Generator install - where to start

[edgarrian]

We have a generac whole house generator. We built in 2015 and the HVAC company we used had just gotten a big shipment of generators in. So we took advantage. I believe it was 5k for everything. The unit and install. If you go on generacs. They have a dealer locator. I maintain my own. Super easy to do. I just changed my battery 2 years ago. I have it set to fire up once a week for 10 minutes.

the last time the unit came in handy. Is when we had my wife's 50th birthday party. We lost power for the whole party. It was hot out so thank goodness for the generator. Our main reason for purchasing the unit. We have two freezers in the garage full of meat. So thats a lot of money down the drain if we happen to lose power for a significant amount of time. At the time I was also working away from home. It gave my wife peace of mind knowing she would always have power as i would be away for 2 weeks at a time for work

 

[WinterDeere]

When these generators do these test runs, do they switch house load onto them, or do they just run unloaded? And if they do switch house onto the genny, what is the transfer / outage time during the switch?

I'm thinking it can't be good for anything with a compressor (HVAC, refrigerators, pool heater, dehumidifiers, etc.) to be switching off and right back on again, if they happen to be running at the moment, let alone the frustration of having the clocks on the microwave and oven resetting all the time.

 

[ponytug]

When these generators do these test runs, do they switch house load onto them, or do they just run unloaded? And if they do switch house onto the genny, what is the transfer / outage time during the switch?

I'm thinking it can't be good for anything with a compressor (HVAC, refrigerators, pool heater, dehumidifiers, etc.) to be switching off and right back on again, if they happen to be running at the moment, let alone the frustration of having the clocks on the microwave and oven resetting all the time.

Generally, no they don't switch, which means that the generator usually runs without a load. That leaves two issues; one, the transfer switch isn't tested, and two, the ability to handle a load isn't tested nor does the generator get fully warm.

On you second point, yes, I think hot restarts are hard on most reciprocating compressors. Inverter and scroll compressors are better at handling the switch as they can ease back into any existing pressure. But I am not an HVAC pro like @Sigarms, and I am sure that he has an informed opinion based on a lot more real world experience than me.

All the best,

Peter

 

[edgarrian]

Generally, no they don't switch, which means that the generator usually runs without a load. That leaves two issues; one, the transfer switch isn't tested, and two, the ability to handle a load isn't tested nor does the generator get fully warm.

On you second point, yes, I think hot restarts are hard on most reciprocating compressors. Inverter and scroll compressors are better at handling the switch as they can ease back into any existing pressure. But I am not an HVAC pro like @Sigarms, and I am sure that he has an informed opinion based on a lot more real world experience than me.

All the best,

Peter

when we install ours. I had it tested. We ran the oven. We ran our air conditioning, Ran stove top. Dryer. Lights were on. It was good. Now in the even you lose power. Id probably not have all those appliances running at the same time so you can save on fuel. But if there is wash in the washing machine by all means finish it.

10 minute run time allows for the unit to warm up. I think any longer run times and you are burning fuel for no reason

 

[tradosaurus]

I was pulling my after-lunch double shot of espresso, when the machine conked out. My first thought, being in the middle of a long stretch of working 7 days per week, with only breaks for eating, sleeping, and whining here, was "oh great... no coffee now."

But no, it wasn't the espresso machine... some A-hole took out a telephone pole down the road, on a perfectly nice a sunny day. Hopefully he's okay, but given the week I've had, I wasn't exactly singing his praises.

Long story short, the portable genny ain't cutting it, I actually ended up losing about 19 hours of computer time that I really couldn't afford to easily lose on my current schedule. I also gave the transfer switches in my UPS's such an extreme workout over the last few hours, that I'll be surprised if they're not headed for the scrap bin soon.

I've already looked up some generator install companies, it's time to move on this now. Since I have basically zero time to put on it myself, I'm going to be calling companies that do complete turn-key solutions.

The computer simulation was just re-started. With no interruptions, I won't have results until Monday night.

