backup "whole house" generators / Auto-transfer recommendations?

[dcg9381]

Any recommendations on "whole house" generators and auto-transfer switches (self-install)? I'm looking at something in the 15-20kw range. It'll be LPG (Propane) power.

Generac and Kohler seem to be the big brands, but what I'm reading is that one or both brands can make commissioning by non-authorized (IE, you didn't buy it from me) persons tricky and may make warranty impossible. Like HVAC, adding "installation" seems to double the price.

I'd even be OK with a suggestion for a solid auto-transfer switch where I can add a generator later.

 

[Kaizen]

hoping you have a big submarine tank already for the house?
one thing to think about with propane is if a disaster hit your area could or would they be rolling propane tanks to you? At least with gasoline you can go get some or use whats in your car tanks.

 

[wyliesdiesels]

Any recommendations on "whole house" generators and auto-transfer switches (self-install)? I'm looking at something in the 15-20kw range. It'll be LPG (Propane) power.

Generac and Kohler seem to be the big brands, but what I'm reading is that one or both brands can make commissioning by non-authorized (IE, you didn't buy it from me) persons tricky and may make warranty impossible. Like HVAC, adding "installation" seems to double the price.

I'd even be OK with a suggestion for a solid auto-transfer switch where I can add a generator later.

You might have issues self installing an auto transfer switch.

Depends on whether your AHJ will let you pull a permit as the utility feed will need to be disconnected.

What setup do you currently have for the meter and main service panel?

Divorced standalone meter no disconnect? Meter and disconnect? Combo service panel?

Also, what are your loads? Do you really need that large of a generator?

 

[Chucktin]

We just had a 20k Cummings and a 500 gallon propane tank with an automatic transfer switch installed.
Doubtful we would be using a full 20k load at anytime but the 500 gallon tank is sized to have it run at that load for approximately a week.
Already kicked in 3-4 times since install so it's proved to be handy. The 10 second gap from Poco to generator seems to stretch on for a long time so I also added one UPS to the TV and a separate one for the router.

 

[Chucktin]

Another thing - we purchased the tank outright. Turns out that way we can purchase propane from any source not just the initial supplier.

 

[killer cougar]

That's a pretty big generator for a whole house unless you live in a mini mansion. 10 - 12kw will cover most 2000 - 2500 sqft houses. I know Briggs and Stratton is starting to make a name for itself in whole house generators.

Like stated above an automatic transfer switch will most likely involve notification to your utility provider to pull your meter so you can install everything correctly. This will require AHJ permits and an electrician.

Next question is what exactly do you plan on running and for how long? Do you have frequent long term outages? Do you really need HVAC and such during those long outages?

For example: I live in the catchers mitt of NC for hurricanes. We loose power about once a year for a day or two at most except for last September which was closer to a week. I've got a 5000 watt portable generator and plan on installing an interlock kit and RV plug. This will allow me to plug my generator into the house and feed my panel safely and legally. I'll be able to run everything but the electrical heavy items (HVAC, dryer, microwave maybe). My house is piped with natural gas so hot water heater and stove are covered. But other than being warm for a few days most everything will operate as normal as long as I have gas. Long term will be adding another connection to my natural gas lines and getting a motor snorkel (gas to NG conversion kit) for my generator.

 

[dcg9381]

hoping you have a big submarine tank already for the house? One thing to think about with propane is if a disaster hit your area could or would they be rolling propane tanks to you? At least with gasoline you can go get some or use whats in your car tanks.

We have not installed a tank yet and it will be purchased out right and be 500+ gallons. House uses propane. I don't want to deal with tanks of gasoline (or diesel). I'm not designing for a hurricane.

 

[dcg9381]

Depends on whether your AHJ will let you pull a permit as the utility feed will need to be disconnected.

I've got a disconnect. We are permitted as required by the county currently.

What setup do you currently have for the meter and main service panel? Divorced standalone meter no disconnect? Meter and disconnect? Combo service panel?

