Standby Generators

[GaryM]

I'm planning on incorporating a 15KW propane powered generator at the new house. I'm looking at a Generac two cylinder unit with an automatic transfer switch.

Does anyone else have a standby generator? Pros and Cons?

[fjseymour]

Gary, I have a 5.5 Kw gas powered standby genset. We have used it probably 2 times a year and find it to be a lifesaver.

We had one power outage from a spring snowstorm that lasted 4 days. I have a conventional forced air gas furnace, one-half hp. Water pump, central air conditioning and a gas cooking range. I am able to power the entire house except for the central air (never tried it). I also have 2 APC UPS units (the PRO series) with power conditioning for our computers so I can safely run them while on the genset. I would not be without the genset.

We have a manual transfer switch to protect the utility workers. The only thing I would do differently is my next one will be permanently mounted and would run on natural gas as we have natural gas service.

[gws]

I have a 10kw Dyna with a manual transfer switch. Great for those stormy nights when the lines are down.

[EJB]

I have a propane 8KW generator that is hardwired into the panel. Its also generac brand, and other than a dead battery on occasion haven';t had any problems with it. Mine is not automatic (i.e. I need to start it with a key and flip some switches to cutover to it when power goes out). If money is no object, by all means get the automatic switch, but for the 1-2 times per year that I need it I find it no problem to start it myself...you might save a grand or so if you forgo the automatic cutover capabilities.

Careful where you install the unit, I bought the house with it already here, but if I had to do it over I would put it outside in the garage...its is REALLY noisy when it is running...

[GaryM]

Thanks for the input!

We don't have natural gas available, so will be going with propane power. The 15KW unit is enclosed in a housing with an automotive type muffler and is supposed to be quiet. It will of course be mounted outside on a pad.

The only one I see has the automatic transfer switch. A manual switch would be Ok too.

[Hank]

<font color="blue"> will be going with propane power </font color>

I, too, am looking at a 15KW sized genset, propane powered. Have you found any realistic info about how much fuel consumption such a unit would take?

[kevinro]

I did quite a bit of research on standby generators for my house. There are several things to consider.

1) Fuel type: The three big choices are Gasoline, Diesel, and LP/NG. Gasoline and Diesel don't store for long term storage, so I ruled them out. Gas deteriorates, Diesel grows algae. Propane stores well, is widely available for home delivery, and can be used for other things in the house. Natural Gas is the best idea since you always get fresh fuel, and won't run out.

2) Size: The size of generator you need depends on what you plan to circuit into the generator. Two schools of thought are to put important things on the genset (heating system, fridge, minimal lights). The other is to put everything on the generator. Your needs may vary. For myself, and the layout of my house, it turned out to be more cost effective to put everything on the generator. I ended up with a 60KW genset. That gives me around 235 working amps of power. Since my house uses heat pumps, I ended up needing a fairly large amount of power to keep the house heated during a power outage. Since I was going to put everything on the genset, I needed something big enough to handle a moderate load for my house. My genset is automatic, so if I wasn't there, and the heating system was still kicked in, then the genset needed to handle it.

3) Cost: I did a cost analysis that swayed me towards the 60KW generator. The layout of my place is such that I have several subpanels in the house (6 of them actually). Each subpanel needed some stuff on the generator, some stuff not on the generator. In my situation, it turned out that running partial loads on the generator would have required dual busses through the house (one on the genset, the other not). The extra cost for the electrical work turned out to be a lot of money.

Here is the kicker: The price difference between a 20kw generator and a 60kw generator isn't as much as you would think! I bought a Cummins/Onan genset. The 20KW setup ended up costing about $16,000. The 60KW setup costed about $20,000. By getting the larger generator, however, I saved about $7,000 on the additional electrical work that would have been required on the smaller genset.

Don't know if this sort of thing would apply in your situation, but I thought I would point that out.

If you get a chance, you might want to look into Koehler and Cummins. The Generac units aren't very expensive, but they can be very loud. My 60KW unit is about as loud as my pickup truck idling at 1800RPM. Unforunatly, I can hear my neighbors Generac unit over my genset, and they are 1500 feet away through the forest.

[GaryM]

All good points to consider. I had never considered anything that big. And I really don't think I can afford to spend that much money either.

In a permenantly installed unit I would only consider gas rather than a liquid fuel. OK, I know it's liquid in the tank, but it's a gas when it gets to the generator!

I plan to put mostly lights and refrig. etc on the generator. We will have an electric resistance furnace and I don't think I can run that. We will have a wood stove in the recreation room so am not too worried about heat, although with a prolonged outage it may become an issue. I guess it would be smart to put the effluant pump for the septic system on the generator also.

[kevinro]

Gary,

Good catch on the septic system. The neighbors missed it on theirs, and that was a rather smelly mistake!

Even though they are a bit noisy, the Generac systems are a pretty good deal for the dollar, especially the one with the automatic transfer switch.

Just curious, why the electric resistance furnace? Seems like a heat pump or perhaps even a propane system would be more economical.

Kevin

[GaryM]

our current house has an air to air heat pump, and it works OK. But as you know the efficency drops with the temperature. We considered a geothermal heat pump but the installed cost is quite high.

This new house we are building is five star plus energy efficient. SIPs for the walls, ICFs for the basement and all that. The house designers claim that for the cost difference of a geothermal heat pump is too long to make it worthwhile. And don't forget that a electric resistance furnace is 100% efficient. At least at the furnace it is!

The current heat pump just doesn't provide the hot air from the vents that you want when it's really cold. And the darn thing runs 24 hours a day too.