In Maryland, we've been having an increasing number of blackouts due to bad weather. We already had a small 3500/4400w (continuous/peak) generator hooked into a 10 circuit transfer switch. When we installed that system, we decided not to consider powering the central air conditioner.
Then a major heat wave combined with a REALLY bad weather, resulted in 100+ degree weather, half the state being blacked out for up to a week, and our decision to upgrade the generator to power the whole house hvac system.
We're running a single phase (~240v) Trane XE1200 with a rating of 12 RLA and 65 LRA. Not realizing the importance of the AC unit's LRA value. We bought the biggest generator we could find sitting on a shelf at Lowes, a Generac Xg8000e 8000/10000w unit. Upgraded the generator side electrical wiring in the house from 10 gauge to 6 gauge. Fed the new wiring into a dedicated sub panel and piggy backed our orignal transfer switch panel off of the new subpanel. We put in a 20 amp dual pole circuit breaker into the new sub panel and feed that into a 30 amp, center-off Leviton 1288 a/off/b dual pole switch, to cleanly switch the ac between line power and generator power, the furnace blower motor was already wired into the original transfer switch panel.
So, after upgrading the generator, supply wiring and power distribution... The ac wouldn't turn over. That's when we realized 65x240= 15600, we were at least 5600 watts short of the power needed to start up the AC, 12x240 = 2880 but we had more than enough power to sustain it, once it was started. We were prepared to exchange our Generac for the larger Gp175000e (17,500/26250w) unit...
Then we read about Hard Start kits and their ability to deliver serious, yet brief jolts of current to an ac unit for easier startup. We ordered a Supco Ssp8e Electronic Potential Relay hard start kit. When I opened up the ac there seemed to be a hard start cap 5-2-1 style already there. Installed the supco in parallel with the existing start cap, across the herm and common connection of the main dual purpose cap.... No luck, still wouldn't start up under generator power.
Then, I removed the old starter cap and just left the supco unit installed, across the herm and common connectors of their dual purpose cap and... Bingo(!) Ac started up and has been running properly all day. On a day when it's 105 degrees out side, we're at 76 degrees inside the house, under generator power. The temp did climb to 79 degrees while I did the hard start kit install but dropped back down within an hour or two.
So what am I missing here? What's the down side of using a 30 dollar hard start kit (capacitor ) vs. paying an additional 1500 dollars to get a 17500w generator? At the very least, I'll probably want to keep a spear Hard Start kit handy. But is there a downside to this setup?