320A meter service going into 2 x 200A main panels. One panel is for the shop (existing) and contains a 90A breaker. Second panel is a feed for new construction. Generator will only power the new construction. I do not want to generator power both main panels due to a grid-tie solar array that exists and distance from the propane tank.

Also, what are your loads? Do you really need that large of a generator?

Goal is power coverage during extended power outages (15-minutes - 2 days) for the new construction. 20KW "covers everything" - I could probably get away with 10KW of generator and identifying critical circuits or doing load shedding, but I'm not sure that I want to do that over being able to power all of it on demand and have it auto-start upon an outage.

Critical circuits would be: (off the top of my head)
* Kitchen
* 2 out of 3 AC systems (4 tons total, this is required - we're at 25+ days of 100+ plus this year)
* Septic system
* Upstairs lighting circuits/outlets
* Water sanitation system / associated water pump
* Network / Internet
* Power to propane hot water systems (for ignition)


I am aware of the manual transfer switch options with a portable generator. This isn't what I'm after.


Minimally, I'd like to have an auto-transfer switch picked out.... I can then deal with the generator later.

 

[mm08822]

I've got a disconnect. We are permitted as required by the county currently.

320A meter service going into 2 x 200A main panels. One panel is for the shop (existing) and contains a 90A breaker. Second panel is a feed for new construction. Generator will only power the new construction. I do not want to generator power both main panels due to a grid-tie solar array that exists and distance from the propane tank.

Goal is power coverage during extended power outages (15-minutes - 2 days) for the new construction. 20KW "covers everything" - I could probably get away with 10KW of generator and identifying critical circuits or doing load shedding, but I'm not sure that I want to do that over being able to power all of it on demand and have it auto-start upon an outage.

Critical circuits would be: (off the top of my head)
* Kitchen
* 2 out of 3 AC systems (4 tons total, this is required - we're at 25+ days of 100+ plus this year) need nameplate pics
* Septic system Is this a chopper/lift pump? need nameplate pic
* Upstairs lighting circuits/outlets
* Water sanitation system / associated water pump need nameplate pic
* Network / Internet
* Power to propane hot water systems (for ignition)

I am aware of the manual transfer switch options with a portable generator. This isn't what I'm after.

Minimally, I'd like to have an auto-transfer switch picked out.... I can then deal with the generator later.

You need to do load calcs first to determine min size of gen needed and what may be required to be on load shedding.
In addition to the above data needed, also provide sq ft of living space for calcs.
well pump (if not part of above list)
Sump Pump
fridge
freezer

10kw could easily be too small with ac loads. AC units quickly increase the size of gens needed.

 

[dcg9381]

Load calc isn't that simple - as we only use 1500 sqft a single floor of a 3000 sqft home that also has an attached 700 sqft apartment. Most appliances / water heat is propane. Our home is almost never fully occupied, but the apartment may be a rental - I don't necessarily need to cover it with power backup.

We can certainly cover 1500 sqft 1 bed, 1 bath, 1 kitchen, with 10KW. The 20KW is in case we want to run more than that. Price difference is nominal, about $2k, which may be worth not having to manage it or deal with load-shedding design.

Anyone have experience or can you recommend an auto-transfer switch or backup generator? Generac isn't my favorite from the RV days, but maybe they make a better genset for standby use.

 

[pentavolvo]

Have a ton of generacs at work and run them near max load when they are on and zero issues

 

[Bigblockyeti]

I have an old Onan CCK 4.0kw and I really like that it's very quite, not super powerful but very quite, largely due to the four pole generator humming at 1800rpm instead of a two pole screaming at 3600rpm and a muffler that looks like it was from a dump truck. Another thing to consider is how clean the power is coming off the generator. I would prefer not to plug my kitchen refrigerator into power from that generator but things with fewer sensitive electronics, like a chest freezer in the garage work just fine. Figure out when your meter is read and take it off yourself the day after they read it, pull the meter and install the transfer switch then put everything back as it was. Call them right after and let them know you "accidentally" broke the tamper evident tag. They'll confirm the hours used (again, over only 1 day), place a new tag on and be on their way.

