AC running on a generator
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You should not have started a new thread. If I remember correctly you were interested in powering a 24,000 BTU unit. I replyed that a 24,000 BTU unit from Lowes required 11 AMPERS @ 220 volts. You need to look up what size generator will put out at a minimue that much power. Ed
Originally Posted By: eljefino
I saw a youtube vid of someone running a 5000 btu window unit on a 800 watt HF 2 stroke gen.
I found it.
http://www.youtube.com/watch?v=O9C4d3ilibg
I saw a youtube vid of someone running a 5000 btu window unit on a 800 watt HF 2 stroke gen.
I found it.
http://www.youtube.com/watch?v=O9C4d3ilibg
Originally Posted By: Eddie
You should not have started a new thread. If I remember correctly you were interested in powering a 24,000 BTU unit. I replyed that a 24,000 BTU unit from Lowes required 11 AMPERS @ 220 volts. You need to look up what size generator will put out at a minimue that much power. Ed
I saw your post but some one indicated they would not run there AC on a portable gen. That's why the new thread. Thanks for the tip you gave, which gave me the info that my 5KW gen has the power to run my AC.
You should not have started a new thread. If I remember correctly you were interested in powering a 24,000 BTU unit. I replyed that a 24,000 BTU unit from Lowes required 11 AMPERS @ 220 volts. You need to look up what size generator will put out at a minimue that much power. Ed
I saw your post but some one indicated they would not run there AC on a portable gen. That's why the new thread. Thanks for the tip you gave, which gave me the info that my 5KW gen has the power to run my AC.
My 10kw Honda will easily start and run my 1.5 ton HP split. But it will barely start my 3 ton package unit. Compressor/motor start loads are what will get you in trouble. Run loads are no biggie. I've used the genset many hours on the package unit in the winter(gas-dual fuel)with no issues from power failures. BTW btu's and amps will never be a constant, there are too many variables. Window units, Splits, Package units will always differ with run and start loads given the same btu's. The biggest difference is Scroll vs Recip compressors and seer ratings.
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Def. get a generator that outputs same voltage ( 110 / 220 )V
with atlease 15% extra headroom on the amps , most generators will run their rmp a little lower if they dont see a full load.
If your getting a more advance generator like the Honda onces, they can even vary RMP based on load.
Having extra amps dont hurt , but its a cheap gen , keep it at around 10% extra room so that nothing overloads when the Ac is working at its maximum capacity.
with atlease 15% extra headroom on the amps , most generators will run their rmp a little lower if they dont see a full load.
If your getting a more advance generator like the Honda onces, they can even vary RMP based on load.
Having extra amps dont hurt , but its a cheap gen , keep it at around 10% extra room so that nothing overloads when the Ac is working at its maximum capacity.
Originally Posted By: Eddie
You should not have started a new thread. If I remember correctly you were interested in powering a 24,000 BTU unit. I replyed that a 24,000 BTU unit from Lowes required 11 AMPERS @ 220 volts. You need to look up what size generator will put out at a minimue that much power. Ed
Unfortunately it is not that simple.
The start current that the entire air conditioner requires must be less than the peak rating of the generator. And also the running current of the entire air conditioner must be less than the running ratting of the generator.
You have to look at both the peak and the running and both must be more than the entire air conditioner requires, peak (the higher number give for the generator), that the generator can put out for a brief amount of time for starting the compressor of the AC and all other things that starts at the same time such as the outside fan, and the inside air moving fan. And running (the lower number for the generator) for the running current that the entire AC unit requires while running.
Some (read very few but they do exist) AC systems have a time delay so the outside fan starts a few seconds after the compressor starts. This is a very big help in reducing the maximum (peak) power required during starting the AC compressor.
You should not have started a new thread. If I remember correctly you were interested in powering a 24,000 BTU unit. I replyed that a 24,000 BTU unit from Lowes required 11 AMPERS @ 220 volts. You need to look up what size generator will put out at a minimue that much power. Ed
Unfortunately it is not that simple.
The start current that the entire air conditioner requires must be less than the peak rating of the generator. And also the running current of the entire air conditioner must be less than the running ratting of the generator.
You have to look at both the peak and the running and both must be more than the entire air conditioner requires, peak (the higher number give for the generator), that the generator can put out for a brief amount of time for starting the compressor of the AC and all other things that starts at the same time such as the outside fan, and the inside air moving fan. And running (the lower number for the generator) for the running current that the entire AC unit requires while running.
Some (read very few but they do exist) AC systems have a time delay so the outside fan starts a few seconds after the compressor starts. This is a very big help in reducing the maximum (peak) power required during starting the AC compressor.
Also, for everyone who may someday run a whole house AC from a generator:
The compressor of most (practically all) AC systems has a heater that keeps the oil of the compressor warm so the refrigerant does not condense into the oil of the compressor.
