Generator install - where to start

[Complete Turf Care]

Back to the size of the pipe and distance question. From where my meter will be installed on my garage, the distance to where I want the manifold in my Utility Room is 100 feet plus the distance up to the attic and down from the attic. Then from the manifold to where I want the generator to be is another 30 feet.

I'm afraid that the distance with a 1-inch line is so long that it will limit the size of the generator that I can run off of Natural Gas. I also plan on using the Natural gas for cooking and heating water but haven't bought either of those things yet.

I have two questions. What size generator should I be looking at? I don't need 200 amps to get through a power outage, but I do want to be able to cool the house in Summer. AC has a 60 amp breaker for the outside unit, and I think the inside is just 20 amps. Fridge and freezers are the next big concern. I should be able to do fine on 100 amps, and even that is probably more then I'll use, but I think it's what I really want as a minimum.

The distance from the Natural gas meter to where my main breaker is 100 feet plus the distance up the wall and down the wall. Should I rethink the location of the generator? If I install it right next to the gas meter, the distance could be as little as five feet. Can I run two gas lines from the meter? One to the generator and one for the water heater and stove on the other side of the house, 100 feet away? Does that allow me to have a bigger generator? Is it worth the cost of the wire to put the generator that far away?

You probably need to get a generator rep out there to advise you on all of these issues.

My suggestion is to get one big enough to run your whole house just as you do without a power outage. I doubt the cost will be a whole lot more to go from a 16kw to a 24kw when it's all added up. That way, when you do have a loss of power, everything continues working without having to do anything.

Also, in my case, the regulator is just before the generator. After the regulator is a 'T' in the gas line. One side goes to the generator and the other goes to my stove.

 

[grsthegreat]

Back to the size of the pipe and distance question. From where my meter will be installed on my garage, the distance to where I want the manifold in my Utility Room is 100 feet plus the distance up to the attic and down from the attic. Then from the manifold to where I want the generator to be is another 30 feet.

I'm afraid that the distance with a 1-inch line is so long that it will limit the size of the generator that I can run off of Natural Gas. I also plan on using the Natural gas for cooking and heating water but haven't bought either of those things yet.

I have two questions. What size generator should I be looking at? I don't need 200 amps to get through a power outage, but I do want to be able to cool the house in Summer. AC has a 60 amp breaker for the outside unit, and I think the inside is just 20 amps. Fridge and freezers are the next big concern. I should be able to do fine on 100 amps, and even that is probably more then I'll use, but I think it's what I really want as a minimum.

The distance from the Natural gas meter to where my main breaker is 100 feet plus the distance up the wall and down the wall. Should I rethink the location of the generator? If I install it right next to the gas meter, the distance could be as little as five feet. Can I run two gas lines from the meter? One to the generator and one for the water heater and stove on the other side of the house, 100 feet away? Does that allow me to have a bigger generator? Is it worth the cost of the wire to put the generator that far away?

Depends on the pressure the nat gas is delivered at. Ive had customers contact their gas companies to increase pressure at house, and add regulator at every device to drop it back down. This allows for smaller pipes and longer distances. Contact a gas contractor but youll need to know what size generator your using so you can tell them the BTU needed at device.

 

[WinterDeere]

You probably need to get a generator rep out there to advise you on all of these issues.

My suggestion is to get one big enough to run your whole house just as you do without a power outage. I doubt the cost will be a whole lot more to go from a 16kw to a 24kw when it's all added up. That way, when you do have a loss of power, everything continues working without having to do anything.

Also, in my case, the regulator is just before the generator. After the regulator is a 'T' in the gas line. One side goes to the generator and the other goes to my stove.

Agreed, on all points. And this is exactly the direction I'm taking. While I'll benefit from it, the real instigation to install a permanent generator is so that my wife and kids don't have to fuss with setting up a portable and carefully managing loads, if I'm not around when the power goes out.

Me not being around could be a temporary or permanent problem, at any point in the future.