 

[mm08822]

Load calc isn't that simple - as we only use 1500 sqft a single floor of a 3000 sqft home that also has an attached 700 sqft apartment. Most appliances / water heat is propane. Our home is almost never fully occupied, but the apartment may be a rental - I don't necessarily need to cover it with power backup.

We can certainly cover 1500 sqft 1 bed, 1 bath, 1 kitchen, with 10KW. The 20KW is in case we want to run more than that. Price difference is nominal, about $2k, which may be worth not having to manage it or deal with load-shedding design.

Anyone have experience or can you recommend an auto-transfer switch or backup generator? Generac isn't my favorite from the RV days, but maybe they make a better genset for standby use.

In your case load calc may have a few curves based upon only feeding 1 of 2 panels. Don't know how the loads are apportioned between panels and areas of the house. So that could cut down of the sqft to consider.
If you are going with an automatic xfer sw, the gen has to be sized for the connected loads. If load shedding has to be added b/c those loads exceed gen output, then that is what you need to do by code. (You promising not to turn something on doesn't cut it.) If your AHJ knows what he is doing will require load calcs.

4 Ton of ac cycling on/off connected to a 10kw unit can easily bury it especially if both cycle at same time.
10kw only puts out 42a and locked rotor of 2.0-2.5t units can run 50-75 each.

Generac Guardian series with ats works reasonably well. I've heard some horror stories and fixed a few crappy installs by others. If installed and maintained properly it will treat you well. I do the annual maintenance on almost all of the units i've installed.
Get a 200a rated service entrance rated xfer switch to feed one of your panels.

 

[dcg9381]

If you are going with an automatic xfer sw, the gen has to be sized for the connected loads.

Give me some clarity here... I think you mean sized by actual devices on the circuits, not by the breakers on individual circuits? Clarify.


It may be that I'm thinking about this wrong. To me, I could ATS the main on a 200A breaker and then "selectively run" what I want, but that doesn't seem to be the case.

After reading, I'm thinking about this as a "service disconnect" ATS that feeds a 200A sub-panel. There seems to be other ATS types that are load-shedding and typically have direct connects to high draw devices, like AC.

I also see ATS' that are basically their own breaker boxes, some of them have a load-shedding priority...

Obviously, I'm still trying to sort it out.

 

[wyliesdiesels]

I've got a disconnect....
320A meter service going into 2 x 200A main panels. One panel is for the shop (existing) and contains a 90A breaker. Second panel is a feed for new construction. Generator will only power the new construction. I do not want to generator power both main panels due to a grid-tie solar array that exists and distance from the propane tank.

where is the disconnect located?

between the meter and panels?

If so then they are not MAIN service panels. They are subpanels.

And this will mean that you need an ATS with a floating neutral. Most are service rated with a bonded neutral.

Can you take some pics of your setup and post them here. Meter and panels with covers on and off.

 

[Nor'Easter]

10+ years on a 13kW Cummins LP, no issues whatsoever except for they installed the pressure regulator horizontally so it wouldn't drain. Froze up once on a 3 day outage.

It ran for two weeks post-wind storm in 2018, burned around 800 gallons I think.

A 3,000SF house and my 5HP compressor will shut it down.

 

[Specracer]

4.3L V-6 GM Vortec Generac here, Generac 200 amp transfer switch also. Unit was initially LP, we converted it to natural gas, when we brought gas in. Unit is ~25 years old, and has been flawless. One storm it ran for a week. It is a fantastic thing to have.

 

[jade97]

2.4L Mitsubishi powered 38kw Generac here with 400 ATS & 500 gallon buried propane tank. Installed 3/2018. Runs 10 minutes every week and had about 2 10-20 hour outages (not counting multiple minute outages). I still have 75% in my tank & have yet to refill.

I had the ATS installed when the house was built & the Gen installed 3 years later.

I would have it installed by a certified dealer just for simplicity if you run into any warranty covered issues.

ATS was about $2500 & Gen installed (including both gas regulators...that was another story) was $18k.

