Choosing a Generator

[EmbarkChief]

I'm happy I came across this thread! I'm in Houston as well and have the same questions and concerns as Ham & Eggs. I keep going back and forth between a Honda EU7000 and either a MEP-802 or 803. I have home electrical monitoring as well, not as extensive as Ham & Eggs LOL but it keeps me informed of my draw at any given time.

I have a 3k+ sqft house with a 3 ton and 2 ton AC units. Running watts with both units and normal household draw is about 6,500 watts this load occurs around every 15 min with a load time of 10 minutes during a typical 100 deg day (like today!). The 3 ton downstairs unit has a starting load of anywhere between 4200 and 3400 watts with a running load of 2600. The 2 ton upstairs unit has a starting load between 3500 and 2800 wats with a run load of 2000 watts. If I only run the downstairs AC along with a typical household load my usage is about 3,700-4000watts. The largest load I have hit so far was around 8000 watts and that came from turning on my electric oven with both AC's going. Everything else (water heaters, dryer, stove) is gas.

With all that in mind I'm not sure if I'd load an 803A enough with my typical load requirements too keep wet stacking at bay. Although I could always turn on the oven every now and then to load it up. I feel like the lazy option is just to get a EU7000, but the more heavy duty option would be a MEP. So many advantages and disadvantages to either one.... Makes for a hard decision. When hurricane IKE came through back in 2008 I was without power for 3 weeks. I don't ever want to to that again, especially now that I have kids. During the freeze I was out for 3 days. My neighbor had a hard time keeping his 20K Generac going under heavy loads due to low gas pressure. I'm not as worried about fuel price as I am about fuel availability. In my experience during hurricanes unleaded runs out fast but you can typically still find diesel. I have 7 Jerry cans (5 gal) for this purpose.

 

[HamAndEggs]

I suspect a lot of people will have issues with gas pressure if we have another outage. I had to argue with my generator installer to get them to pay to upgrade my meter

In the end I contacted CenterPoint Energy myself and got the meter upgraded, and then got a refund from the generator installer for the cost, since they were incapable of picking up the phone and requesting it

Right now I'm holding off on getting something, with net metering being nerfed so much I'm looking at getting 4 x Encharge 10's from Enphase, which has full generator integration

 

[Light in the Dark]

I'm happy I came across this thread! I'm in Houston as well and have the same questions and concerns as Ham & Eggs. I keep going back and forth between a Honda EU7000 and either a MEP-802 or 803. I have home electrical monitoring as well, not as extensive as Ham & Eggs LOL but it keeps me informed of my draw at any given time.

I have a 3k+ sqft house with a 2 1/2 ton and 2 ton AC units. Running watts with both units and normal household draw is about 6,500 watts this load occurs around every 15 min with a load time of 10 minutes during a typical 100 deg day (like today!). The 2 1/2 ton downstairs unit has a starting load of anywhere between 4200 and 3400 watts with a running load of 2600. The 2 ton upstairs unit has a starting load between 3500 and 2800 wats with a run load of 2000 watts. If I only run the downstairs AC along with a typical household load my usage is about 3,700-4000watts. The largest load I have hit so far was around 8000 watts and that came from turning on my electric oven with both AC's going. Everything else (water heaters, dryer, stove) is gas.

With all that in mind I'm not sure if I'd load an 803A enough with my typical load requirements too keep wet stacking at bay. Although I could always turn on the oven every now and then to load it up. I feel like the lazy option is just to get a EU7000, but the more heavy duty option would be a MEP. So many advantages and disadvantages to either one.... Makes for a hard decision. When hurricane IKE came through back in 2008 I was without power for 3 weeks. I don't ever want to to that again, especially now that I have kids. During the freeze I was out for 3 days. My neighbor had a hard time keeping his 20K Generac going under heavy loads due to low gas pressure. I'm not as worried about fuel price as I am about fuel availability. In my experience during hurricanes unleaded runs out fast but you can typically still find diesel. I have 7 Jerry cans (5 gal) for this purpose.

55 gallon drums can very easily be 'out of sight, out of mind' and full of diesel when you need it.

 

[Coug]

I'm happy I came across this thread! I'm in Houston as well and have the same questions and concerns as Ham & Eggs. I keep going back and forth between a Honda EU7000 and either a MEP-802 or 803. I have home electrical monitoring as well, not as extensive as Ham & Eggs LOL but it keeps me informed of my draw at any given time.

