Whole house generator

[wpiman]

We are purchasing a new home next month and the home comes with a whole house backup generator that automatically starts up. This is great- however it uses propane and from what I can gather; it uses between 2-3 gallons per hour. For outages of a day; not a big deal. Beer stays cold.

If we lost power for a week or so; it could really add up ($6 an hour or so; $150 a day).

Ideally, I'd like it to come on automatically; and have Homeseer turn it off if it has been on for a few hours; and kick it back in after a few hours or until the UPS battery is low.

System is made by Kohler... not sure if anyone has an experience with these things.

I also need to add a propane monitor...

[Uncle Michael]

Do you know if the model you are looking at is compatible with a remote panel? If it is, it might be possible to use a relay closure to simulate the remote switch, but it doesn't sound like robust setup. Having HS operation dependent on the generator, which is, in turn, dependent on HS, seems risky at best.

[IanIreland]

Do you know if the model you are looking at is compatible with a remote panel? If it is, it might be possible to use a relay closure to simulate the remote switch, but it doesn't sound like robust setup. Having HS operation dependent on the generator, which is, in turn, dependent on HS, seems risky at best.

If the UPS in the equation can send HS info on it's state - then it should work.

[vasrc]

We are purchasing a new home next month and the home comes with a whole house backup generator that automatically starts up. This is great- however it uses propane and from what I can gather; it uses between 2-3 gallons per hour. For outages of a day; not a big deal. Beer stays cold.

If we lost power for a week or so; it could really add up ($6 an hour or so; $150 a day).

Ideally, I'd like it to come on automatically; and have Homeseer turn it off if it has been on for a few hours; and kick it back in after a few hours or until the UPS battery is low.

System is made by Kohler... not sure if anyone has an experience with these things.

I also need to add a propane monitor...

Unless you have a huge UPS, it's probably not to your advantage to cycle the generator on and off. Low load still burns fuel no doubt, but most UPS's will only give you 30+ mins so you'll end up starting/stopping the generator all day long. Starting is the hardest on any reciprocating machine, they like it best to just keep running. If it's a whole house setup, it's probably around 15KW or so and has a 100 gal propane tank. It would make more sense to beef up your UPS so you only need to startup every 6+ hrs. I think you'll find though that the family wants it on all the time for lights, AC, heating, etc..

www.tankutility.com has a nice tank monitor, but it's cloud based so your internet will need to be up (ie more load on your UPS ..

And you're right, they are propane hogs. I have a 500 gal tank and two 15KW generators and I can almost get 2 1/2 days fully loaded.

Z

[Uncle Michael]

I think you'll find though that the family wants it on all the time for lights, AC, heating, etc..

I agree. How likely is it that you will have a long outage, and how frequent are they likely to be? Compared with the cost of buying and installing a whole house generator, the cost of running the generator for a week every 10 years is probably not worth worrying about. Once a month would get expensive. How expensive, disruptive, and inconvenient would a long outage be without the generator?

[jrfuda]

My in-laws have a whole house generator and a 100lb propane tank, which will get them a day or two based on the load. They only use it for short outages. After an hour or so (ir first thing in the morning if they're asleep), my Father-in-law starts running drop cords to key appliances and sets up a ~5k gasoline generator to keep the fridges, a few lights and a TV running. If the power comes back before he's done, not big deal. If not, he turns the whole house gen off and runs the gas gens until power is restored. Got them through Matthew last year when they went a week without power.

The good thing about this is it gives them the convenience of an auto-start whole house gen with the longevity of a gasoline gen only powering a handful of items.

[wpiman]

Unless you have a huge UPS, it's probably not to your advantage to cycle the generator on and off. Low load still burns fuel no doubt, but most UPS's will only give you 30+ mins so you'll end up starting/stopping the generator all day long. Starting is the hardest on any reciprocating machine, they like it best to just keep running. If it's a whole house setup, it's probably around 15KW or so and has a 100 gal propane tank. It would make more sense to beef up your UPS so you only need to startup every 6+ hrs. I think you'll find though that the family wants it on all the time for lights, AC, heating, etc..

www.tankutility.com has a nice tank monitor, but it's cloud based so your internet will need to be up (ie more load on your UPS ..