 

[Bretny]

Warrenty is one thing but parts availability is another. Are you going to want to wait 3 weeks for a control board or valve cover gasket when your without power right now? The lower grade generac, briggs and kohler all use air cooled engines, basicly lawnmower engines. I wouldnt even consider one of these. Get a cummins, onan or other quality brand.

If alot of your house is also propane i would get a second 500gal tank or a bigger single tank. You have to remember that they can only fill propane to 80* and the bottom 20* dosnt vaporize as easily as the top of the tank.

 

[cory58]

Bretny - Are the better units liquid cooled with a radiator like an automobile engine, or cooled some other way?


Sent from my iPad using The Garage Journal mobile app

 

[slow]

liquid cooled, yes, cooling system like a car with a radiator.

 

[dcg9381]

where is the disconnect located?

between the meter and panels?

If so then they are not MAIN service panels. They are subpanels.

And this will mean that you need an ATS with a floating neutral. Most are service rated with a bonded neutral.

Can you take some pics of your setup and post them here. Meter and panels with covers on and off.

This may help.
I can pull the covers, if necessary.
The panel on the left: 90A shop breaker, 50A RV-subpanel breaker. (conduit was not in when taken)

Panel on the right will be for the residence.

Note, I can have the meter disconnected if absolutely necessary.

 

[yeldogt]

I have the 22K Cummings unit .. it was redesigned about 18 months ago. Propane and 1k tank -- propane for house as well.

Above 22k -- you need to go water cooled. When you price the units and look at fuel use -- the larger Cummins air cooled unit did not use much more fuel vs the much smaller generator sets and when bought as a kit with the 200amp transfer switch -- not much more expensive. The cummins unit will also run the starter motor to exercise the generator vs starting the motor every time .. saves more fuel.

Getting one large enough to do the whole house make it an easy install -- just cut the transfer switch into the line between the meter and the main panel. In my case I did need to add load shedding for code -- as the house is large w/ outbuildings. but I will never need the full 22k. This is for a rural weekend house -- lose power all the time .. normally short.

I bought the unit online -- it comes with free shipping so I ordered the proper pad (heavy) -- and extra control for inside the house. load relays

With an auto transfer system .. code requires a load calculation. The unit needs to be able to handle whatever is going on when the power fails ... it's not like a manual system where you are there to switch things off. You can't have an overload situation ... often this requires the load relays on a large electric stove/ oven .... dryer or AC unit.

In my case I needed it on my second AC/HP and big stove ... it's an easy hook up.

 

[dcg9381]

I completely agree with all of you that a water-cooled Onan would be the best option. If I was on the coast or highly dependently on it, I completely agree.

I'll run the load calculations, but with a "mostly propane" house, I expect most of the major electrical load to be running HVAC.

There seems to be three types of ATS setups:
1) A "service entrance" ATS, which switches the whole main over.
2) Basically sub-panel ATS without load shedding, individual protected circuits.
3) Sub-panel ATS with load shedding, individual circuits and "shed" circuits.


It IS possible, from the right panel above, that I could run 3 x 90A feeds to sub panels. two for the house, one for the garage. I could design such that only one of these feeds was "critical systems" that have ATS / generator backup.

The other alternative seems to be a "service entrance" ATS that covers all of it. I don't want to spend more than $5-$6k on a generator... At least get the ATS in place as this goes up.

 

[dcg9381]

So a load calc (Kohler) comes back as 38KW. If meeting this is required by code for a service-entrance ATS, it's a no go.

Options I've got left (other than a 40KW generator):

1) Feed the residence with 3 x 90A feeds. Lower residence, Upper residence, Garage. Use an ATS and generator only to protect "upper residence" - basically a 1500 sqft house with a 2-ton AC, which gets us down below 20KW.

2) Install a manual transfer mechanism (generator lock-out) and do not use an ATS. I moderate my own load, but lose auto-start.

3) Install a "load shedding" ATS that can drop the big loads (mainly HVAC) as necessary

 

[Bretny]

Bretny - Are the better units liquid cooled with a radiator like an automobile engine, or cooled some other way?


