Why won't my 4456 12KW run my AC?

[newguy]

I just got through setting up my 4456 to the new house and the transfer switch. It works well and I got the idle speed set along with the fuel mixture for optimal performance.

There are a few things I noticed as I was tweeking the unit.

- Using my Fluke 123 scope the sine wave output is not really all that pretty. It's got a decent rise to the slope, then on the downward portion of the sine wave it's like an inverted curve. Rather than looking like a half circle (so to speak) on the first 180 degrees it's "normal" for the first 90 degrees, but from 90-180 it falls off very fast. It changes with no load vs. loaded. When it's no load it's sorta like an inverted "V" when it's loaded it gets more ugly. Is this just a normal charecteristic of the unit?

- I have a 4 ton A/C that's a high efficency unit. It has a 30A breaker that feeds it and when I went to start the A/C the voltage at the unit went from 240VAC down to 111VAC and the AC never started up. After about 2 seconds I pulled the power as I could tell it wasn't going to work.

Is the simple answer that the unit isn;t big enough to power the AC? Too much inrush current needed? can I add a soft start capacitor to the AC to get it to work? I know once the AC is running it only needs about 23A at 240VAC.

Comments?

[Kelly Myers]

Post up the LRA number on the side of the ac condenser. This should be right on the name plate. Also post up the RLA.

I will tell you how big of a capacitor you need. I also need to know what revision gen-set you have. The generator should be a 004456-?
This could be anywhere from 5 to 2 years old depending on the revision. Did you buy this new, or was this moved from your old residence?

[newguy]

going from memory the LRA was something like 95A. It's an amana 42,000 BTU A/C unit. I have to check the numbers tonight to get the exact...

the 4456 is probably about 4-5 years old. It's got the spring governer and I was just tweeking the "idle" speed and mixture screws to get it to run at the proper speed.

It was moved to this house, but it has very low hours on it. My last home didn't have power outages like this one does. I have lived in this house for about 1 year and already had 4-5 power outages that typically last 3-5 hours.

I also did put in a 200A whole house transfer switch on this house to use with the generator.

Is the revision number on the placard on the unit?

[Kelly Myers]

Is the revision number on the placard on the unit?


On those units, you lift the lid and look on the engine side of the engine/battery divider wall.

That unit will not be able to start a 95LRA ac condenser. You may be able to get it to start off one 6x hard start capacitor. A 6x capacitor removes roughly 33% of starting current. This would leak you with roughly 62 amps of starting current. The generator can handle that.

Guardian generators can handle roughly 150% of its rated capacity for up to 3 seconds.

[newguy]

Where should I get the capacitor from to try it?

I'm also curious as to what the capacitor really does? I have a similar situation that I fixed with a capacitor for my RV's A/C unit and the 2400W Yamaha generator I have. It is a Carrier Air V that is a 13,500 btu unit that would run fine on a 3500W generator, but the generator would bog a bit when the AC started up. I bought a Yamaha 2400W Inverter generator (the real quiet type for camping) and it wouldn't start it, so I added a Supco SPP6E capacitor and it works just great.

Would I add a capacitor like the Supco to my Amana AC unit? Am I doing damage to the generator if I add a capacitor and expect it to start the AC? From what it sounded like the motor on the Generac didn't bog much from the AC trying to start, but the lights dimmed quite a bit.

My 4456 has the 992CC 30HP engine in it from what I can tell. The air cleaner says 1L and there is a sticker on the motor that says 992CC.

Would I be much better off to sell the 12KW and buy a 16KW unit? Other than the AC, everything else in the house works great with the 12KW unit. Are there many differences in the newer units that make them better than my 12KW?

Any thoughts on the "quality" of the sinewave coming out of my 12KW unit? I can take photo's of the sine wave and post them if that will help. I'm assuming that these units don't put out a very pure sine wave to begin with, but I want to make sure there isn't some other problem with mine.

[Kelly Myers]

You have to remember that you own a generator that wasn't super expensive, and it is designed for home use. If you're looking for a absolutely clear signal, then you have to go with a much more expensive digitally controlled generator. Guardian generators yield power that is clean enough for most household uses. if we can get your AC unit fired off the 4456, there is no reason to upgrade to the 16kw. Those 12kw are great units, and actually use the same engine that the 16kw uses!

You can put a hard start capacitor in the ac unit. It would piggy back your run start capacitor, and it simply plugs in.

I'll put them up on our website soon, or you can call us to order. they are $29.99 per unit.

[newguy]

Here's the info:

Generator:
Model # 0044560
Serial #3533769

A/C unit:
Compressor
LRA 95A
RLA 16.5A
Min Voltage 197V
Fan
FLA 2.1A

Model RCE42A2D
MFG No P1218716C
Serial No 0201100337

Max Fuse 35A, Min circuit Ampacity 22.7A
1Phase 208/230VAC

Is this the type of capacitor you would reccommend?

http://www.supco.com/eclass.htm

Thank you for all your time and advice - it's much appreciated!

[Kelly Myers]

Purchase that 6x cap. That should do the trick for you!

[newguy]

Super cool man! I installed the Supco SPP8E and it works like a charm. It starts easily with the generator running. Using my clamp on amp meter - I saw about 35A on startup, then about 12A running. I'm sure it's not fast enough to react to the current draw spike, but none the less it started up and runs fine.

I did get some photo's up on my photobucket site that show what the sinewave looks like. I'll see about posting them soon to get some feedback on if it's normal or not.