I might have missed the info but how often do you lose power and on average how long is the power outage?
The power pole taken out was a fluke.
I have a 15Kw portable generator with electric start that will power the essentials.
I've been out of power the longest for about 3 days but that is rare. Normally around 6 hrs once a year.
I don't have natural gas nor propane.

 

[JRH02]

Happy Generac whole house user here. I had mine installed by a local electrical contractor that is an authorized Generac dealer/installer. I'm on natural gas and that knocks the power output down to 19,500 from 22,000 watts. It is NOT brushless as I initially stated. grsthegreat pointed that out and i looked at the parts break down and confirmed I was wrong. I have had it for not quite 2-1/2 years. It's not logged a lot of time working. After a Derecho went through just 3 or so miles north in 2023 and all the carnage that brought with some people being without power for up to 2 weeks I felt it was a good investment. It runs I believe 30 seconds after start up before the power transfers. Upon power restoration it's seamless and instantaneous on return to line power. It exercises every 2 weeks for I think 5 minutes. It sets outside my shop on a pad and is very quiet. According to Generac 67 decibels under full load.

Gotta love a 22kw generator buzzing along for a few thousand watts load. But you sure don't have to worry about load management or surge starts.

 

[grsthegreat]

generac units DO NOT transfer load during exercise. so you dont have to worry about constant resets. That being said, i recommend to my customers to manually throw the transfer switch and do an extended run prior to winter to test everything under load.

my unit is hooked into the Genmon system, so i can remotely run generator AND transfer a load while utility power is present. this prevents and reset issues AND can exercise under load for as long as i want by the settings.

 

[grsthegreat]

honestly. a 22kw generator running a house that pencils out to a 16 kw running load uses LESS fuel than a 16 kw would maxed out. Generacs 22kw units seem to me to be the best of the best of Generacs units. ive had the absolute least issues with this sized generator. it was the best mix of engine and alternator size. ive had more issues with the 24 and 26 as of late. i think alternator size outpaced engine power myself...but thats my own opinion only.

and i only have about 300 generaqtors to base this off of ...while there are millions out there/

 

[WinterDeere]

I might have missed the info but how often do you lose power and on average how long is the power outage?

It's unpredictable and inconsistent, as you'd imagine. When I moved into this house 15 years ago, the prior owner showed me where he'd installed a panel feed for a generator 16 years prior to that, before telling me he never got around to the genny install "because we never lost power". Then we had a 2-day outage with hurricane Irene 1 week after settlemen, followed by a 4-day mid-winter outage due to an ice storm that winter, followed by another 4-day outage due to hurricane Sandy the following summer. That's 8 full days in a single year!

I mentioned this to a neighbor, that the seller was full of sh*t, and they said no... he was correct. They'd never had any extended outage in 20 years, until the day I moved in.

In the time since I'd guess we average one outage per year, that's long enough that I bother to pull out the portable genny and set up the backfeed. But they can often be a full day, if not a few days, and my wife and kids aren't going to be able to set up if I'm not around to do it for them.

The power pole taken out was a fluke.

Mostly true, but less so than you'd assume, unless you're familiar with Pennsylvania roads. Most of our roads are narrow, winding, zero shoulder, and poles are sometimes right on the edge of the road. We also have no local speed enforcement, so people drive whatever speed their car can manage. It's great fun for anyone who owns a sports car end enjoys driving fast, but accidents do take out poles on a more regular basis than those in other regions might see.

Having said all that, yeah... more outages are probably caused by falling trees and branches, or ice on the lines, than cars taking out poles.

I have a 15Kw portable generator with electric start that will power the essentials.

I'm cheaper than you! I've been running this place on 7 kW, but it does mean turning off HVAC during an outage. That's fine for a day, but miserable in extended summer outages, in our climate.

 

[ning]

honestly. a 22kw generator running a house that pencils out to a 16 kw running load uses LESS fuel than a 16 kw would maxed out. Generacs 22kw units seem to me to be the best of the best of Generacs units. ive had the absolute least issues with this sized generator. it was the best mix of engine and alternator size. ive had more issues with the 24 and 26 as of late. i think alternator size outpaced engine power myself...but thats my own opinion only.

and i only have about 300 generaqtors to base this off of ...while there are millions out there/

I'm curious, how many houses average a 16kW running load?

