need help on generator !!

i was wandering if any one new if a 6.5 kva generator would power a 4200w  gutter vac 

@spruce   u seem to be very clued on on these sorta things  :1f609: :2_thumbs_up_-_animated:

tench0771 said:

i was wandering if any one new if a 6.5 kva generator would power a 4200w  gutter vac 

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I believe that to start a motor it takes twice as much power as it does to run it. So when you have 2 motors running you're using 2800 watts. When you then start the third motor that briefly takes you up to 5600 watts so the 6.5kva should be big enough. 

The above might be a load of rubbish though, I bought a 6.5kva generator and I'm sure this is how the technical guy explained it. 

tench0771 said:

i was wandering if any one new if a 6.5 kva generator would power a 4200w  gutter vac 

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I saw your post on the other side and decided I would stay out of answering it. :1f602:

I honestly don't know the exact answer tbh.

I have a 1500w gutter vac with a single motor. The Chinese factory tell me in the worst case the vac motor will draw just over 3 times the running current for a fraction of a second. So in my case I would need a 5.0kva to be certain.

I'm guessing that the 4200w vac is 3 motors at 1400w each. Is this correct?

If so you aren't starting all 3 motors at exactly the same time are you? (Some vacs have 3 motors with 3 on/off switches.) If so then its my assumption that a 6.5kva (approx 6500w) is well within its capability. (Remember that a 6.5kva will probably only effectively produce 10% less than its spec in real conditions.)

Now, some charts that I've seen tell you to you should allow 2 times the starting current of each motor when calculating gen set size, so that's even better.

Nick Day who sells gutter vacs says his 1400w gutter vac can be used on a 2kva gen set. I'm sure he wouldn't say something if he hasn't experienced it, but it could also be that the vac motor in his gutter vacs may have some 'booster' such as 'soft start' or a 'starter capacitor'.

If I was going to buy a gen set I would hire that size from a Hire center to make absolutely sure before shelling out the notes. A 6.5kva gen set is a beast so I might hire a 5.5kva (very comon size) and see if I could get away with it.

I forgot to include:

The other thing you could do is ask the supplier of your vacuum unit what size gen set you need as I did.

Part Timer said:

I believe that to start a motor it takes twice as much power as it does to run it. So when you have 2 motors running you're using 2800 watts. When you then start the third motor that briefly takes you up to 5600 watts so the 6.5kva should be big enough. 

The above might be a load of rubbish though, I bought a 6.5kva generator and I'm sure this is how the technical guy explained it. 

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It will probably be much less than that as the motors aren't under load.

spruce said:

It will probably be much less than that as the motors aren't under load.

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I did say it might be a load of rubbish  :1f602: Once you go beyond wiring a plug I'm lost. 

I think you should be fine , I have a 5kva and run an omnivac 3600 watt 3 motor vac works perfectly never had a problem turn on one motor at a time let it get up to speed then turn on the next motor and so on 

phone a hire shop if you are concerned they would be able to give you the technical blurb 

Part Timer said:

I did say it might be a load of rubbish  :1f602: Once you go beyond wiring a plug I'm lost. 

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There's nothing wrong with what you said. The best is always to work on the motor's maximum current draw - if you do then you can't go wrong. :1f44d:

thanks for all the replys  yrs spruce its 3x 1400w moters  i do use a 2400w vac at the minit but if i upgrade ill probly get the 4200w vac with 100mm inlet ,its been a wile now ive been desiding on geting a generator but ive had enough of the messing about with finding power points ect , dare i even log in to the other side  :1f602:

tench0771 said:

thanks for all the replys  yrs spruce its 3x 1400w moters  i do use a 2400w vac at the minit but if i upgrade ill probly get the 4200w vac with 100mm inlet ,its been a wile now ive been desiding on geting a generator but ive had enough of the messing about with finding power points ect , dare i even log in to the other side  :1f602:

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Good replies on there as well as an electrical calculator.

The biggest problem is finding place in the van for a gen set. 6.5kva is heavy. So its best to mount it permanently which adds further complications with regard to fueling and exhaust. If we had a long wheel base van then this would have been a worthwhile addition, but we don't. We also aren't offering this service to new customers and not activately offering it to existing customers either. If someone wants their gutters done then it has to be prearranged.

I've got lwb vivaro I'll only put it in when I book job in get some ramps

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In an electrical workshop talking about fitting a 240v socket in my van. He said I would need a big inverter. Then he said do you want to buy a generator? The guy that rented the workshop left it. It was a 6.5 and had many years of dust on it and hadn't been started for years. He said if it works I can have it for £80. I looked it up on the net and I think its worth £200. Don't know if its worth 80, he is desperate to get shot of it. If I can get it started and it works then I will probably buy it. Any thoughts most welcome, cheers m.

for that price i would take a punt on it as long as it powers your vac that is, having said that the old saying buy cheep buy twice springs to mind, choice is yours m8 if it last u a year it would have payed for its self over and over, its wether u wana take a punt or not realy good luck with what ever rute u take tho   :1f44d:

tench0771 said:

for that price i would take a punt on it as long as it powers your vac that is, having said that the old saying buy cheep buy twice springs to mind, choice is yours m8 if it last u a year it would have payed for its self over and over, its wether u wana take a punt or not realy good luck with what ever rute u take tho   :1f44d:

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If I can get it started then I will buy it, he is an auto electrician and doesn't want it. See about it next week, busy catching up like everyone else and got that big molar out so not the full shieling at mo :1f602:

im shore it will be fine mate  :1f44d:

tench0771 said:

im shore it will be fine mate  :1f44d:

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What about those £200 generators? has anyone bought one and do they last long?

any info most welcome. cheers m 

what make is it?

if i was looking at a long turm generator ide spend £900 up and it would be a honda as u then no it will be relible when u need it ,a cheep one may not start or pull cord snaps on the job that would be a daster 

looks like one of those Clark one's. All I seen was the 6.5 on the side but resembles the clark.

clark  are very good so ive hurd snap it up if thats the case  its the cheep chinese ones that are crxxxxap 

tench0771 said:

clark  are very good so ive hurd snap it up if thats the case  its the cheep chinese ones that are crxxxxap 

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They are made in China now and the new ones aren't as good as the older ones