Sent from my iPad using The Garage Journal mobile app

Yes the better units are liquid cooled an even better unit is a 1800rpm liquid cooled unit.

 

[Bretny]

I completely agree with all of you that a water-cooled Onan would be the best option. If I was on the coast or highly dependently on it, I completely agree.

I'll run the load calculations, but with a "mostly propane" house, I expect most of the major electrical load to be running HVAC.

There seems to be three types of ATS setups:
1) A "service entrance" ATS, which switches the whole main over.
2) Basically sub-panel ATS without load shedding, individual protected circuits.
3) Sub-panel ATS with load shedding, individual circuits and "shed" circuits.


It IS possible, from the right panel above, that I could run 3 x 90A feeds to sub panels. two for the house, one for the garage. I could design such that only one of these feeds was "critical systems" that have ATS / generator backup.

The other alternative seems to be a "service entrance" ATS that covers all of it. I don't want to spend more than $5-$6k on a generator... At least get the ATS in place as this goes up.

Its sad to say but you dont get much quality in a $6k 20kw generator. I think they spent the money on the controllers not the actualy build quality.
But i havnt been generstor shopping in a few years after i bought my mep802.

 

[yeldogt]

Make sure you are doing the load correctly. Most can manage 4 load relays -- the cummins relays are two in a box ... each 50amp. The unit will bring them online in order.

With the AC units -- it's the starting. The 22k will start a 5 ton.

Generally we loses power for short periods in the summer -- wind storms knocking down trees. Power out for under an hour. Winter time is less frequent but has the potential for longer outages .... it has been days ... but this is very rare.

When you add up the total hours -- it's not much. The air cooled units are reliable and work very well .... they have been around for a long time. The new ones are even better.

For the average homeowner the air cooled are just fine .... The water cooled are quieter .. still not quiet. I mounted mine in the back of the property away from everybody.

 

[yeldogt]

Its sad to say but you dont get much quality in a $6k 20kw generator. I think they spent the money on the controllers not the actualy build quality.
But i havnt been generstor shopping in a few years after i bought my mep802.

I can't say I agree -- I found mine to be well built. Even the less expensive Generac units seem to be well received ... there are many that I know with them.

There is not much to them ...

Without load shedding I would have had to go liquid -- more than 2x the unit prices and much harder install .... more maintenance and no more functionality.

Greater fuel use

For people needing Propane -- fuel use is the problem if you have winter conditions.

 

[dcg9381]

I'm in Texas. Winter is not a concern.
Agree that for $6k, I'm getting a loud, 3600 rpm, device that isn't even beginning to be equal to a diesel water cooled Onan. This isn't for "end of the world" use or even for coverage beyond more than 24-48 hours.

Just trying to sort out the engineering and basic power distribution design here... Enough so that I can tell the electricians what they need to do.

 

[wyliesdiesels]

This may help.
I can pull the covers, if necessary.
The panel on the left: 90A shop breaker, 50A RV-subpanel breaker. (conduit was not in when taken)

Panel on the right will be for the residence.

Note, I can have the meter disconnected if absolutely necessary.

the pics did not load

 

[grounded-b]

So a load calc (Kohler) comes back as 38KW. If meeting this is required by code for a service-entrance ATS, it's a no go.

How did you do you load calc? Nameplate values of all major appliances? Certain number of watts per sqr foot for lighting and general purpose outlets?

Or did you multiply breaker ratings in your panel by the voltage, to get watts? ( this is NOT the correct way )

Your 38KW seems high, as you said, you have mostly LP appliances.

Steve

 

[dcg9381]

Just a simple load calc from Kohler (very basic, HVAC, major appliances, frequent/occasional use, sqft). Obviously they are in the business of selling generators and I don't think this is an official load calculator.

I don't think we'll come in under 20KW on any real load calculator. 50A circuit for a EV, 2 RV outlets, 6 tons of AC, 3700 sqft, septic pump, etc. The problem is that I have a lot of electrical and in theory could "use it" in parallel which impacts the load calc.. It might be better to divide the service entrance into 3 parts, but I'm open to ideas. I really only want to cover 1500 sqft, 1 HVAC unit, and critical systems - which is the part of the house that we'll use.

