Opinions on new install wanted

[M Miller]

I got 2 quotes to install a standby generator. Both dealers recommended the 16KW guardian (15KW gas) if I wanted to power my whole house with transfer panels (2). I have two 2 1/2 ton A/C units (heat pumps) with a LRA of 73 and 75 and a RLA of 13.7 and 13.8. With just the A/C's, condenser fans and air handler fan I would be using about 7.5 KW continious. They would also have to use a relay to disconnent the backup heat strip in one air handler. The other one is gas backup. I don't lose power that often and my real need is to have automatic standby power for a basement sump pump that runs a lot with a heavy rain.

I have about decided to use a 7KW unit (6KW with gas) and forget the AC. I will use a 16 circuit transfer panel instead of the standard 8. I think I will be OK. With the 16 KW unit I would have had only about 7.5 KW left over anyway after the AC draw and the whole house transfer would have included a clothes dryer. I have a 5KW continious portable now and a 6 circuit manual panel but I have the heavier loads on it including kitchen appliances, sump pump, refrigarator, the gas furnace blower and some lights and the 5KW doesn't even break a sweat. The additional circuits in the 16 circuit panel would be mostly lights and an ejecter pump and garage door opener. I have gas hot water.

Sorry to be so long. Any thoughts on this Kelly? Thanks

[Bill Liedtke]

Kelly will give you a definitive answer, but I doubt even the 16KW would have started even one of your AC units. I have a 13KW and I would not even try to start an A/C unit. I care about lights, furnace in winter, appliances, sump, well pump, etc. I am always somewhat amazed when I see people ask about A/C units. I'm just damn glad to have electricity- Can't we live any more without running our big A/C units until the utility is restored??!! These units are great, but the small to mid-sized units are not really designed to run a regular A/C unit with LRA's in the 50's and above. These mid-priced units should be viewed as emegency power- not a replacement for the electric company! Just my .02.

Bill

[Slice]

If you were in the South east Texas area you would understand the a/c issue.
When I designed my home, i installed two 1.5 tons ac's so my generac 16 kw would fire them both. both of them running with air handlers and lights on in the house pull 19.2 amp. not too bad of course propane is not cheap and the generator loves that stuff.......

[msqd628]

I have a similar situation with the (2 ) 2 1/2 ton heat pump units. I can tell you that wth a 15KW generator hooked to a 12 circuit transfer panel I can only draw 7500W with (1) 2 1/2 ton heat pump, Ref, kitchen, MBR, LR, fans, garage and kitchen all wide open. I have snce swapped the 12 circuit panel with a 16 circuit ATS/load center to get additonal load.

In short I would say that you could run both AC units with a 15/16KW as long as they didnt start at the same time.

I like the relay option so the heat strip doesnt run at the same time as the AC. However, I wold have to do some jumpering to my tstat for this to happen.

Hope my example helps.

[Bill Liedtke]

1.5 ton units are very small so you should be ok. You are lucky that you can get by with two units of such minimal size. I have a 5 ton and a 3 ton and I wouldn't want to find out if the generator could power them. Even in Tx. I could live with a fan until the power came back and if I couldn't stand the heat, I'd probably go to a hotel. I am most concerned with things like sump, fridge, furnace in winter, lights, microwave, well pump, computer, stuff like that. I can live w/o AC for a couple hours or even a couple days, but if it's raining hard I can't live without a sump pump.

[MSLV70]

My 15kw propane unit runs my 3 ton A/C unit for the 2nd floor of my house. I do not run the first floor 2.5 ton unit. I do turn on the fan only switch on the 1st fl a/c to circulate the cool air that drops from the 2nd floor. It has kept my house cool during one 18 hour outage this past July when it was 95F outside.