 

[ponytug]

@EddieWalker if you have a long run to the house/generator, generally the gas company will boost the pressure from the meter, and then use a secondary regulator for the generator, and another secondary regulator for the house. The goal is to ensure that the generator has enough fuel at full power, and that the home appliances get enough at the same time, with no pressure droop.

Easy to do, but not every utility wants to do things differently. Ours has a thick rule book of required rules, and at least one hidden rule book not made available to the public that can cause projects designed under the public rules to be turned down. My moral of that is to contact the utility as soon as you can and explain what you want to do to avoid changes late in the game.

All the best,

Peter

 

[EddieWalker]

I wasn't really looking for this, so I was surprised when it popped up.

Are Amazon prices any good?

Generac 22kw generator with 200amp transfer switch for $6,839 with free delivery.

Amazon.com

 

[WinterDeere]

That's pretty close to the list prices shown on the Generac site, depending on specific model and configuration.

I just spent a half hour turning on most of the major loads in the house, and measuring usage. Without the electric water heater on the 3rd floor kicking on, electric dryer turned off, and none of the pool equipment running, we're only seeing about 15 kW. Dryer alone adds 4 kW, which takes us to 19 kW, and I'll bet the pool can suck about 8 - 9 kW if I fail to turn the heater off before the genny kicks on.

All-told, I'm guessing we're just shy of 30 kW, with zero margin... should all HVAC and pool equipment be running at changeover.

Of course, it's possible to set up transfer switches to separate pool out, and just let it stagnate during an outage. That'd probably be fine, but maybe no less expensive than just sizing the generator to handle it.

 

[groundcover]

A good electrical contractor can set you up to shed load to non priority circuits, then they can re energize 'off peek'. A oversized generator can be a fuel hog. I have known some very wealthy individuals that were taken aback by the propane bill after an extended outage.

 

[WinterDeere]

A good electrical contractor can set you up to shed load to non priority circuits, then they can re energize 'off peek'.

Sounds expensive! But so are 30 kW genny's, so we'll have to learn the trade-offs.

A oversized generator can be a fuel hog. I have known some very wealthy individuals that were taken aback by the propane bill after an extended outage.

I'm surprised to hear this, I'd expect fuel usage to be almost entirely dependent on load, but I'd also be a little surprised if it even matters. I'm pretty certain we average under 10 hours of total outage per year, so I wouldn't expect any difference in efficiency of one system compared to another, to make a huge difference in my yearly expenses.

The bigger issue with fuel usage is supply. I use so little propane, that I have never signed up for an automatic refill contract. I just watch the tank and call in for a fill when I need it, usually once every 2nd or 3rd year if we use it a lot, but sometimes as seldom as 5 - 8 years. This means the tank can sometimes spend long periods at relatively low charge.

 

[groundcover]

Load makes a big difference ! I ran a 60 KW ten days ( V10 ford ) for a serious ice storm. 600 gallons used. Not bad but it wasn't working very hard either. Not a big deal with LP but with a diesel "wet stacking " can be an issue. The liquid cooled 1800 RPM units are a cut above but just went through that with a couple of friends, they ended up going the same way you are thinking, 3600, air cooled. One went Generac one Kohler.

 

[civilian]

When my Cummins generator system was designed into our new house build, there was some reason the electrician went for partial loading. Codes or something. So when the transfer switch senses loss of utility and kicks the generator on, the second electric subpanel is the only panel receiving power from the generator. All the other circuits in the main panel remain dead. That's the washer and dryer, living room plugs and lights, same in dinning room, some kitchen outlets, laundry room. Garage is on generator feed for the garage door openers. Woodshop and storage building are on separate feed from electric meter, so that is dead also. Boiler for heat in woodshop can be plugged into portable generator.