I have a 3k+ sqft house with a 2 1/2 ton and 2 ton AC units. Running watts with both units and normal household draw is about 6,500 watts this load occurs around every 15 min with a load time of 10 minutes during a typical 100 deg day (like today!). The 2 1/2 ton downstairs unit has a starting load of anywhere between 4200 and 3400 watts with a running load of 2600. The 2 ton upstairs unit has a starting load between 3500 and 2800 wats with a run load of 2000 watts. If I only run the downstairs AC along with a typical household load my usage is about 3,700-4000watts. The largest load I have hit so far was around 8000 watts and that came from turning on my electric oven with both AC's going. Everything else (water heaters, dryer, stove) is gas.

With all that in mind I'm not sure if I'd load an 803A enough with my typical load requirements too keep wet stacking at bay. Although I could always turn on the oven every now and then to load it up. I feel like the lazy option is just to get a EU7000, but the more heavy duty option would be a MEP. So many advantages and disadvantages to either one.... Makes for a hard decision. When hurricane IKE came through back in 2008 I was without power for 3 weeks. I don't ever want to to that again, especially now that I have kids. During the freeze I was out for 3 days. My neighbor had a hard time keeping his 20K Generac going under heavy loads due to low gas pressure. I'm not as worried about fuel price as I am about fuel availability. In my experience during hurricanes unleaded runs out fast but you can typically still find diesel. I have 7 Jerry cans (5 gal) for this purpose.

If your "normal" draw is 6500 averaged out, then you'd definitely want the 803 as opposed to an 802 or 7kw gas unit. The surge is very short, but the gasoline generators are just built too lightly to handle the startup surge of multiple aircons if they decide to cycle at the same time.

Your "starting load" seems a little low to me, but I'm used to older aircon units. The startup surge can be anywhere from 3-10 times the running current, depending on design and capacitors used. It's only for a split second, so not long enough to trip thermal breakers in a house, but most generators really don't like them.
The additional rotating mass of the heavy diesel generators is a lot more forgiving for the inrush current.


As for your neighbor having issues keeping his generator under heavy load, I've argued with more than a few installers and plumbers that the gas pipe they are trying to use is undersized for the load. Either that or it's sized for the generator load, but isn't it's own dedicated circuit, and the piping from the LP Tank or NG Regulator to the house isn't sized to handle both the house and the generator at the same time. Or the tank regulator is undersized for both together. I've seen things like 1" piping from the house to the generator, but the LP tank is on the other side of the building, goes into the house to handle the appliances there, all run in 3/4", before exiting the house and going up in size to 1" the rest of the way to the generator.
I think the standard household NG regulator is around 250-300k BTUs. Enough to handle a generator at partial load and most household loads, but not everything together at high load. With on-demand hot water heaters becoming more common, it's even worse. Some of those need 200k BTU dedicated to them to use, then 300k btu for a 20kw generator plus the gas stove, dryer, oven, furnace, etc, it's a major struggle to keep anything going.

Also, if it's on a propane tank, the cold weather vaporization rate of the liquid propane inside the tank might not be able to keep up. That 20kw generator at full load requires around 300k BTUs of fuel for that kind of output and at colder weather an above ground tank, especially if someone cheaped out and is running a 420lb upright or 125 horizontal tank just won't handle the demand.

Just meaning to say, there is actually a lot more involved in LP or NG setups than most people really think.

 

[nextalcupfan]

I have a 3k+ sqft house with a 2 1/2 ton and 2 ton AC units. Running watts with both units and normal household draw is about 6,500 watts this load occurs around every 15 min with a load time of 10 minutes during a typical 100 deg day (like today!). The 2 1/2 ton downstairs unit has a starting load of anywhere between 4200 and 3400 watts with a running load of 2600. The 2 ton upstairs unit has a starting load between 3500 and 2800 wats with a run load of 2000 watts. If I only run the downstairs AC along with a typical household load my usage is about 3,700-4000watts. The largest load I have hit so far was around 8000 watts and that came from turning on my electric oven with both AC's going. Everything else (water heaters, dryer, stove) is gas.

Your "starting load" seems a little low to me, but I'm used to older aircon units. The startup surge can be anywhere from 3-10 times the running current, depending on design and capacitors used. It's only for a split second, so not long enough to trip thermal breakers in a house, but most generators really don't like them.
The additional rotating mass of the heavy diesel generators is a lot more forgiving for the inrush current.

