View Full Version : Whole house backup generator
My power company is absolute garbage. I have multi-hour power outages at least once a month, along with several "bumps" that take us down for short periods. Probably once a week. (I come home to reset clocks and such). I need a backup solution to run my house when this occurs.
Priority goes to maintaining climate in the house. I need to keep the house below 80 and above 65 or so. I am on AC and propane furnace. Well pump and pressure pump need to run, or I get no water, and I have a stand up deep freezer. 1620sq ft house, 3 bed, 2 bath, unfinished basement.
Need an automatic transfer switch for when I'm not home.
Looking at Generac, Briggs, Kohler, whatever. Any particular one to get? I'm thinking 12k+ watts. I have propane on site, but would actually prefer gas/diesel (but I know those get spendy).
If I get time I’ll snap a picture of one I just saw in our warehouse the other day. It must be pretty swanky. It’s powered by a Cummins diesel.
It was cheaper for us to get a 20 kW than a 12 kW because the latter would have required a lot more labor for a special panel of critical circuits. With the 20, they just wired straight into the main board. Very happy with the propane Kohler. It's nice getting emails whenever it starts up and shuts down. I bought from electricgeneratorsdirect.com and found local electrician and a plumber for the propane hookup; no regrets.
Grant H.
09-18-2018, 12:20
In the price range that I think you are looking at, I would go with Generac.
Gas/diesel, as you mentioned, are spendy and a lot more maintenance intensive. For what you want, especially with propane on site, I would go propane.
I would just work with Generac and let them know what you want/need. The last set of generators I did for a customer ended up being from Cummins with their ATS, but Generac was very helpful in the quoting process. (They were slightly bigger than you're looking for - 80KW gensets).
I had a 22KW Generac installed when our house was built. Runs off propane and is enough to run the well, Air conditioner and anything else we need. Also had the automatic transfer switch installed. We have needed it a couple of times and works great.
thedave1164
09-18-2018, 12:50
Propane would get real expensive for any real length run time, gasoline powered will be quite a bit cheaper than diesel.
that is all I got
I'm gonna vote 20Kw minimum. Add up your loads, multiply by 1.5 (round up). Keep in mind that 150 amp service @ 120V equals 18Kw...
Hmm. Was going to snap a shot of that brand new generator in the warehouse but seems someone moved it. It was likely a backup for purchase power at one of our meter sites and probably got moved to the location for installation.
They saw you drooling over it the first time and muttering "Cummins" over and over and figured they had better move it [Coffee]
I'm interested in what you decide on because I plan to include a backup gen system in a remodel. I'm also on propane and plan to use that for the generator because it has big storage, doesn't deteriorate, and has lower engine maintenance. I have a 5K Honda gen but it isn't set up for automatic.
I know a fellow in Ned who sells and services GE whole house generators, but I haven't studied the options.
https://gensizer.assurancepower.com/index.php?option=com_aps&view=calculator&layout=wholehouse&Itemid=55
A Load calculator for generator sizing. I put some numbers in quick. Figured on a 3 ton Ac. Came out as 22kw. To meet code with an automatic transfer switch for the whole house you either need to size generator to load calc or rent a power logger for 30 days to see what your peak kw was. I don't know if you power company can give you that information or not.
Screenshot of sample load calc.
76160
NEC 220.87
220.87 Determining Existing Loads. The calculation of a feeder or service load for existing installations shall
be permitted to use actual maximum demand to determine the existing load under all of the following
conditions:
(1) The maximum demand data is available for a 1-year period.
Exception: If the maximum demand data for a 1-year period is not available, the calculated load shall
be permitted to be based on the maximum demand (measure of average power demand over a 15-
minute period) continuously recorded over a minimum 30-day period using a recording ammeter or
power meter connected to the highest loaded phase of the feeder or service, based on the initial
loading at the start of the recording. The recording shall reflect the maximum demand of the feeder or
service by being taken when the building or space is occupied and shall include by measurement or
calculation the larger of the heating or cooling equipment load, and other loads that may be periodic in
nature due to seasonal or similar conditions.
(2) The maximum demand at 125 percent plus the new load does not exceed the ampacity of the feeder or
rating of the service.
(3) The feeder has overcurrent protection in accordance with 240.4, and the service has overload
protection in accordance with 230.90.
NEC 702.4
(B) System Capacity. The calculated load on the standby source must
be in accordance with Article 220 or by another method approved by
the authority having jurisdiction.
(1) Manual Transfer Equipment. The optional standby power source
must have adequate capacity for all equipment intended to operate at
one time as determined by the user.
Author’s Comment:
n When a manual transfer switch is used, the user of the
optional standby system selects the loads to be connected to
the system, which determines the system kVA/kW rating.
(2) Automatic Transfer Equipment.
(a) Full Load. The optional standby power source must have adequate
capacity to supply the full load transferred.
electronman1729
09-22-2018, 22:41
My power company is absolute garbage. I have multi-hour power outages at least once a month, along with several "bumps" that take us down for short periods. Probably once a week. (I come home to reset clocks and such). I need a backup solution to run my house when this occurs.
Priority goes to maintaining climate in the house. I need to keep the house below 80 and above 65 or so. I am on AC and propane furnace. Well pump and pressure pump need to run, or I get no water, and I have a stand up deep freezer. 1620sq ft house, 3 bed, 2 bath, unfinished basement.
Need an automatic transfer switch for when I'm not home.