We are on propane. 1000 gallon propane tank and generator set by house. Line off tank goes to a "T" where one side goes to generator, 15 feet from tank. A regulator feeds the generator. Other side of "T" goes to regulator on side of house for gas boiler, water heater and stove. That regulator is about 25 feet from tank. Boiler in the workshop has its own 300 gallon propane tank, about 15 feet from the wall mounted boiler. And yes our outage are not usually long, at most a day. We are also the last residence of the power line. But the end of March last year, major ice storm in northern MI knocked out our power for 16 days. We were glad not to deal with a portable generator and hauling gas. Local power company had to replace over 3000 poles and some 4000 miles of cable. Jon

 

[JRH02]

I wasn't really looking for this, so I was surprised when it popped up.

Are Amazon prices any good?

Generac 22kw generator with 200amp transfer switch for $6,839 with free delivery.

Amazon.com

Warning! Warning! Just know you can't return it!

 

[ponytug]

That's pretty close to the list prices shown on the Generac site, depending on specific model and configuration.

I just spent a half hour turning on most of the major loads in the house, and measuring usage. Without the electric water heater on the 3rd floor kicking on, electric dryer turned off, and none of the pool equipment running, we're only seeing about 15 kW. Dryer alone adds 4 kW, which takes us to 19 kW, and I'll bet the pool can suck about 8 - 9 kW if I fail to turn the heater off before the genny kicks on.

All-told, I'm guessing we're just shy of 30 kW, with zero margin... should all HVAC and pool equipment be running at changeover.

Of course, it's possible to set up transfer switches to separate pool out, and just let it stagnate during an outage. That'd probably be fine, but maybe no less expensive than just sizing the generator to handle it.

Were your AC units part of that HVAC number?

Sounds expensive! But so are 30 kW genny's, so we'll have to learn the trade-offs.


I'm surprised to hear this, I'd expect fuel usage to be almost entirely dependent on load, but I'd also be a little surprised if it even matters. I'm pretty certain we average under 10 hours of total outage per year, so I wouldn't expect any difference in efficiency of one system compared to another, to make a huge difference in my yearly expenses.

The bigger issue with fuel usage is supply. I use so little propane, that I have never signed up for an automatic refill contract. I just watch the tank and call in for a fill when I need it, usually once every 2nd or 3rd year if we use it a lot, but sometimes as seldom as 5 - 8 years. This means the tank can sometimes spend long periods at relatively low charge.

Can I point out a few things?

One, if you plan on using propane for backup, keep the tank full (80%). Attempting to run the generator at low tank levels will cool fuel in the tank, and if it is wintertime, the evaporation rate becomes rate limiting, and the generator runs out of fuel well before the tank is empty. The exact details are depending on the generator consumption (base size and actual load) and the temperature. Burying the tank helps. I would look around for a keep full service that has a WiFi monitor on the tank, and a commitment to keep it more than 50% full.

Two, if the tank is half empty when the lights go out, and it is cold out, you might only have 35% of the tank as usable capacity. That then affects your calculation on how much load for how long. Generac has some great manuals that will cover the usage, and lower limits of each model. Bear in mind that both high temperature and low temperature can increase the total fuel consumption.

Three, speaking of consumption, just turning the generator on will use fuel. There is basically a fixed propane consumption even under no load, and then a more linear addition as the load goes up. If you look at this page, there is a great deal of useful information;
Generac Help Center
To take the 26kW next generation series, one can deduce from the table that at no load, the 26kW is pulling roughly 1.1gal/hr at no load, (+/-), whereas the 14kW consumes closer to 0.6gal/hr at no load. So the base size does matter for overall efficiency, which is why being able to shed loads is useful.

The actual amount pulled at low loads will depend on the particulars of the exact model and its design, as the base consumption is driven by things like outside air temperature, engine friction, and alternator construction.

Generac, and others, sell propane monitors, and load shedding controls, so in the case of the outage, some loads might get turned off by default to save energy, and prevent generator overload.

That 26kW probably consumes between 50gal, and almost 100gal, of propane a day, depending on load. (27gal/day no load...) It adds up, and you may decide that you want a larger tank. A half full 500gal tank in the cold part of winter might only get you three days at half load, but probably a little longer as you probably would be proactively turning things off. Still.

Details, details, details.