If the power to the compressor was off for a while such as over night, and the temperature of the outside unit (including the compressor) was colder than the other parts of the system located within the house, then the refrigerant probably condensed within the compressor oil section and has thinned out the oil inside of the compressor. And while the oil may be too thin while contaminated with liquid refrigerant, it will be even worse when the oil warms up while the compressor runs because as the refrigerant and oil heat up, the refrigerant boiling off of the oil will foam up the oil, making it have even less protection of the compressor.
We have a member of the family who has a heating and AC repair business, and he said that if you turn off the breaker to the AC during the winter so the heater does not cost you money to keep it on all winter, you should at least turn on the power to the AC for a day or more so the refrigerant can be heated for a long enough time to really get most of it out of the oil within the compressor.
The compressor of most (practically all) AC systems has a heater that keeps the oil of the compressor warm so the refrigerant does not condense into the oil of the compressor.
If the power to the compressor was off for a while such as over night, and the temperature of the outside unit (including the compressor) was colder than the other parts of the system located within the house, then the refrigerant probably condensed within the compressor oil section and has thinned out the oil inside of the compressor. And while the oil may be too thin while contaminated with liquid refrigerant, it will be even worse when the oil warms up while the compressor runs because as the refrigerant and oil heat up, the refrigerant boiling off of the oil will foam up the oil, making it have even less protection of the compressor.
We have a member of the family who has a heating and AC repair business, and he said that if you turn off the breaker to the AC during the winter so the heater does not cost you money to keep it on all winter, you should at least turn on the power to the AC for a day or more so the refrigerant can be heated for a long enough time to really get most of it out of the oil within the compressor.
Originally Posted By: JimPghPA
Originally Posted By: Eddie
You should not have started a new thread. If I remember correctly you were interested in powering a 24,000 BTU unit. I replyed that a 24,000 BTU unit from Lowes required 11 AMPERS @ 220 volts. You need to look up what size generator will put out at a minimue that much power. Ed
Unfortunately it is not that simple.
The start current that the entire air conditioner requires must be less than the peak rating of the generator. And also the running current of the entire air conditioner must be less than the running ratting of the generator.
You have to look at both the peak and the running and both must be more than the entire air conditioner requires, peak (the higher number give for the generator), that the generator can put out for a brief amount of time for starting the compressor of the AC and all other things that starts at the same time such as the outside fan, and the inside air moving fan. And running (the lower number for the generator) for the running current that the entire AC unit requires while running.
Some (read very few but they do exist) AC systems have a time delay so the outside fan starts a few seconds after the compressor starts. This is a very big help in reducing the maximum (peak) power required during starting the AC compressor.
My generator is a 5KW with a 6250 start. My AC unit is 24000 BTU, and even though ACs vary, the best numbers I have come up with tells me my gen has plenty of power to run my AC. It looks like my AC will run on about 2800 to 3400watts with a start of less than 5000 watts. Of course other factors come into play such as the frig, lights, etc. Back to my original question. Has anyone actually ran their AC on a portable generator for any length of time? If so what size gen and what size AC in BTUs. Thanks.
Originally Posted By: Eddie
You should not have started a new thread. If I remember correctly you were interested in powering a 24,000 BTU unit. I replyed that a 24,000 BTU unit from Lowes required 11 AMPERS @ 220 volts. You need to look up what size generator will put out at a minimue that much power. Ed
Unfortunately it is not that simple.
The start current that the entire air conditioner requires must be less than the peak rating of the generator. And also the running current of the entire air conditioner must be less than the running ratting of the generator.
You have to look at both the peak and the running and both must be more than the entire air conditioner requires, peak (the higher number give for the generator), that the generator can put out for a brief amount of time for starting the compressor of the AC and all other things that starts at the same time such as the outside fan, and the inside air moving fan. And running (the lower number for the generator) for the running current that the entire AC unit requires while running.
Some (read very few but they do exist) AC systems have a time delay so the outside fan starts a few seconds after the compressor starts. This is a very big help in reducing the maximum (peak) power required during starting the AC compressor.
My generator is a 5KW with a 6250 start. My AC unit is 24000 BTU, and even though ACs vary, the best numbers I have come up with tells me my gen has plenty of power to run my AC. It looks like my AC will run on about 2800 to 3400watts with a start of less than 5000 watts. Of course other factors come into play such as the frig, lights, etc. Back to my original question. Has anyone actually ran their AC on a portable generator for any length of time? If so what size gen and what size AC in BTUs. Thanks.
My generator is a Coleman Power-Mate 5000 Watt running 6250 Peak.
The outside AC unit has the following specks:
Goodman Manufacturing Co.
