New 12K Standby Generator Install - PeachParts Mercedes-Benz Forum

KarTek · #1 12-04-2011, 07:27 PM

I picked up a Honeywell (Generac) 12.5 k generator a few weeks ago and since it's getting on towards Winter and ice, SWMBO gave me direct orders to get it installed ASAP.

I thought I'd document the process here in case anyone was interested and you can see how much trouble it is. I wouldn't want to guess how much it would cost to have it installed by someone else!

First step is installing the automated transfer switch. This looks like a likely location - Easy access, out of the way...

OK, the "boss" said it can't go by the door so I'll put it over on the wall:

Conduit run, wire pulled from main breakers:

Final wiring:

The old generator is now mobile with a set of wheels and provides power for me to work while the mains are disconnected from the house.

Next I moved on to the actual generator install. First I removed the old housing and cleared the old concrete pad of debris:

Next I dug the holes for the posts and the new protective enclosure and larger pad:

Forms for the concrete slab:

After the concrete was poured and set:

Setting the new generator in place:

And completing the shelter:

The housing on the generator is fully weatherproof but I wanted to give it some extra protection against falling limbs and other debris.

Next step will be to run the LP feed and then dig the trench to bury the feed and control cables.

Stay tuned!

The Clk Man · #2 12-04-2011, 07:46 PM

Cool man, I like to read these DIY kind of threads.

Dubyagee · #3 12-04-2011, 07:56 PM

Whole house transfer or select circuits? I have a 10k rig and was going for a whole house manual transferred setup.

jplinville · #4 12-04-2011, 08:01 PM

Nice looking install so far. I demanded one be installed when mom and dad's house was built due to the old neighborhood trees. That was a good thing, as it goes out at least once a month.

I'd like to get one for this house, after a garage gets put up.

engatwork · #5 12-04-2011, 08:04 PM

Are you running it off of a propane tank? How long with the tank capacity let it run for?

Dubyagee · #6 12-04-2011, 08:11 PM

It looks like a propane tank right next to the backhoe.

From another forum.

"The Kohler 12kW uses about 2.5 gallons of propane per hour at idle speed which is also 50% power output. When we lose power my genset never needs to accelerate beyond idle spreed. At 2.5 gal/hour I can run for 2-3 days assuming I let it run continuously. I have a 500 gallon burried propane tank but assumed that it would be at 40% full when we got the outage which is 200 gallons. These are all assumptions that I made when deriving my needs. You can get smaller above ground propane tanks (e.g. multiple 100 gallon tanks) and that might work just fine depending on what your backup needs. You can also manuallly turn the genset on and off to extend the operating life if you know the outage will be longer than the fuel you have. "

SwampYankee · #7 12-04-2011, 08:15 PM

Nice, Evan! My $12K is going to my kids' orthodontist.

KarTek · #8 12-04-2011, 08:37 PM

Quote:

Originally Posted by Dubyagee

Whole house transfer or select circuits? I have a 10k rig and was going for a whole house manual transferred setup.

The mains power is 200A that runs from the meter into a panel that sends 100A to the garage sub panel, 100A to the house sub panel, 50A to the oven and 30A to the dryer.

The house sub panel feed runs through the generator transfer switch so the generator will run everything in the house - lights, outlets, well pump, HVAC, etc... Even the little 5K unit I was running before would handle these loads fairly well.

I wanted to upgrade because I got a screamin' deal on the whole setup. The new technology generator/transfer switch will exercise itself weekly, warm up and switchover automatically and even waits for a set amount of time before shutting down in case the power comes on temporarily and then goes away again.

It also has load management and will control the HVAC based on the load at any given time.

To make sure each leg of the 220v is loaded properly, I did a seat-of-the-pants load analysis. Once everything's installed, I'll measure it with test equipment and make sure everything's OK.

And yes, it's plumbed into the propane tank. It's 300 gallons and with an average consumption of 1.68 gal/hr at an average 50% load, it would probably run for a week or so.

Hatterasguy · #9 12-04-2011, 09:50 PM

I'm going to install a 20k Generac on a house I'm doing now, or well my electrician is.

Amazon.com: Generac Guardian Series 5875 20,000 Watt Air-Cooled Liquid Propane/Natural Gas Powered Standby Generator With Transfer Switch (CARB Compliant): Patio, Lawn & Garden

Natural gas in my area so the fuel supply is essentially unlimited, however it only puts out 18k on NG if you read the fine print.

Angel · #10 12-05-2011, 12:13 AM

Quote:

Originally Posted by Dubyagee

It looks like a propane tank right next to the backhoe.

From another forum.

