getting the right size vacuum pump

[chrashley]

What would be a good cfm of vacuum pump to have. I do only resi work. What are the best brands and why? Thanks!!

[weber]

I recommend the YJ 1.5, because its the best setup I have ever used.

[beachtech]

we use 5 cfm and 6 cfm pumps

[weber]

we use 5 cfm and 6 cfm pumps

Well, that explains alot

[BigJon3475]

I have a 3 cfm dual stage I think it's a bit to big for the systems I have. I would try and get the smallest dual stage possible.

[beachtech]

Well, that explains alot

i use what they give me

http://robinair.com/product-new/deta...=1061&catid=11

[mario_m]

This thread may help you:
http://www.hvac-talk.com/vbb/showthread.php?t=159232

Go to the JB website (jbind.com). There is plenty of literature available on selecting a vacuum pump that is right for you. Try to find a distributor of JB, they may let you test out some vacuum pumps. I'm currently testing a 7 cfm and a 3 cfm.

The most simple way to sum things up is that cfm doesn't mean a whole lot. Once the system reaches a vacuum, which is usually less than a couple minutes on small systems, a 1.5 cfm to a 10 cfm work pretty much the same.

[beenthere]

They work the same. But the larger one will still be drawing quicker. The primary is still bigger.
If you draw too quick, you could form ice crystals.

[bdivell]

I personally use a 6 cfm Yellow Jacket and have a never had a problem with it very easy to use and quick

[beenthere]

I use a 6 also.
Have seen a lot of guys use 7's.

No need for a large vac, for small resi stuff though.

[BigJon3475]

All I work pon is small residential sized systems. I have to play with the ballast within a few minutes to keep it around the 3000-5000 microns.....I'd rather it take a little longer to make sure it's not forming crystals instead of boiling off.

[chrashley]

So a 5 or 6 cfm YJ, robinair, or JB pump would be the best way to go. And always dual stage...right?

[beenthere]

If your not going to work on anything bigger the 20 ton, a 3 CFM works good.

But a 5 or 6 will do also.

[weber]

So a 5 or 6 cfm YJ, robinair, or JB pump would be the best way to go. And always dual stage...right?

Or 1.5

[chrashley]

OK, OK, I'll bite. Why the YJ 1.5. How long does it take to pull down an average system. I went to the Yellow Jacket site and I do like what I see. I'm a big fan of most of the Yellow Jacket stuff. But according to the JB site vacuum pumps are rated by multiplying the cfm of the pump by itself and that gives you the tonnage that the pump is rated for. So a 1.5 cfm vacumm pump is only rated to handle a 3 ton system. Wouldn't the 4 cfm unit do better? Just asking, not preaching.

[BigJon3475]

Check out triple point.
http://en.wikipedia.org/wiki/Triple_point

@ a certain point all three phases can be together.

If you were to translate into standard numbers it would be:

32.1ºF and 4588 microns someone correct me if I'm wrong. (273.1598 K (0.0098 °C) and a pressure of 611.73 pascals (ca. 6.1173 millibars, 0.0060373057 atm)

If you pull down to fast the moisture in the system will freeze over and after it freezes unless you add more heat it won't remove the moisture. I use my ballast on my vac. pump to keep it around 3000-5000 microns to help promote vaporization of the moisture in the system since the temp is usually well above 32.1º you have more room to play with as your microns drop......i.e.....as temps rise the triple point absolute pressure drops.


So basically why waste your money/time/energy on using something that will be to big....can it be used yes....but to be sure your removing the moisture you need to you might have to baby sit it.

[weber]

OK, OK, I'll bite. Why the YJ 1.5. How long does it take to pull down an average system. I went to the Yellow Jacket site and I do like what I see. I'm a big fan of most of the Yellow Jacket stuff. But according to the JB site vacuum pumps are rated by multiplying the cfm of the pump by itself and that gives you the tonnage that the pump is rated for. So a 1.5 cfm vacumm pump is only rated to handle a 3 ton system. Wouldn't the 4 cfm unit do better? Just asking, not preaching.

1.5 cfm is good upto 10 tons.

Evacuation time is very quick, but that has alot to do with the setup and the system.

[chrashley]

1.5 cfm is good upto 10 tons.

Could you site your source on that please.

[weber]

Could you site your source on that please.

Its everywhere!

But heres a link if you dont trust me!

http://www.yellowjacket.com/techques...erevacfaqs.asp

[chrashley]

Perfect. I think I'll probably go with that then. It looks like a really good line of pumps. The features seem all beneficial and (of course) it looks to be a quality product.

Didn't mean to ruffle your feathers there. You just seem to be on the small side of things...as it pertains to cfm's and vacuum pumps. I wouldn't know otherwise!!