Looking at Generac, Briggs, Kohler, whatever. Any particular one to get? I'm thinking 12k+ watts. I have propane on site, but would actually prefer gas/diesel (but I know those get spendy).
My guess is your seeing the power drop when a gas compressor is started.
porterdavid98
09-24-2018, 14:39
Propane would get real expensive for any real length run time, gasoline powered will be quite a bit cheaper than diesel.
that is all I got
I disagree that any extended use with propane would be much different from gasoline or diesel. Call your propane supplier and ask their experts what they think. I went with propane primarily because it is so much cleaner. Gasoline in storage for long periods degrades and additives increase the cost so that needs to be considered as well. Then all commercial generators made for gasoline will specify non-ethanol fuel. Very expensive. Now diesel could be a good choice but see how easy it can be had in your area using farm or non highway use fuel. About a 40 cent per gallon savings.
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I had a whole home one and I had 400 amp service for the home because I had a large home and lots of electricity being used in it. I had a Generac and transfer switch that could handle the whole load and never had an issue with it. Would do its weekly self test and come on by itself which was comforting to hear. Ran on propane out in the country north and east of Kiowa so I know what you are saying about not wanting to count on the electric always being there.
Bumping this up with a more realistic expectation for my allowed budget. (The big genset will have to wait)
Looking at a (3700w running/4500w starting) inverter generator (dual fuel- propane/ gasoline). Too many sensitive electronics in everything these days. (And I dont necessarily need to run the well all the time since I have a 400 gal storage tank in the basement)
Current questions for the better informed out there:
1. Does my reasoning sound about right? I want furnace, fridge (or freezer), a secondary pressure pump for my water tank (other is 240), kitchen lights, the damn propane valve that kills gas without power, TV/modem/PC would be nice.
2. Are there 120v only manual transfer switches out there, or am I relegated to running cords? Most everything I see references the 240 plug.
I have a 1000 gal propane tank on site that I could run a line off of for fuel, along with several BBQ tanks I keep around. I try to buy ethanol free gas for the RZR, so rotation is not an issue.
Grant H.
04-12-2019, 22:45
Never used this one, but quick search netted this: https://www.amazon.com/Go-Power-TS-30-Automatic-Transfer/dp/B00153EYTO
I've used other Go Power! options for things, and they work. Not the best, but functional.
I can't remember the brand of the big ones we used for towers in WY, but when I come up with it, I'll share.
In general, I agree with your thoughts of a smaller genset. You can always offload some circuits to refill the tank with the well when you don't need XX.
Colorado Osprey
04-13-2019, 05:34
Never used this one, but quick search netted this: https://www.amazon.com/Go-Power-TS-30-Automatic-Transfer/dp/B00153EYTO
I've used other Go Power! options for things, and they work. Not the best, but functional.
I can't remember the brand of the big ones we used for towers in WY, but when I come up with it, I'll share.
In general, I agree with your thoughts of a smaller genset. You can always offload some circuits to refill the tank with the well when you don't need XX.
That GoPower transfer switch is an RV solar style transfer switch. Be aware that all these transfer switches do fail and need to be installed in an enclosed location. A good policy is plan to replace the transfer switch every couple years as you service your generator for ultimate reliability. The relay contacts will burn up after repeated uses. These RV transfer switches were designed for safety rather than a power switch so that you could not have 2 power sources working at the same time doubling incoming power.
Grant H.
04-13-2019, 07:24
Good info to add. Thanks.
We have used similar ones with generators, and they work, but you are correct they are a solar product first.
ETA:
As you're taking about manual, why not just have an additional service breaker put in, upstream of your panel, and add a 240v plug in between the additional breaker and original, and then just plug your generator in after isolating the house? A generator of that size will have a 240 source (at least ours do). Then use your normal breakers to serve what you need.
Good info to add. Thanks.
We have used similar ones with generators, and they work, but you are correct they are a solar product first.
ETA:
As you're taking about manual, why not just have an additional service breaker put in, upstream of your panel, and add a 240v plug in between the additional breaker and original, and then just plug your generator in after isolating the house? A generator of that size will have a 240 source (at least ours do). Then use your normal breakers to serve what you need.
I havent found a budget friendly inverter generator with a 240 plug. The one I'm looking at sure doesn't and it's a grand.
https://www.homedepot.com/p/Westinghouse-4-500-3-700-Dual-Fuel-Gasoline-or-Propane-Portable-Inverter-Generator-with-LED-Display-and-Remote-Electric-Start-iGen4500DF/308134845
Here’s a similar transfer switch I have, it’s pretty fool proof.
https://www.lowes.com/pd/Reliance-30-Amp-10-Circuit-Transfer-Switch/4712891
I've had two houses set up for generators and they are essential to me now that I've used them. I installed a transfer switch at my last house and it worked well to supply heat, a few light circuts, and power for the well.
I found a system that works better for me when I moved to a different home. The "interlock" is used instead of a transfer switch and it is so much better for me and my usage. It's easy to install, less expensive, and offers much more flexibility in what I can run during power outages. I lost power for about 20 hours in the March blizzard and I had power for all my essentials and for lights. I can use power in any room and I just have to manage the total amount of power I am using. It's a much better option for me and I wanted to share this with others. I am listing one company which sells the interlock but there are many out there if you search around. This is the company I used and I am happy with the product and the price.
https://www.geninterlock.com/
Good luck in which ever way you go.
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