I have a Lennox 3-ton AC from 2011.
Its starting current is 18,480 watts (according to the sticker)
and running is 3,384 watts (under max load, most of the time its lower)



Your numbers seem quite low for inrush, unless you have soft starts or inverter AC units.

I can say this for sure, when that AC kicks on my 803a jumps.

 

[EmbarkChief]

If your "normal" draw is 6500 averaged out, then you'd definitely want the 803 as opposed to an 802 or 7kw gas unit. The surge is very short, but the gasoline generators are just built too lightly to handle the startup surge of multiple aircons if they decide to cycle at the same time.

Your "starting load" seems a little low to me, but I'm used to older aircon units. The startup surge can be anywhere from 3-10 times the running current, depending on design and capacitors used. It's only for a split second, so not long enough to trip thermal breakers in a house, but most generators really don't like them.
The additional rotating mass of the heavy diesel generators is a lot more forgiving for the inrush current.


As for your neighbor having issues keeping his generator under heavy load, I've argued with more than a few installers and plumbers that the gas pipe they are trying to use is undersized for the load. Either that or it's sized for the generator load, but isn't it's own dedicated circuit, and the piping from the LP Tank or NG Regulator to the house isn't sized to handle both the house and the generator at the same time. Or the tank regulator is undersized for both together. I've seen things like 1" piping from the house to the generator, but the LP tank is on the other side of the building, goes into the house to handle the appliances there, all run in 3/4", before exiting the house and going up in size to 1" the rest of the way to the generator.
I think the standard household NG regulator is around 250-300k BTUs. Enough to handle a generator at partial load and most household loads, but not everything together at high load. With on-demand hot water heaters becoming more common, it's even worse. Some of those need 200k BTU dedicated to them to use, then 300k btu for a 20kw generator plus the gas stove, dryer, oven, furnace, etc, it's a major struggle to keep anything going.

Also, if it's on a propane tank, the cold weather vaporization rate of the liquid propane inside the tank might not be able to keep up. That 20kw generator at full load requires around 300k BTUs of fuel for that kind of output and at colder weather an above ground tank, especially if someone cheaped out and is running a 420lb upright or 125 horizontal tank just won't handle the demand.

Just meaning to say, there is actually a lot more involved in LP or NG setups than most people really think.

Below I’ll attach some screenshots of my monitor showing my starting load and running load of my downstairs 3ton unit. As you can see there is a variation in the starting load. The last shot shows the running load for that unit.

 

[Light in the Dark]

Part of specifying the right genset for your needs are differentiating between the MUST RUN items, and the WANT TO RUN items. Those two lists are very different between each person. A balance between fuel burn, fuel storage, and typical (and planned for) outage lengths.

It is typically a bit easier for us in the north, as ACs aren't as 'mandatory' than those down south... but depending on your realistic buildout of the two lists I mention... sizing may become a bit easier if you are truthful with what you MUST run. For some owners, they MUST run life uninterrupted.. and I get that. For some, they want water, their fridge and freezers, etc...

Whole swath of the spectrum between those two for every individual owner.

 

[EmbarkChief]

I have a Lennox 3-ton AC from 2011.
Its starting current is 18,480 watts (according to the sticker)
and running is 3,384 watts (under max load, most of the time its lower)

View attachment 871498

Your numbers seem quite low for inrush, unless you have soft starts or inverter AC units.

I can say this for sure, when that AC kicks on my 803a jumps.

As luck would have it last night my 3ton and 2ton unit started simultaneously! I could hear it when they lit off as the units are not too far from my master bedroom. Pic attached showing start load. Note, on all these screen shots the moment showing the wattage is on the far right hand "grey" line.

 

[EmbarkChief]

All that being said right our temps have been in the 100's with overnight lows around 80 deg. So I'm running these AC's significantly more than usual. During the day I maintain 78 deg upstairs and 74 down. Even with that, yesterday my upstairs unit ran over 6 hours straight just trying to hold 78 deg.... So with that in mind I can obviously shed load and only run my downstairs unit. I could even turnoff the downstairs unit and the run the upstairs to catch up a little bit. Once thing for sure, I wouldn't have any wet stack concerns! Most of my other loads are pretty darn light, the biggest hogs besides the AC is the microwave (1500 watt) and the coffee maker which is about the same. Both of those are optional items to say the least. During the last freeze I was making French Press boiling my water on my gas stove. No watts there!

