My husband is looking for a smaller generator than the 6000w he has, I was told today that in order to run an air compressor he would require a minimum of 5000w, the compressors not a large one, its a portable dual hotdog. He wants to get a 2500w so its easier to move around. The sales person I was speaking to said that the air compressor would burn out the motor of the generator due to the power required to start the compressor.
So what do you guys think? Opinions please
From building boxes and fitting face frames to installing doors and drawers, these techniques could be used for lots of cabinet projects.
"I have learned so much thanks to the searchable articles on the FHB website. I can confidently say that I expect to be a life-long subscriber." - M.K.
Dig into cutting-edge approaches and decades of proven solutions with total access to our experts and tradespeople.
Start Free Trial NowGet instant access to the latest developments in green building, research, and reports from the field.
Start Free Trial Now
Replies
2500W would be sketchy. The starting current required by electrical motors can be many times what the running current is, especially for compressor motors. I'd stick with the 6K unit.
Scott.
Always remember those first immortal words that Adam said to Eve, “You’d better stand back, I don’t know how big this thing’s going to get.â€
Thanks Scott.
why the "easier to move around?"
Can he get a gas driven air compressor and mount it in the back of his truck, then drive it near the house he is working on?
Welcome to the
Taunton University of Knowledge FHB Campus at Breaktime.
where ...
Excellence is its own reward!
Oh..... one thing I forgot to mention... it's his brother- in- laws 6000w. When we borrowed it, (which he didn't like doing) we gave it back in the fall. We can't leave anything at the cottage yet, since it's not built yet. But he has other jobs that he needs to keep lifting the generator up and down from the back of the truck into the garage and at the cottage it's the same thing. So the 6000w is quite heavy.
Just wondered if the sales guy was correct in what he was telling me. We have a friend that rented a small generator and started his compressor up with it no problem. But how many times will this happen before the engine goes.
Think outside the box a little. Could he build 2 small platforms (one at home and one at the cottage) at tailgate height? Then the generator could just be slid in and out, rather than involving any lifting. And with a wheel kit, it would be even easier.
You'd have to make provisions so the vibration wouldn't walk it off the edge, but a simple 2x4 lip at the edge would do it.
Now that sounds promising, great idea. I will propose it to him. It makes sense to buy the big generator since we could probably use it as a backup at the cottage.
thanks alot for your suggestions.
Speaking of backup at the cottage, I have a suggestion. You'd have to check it out with the local code officials.
When you're wiring the house, put in some outlets that are NOT CONNECTED in any way to your panel. Home run these to the generator location. That way, when the power goes out, switch a few lamps to the generator circuit, turn it on, and you're good to go. Saves the cost of a transfer switch, and beats running extension cords everywhere.
Now, thats a different issue, great idea will include it in my wiring notes/suggestions for when we get to that stage. But we are going with a full solar system with propane as a backup, but there may be times that we will require the generator just in case. To pull hydro down was almost 10,000.00, we could buy the full generator system for that type of money or go solar.
I LIKE the idea of tailgate at platform height.But dual wiring would be more expensive than a transfer switched system IMO
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
I don't know. When I built my last home, the transfer switches I saw were almost $1000 just to purchase them. Seems to me that a dozen duplexes placed strategically throughout the cottage would have to be cheaper. It would also be easier to limit the amperage draw, IMO.
My last was six hundred for either six or eight circuits, forget which
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
WE might even be jumping the gunn on that issue.
Cabin as second home out in the back skeeter land and they need a generator to build it...maybe there is no power available and the genset will power the whole cabin.I wonder if skeeters can be harnessed to provide power...??
;)
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
It does help to know the whole situation.A 2500 might get you by, but like the others said, it would be borderline. This sounds like one wheere the salesman gave good advise. Sometimes they really are your freind and not just trying to upsell you.But the coist of replacing a genset if it does happen to wear out too soon vs the cost of a damaged back from lifting a 6000 in and out...I have a 6000 Onan and there is no way I would do that without wheels and a ramp. If I absolutely had to have one to evac in and out like that, I might take a chance on the smaller one and baby it - that means you don't get to make milkshakes on the blender while his compressor is running...;)
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
Still thinking on this
They make wheel kits for generators too. There is a Honda one that has two wheels and a pair of handles so it moves like a wheelbarrow.
