Home Generators

[Jims5543]

I am shopping for one... well actually two. I need one for my office and one for my house. After the hurricanes last year and being without power for 10 days then 12 days all in one month I have decided this is the way to go.

I have a 7500 watt portable but I want to get something that will run the house like nothings wrong in the world.

I am looking at a 15KW Generac Guardian LP generator. Its air cooled and modestly priced at $2975.

I want to be able to run a normal house (few lights, TV, fish tank, Fridge, etc..) and be able to run my 2.5 Ton central air.

Will 15KW be enough? A friend ran his central air with a 7500 portable but could run nothing else he also had to stage the startup of the compressor and air handler, if they both powered up at once it would overload.

Sorry for the long post. I am hoping someone out there has more experience than I with this. Thanks in advance for any input.

[widebody911]

You really need to talk to an electrician. It's impossible to spec out a power supply without knowing what your expected load is, which involves inventorying everything you'd be running and doing some math. I've spec'd UPS's for data centers, so I have kind of an idea of what you're up against. Get the setup with the shunt into the main panel - that would be the bomb.

[joehahn]

If no one steps up PM me. My in-laws just installed the mac-daddy whole house system that operated for the first time w/in the last week. I can get the details if needed. It is phenomenal. I def. see one of these in my future.

joe 68 L

[URY914]

You need to speak to a electrician or electrical engineer. There is much more than just buying the generator if you plan on running the entire house on it. You'll need a transfer switch which "transfers" from the perminate power source to your gen unit. You'll also need another electrical panel and conduit. The panel and switch can cost you more than the gen unit. All this takes up room so plan on giving up part of your garage walls and floor space.

Not saying it can't be done but you need talk to a pro.

Paul

[azasadny]

You also need to ensure that your natural gas meter has the capacity to handle the generator if you want to use natural gas. I'm looking into this because as a Ford employee I can get a 30% discount off the price of the Generac 15K generator (actually gets 12K using natural gas). My electrician says it's no problem and he will hook it up for me (I fix his computers) but my heating/cooling guy said my meter may not be able to handle the additional load on it. Winters wouldn't be too bad because you're primarily running the furnace and lights, but the summer with A/C, refrigerator, lights, etc... may be a problem. Best bet is to get an electrician and HVAC guy to look at it first.

[DByers]

Definatly talk with a local electrician or EE with background in this area. Not sure about Florida, but in Ca. that model wouldnt pass the Db levels for residential use without a special barriar. Permits may also be a problem since it is not considered portable. Local codes and inspectors will dictate the ease or diffulculty of doing this.
Also the generator itself is the cheapest part of the equation if not planned for properly.
Think of what you truely would want to able to have powered and for what duration in case of an emergency. Whole house is overkill in an emergency outage.
Again, a reputable EC can help you with all this.

[skipdup]

There's also some issue about hooking it up right. Something about a barrier/insulator to the lines feeding the house. Very serious... A "lineman" for the electric co. can be easily killed by a generator hooked up incorrectly, while he repairs the damage that caused the outage in the first place. I can't remember how/why... but seems like it has something to do with stepped up power when it goes backwards through the feeds... Or, something like that...

- Skip

[competentone]

Originally posted by Jims5543
I want to be able to run a normal house (few lights, TV, fish tank, Fridge, etc..) and be able to run my 2.5 Ton central air.

You may want to consider forgetting about running the central system and just use a smaller generator with a window a/c unit. Considering that your generator may not be used except for a few days every 10 years or so, keeping the capital outlay to a minimum -- and "roughing it" a little after a storm -- can make a lot of sense.

You can buy a small window a/c unit for very little money (less than $100) and use it to keep the temperature and humidity down to a tolerable level in a room or two of the house.

[Jims5543]

I have a 7500 watt portable unit now and it was a major PITA after the Hurricanes. Where I live, we were hit dead on by 2 of the 4 storms that hit Florida last year. Getting gasoline after the storms is next to impossible. I had 40 gallons on hand but, unfortunatly, that lasted 5 days then I got to stand in line for gas for 3 hours to get more. Even then I was limited to how much I could buy.

We tried the "roughing it" thing and it was fun for 2 days. Remember a hurricane came through our screens are ripped and mosquitos are everywhere. The daytime temps hit high 90's and humidity is 100%. Florida in September is not a fun place to be without air conditioning.

I am looking at 15KW units. They come with the fuse box and autoswitching mechanism so that is covered. Yes, this has to be professionally installed. The unit, when running, is not louder than a A/C compressor.

They are predicting the same atmospheric conditions this summer again. So we are expecting a nasty hurricane season. I am not playing the portable generator game again.

[dhoward]

Originally posted by skipdup
There's also some issue about hooking it up right. Something about a barrier/insulator to the lines feeding the house. Very serious... A "lineman" for the electric co. can be easily killed by a generator hooked up incorrectly, while he repairs the damage that caused the outage in the first place. I can't remember how/why... but seems like it has something to do with stepped up power when it goes backwards through the feeds... Or, something like that...

- Skip

That's why you need a properly wired transfer switch.

[gaijindabe]

Can the supply of natural gas be interupted by a hurricane? As for LP - how much can be stored? Does anyone use diesel? Doesn't it store better than gasoline?

[RickM]

I used to buy and sell these things...more as a hobby for pocket money than for a living. So here's a brain dump.....

Much of your choice will come down to budget.

While planning you have to consider what will be used while there is a power outage. Critical circuits only or what you'd typically use with utility power. Start-up load is very important. A well pump may only consume 4kw of power when running but may require 8kw to start. There goes the 5000kw (Surge, not continuous) rated Home Depot generator.

IMO the best choice is to go with NG if it's available. Diesel units can tap into a home heating oil tank for fuel...there a bit louder and smelly but live a very long time. Gasoline is messy, can go bad and may not be available and you have to transport in small quantities. Propane is expensive and requires tank refills.

Output from a NG unit will be less that the same running on propane or gasoline. However it's a bit quieter and you'll likely never have a shortage of the fuel.

You want the lowest RPM machine you can afford. For home back-up I would not buy above 1800RM. Lower RPM ranges are from 1100-1800. Other units are considered by many to be "Lawn Mower" engines. They're louder and comparitively short lived. These units are typically sold at Costco, Home Depot etc and run at 3600rpm. Do they work? Yes. Will they suit your needs? Maybe. Will it last as long as an Onan, Winco or higher end Generac? Not close. Hmmm, how is it that the discount store 15KW units are 20-30HP and the "commercial" level ones are 50-70HP?????

Transfer switches are what isolate power sources. Manual units look like big Frankenstein switches. Automatic switches are great but as you go up in Amperage the amount of the check you're writing gets much larger. Again a choice you make. Is it critical that power be continued if you aren't present? Do you mind throwing a switch, starting the generator and vice versa when the utility is restored? Traditionally 200-300 amp manual tranfer switches were in the thousands of $$$. My Square D lists for about $1800 (a good price). However, I've seen equally rated units at Harbor Freight for $200-$400.

Below is the 4 cylinder/65 HP Onan I have on a trailer.....sold to a gentleman in CA. Waiting to get picked up. I'll replace it with another similar Pre-owned unit (cost $1000-$3000). These things can handle a good sized house with many appliance running concurrently. Take the advice from others.....get an electrician to help plan and install.....further, an electrician that has experience in this field or else you'll end up being a guinee pig.

Edit: Remember if looking at used generators for a home you want 1 phase / 60 Hz.