My house is typically around 2.5kW (fridges, freezers, lights, computers, etc) during the day, plus probably 3-5k more for AC during the summer, and more intermittent well pump; about 1kW at night.

 

[WinterDeere]

I'm curious, how many houses average a 16kW running load?

My house is typically around 2.5kW (fridges, freezers, lights, computers, etc) during the day, plus probably 3-5k more for AC during the summer, and more intermittent well pump; about 1kW at night.

We average near that in summer, but we're in 8000 sq.ft. with four HVAC systems and a heat pump keeping our swimming pool at 87°F. Three of our six refrigerators are also in an unheated and often stifling hot garage, and my business computers eat electrons all day and night.

I've always joked this house has the carbon footprint of some small towns.

That said, right now with lights off, no well or HVAC running, and my computer idling (not running calculations), we're holding 2.84 kW. Our primary heat is wood and oil, but we do have two minisplits for smaller areas.

 

[grsthegreat]

I'm curious, how many houses average a 16kW running load?

My house is typically around 2.5kW (fridges, freezers, lights, computers, etc) during the day, plus probably 3-5k more for AC during the summer, and more intermittent well pump; about 1kW at night.

we have LOTS of all electric homes up where i live because electric is so cheap (hydro). they can easily top 16 kw. heck, i have customers on 48kw and one on a 130 KW that cant handle entire house. did i mention there are loads of wealthy people out here.

 

[ponytug]

We average near that in summer, but we're in 8000 sq.ft. with four HVAC systems and a heat pump keeping our swimming pool at 87°F. Three of our six refrigerators are also in an unheated and often stifling hot garage, and my business computers eat electrons all day and night.

I've always joked this house has the carbon footprint of some small towns.

That said, right now with lights off, no well or HVAC running, and my computer idling (not running calculations), we're holding 2.84 kW. Our primary heat is wood and oil, but we do have two minisplits for smaller areas.

Ever considered putting an exhaust fan in the garage? That would seem as if it would pay for itself pretty quickly helping the refrigerators use less power.

For outages, I used to use a 4kW generator, then upgraded to a 5kW diesel set. It worked great except for the manual connection part, and being jackhammer loud. Neither could start the almost never used AC. Our current genset is 10kW diesel that purrs like a kitten, inside its sound attenuating enclosure, but you absolutely need hearing protection if you open a door while it is running. I'm not sure what happens if we switch to a heat pump for heating. TBD.

The new fridge seems to have reduced our base load somewhere between .1-.2kW. That is a chunk for us, but we operate a much smaller footprint here, smaller house, no pool.

All the best,

Peter

 

[JRH02]

I boggles my mind the amount of power people can use.

 

[Larry Caldwell]

Generally, no they don't switch, which means that the generator usually runs without a load. That leaves two issues; one, the transfer switch isn't tested, and two, the ability to handle a load isn't tested nor does the generator get fully warm.

On you second point, yes, I think hot restarts are hard on most reciprocating compressors. Inverter and scroll compressors are better at handling the switch as they can ease back into any existing pressure. But I am not an HVAC pro like @Sigarms, and I am sure that he has an informed opinion based on a lot more real world experience than me.

All the best,

Peter

I'm not smart about AC, but I have noticed that if there is a power dropout, my heat pump takes a significant amount of time to start up again. 10 minutes?

 

[WinterDeere]

I'm not smart about AC, but I have noticed that if there is a power dropout, my heat pump takes a significant amount of time to start up again. 10 minutes?

Most modern heat pumps have a built in timer circuit, to prevent trying to start an already charged-up compressor. Even some dehumidifiers and refrigerators have these circuits now, although not as universally as heat pumps.

Our mini splits and newest HVAC compressor have these delay circuits, as I think does our kitchen refrigerator and one dehumidifier. But our largest HVAC compressor is something out of the last millenia, very old-school bang/bang contactor control, and we have several smaller refrigerators and one commercial dehumidifier, which all lack any sort of time delay or soft start.