Welcome to the
Taunton University of Knowledge FHB Campus at Breaktime.
where ...
Excellence is its own reward!
I think this is the one he would be interested in definately a Honda and it must have handles and wheels.
Thanks
I have to agree with SCOTT. Without knowing the start-up wattage and run wattage of the compressor and generator eyeball figuring says its too small.
"If all else fails, read the directions"
<<So what do you guys think?>>
I'd suggest that y'all get back to basics, nail by hand. Then you can buy a smaller generator to run your saw, etc.
Did I forget to tell you that we live in Ontario ,so between blackfly season (they can almost carrry you away their so big) rainy season, mosquito season and the 6 months of snow we get, we only have about 2 weeks to build, so... hence the generator now I'm sure there will be lots of nails, but they will probably be hammered in by me in a very controled enviroment, I don't always get the "good" jobs when I'm working with my husband on things.
So, since I want the cottage soon, I will get him the Honda generator that you guys tell me I need to look at , and I want to buy it next week.
<<Did I forget to tell you that we live in Ontario ,so between blackfly season (they can almost carrry you away their so big) rainy season, mosquito season and the 6 months of snow we get, we only have about 2 weeks to build, so... hence the generator >>
I thought you Canadiens were made of steel!
I spent two summers, canoeing in the Quetico when I was a teenager so I certainly recall the mo-skeeters. When I first saw them I thought they were a loose formation of humming birds.
And I can appreciate why you'd prefer to use a nail gun. So why not get a Paslode? I'm not real well acquainted with them but that seems like a good answer for your situation. No hoses to drag around either.
Another solution, one which I've used for many years, is a folding utility trailer. They're low to the ground, will carry a half ton of stuff, fold up and caster against a garage wall, taking up about one foot of floor space. They're very useful for things that are hard to load in a pickup, motorcycles and atvs for example. I've trailered bikes for thousands of miles, just so I could ride in some great place where a truck just doesn't cut it. You can buy a folding utility trailer off Ebay for $350 US.
Edited 3/28/2007 2:43 pm ET by Hudson Valley Carpenter
For a remote location like that, he might consider a Paslode nail gun. Gas fired piston
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
Yep. I can see it now!Piffin shooting down clouds of hummingbird sized 'skeeters with his trusty Paslode... :)Think of the ad revenue!
Revenue generators - do they ccome in the 6K size?
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
Your in Ontario????
http://www.leevalley.com/garden/page.aspx?c=1&p=10137&cat=2,51520
This is alot better than platforms at each end."No doubt exists that all women are crazy; it's only a question of degree." - W.C. Fields
O.K. the compressor is a 3HP, we have not hydro and no propane, the paslode gun is a life saver and has been used. We have the basment walls up and the subfloor is on. THe 6,000w Honda is already killing his back and you guys know the size of the blackflys. So back to my question, will a 2500w do the job if only the compressor is being used.
NO. Too Small a generator for that size motor.
Edit to put advice at top - the 2.5 kW genset will probably run your compressor just fine, check the nameplate amps against the advice below. I just went and looked at a 3 HP motor in the basement and it is rated 9.3 A at 240 V which is still less than 2500 KVA, YOU WILL BE OK with the 2.5 kW genset.
Typical compressor motor is 3450 RPM and are slightly higher efficiency than the 1750 RPM, so I'll guess for your compressor at an 83% efficient motor.
746 watts per HP X 3 /0.83 = about 2.8 kW.
Now however, the compressor motor rating is probably a commercial rating where they calculate the advertised HP on total watts, heat, losses, peak!!even; so an advertised 3 HP is really only 2238 watts divided by sqrt of 2 which is only about 2.1 HP or only 1600 watts.
The motor is probably about 0.85 power factor so if you look at the nameplate, the amps should be in the 8-9 amp range for 240 V. That means the motor pulls about 2 KVA, which is kilo-volt-amps, and is different than watts.
Your gen set is rated 2.5 kW, so you will be OK as the KVA capability of the genset is definetely higher than the kW rating, they at least have never tried to advertise like that.
Note that when the compressor starts, the 2.5 kW rated gen set will really change pitch but will chug back up to speed.