 

[jade97]

My set up has the electrical meter outside the house, feeding the 400A ATS, then splits to (2) 200A panels.

The 38kw Generac is a water cooled 4cyl that runs at 1800 rpm. Like I said, over the past 1.5 years, it has only consumed about 5% of a 500 gallon propane tank.

The installer included (2) load shedding devices, one connected to the Heat Pump backup coil and the other on the water heater.

When they did the initial test, with the gen providing power, the idle didn't even change when they turned on everything they could in the house.

 

[Fasthotrod]

Just a simple load calc from Kohler (very basic, HVAC, major appliances, frequent/occasional use, sqft). Obviously they are in the business of selling generators and I don't think this is an official load calculator.

If you want the 'real deal' Kohler load calculator, here it is:

https://kohlerpower.com/en/generators/industrial/sizing-program

I'll warn you in advance that it's more than you'll ever need to properly size your home system, but if you wanted to get into that level of detail, there it is.

Mark

 

[Bretny]

My set up has the electrical meter outside the house, feeding the 400A ATS, then splits to (2) 200A panels.

The 38kw Generac is a water cooled 4cyl that runs at 1800 rpm. Like I said, over the past 1.5 years, it has only consumed about 5% of a 500 gallon propane tank.

The installer included (2) load shedding devices, one connected to the Heat Pump backup coil and the other on the water heater.

When they did the initial test, with the gen providing power, the idle didn't even change when they turned on everything they could in the house.

In this case you dont want to hear the load come on. If you did most likely your HZ or voltage would be dropping.


The 1800rpm units is where its at. You will get a long service life out of them, generaly burn less and should be more quiet.

 

[Bretny]

I'm in Texas. Winter is not a concern.
Agree that for $6k, I'm getting a loud, 3600 rpm, device that isn't even beginning to be equal to a diesel water cooled Onan. This isn't for "end of the world" use or even for coverage beyond more than 24-48 hours.

Just trying to sort out the engineering and basic power distribution design here... Enough so that I can tell the electricians what they need to do.

$6k is alot to spend for 2 days of outage per year then.

 

[wyliesdiesels]

Just a simple load calc from Kohler (very basic, HVAC, major appliances, frequent/occasional use, sqft). Obviously they are in the business of selling generators and I don't think this is an official load calculator.

I don't think we'll come in under 20KW on any real load calculator. 50A circuit for a EV, 2 RV outlets, 6 tons of AC, 3700 sqft, septic pump, etc. The problem is that I have a lot of electrical and in theory could "use it" in parallel which impacts the load calc.. It might be better to divide the service entrance into 3 parts, but I'm open to ideas. I really only want to cover 1500 sqft, 1 HVAC unit, and critical systems - which is the part of the house that we'll use.

I could maybe understand charging the EV when the power is out so you can use the car but why do you need to power the 2 RV outlets and 3700 sq ft of lighting when you couldnt use all that at once.

seems to me youre way over estimating the loads you will have in an outage.

get load shedding modules and have them disconnect non critical loads

Also, what type of lighting do you have? if not LEDs you could switch to them and reduce your lighting load

 

[dcg9381]

seems to me youre way over estimating the loads you will have in an outage.

I agree with you.

My estimate is <100 amps draw during an outage. But per what I'm understanding (correct me if wrong) - I need a real "load calc" if I'm going to auto-transfer at the service - and that's based on what is IN the house, not my particular under-use.

It sounds like you're indicating that I do an ATS that is per circuit, maybe with load shedding - not full service-entrance?

 

[wyliesdiesels]

I agree with you.

My estimate is <100 amps draw during an outage. But per what I'm understanding (correct me if wrong) - I need a real "load calc" if I'm going to auto-transfer at the service - and that's based on what is IN the house, not my particular under-use.

The requirement for an ATS is the generator must be able to run the entire connected load OR have load shedding modules.

The latter will be your friend in this case.

BTW your pics dont load and id like to see what you have.