps the same
Voltage dropped to 161 measured at the contactor when AC started
Voltage stable at 241 measured at the contactor when AC is running

Normal grid power
NO voltage drop at the contactor
Could not measure frequency

This leads me to believe that the roughly 80 feet from the main panel to the AC is the problem. But I am no expert.

In the mean time, I plan to get a 50 amp plug and wire the AC directly to the generator. If that solves the problem then I don't have many options left. All I can think of is installing a second inlet box right next to the breaker box by the AC itself and backfeed the main panel from the AC line (which I don't want to do). Or, install the inlet box by the AC and physically move the generator if I need to run the AC to cool the house for a while. Thoughts?
 
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