If you buy a cheap 2.5 kW genset with a briggs or tecumseh engine and the compressor starting stalls the engine out (unlikely if a Honda engine) you still have an out - just change the motor pulley on the compressor to one about 20% smaller.
Edited 3/28/2007 10:43 pm ET by junkhound
You may well be right,
I was forgetting to convert the gen. to 220.
My error.
You are assuming this 3HP motor is wired for 240 - which is best, but not certain- so if it is wired to 110, the amp draw could be in the range of 18-20 and more by far on start-up or cold mornings.Agree that a Honda would be the only way to go for this challenge
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
We will check out the amps tonight and advise.
thanks
See if it is wired for 110 V or 220V.And if you have a tester - Example - I have a motor that can be wired either or. I have it as 110V because I often take it on jobs where no 220V is available. It is suppsed to draw no more than 18amps running, but tester shows that it routinely draws down 19.8 amps.
On startup, the spike is nearly double that. This is when your compressor will make a gen engine grunt for a second under the new load, then things even out. A Honda will handle that. a cheap Briggs engine is just as likely to sputter and stall - remember learning to drive with a clutch?
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
I read somewhere that starting a compressor with the petcock open reduces the start up load, since there is no pressure in the tank to fight. would this help the situation?
bobl Volo, non valeo
Baloney detecter WFR
"But when you're a kibbutzer and have no responsibility to decide the facts and apply the law, you can reach any conclusion you want because it doesn't matter." SHG
bobl,
You are partially correct. Every compressor I have ever dealt with has an "unloader" valve. This valve releases the pressure in the compressor cylinders. That makes for a no load start up.
However once the compressor starts it's work of compressing the air that valve closes and the compressor is fighting the pressure in the tank. The longer it runs the more pressure it has to overcome.In cold weather most compressors have a difficult time turning over due to the stiff oil in the case and adding the built up tank back pressure causes over loading of the motor.
I pull out the pressure relief valve and hold it until the compressor reaches full operating speed before alowing it to close . This helps because the compressor then doesn't have to fight back pressure as it warms the oil. Better yet is to store the compressor in a warm place or warm it up prior to starting.
I never thought about it. We always open the drain cock at night to let the water out of the tank, so in AM we turn it on first too , then close the drain.
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
Thanks for all that info. we will check it out tonight and advise.
You have been a great help.
I scanned the posts, some mis-information out there making you do more than you need to.
A small 1HP or smaller compressor can easily run off even a 1500 Watt gen set, a 2.5 kW genset is fine.
All that happens is the smaller genset voltage droops and frequency slows down while the motor starts, the gas engine chugs everything back up to speed together, nothing is overloaded, no damage to anything. Just like hitting a clump of tall grass with your lawnmower.
A 2500 W genset can easily handle a small compressor, esp. if the compressor is the only thing on the genset. I run my small 1 HP compressor off an 1800W generator with no problems .
If you are tying to watch TV or run a computer off the genset at the same time the compressor starts, the computer may shut off due to low voltage and the TV picture flicker off, etc. But the compressor will start and no damage done.
Yes, I 'is' an EE if you wonder.
How about this? Consider a Honda EB 3000 generator and a Jenny AM780HC4V gasoline powered compressor. The Jenny compressor is identical to the old Air Mate series from Emglo. When I am working by myself I use this set up because I can lift it all and not throw out my aging back. I do have to use my Honda 6000 with a larger crew but we run that up and down a ramp that was made for a lawn mower.
Like the previous poster I have a Honda generator, mine is 3500 w. and I use it all the time to start and run an old Emgloe twin tank finish compressor. Compressor is 1 1/2 hp.
I finally burned the compressor motor up after 8 yrs. of using them together, the generator is just fine. The compressor actually burned the motor out when on line power.
Problems occur during cold weather, the generator simply lacks the start up capacity when the temps are near freezing. I warm the compressor first by setting it near the idling generator exhaust until the crankcase feels warm to the touch.
Now another idea is a small bed mounted hoist for the generator.
readily available , hand or battery powered, and will lift the beast right into the bed.
Edit: The compressor will handle one framing gun without problems, it does not keep up with a stapler being run at high speed however.
Edited 3/28/2007 8:29 pm by dovetail97128
Oiled compressors will need alot more power to operate than the oil-less models. Especially in colder weather.
Thoughts determine what you want,Action determines what you get