I'm asking out of curiosity. My house is gas heat, so it's on a 15 amp breaker (for the control board/thermostat). My parents are on a mini split and pellet stove. Haven't seen a 40A hvac in a ~1300 sqft space.
Josh Luthman Office: 937-552-2340 Direct: 937-552-2343 1100 Wayne St Suite 1337 Troy, OH 45373 On Mon, Feb 10, 2020 at 10:15 AM Adam Moffett <dmmoff...@gmail.com> wrote: > It's likely that there isn't 40A load on the 40A breaker. The A/C > installer would have sized it high if they had any brains. However, the > full picture here is that a bigger generator might cost a few thousand > more, but buying it too small means buying it twice. > > If you cut it too close you can have the engine have trouble starting, > stall when loads change, and wear out sooner than expected. IMO you don't > want "big enough", you want "excessively big". I know I've harped on this > point before, but if your two hot legs are unbalanced then there's more > resistance on one side of the generator than the other....the smaller the > generator the easier it is to have problems with that. How many people are > bothering to check how well balanced the two hot legs are on their electric > panel? I got educated about that problem by an 8Kw generator with 13A on > one leg and 2A on the other. The engine ran noisy and stalled every few > minutes, and we had to hastily rewire to fix it. A bigger engine wouldn't > have cared so much. Chuck's suggestion of ((load + 50%) *2) is good sense > for all of the above reasons. > > Also pick a Sunday morning sometime and shut off your main breaker for a > few hours to see how well your generator carries everything. You can turn > the breaker back on if there's a problem, but if there's a problem during > an outage you just have to suffer until it's over. > > -Adam > > > On 2/10/2020 9:59 AM, Josh Luthman wrote: > > Is that 40A HVAC an electric heater or something? That's massive. > > I have a 30A two ton mini split that only pulls about 9 amps (110) at full > throttle heat. > > Josh Luthman > Office: 937-552-2340 > Direct: 937-552-2343 > 1100 Wayne St > Suite 1337 > Troy, OH 45373 > > > On Sun, Feb 9, 2020 at 9:04 AM <ch...@wbmfg.com> wrote: > >> If your HVAC is 240 then you have more HVAC load than that generator can >> pull on just that one load. >> >> 40 amps x 240 Volts is 9600 Watts. >> >> 7.5 kW generac will only deliver 31 amps at 240 VAC And you really don’t >> want to load a generator up that much. 50% is a good derating factor. >> Also, generators publish their power output at sea level. >> >> Knock off 3% for every 1000’ above sea level and 2% for every 10 degrees >> above 70 degrees F >> Rounding up, you are close to 5000’ so that is 15% lost for altitude and >> in the summer at 110 degrees that is another 8%. >> So you lose as much as 23% of capacity on a hot summer day. Worse if >> you power it from natural gas. >> >> I would add up all your loads, add 50% for growth then double that figure >> for not loading the generator too much and to account for derating. >> >> The installation is the expensive part. Don’t scrimp on kW at this stage >> of the game. Sounds to me like you need a 20 kW or more depending on your >> true HVAC loads. >> >> *From:* Sterling Jacobson >> *Sent:* Saturday, February 8, 2020 6:04 PM >> *To:* AnimalFarm Microwave Users Group >> *Subject:* [AFMUG] Generator for office >> >> >> I need a smaller footprint generator for my 1300 sqr foot office. >> >> >> >> Was thinking of getting the 50A 7.5KW Generac 6998 for $2050.00 that >> includes the 50A transfer switch. >> >> >> >> I think my breakers has several 20A switches and 40A for the HVAC. >> >> >> >> Not sure if this would cover the power needed for the whole unit, or just >> the fiber cabinet/rack I have that has max 20A circuit to it? >> >> >> >> The next highest power draw is probably the HVAC and/or water heater. >> >> >> >> The lights only draw about 500W since I switched them all to LED. >> >> >> >> >> >> ------------------------------ >> -- >> AF mailing list >> AF@af.afmug.com >> http://af.afmug.com/mailman/listinfo/af_af.afmug.com >> -- >> AF mailing list >> AF@af.afmug.com >> http://af.afmug.com/mailman/listinfo/af_af.afmug.com >> > > -- > AF mailing list > AF@af.afmug.com > http://af.afmug.com/mailman/listinfo/af_af.afmug.com >
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