All the best,

Peter

 

[WinterDeere]

Yes, the HVAC number was with all air conditioning running, as it might be on a hot day. We use wood, oil, and propane for most of our heat, other than two small minisplit systems for a 1200 sf shop and 300 sf music studio. So, it's really only on hot days that we see all of that high load.

We have one 500 gal. propane tank, and it's presently only plumbed to a wall furnace in our attached garage (heated to 53F), a gas fireplace on our patio (almost never used), and a propane stove in our basement rec. room (seldom used). Our propane supplier asked me to notify them when capacity gets down around 30%, so they can just put us on the fill schedule, rather than having to rush straight over.

But if power goes out and I'm low on fuel, I have no doubt I could have them here inside of 24 hours. It might cost me in overtime or emergency rate service fees, but there's always someone willing to jump if you're willing to throw enough cash at them.

That said, I will ask the propane company how full I can have the tank when calling them for a fill. I think they get real irritated if they send a truck out for only 100 gallons, but perhaps I could call them at 50% (250 gal) or thereabouts.

What I hadn't posted above is our average usage. It's only 2 MWh per month in winter, and 4 MWh per month in summer, so average daily usage of 66 - 132 kWh/day. That's only 2.7 - 5.5 kW average load.

I didn't see whatever detailed load table you're referring to, but I did find this: Generac Help Center

So, their 32 kW "RG Protector Series" generator uses 2.7 gal/hr at 1/2 load and 4.6 gal/hr. at full load. That works out to GPH = .119*kW + 0.8, or 27 to 35 gallons per day. Even under your 35% capacity on 50% full estimate, that still gives me 5.0 to 6.5 days of run time. That's plenty of time to call the propane company by day 2 of an event, and suggest they schedule me for a delivery.

Coming back to my earlier point about battery storage, it looks like I could get away with a genny as small as 6 kW, with infinite battery. Maybe a more realistic cost compromise would be a very common 15 kW genny with 50 kWh of battery, there's always a "sweet spot" where manufacturing volume creates a low point in the pricing curve.

 

[grsthegreat]

Warning! Warning! Just know you can't return it!

I cant return it to generac either…….

 

[grsthegreat]

A good electrician can separate out heavy non essential loads to a separate panel that wont run on generator. Or they can install good load shedding devices (i like PSP Products) that can auto disconnect heavy loads and auto reconnect them when more power is available. Allows for a smaller generator.

 

[RayIN]

My only comment is to avoid Generac brand whole-house generators.

 

[grsthegreat]

My only comment is to avoid Generac brand whole-house generators.

Whatever floats your boat. Ive had nothing but good luck installing and servicing generac units for past 12 years

 

[ponytug]

@WinterDeere around here, in an emergency event, generator refills are behind every other customer, so I would check that there is no force majeur clause buried in the propane supply agreeement. In general, the solution where I have lived is to install a tank big enough to handle 2x the worst outage anticipated. Unlike gasoline or diesel, propane remains a good fuel indefinitely.

I agree that a smaller generator into a sufficiently large battery bank lets you plan for the average usage, with the twin caveats that the battery alone, or the battery plus the generator have to be able to handle the maximum surge load, and that for most homes the load is above average during the day, and lower at night (e.g. cooling and heat loads tend to follow the occupancy). Plus battery systems also have their own parasitic loads (generally a few kWh/day, but depends on the size and model, e.g. internal resistance, powering the control electronics and inverters, and potentially heaters to keep them warm and fans to keep them cool).

This was the main table that I was referring to;

I am sorry, but I think am missing something with the consumption math above. In doing the 32kW example propane math that you posted with 2.7gal/hr, I get 24x2.7= 64.8gal/day or at a full 32kW load 110gal/day. You may have been making a point that I missed. Sorry. (And those Generac numbers are under ideal conditions, not too hot, not too cold. I would plan on slightly higher consumption.)

Finally, I am not pushing any particular manufacturer or battery system. Generac just happens to have some fairly detailed manuals and informational documentation on their website.