And you're right, they are propane hogs. I have a 500 gal tank and two 15KW generators and I can almost get 2 1/2 days fully loaded.

Z

Yeah; this one is a 45 kW with a 500 gallon tank. The propane is used for heat and hot water as well. I will look at the tank utility.

I almost wonder if maybe a Tesla Power Wall or something similar would help as well. The generator even idling uses up a lot of juice. Running it for a shorter amount of time to charge up a whole house battery might be more efficient.....

[S-F]

Yeah; this one is a 45 kW with a 500 gallon tank. The propane is used for heat and hot water as well. I will look at the tank utility.

I almost wonder if maybe a Tesla Power Wall or something similar would help as well. The generator even idling uses up a lot of juice. Running it for a shorter amount of time to charge up a whole house battery might be more efficient.....

45 KW! Great Cesar's ghost! Maybe time to look into other forms of making hot air and water!

[wpiman]

45 KW! Great Cesar's ghost! Maybe time to look into other forms of making hot air and water!

Somebody's wife really bitched during a blackout...

[vasrc]

Yeah; this one is a 45 kW with a 500 gallon tank. The propane is used for heat and hot water as well. I will look at the tank utility.

I almost wonder if maybe a Tesla Power Wall or something similar would help as well. The generator even idling uses up a lot of juice. Running it for a shorter amount of time to charge up a whole house battery might be more efficient.....

Considering the price of the powerwall ($6K / 14KW) + inverter, wiring etc, you'd probably need to add an alternative charge source (solar/wind) to justify the cost.

45KW is huge.. 500 gallons is going to go fast. I'm surprised they didn't put in a diesel tank..
Why so large? What's your normal household load?

Z

[S-F]

Why so large? What's your normal household load?

Amen!

That's enormous. I'm all for having a generator but I think I could survive personally with a few KW. No luxuries could run. I'd have to keep the hot tub off, but man! I have run my house on a 1 KW generator before. It's just enough to keep my desktop, the server and related infrastructure, the boiler and lights for one room up and running.

[wpiman]

Amen!

That's enormous. I'm all for having a generator but I think I could survive personally with a few KW. No luxuries could run. I'd have to keep the hot tub off, but man! I have run my house on a 1 KW generator before. It's just enough to keep my desktop, the server and related infrastructure, the boiler and lights for one room up and running.

I did not put the generator in; it is in the house we are purchasing.

It is essentially 200 Amp service.... I see why they picked the size.... worst case analysis.

If it were me; I would only have powered one phase and put the fridges and heat on them.

I should rent out the room in the basement during outages to defray the cost.

[Uncle Michael]

I did not put the generator in; it is in the house we are purchasing. .... worst case analysis.

Unless the house is over 10,000 SF and extremely energy inefficient, I have trouble believing there was any analysis done. More likely an accomplished salesman and naive customers. We almost never use more than 8 KW, even with the AC running. The only time we'd use more is if the compressor and an oven cycle on at the same time at night when there are lots of lights on. I'm having trouble imagining the circumstance that would result in 5-6 times more electricity consumption. (Charging a couple of Teslas at max speed? Electric resistance heating in Fairbanks? . . .including driveway snow melting?)

[wpiman]

200 amp service at 240 VAC... 48kW.....

My current house has 100 amp service; and we have never ever come anywhere near using that.

It is total overkill-- but I get where the numbers derive from.

[vasrc]

200 amp service at 240 VAC... 48kW.....

My current house has 100 amp service; and we have never ever come anywhere near using that.

It is total overkill-- but I get where the numbers derive from.

The good news is the fuel consumption is pretty linear with load, so if you run at 25% (12KW) it's only about 100cf/hr (2.8 gals) which is average for home generators. Loading it more, just cost you more. I can't find number for below 25% but I suspect it becomes non-linear somewhere before idle, but it's still going to be better to just let it idle on low load (usually overnight) than starting/stopping it I suspect. If it's the newer 3600 RPM model then it's pretty stable down low as well.

Z