Houston Texas 77008
Model CK30 - 1B
Voltage 187 - 235
Minimum Circuit Amps 19.7
RLA 14.7 LRA 73.0
Fan FLA 13 HP 1/6
R22
Pressures 150 - 300
With nothing else powered, the engine on my gen-set really loads up when it starts the whole house AC. But it is capable of running it. I have also powered one small compact fluorescent light and one very small TV along with one cable box while the AC was running.
I really keep everything else off while that generator is used to run the AC.
If the temperature is very hot outside it probably would be a great idea to plug a big box fan into the gen-set and aim to come in from the side so it adds cooling to both the engine and the electric generation section.
Air flow to a gen-set and keeping all loads well within the ratings (both run and peak) go a long way to keeping a generator running properly. Do not under estimate the start current of motors and microwave ovens. They often pull a lot more than you would think. Our modern fridge only requires 110 Watts running, 155 Watts with the door open and the lite on, and I do not know how many watts when the defrost timer kicks in. But starting the compressor on that fridge takes 11 Amps on the 120 Volt leg that it is on. I would NEVER run the fridge from the same generator when the whole house AC is running from the generator.
BTW I have a D.P.D.T. 30 Amp contact relay / breaker installed on the line from the fuse box to the fridge. And another line from the furnace blower motor that has an enable switch and then is wired to the coil of that relay / breaker. Both N.C. contacts of that relay / breaker are wired in parallel and normally it just sits there and allows power to go from the fuse box to the fridge. But if I enable it such as when running the furnace in either heating or AC mode, when the fan for the furnace comes on, the relay / breaker energizes and opens the line so no power can go to the fridge.
The outside AC unit has the following specks:
Goodman Manufacturing Co.
Houston Texas 77008
Model CK30 - 1B
Voltage 187 - 235
Minimum Circuit Amps 19.7
RLA 14.7 LRA 73.0
Fan FLA 13 HP 1/6
R22
Pressures 150 - 300
With nothing else powered, the engine on my gen-set really loads up when it starts the whole house AC. But it is capable of running it. I have also powered one small compact fluorescent light and one very small TV along with one cable box while the AC was running.
I really keep everything else off while that generator is used to run the AC.
If the temperature is very hot outside it probably would be a great idea to plug a big box fan into the gen-set and aim to come in from the side so it adds cooling to both the engine and the electric generation section.
Air flow to a gen-set and keeping all loads well within the ratings (both run and peak) go a long way to keeping a generator running properly. Do not under estimate the start current of motors and microwave ovens. They often pull a lot more than you would think. Our modern fridge only requires 110 Watts running, 155 Watts with the door open and the lite on, and I do not know how many watts when the defrost timer kicks in. But starting the compressor on that fridge takes 11 Amps on the 120 Volt leg that it is on. I would NEVER run the fridge from the same generator when the whole house AC is running from the generator.
BTW I have a D.P.D.T. 30 Amp contact relay / breaker installed on the line from the fuse box to the fridge. And another line from the furnace blower motor that has an enable switch and then is wired to the coil of that relay / breaker. Both N.C. contacts of that relay / breaker are wired in parallel and normally it just sits there and allows power to go from the fuse box to the fridge. But if I enable it such as when running the furnace in either heating or AC mode, when the fan for the furnace comes on, the relay / breaker energizes and opens the line so no power can go to the fridge.
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You'll make it a little tough on your 5kw genset. That compressor will pull for a millisecond nearly your locked rotor amps(LRA) upon start-up. Remember you're starting nearly a 2.5hp compressor plus the condenser fan motor. Inductive start loads(impluse) are insane.
My house has an "American Standard" 16 SEER, 5 TON central air system. The compressor consists of a 2.5 TON + a 5 TON compressor (dual compressors) . Only one runs at a given time.
My 11HP, Subaru powered, portable 5500W genset will easily start and run the 2.5 TON compressor, condenser fan and air handler, along with my fridge and TV.
However, remember that this unit is designed to be very efficient and is quite similar to the "Trane" 19 SEER units (using the very same compressor) . So the 2.5 TON compressor itself, according to the published data, draws 980W.
The condenser fan draws some power, and the air handler draws a good bit of power.
I can't guess how much total draw is there, but it's not a problem for my 11HP portable genset. I think it actually ran my old 1.5HP well pump at the same time. As long as both don't start simultaneously.
My 11HP, Subaru powered, portable 5500W genset will easily start and run the 2.5 TON compressor, condenser fan and air handler, along with my fridge and TV.
However, remember that this unit is designed to be very efficient and is quite similar to the "Trane" 19 SEER units (using the very same compressor) . So the 2.5 TON compressor itself, according to the published data, draws 980W.
The condenser fan draws some power, and the air handler draws a good bit of power.
I can't guess how much total draw is there, but it's not a problem for my 11HP portable genset. I think it actually ran my old 1.5HP well pump at the same time. As long as both don't start simultaneously.