"The Kohler 12kW uses about 2.5 gallons of propane per hour at idle speed which is also 50% power output. When we lose power my genset never needs to accelerate beyond idle spreed. At 2.5 gal/hour I can run for 2-3 days assuming I let it run continuously. I have a 500 gallon burried propane tank but assumed that it would be at 40% full when we got the outage which is 200 gallons. These are all assumptions that I made when deriving my needs. You can get smaller above ground propane tanks (e.g. multiple 100 gallon tanks) and that might work just fine depending on what your backup needs. You can also manuallly turn the genset on and off to extend the operating life if you know the outage will be longer than the fuel you have. "

No offense to the poster - but this sounds fishy. Most AC generators never change "speed" - they run at 720/900/1800 (or 3600 in the old day) rpm and keep running at that speed reguardless of load. If your genset were some kind of DC generator with inverter (like those small 2000w red things) then you'd change speed with loading, but I'm guessing that its going to be difficult for a homeowner to check their generator loading by listening to it - you'd have to hear the exhaust note change (as load was added) or look at a load/watt/amp meter mounted on the generator (which I'm sure they all have). I just don't think they are going to change speed when you turn the A/C on (other than a momentary dip as the regulator catches up).

Thank you for the writeup - but did you say that this thing exercises and performs 2 switchovers weekly ? that sounds excessive to me- I thought that monthly was sufficient. I'd be a bit concerned because every electric motor in your house (that is running during the switchover) will get a small hiccup when the power switches from the line to the generator (and back). This won't hurt anything by itself but I'd be concerned that doing it 2x a week might shorten the lifespan of refrigerators, blowers, pumps etc. Is there a 'test monthly' option ?
(you are not the first person to buy one of these though, so I'm sure its not a big deal)

-John

KarTek · #11 12-05-2011, 05:19 AM

John, that sounded a little strange to me as well. I know some generators have a no-load idle feature for construction sites and such with intermittent loads but that would never work in a standby situation. As for RPMs, this is a 3600 RPM unit believe it or not. I was surprised the engine is rated at 32HP which is massively over powered for 12.5kw.

I think they just use the same chassis all the way up to 20kw.

Regarding the exercise schedule, I was just going off memory but I think it only runs once a week or month and doesn't completely switch over to gen power, just runs the engine to keep things charged/lubricated.

G-Benz · #12 12-05-2011, 11:15 AM

LOL! I like the use of the term "DIY" (just get the ole' tractor out of the garage and place unit on the concrete slab you expertly poured)!

Excellent effort for sure, but from the looks of things, I could visualize my impending "death by electrocution" just from the box install!

KarTek · #13 12-05-2011, 05:57 PM

Quote:

Originally Posted by Hatterasguy

I'm going to install a 20k Generac on a house I'm doing now, or well my electrician is.

Amazon.com: Generac Guardian Series 5875 20,000 Watt Air-Cooled Liquid Propane/Natural Gas Powered Standby Generator With Transfer Switch (CARB Compliant): Patio, Lawn & Garden

Natural gas in my area so the fuel supply is essentially unlimited, however it only puts out 18k on NG if you read the fine print.

That unit looks like the same series as the one I got. Even 18k is far more than the average home needs unless you're trying to run the dryer, oven and electric water heater too.

This one was $2400 at Costco, complete with the Txfer switch.

G-Benz, wiring is easy! 4 in and 4 out and some low voltage control. I've seen the work you've done with stereo installs and you could do it!

Brian Carlton · #14 12-05-2011, 06:10 PM

Quote:

Originally Posted by KarTek

This one was $2400 at Costco, complete with the Txfer switch.

G-Benz, wiring is easy! 4 in and 4 out and some low voltage control. I've seen the work you've done with stereo installs and you could do it!

How does that transfer switch work?

It appears to be a type of whole house transfer where the load is either fully on the generator or fully on the utility............quite different than the "traditional" transfer switch that provides six or ten circuits with individual breakers that interrupt power from the main panel.

If this transfer switch does have the incoming lines from the street routed directly to it, how did you make the connections to those lines in the existing house panel?

I'm thinking about a similar setup and I don't have what I consider a clean method of extending the existing lines that enter the main panel.

KarTek · #15 12-05-2011, 07:47 PM

It is indeed a "all or nothing" type transfer switch, essentially an "A/B" electromagnetic selector switch. The transfer switches you are describing are for lower power generators where you have to be very choosey about what you are powering during an outage.

Obviously, the more power you have at hand, the less you have to worry about an overload.

For the incoming power feed, I have a "master" breaker box combined with the meter at the service entrance. This master box feeds all the high power circuits - the garage, the whole house panel, the dryer and the stove/oven.

I simply intercepted the 100A feed going to the whole house panel and ran it through the transfer switch. Since it's downstream of a 100A breaker, I just shut the power off while I did the wiring.

Now, if you have an integrated meter socket/breaker box with all the house circuits in one unit, you will have to install a 50 or 100A breaker in it and add a smaller box nearby to contain the critical circuits you wish to back up - the fridge, lights, well pump if needed, HVAC, etc...

Then, you can run that 50 or 100A feed circuit through the transfer switch.

On the other hand, if you have a simple meter socket which has an unprotected output that runs to your house breaker box, you will have to coordinate with your utility so they can remove the meter temporarily for you to do the work without having to work with energized wires.

If you can describe your setup or maybe snap a pic, I can take a look and offer a suggestion.