[dave]

Hey Mr. Newguy, I am about to break open the vault and buy the new Fluke 125 with Flukeview. How do you like the 123?

[newguy]

I like the Fluke a lot... I have not used it all that much, but it seems to work very well and I have had great experience with Fluke on stuff from the past...

I got the photos to load!! here goes nuthin...

http://i50.photobucket.com/albums/f307/TDInewguy/image_00132.jpg

This is the NO LOAD output I get off the generator.

http://i50.photobucket.com/albums/f307/TDInewguy/image_00136.jpg

Here is the LIGHT LOAD - probably 5-10A or so.


http://i50.photobucket.com/albums/f307/TDInewguy/image_00137.jpg

Here is the HEAVY load - probably more like 25A...

Thoughts??? why does the sine wave get so "ugly" as the load increases?

[newguy]

hello,

any comments on the photo's above?? thoughts on why they get "ugly"?

Thanks!

[Kelly Myers]

I wish I could help you!

Hopefully someone else can

[newguy]

Thanks for your reply Kelly -

Do you know by chance if this is normal of all Generac units? That's my main concern - if my unit is operating normally or if there is a problem.

[Namvet34]

Hi Kelly,

I purchased my Guardian 10Kw generator from Ziller in early January of this year and it was installed shortly after arrival. Installation included all house circuits, with the exception of the whole house air conditioner.

With the onset of unusually hot weather already this season, I?ve had a change of plans. Today I removed some lower priority circuits from the generator backup system and wired in my 3 /12 ton air conditioner, with the following results.

If the generator is ALREADY RUNNING and I turn on the air conditioner, the generator will start the air conditioner and all other circuits without any problems. The engine RPM?s drop down somewhat when the air conditioner starts, but then returns to full speed very quickly and the air conditioner and everything else works just fine.

On the other hand, if the air conditioner is running and utility power is interrupted and the generator is forced to start under the load of the air conditioner, the generator really has to struggle. The engine bogs down for several seconds and the lights dim but the generator eventually will get everything up and running. Starting under the load of the air conditioner obviously puts quite a strain on the generator. I?m afraid that I may end up causing damage to either the generator or the air conditioner or possible something else if I leave things this way, so for the time being I?ve removed the air conditioner from the emergency backup system. However, I would eventually like to wire it back in permanently.

Having read all of the posts on the board, it sounds like I need a capacitor assist. Could you give me idea as to what capacitor I need to buy to give my air conditioner a boost at start-up?

Here?s the information that I believe you?ll need to answer my question.

My generator is a 10 Kw, model # 5421-0, serial # 4676586.
Air conditioner information from the plate mounted on the side of the compressor unit:

22.6 min amps
35 max amps
Voltage 197min 253 max
LRA 105
RLA 17.1
Fan motor 1/6 h.p.

Thanks for your help and all of the great advice you?ve given me and everyone else on this board in the past. It?s invaluable. I wouldn?t even consider doing business with anyone else.

Best regards,

Namvet34

[newguy]

I bought the Supco SPP8E. They can be found all over the place on Google for about $30 or so. I bought mine locally from Grainger.

The problem you may be having with the AC running then the generator picking up the slack is that the AC system may be already pressurized and it's a lot tougher for it to start something that has the pressure pushing against it, vs. the AC isn't running, then there is no residual pressure for it to try and start against.

(that is my laymen's opinion... I may be wrong, but it's my .02)

[Kelly Myers]

When you have the generator running, and you go to turn on your AC, every motor in your house has already cleared the locked rotor amperage.

If your AC is running, and any of your Fridges, Freezers, Well Pumps, Sumps, Etc.. And the generator starts up, you have a TON of demand. Once the generator clears all the LRA, or initial load, you may have enough power available to start the generator.

You need to do two things. The 10kw will have a hard time starting that AC unit. 105LRA is a lot of power. You will definitely need a start capacitor. (You can call us, and I will ship you out one. I think they are $28.00).

The next thing you need is a time delay on the ac condensor. You can have a heating and cooling person install it, or you can buy one and install it yourself. Set it for a minute. This will prevent the AC unit from starting, and adding to the initial generator inrush.

Hope this helps

[Namvet34]

Thanks for your responses newguy and Kelly. Newguy, your thoughts regarding my air conditioner in a pressurized state made perfectly good sense to me. I just didn't know how to address it.

Kelly, I purchased the DST-6 hard start capacitor from Ziller last week and it was delivered very quickly, as have all of my purchases from Ziller. Yesterday my HVAC budddy picked up a delay timer for the condenser unit and we installed both the capacitor and the timer.

On the first attempt at testing the setup by switching over to my 10Kw generator from utility power, the A/C unit didn't start. As a matter of fact, it didn't even appear to try to start. The A/C unit made a single 'clicking' sound but the compressor motor never engaged. We tried it again without making changes to the wiring installation and it started just fine. We ran several more tests and the air conditioner started every single time.

I've said it before and I'll say it again, I wouldn't choose to deal with anyone other than Ziller. The level of technical support is nothing short of outstanding, order handling and delivery is the best in the business and this interactive board that you actively support is invaluable. You guys are the BEST!!

Thanks again,

Namvet34

[Kelly Myers]

Thanks for the kind words!

The initial delay could be that the cap wasn't fully charged, so it was actually taking electricity from the generator, instead of having the ability to dicipate into the AC unit!

Glad you're all set!