The CK30-1B is an older 10seer rated unit with a 28k btu recip compressor. Quite a energy hog.
When our AC cycles on because of the thermostat demanding cooling, the furnace blower motor comes on about 8 seconds after the compressor first makes any noise. By then the start surge for the compressor is over with. The fan on the outside unit does start at the same time as the compressor. So far the few times I ran the whole house AC just to see that the generator could handle it, the generator makes one heck of a lot more noise when it is under that kind of load, but everything does work OK.
Originally Posted By: Keith_Stone
You'll make it a little tough on your 5kw genset. That compressor will pull for a millisecond nearly your locked rotor amps(LRA) upon start-up. Remember you're starting nearly a 2.5hp compressor plus the condenser fan motor. Inductive start loads(impluse) are insane.
I wonder if the connectors and wires from the generator to the fuse box, combined with wires from the fuse box to the compressor, help protect the generator by acting as a series resistance that drops enough voltage to limit the surge, or if the voltage drop from said wires and connectors hinders the generator by requiring the start current to be of a longer time duration due to the voltage being lower, compared to how long it would take to start with very thick wires over a very short distance with very heavy connections.
You'll make it a little tough on your 5kw genset. That compressor will pull for a millisecond nearly your locked rotor amps(LRA) upon start-up. Remember you're starting nearly a 2.5hp compressor plus the condenser fan motor. Inductive start loads(impluse) are insane.
I wonder if the connectors and wires from the generator to the fuse box, combined with wires from the fuse box to the compressor, help protect the generator by acting as a series resistance that drops enough voltage to limit the surge, or if the voltage drop from said wires and connectors hinders the generator by requiring the start current to be of a longer time duration due to the voltage being lower, compared to how long it would take to start with very thick wires over a very short distance with very heavy connections.
That answer is above my pay grade.
Originally Posted By: JimPghPA
The outside AC unit has the following specks:
Goodman Manufacturing Co.
Well, there's the first part of the problem. Goodman is (I don't mean to be insulting) the bottom of the line. Builder's specials made of generic components. That kind of thing. They're okay as long as they're installed competently, but you can rest assured that they contain the lowest of the low grade components.
Given that, you can probably assume that your compressor does not have a "hard start kit" installed. Because that costs about $100-$200 extra and Goodman would simply never include anything that's not absolutely necessary.
The hard start kit is basically one (or sometimes more) capacitors and a load/speed sensing relay that switches them into a phase-shifting circuit whose purpose is to generate more starting torque while pulling LESS starting current. The idea is that the hard start kit raises the probability of a successful start under marginal -- poor wiring, high source impedance, low line voltage, etc -- conditions. Well, that's basically what you're facing with a generator. The high source impedance part of it.
So, if you're experiencing a heavy load that bogs down the generator, you should probably ring up your HVAC guy and get him to install the kit for your compressor. Assuming that there is one, but there should be.
I can tell you that I have a similar situation. Honda ES6500. Trane 2.5T split high-efficiency heat pump RA ~7A depending. Hard start kit is standard equipment in this. The generator hardly burps when the system switches on.
The outside AC unit has the following specks:
Goodman Manufacturing Co.
Well, there's the first part of the problem. Goodman is (I don't mean to be insulting) the bottom of the line. Builder's specials made of generic components. That kind of thing. They're okay as long as they're installed competently, but you can rest assured that they contain the lowest of the low grade components.
Given that, you can probably assume that your compressor does not have a "hard start kit" installed. Because that costs about $100-$200 extra and Goodman would simply never include anything that's not absolutely necessary.
The hard start kit is basically one (or sometimes more) capacitors and a load/speed sensing relay that switches them into a phase-shifting circuit whose purpose is to generate more starting torque while pulling LESS starting current. The idea is that the hard start kit raises the probability of a successful start under marginal -- poor wiring, high source impedance, low line voltage, etc -- conditions. Well, that's basically what you're facing with a generator. The high source impedance part of it.
So, if you're experiencing a heavy load that bogs down the generator, you should probably ring up your HVAC guy and get him to install the kit for your compressor. Assuming that there is one, but there should be.
I can tell you that I have a similar situation. Honda ES6500. Trane 2.5T split high-efficiency heat pump RA ~7A depending. Hard start kit is standard equipment in this. The generator hardly burps when the system switches on.
To determine the size of gen needed for your A/C or anything else, here is how you calculate.
Volts X Amps = running watts required,,,, almost double is needed for start up!
Volts X Amps = running watts required,,,, almost double is needed for start up!
I have a two ton unit which I run on a Kubota diesel at 11000 watts. It lugs the engine on startup but I manage to stay within frequency. The panel lists LRA at 60 amps, and I have fifty amps at 240 volts. I am planning on installing a hard start kit to soften the blow. My setup starts the blower before switching on the compressor.
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