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Backup generator location etc.

Posted by tomplum 7-8 (My Page) on
Fri, Nov 14, 08 at 21:05

I have a Onan RV generator that I decided would be more useful as a backup generator. If we found ourselves with no power in our greenhouse especially it would be bad as we need to drive our fish tank pump at a minimum. So my thought was I could locate it in the corner of the garage, put in a transfer switch, etc and be able to maintain a few circuits.
As you research things such as exhausting, venting, etc -it gets a bit overwhelming. When these things are built in an rv box, they don't seem to overheat or have huge venting requirements. The generator install manual shows 500 cubic feet/ min needs to be able to be drawn through. Any examples you see are big generators. Am I just better off building a little shack out back and running cable to the main panel? Taking a couple feet of space out of the shed attached the the greenhouse is fightin' words!

Also, is the power from these clean enough for electronics? I've always heard the better generator manufactures claim they were more consistent that the basic say contractor type generator.


Follow-Up Postings:

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RE: Backup generator location etc.

  • Posted by canguy British Columbia (My Page) on
    Fri, Nov 14, 08 at 23:14

You should run it a minimum of 10' from a window or door so you don't suck fumes through a fresh air inlet.DO NOT put it in an attached garage.
The RV gens provide reasonably clean power but you should provide some surge protection for electronics. Also, run it through a transfer switch that isolates it from the main power. Bad things happen if the power comes on and back feeds the generator.


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RE: Backup generator location etc.

canguy, Didn't you mean to say, "Bad things happen when a generator is back feeding a line when the linesman is trying to repair it?" That's what transfer switches are all about.


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RE: Backup generator location etc.

  • Posted by canguy British Columbia (My Page) on
    Sat, Nov 15, 08 at 22:47

Yes, it ruins a lineman's day too but the generator will also suffer if it is not protected when the line power is restored.


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RE: Backup generator location etc.

I agree that it certainly needs to have a transfer switch, but I am unsure that with a proper installation- why you would be concerned about having it in an attached garage? Please enlighten me. Code issue?


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RE: Backup generator location etc.

  • Posted by canguy British Columbia (My Page) on
    Sun, Nov 16, 08 at 19:15

The exhaust could be drawn into the living area and there is an increased risk of fire. Our local codes mandate that the unit be placed outside 3 feet from a wall and ten feet from an opening.The main concern is exhaust being sucked in through a fresh air inlet.
The unit also requires a large amount of cool oxygen rich air for proper running and cooling. As well, the heated air must be moved out so it can be replaced.


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RE: Backup generator location etc.

if you put it in teh garage you MUST vent it outdoors and the exhaust must terminate higher than your roof and above any windows. by teh time you get the exhaust plumbed in porperly you might as well have just built a little shack for it outside. some people even put them in those plastic dog hsoues and then simply pop the roof off to run it.

double check that the genny is 240/120V, as many RV gen sets are 120v only. not a big deal, just means you can't run any 240V items off it.

i have my genset sitting on teh back porch right now. it normally sits by my shop, but i moved it there a week before my wife went into labor and never moved it back yet. if i run it under the back porch you smell exhaust in our breakfast room and laundry room, the 2 rooms surrounding the porch. and this is with 2 sides of the porch wide open and a 10ft ceiling to boot! imagine what would happen if it were running in a garage. all you have to do is search for storm related generator deaths, most all of them are caused by CO not by electrical shocks/fires. people run them in garages and under carports and the fumes get into the house and kill them.

why not get a wheel kit for it, store it int eh garage, and when needed roll it outside and hook up teh cords?


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RE: Backup generator location etc.

I had this vision that if I chose the garage, I might be better off doing the shack outside of the wall. I also had the thought that an enclosure could be created to handle the venting, cooling and exhaust concerns. You are correct on the limited capacity of the genset. Fortunately, we seldom lose power- but we can't have the greenhouse/ fish tanks unpowered for too long at a time. Thanks Canguy for the clarification. Also thank you davidandkasie for your input as well. The doghouse idea joggled my brain. We have a rubbermaid storage unit which could have the same effect with some venting and anti-meltdown mods. I thought about the cart- but it needs to be as easy for the misses for when I'm gone. Plus, I would need a a different tank set up and who knows what on the exhaust.


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RE: Backup generator location etc.

Output question-

I welded up a stand and did the initial run this afternoon. I haven't ran this unit in a couple of years so I thought it best to get some maintenance done whilst it was in the shop. My AC voltage was a bit high. w/ no load it ran a relatively steady 129v w/ a fluctuation of about .5 volt. With a 1500w load (heater), output was 124.5- 126.4. I'm hoping it might be that the rpms might be a little high. Sound feasible? It is about 10 year old Onan BGE. Are there voltage stabilizers that are inexpensive enough that I could use in line?
On the DC side of things I have a .35 v draw when it isn't running that I want to isolate. I went to pull the main control fuse and it seems stuck. Does it just pull straight out?


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RE: Backup generator location etc.

as far as teh voltage being high, that is within specs and normal for low end gensets. under a bigger load it should come right at 120v. it also matter whether your voltmeter is a true RMS meter. i have seen 5 different meters give 5 different readings hooked to the same supply voltage.


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