 

[nextalcupfan]

Startup on the unit you posted is 21,120 watts.
Keep in mind that's only for a fraction of a second so maybe your monitor isn't picking up on it.

 

[EmbarkChief]

Startup on the unit you posted is 21,120 watts.
Keep in mind that's only for a fraction of a second so maybe your monitor isn't picking up on it.

That is a possibility. However even the RLA comes out to 3,500 and as you can see it’s only using 2,671. I’m of the opinion (I’m not an electrician) that we are not seeing LRA loads on startup. If that was the case even an 803 would choke on that IMOP.

 

[nextalcupfan]

That is a possibility. However even the RLA comes out to 3,500 and as you can see it’s only using 2,671. I’m of the opinion (I’m not an electrician) that we are not seeing LRA loads on startup. If that was the case even an 803 would choke on that IMOP.

All I can tell you is my 2.5ton hits my 803 pretty hard.
But I believe it's possible to start one on an 802 if pretty much everything else is off.

 

[Coug]

The 15 amps running vs 88 startup on the sticker is a factor of about 5.7 to 1, so even if you're down at 2700 watts running, you're probably looking at a minimum of at least 5 times that number, and probably closer to 6, so 18kw for a split second isn't unheard of.

I don't do installs and sizing calculations, but I've looked at requirments before.
Quick search is showing for a central aircon at 2 ton rating you'd want a minimum of 9kw for startup. For a 3 ton that would be 12k. Keep in mind though those numbers are ONLY for the aircon, and doesn't account for anything else being run at the same time.

If this was sizing for an automatic standby generator, you'd be looking minimum of 22kw to be able to handle both aircon plus other minor loads because everything is automatic, and would likely have load shed modules installed on at least one of the aircons as well as possibly on other major appliances. Because this is a backup gen and not an automatic, you can do manual load management and not worry about any local regulations there may be for backup generators (I think some municipalities around here they have to be sized for the load in the panel, not just what you expect to run on them if you have it as a whole house standby)


As was mentioned, a lot of monitoring gear isn't capable of capturing actual peak numbers because it is such a short amount of time.

 

[HamAndEggs]

Hey guys, quick question for you all. Are the MEP's good being left out in the sun, rain etc? Or is it suggested they are kept covered?

I just installed another mini split. My peak load today with all AC's running is 4.6kw. Best of all, these inverter mini splits have ZERRROOOOO inrush. They ease up to RLA, if ever. The one cooling my living room is running on a 15a double pole breaker, max total amps is 13. Much better than my horrible 4 Ton unit

The MEP 802a or 1030 seems like the best choice now, or a Kubota GL7000

 

[Light in the Dark]

MEPs are designed to be fielded anywhere on Earth as is. You don't have to worry too much where you live, but folks in northern climates should take heed in the winter months to keep ice off the roof and out of the inlets (as it can cause damage, and block the exhaust port from opening under use).

 

[Light in the Dark]

And in the way of the world... just looked up what a GL7000 goes for these days ($6500+) most sites show the following:

" Availability: Backordered until approximately January 2023 "

Thats based on no further supply chain issues. Crazy stuff.

 

[HamAndEggs]

Apparently the GL7000 is a favorite in Puerto Rico, and they pretty much get bought up instantly, but that is third hand information.

I've been keeping an eye out for solar trailers, almost all of them have either a GL7000 or a GL11000 on it. If I can find one for a good deal, I could snag the generator and resell it assuming I don't grab an MEP first

 

[Light in the Dark]

I don't believe the Kubota genset is actually prime rated... I think it has a standby rating (and incorrectly uses 'prime' verbiage on their website... not really meaning prime power designation). Also the Kubota has a brushed head, not brushless like the MEPs.

 

[FarmingSmallKubota]

GL7000 on Ebay right now 6639. seems 802 is a lot cheaper

 

[HamAndEggs]

Yep, pretty much new prices. Been doing some math and power testing this morning and the 802 does make the most sense. The only times I see peaks to over 5kw are when I'm using the electric range. Of course if I was running on the MEP, I just wouldn't use it

Whole house cooled to 74, these mini splits just kick ass at sipping power