All the best,

Peter

 

[Complete Turf Care]

It's interesting that the 22kw has the highest fuel consumption

 

[WinterDeere]

A good electrician can separate out heavy non essential loads to a separate panel that wont run on generator. Or they can install good load shedding devices (i like PSP Products) that can auto disconnect heavy loads and auto reconnect them when more power is available. Allows for a smaller generator.

Yep. But this house has 7 breaker panels, and many of those non-essential loads are scattered into those various panels. There's also precious little space remaining for mounting more hardware in the utility room where the mains enter, and where we have the mains panel and two of the larger subpanels.

But to your point, it may be easy to shed the entire pool, especially if the pump can be reconnected and run during off-peak times, as that's on its own sub-panel connected into one of the panels in the basement. And I guess the entire shop/barn could be treated the same, but it will be hell trying to keep it warm on only a mini split runnig off-peak (cold overnight hours), to the point where there'd have to be some pretty high cost to keeping it connected for me to even consider it a good option.

If it comes down to adding complexity via load shedding, versus just buying more generator and battery, I anticipate just buying more generator and battery to sit outside is going to be far easier.

@WinterDeere around here, in an emergency event, generator refills are behind every other customer, so I would check that there is no force majeur clause buried in the propane supply agreeement.

Interesting. I guess I could see that, if our outages happened in cold weather. We have had one or two extended outages due to ice storms, but more are due to hurricanes, big summer storms, or in one case... a tornado! All periods where demand for propane heating is minimal.

In general, the solution where I have lived is to install a tank big enough to handle 2x the worst outage anticipated. Unlike gasoline or diesel, propane remains a good fuel indefinitely.

I wouldn't be opposed to burying a second tank next to the one we already have in the back yard, or just digging out the first and replacing with something larger, if warranted.

What's the lifespan of a buried tank? If the one we have here is due to expire during our ownership of the house anyway, then just swapping it out now seems like a slam dunk.

This was the main table that I was referring to;

Okay... same page I used for my math, except I chose numbers off the RG Protector Series, since the largest Next Gen looked too small for a non-battery install here.

I am sorry, but I think am missing something with the consumption math above. In doing the 32kW example propane math that you posted with 2.7gal/hr, I get 24x2.7= 64.8gal/day or at a full 32kW load 110gal/day.

Average yearly usage is 2 - 4 MWh, with lows in April and October and highs in July and August, which should rub out to about 2.5 - 5.5 kW average loading, for the purpose of calculating daily fuel consumption. That puts average burn rate on a 32 kW RG Protector series around 1.12 - 1.45 gal/hr, just linearly extrapolating the two points they gave us, which indicates a fixed 0.8 gal/hr. for just running + P*.119 gal/kW. Simple y = mx + b, which should be close enough for this purpose.

So 1.12 - 1.45 gal/hr = 27 - 35 gal/day, as I figure it. It should actually be a bit lower, since my actual usage last year was only 1688 - 3697 kWh/mo, the "2 - 4 MW" I quoted above just being a quick estimate for the sake of round numbers.

And those Generac numbers are under ideal conditions, not too hot, not too cold. I would plan on slightly higher consumption.

Good point. My over-estimation / rounding may have already taken care of that, but I'll be sure we aren't shaving too close.

Finally, I am not pushing any particular manufacturer or battery system. Generac just happens to have some fairly detailed manuals and informational documentation on their website.

yep. I'm not married to Generac, in fact I'll be getting quotes for at least Kohler in addition to, and maybe one or two others.

I'm sure Generac has perfected the art of making everything as cheaply as humanly possible, but with a zillion units deployed in the field, they also have more data and experience on where cost is wasted versus valued. No need to build "Part A" heavier, when it's always "Part B" that fails first... and they probably have more FMA data than any other manufacturer.

It's interesting that the 22kw has the highest fuel consumption

They make a comment about that on their site, essentially stating that some of their models in a series are much newer or older than other models in the same series, and that fuel consumption tends to be better on the models released at later dates due to continuous design improvement. Probably half true and half BS, covering other factors we will never know.