Generac Guardian 5871 10kW NG/LP Backup Gen

[ndavid79]

Not exactly cogen, but figured ya'll would like to see it.

So my Dad has gotten me a Generac Guardian Series 5871, 10kW LP / 9kW NG, for my backup power needs (I'm ventilator dependent).
It has a Generac designed air-cooled 530cc 18hp 90deg V-twin OHV engine, aluminum block & cylinders w/ iron sleeves, 9.5:1 compression, solid state magneto ignition, electronic governor. Generator is direct drive 2 pole 120/240 60Hz 3600rpm w/AVR

With exception of starter battery, gas line, & 1st stage LP reg (if needed), comes with everything needed for a simple install:
Key locked sound & weather enclosure on a composite pad,
EZ Switch 100A automatic transfer switch / 12 slot load center prewired w/ selection of breakers / 2ft main panel umbilical / 30ft Gen cable,
Gen side connection box prewired to Gen w/ 5ft cable,
1ft 1/2" outdoor rated flexible gas line for vibration isolation + a dandy swivel connector (which you tighten to a o-ring seal separately) negating the need for a union at the gen.

Its fully electronic controlled, with a 2 line LCD display control panel under the hood, it'll display:
Alarm Log (stores up to 100 events), Run Log, Engine Hours, RPM, Gen Frequency, Battery Volts, Hours under load, and debug I/O.
There's also an optional Advanced Wireless Monitor (which he got me as well), which does everything above + Graph out Battery Volts, RPM, & Volts and manually initiate a Normal Start or Start & Transfer (for test purpose), or a Gen Stop command.

He's a HVAC installation & service contractor (residential & commercial) of 25yrs, so is doing the install himself.
Installation tomorrow

Things I would like to add later:
An energy monitor (Open Energy Monitor based) for volts/hz monitoring / load management / overload warning / fuel use prediction.
Propane backup via 3way switchover valve & manual choke cable attached to carburetor's fuel selector switch.
An Arduino based sensor package, thinking ambient enclosure & engine temp sensors, maybe an exhaust K type thermo down the road, oil pressure transducer, oil level sensor.

[SHIPCHIEF]

Does this have an overload protection feature?
I seem to recall that briggs & stratton has a similar generator package with an optional programmable controller to control the start of some loads when other more important ones are being used. Like preventing 2 air conditioners from starting at the same time, or turn off the water heater when the stove is on if Kw output is getting near the max.
It's a good option for generators that don't quite have enough power for the whole house' load to be on all at the same time. Although the energy monitor you have in mind will help you avoid an overload too.
I've seen similar Generac units for sale at Costco. It's a neat concept that I think my brother in law should have for a back-up. He has natural gas, so I think it would be a 'natural'.  

[ndavid79]

Installation took most of the day saturday.. At testing time, it wouldn't start for anything, sounded & smelled (plenty of NG pumped out the exhaust) like no spark.. Digging into the "crank but no fire" diagnostic checklist, found the choke flapper was stuck open / out of position, easy enough to put back in position.. Put mode switch on manual to initiate a start, 1st crank attempt it got one puff, 7sec later it made another attempt & fired right up!

After doing the panel connections we tested the shebang.. Put mode switch on auto & flipped the main breaker, 15sec later it auto started, 15sec after that the transfer switch flipped, but no power, forgot the 45A breaker on the Gen, fixed that & all's lit! The UPS on my equipment table agreed with it after a min, turned on my 5000btu window A/C, all's good. After about 10min he turned on the 2.5ton central A/C, Gen/lights did a big double dip but managed to start the compressor (which surprised the heck out of me considering I noticed he plumbed the damn thing with [at least] 30ft of 1/2" black pipe, which code says can only flow ~96CFH at 1/2psi (residential nominal), which I guestimate as about 4kw on this unit (specs say 1/2 load/4.5kw requires 102CFH & full load/9kw requires 156CFH). I need to get some proper instrumentation & do a real load test, but in the mean time it'll keep my critical equipment running.

Does this have an overload protection feature?
I seem to recall that briggs & stratton has a similar generator package with an optional programmable controller to control the start of some loads when other more important ones are being used. Like preventing 2 air conditioners from starting at the same time, or turn off the water heater when the stove is on if Kw output is getting near the max.
It's a good option for generators that don't quite have enough power for the whole house' load to be on all at the same time. Although the energy monitor you have in mind will help you avoid an overload too.
I've seen similar Generac units for sale at Costco. It's a neat concept that I think my brother in law should have for a back-up. He has natural gas, so I think it would be a 'natural'.  

The EZ Switch this package came with doesn't have any overload protection (other than breakers) or load shedding features.. Upgrading to one of Generac's Nexus Smart Switches adds load management with builtin control of 2 A/Cs, plus ability to automatically manage upto 4 additional loads via add-on DLM modules.

This house is NG heat/hot water/cooking, the main distribution (sub) panel is 220@30A, the central A/C has its own feed, & my room has 2 dedicated 110@20A circuits (for my medical equipment).

[Ronmar]

After about 10min he turned on the 2.5ton central A/C, Gen/lights did a big double dip but managed to start the compressor (which surprised the heck out of me considering I noticed he plumbed the damn thing with [at least] 30ft of 1/2" black pipe, which code says can only flow ~96CFH at 1/2psi (residential nominal), which I guestimate as about 4kw on this unit (specs say 1/2 load/4.5kw requires 102CFH & full load/9kw requires 156CFH). I need to get some proper instrumentation & do a real load test, but in the mean time it'll keep my critical equipment running.

A manometer(inches of water column) hooked up to the gas supply at the generator should show if you have sufficient flow.  IF it is insufficient, the pressure will fall off under load.  There are gas pressure specs for required pressure at the genset.  I dealt with a similar issue and a problematic regulator on a 100KW propane fired generac, and the manometer was invaluable in troubleshooting the issue.  For my initial testing I made my own to prove that fuel supply was indeed the problem.  Not strictly accurate, but an inch of change in a water column is an inch of change...  It may run pretty well under steady state with a restricted supply, but it will be much slower to respond to load increases as the gas pressure falls on it's nose when the throttle opens. Depending on how the generator is excited/regulated, this can, in addition to frequency excursions, cause some pretty severe voltage droop.  This will in turn cause larger current flows to make up for the lost voltage such as when starting an induction motor.  This is hard on those motors.   

[Tom Reed]

And low gas pressure can cause a lean running condition that can burn pistons and valves. So please have this checked so it doesn't fail when you really need it.