smpha8

I heard rotary vane type wasn't the best way to go. I know I want a 2 stage,lowest micron rating, 7 to 10 cfm pump but is richie,jb, and yellowjacket my only options or does anyone have other opinions and good reviews on vacuum pumps. Thanks---Steve Meyer in Louisville Ky.

RoBoTeq

What kind of work do you do? If residential, then a 5 cfm pump is more then enough.

There are several reasons to not evacuate too fast or too deep. Too fast can freeze vapor molecules which then causes them to take longer to evaporate by sublimation. Below 250 micron oil boils. This is fine if you are evacuating a new line set with new coil, but if you are evacuating an existing coil or an entire system, you are going to be boiling off oil below 250 micron. You will know when this happens as the oil vapor starts bellowing out of the pumps exhaust.

smpha8

Thanks for the info. I do more residential than commercial but really want a higher cfm pump for installs (lineset and coil) and I'll use my 6 cfm for 2 to 5 ton existing system service work. I also know the oil in the R-410-A systems is quite different than R-22 systems. I only install 410 systems now because of the code changes as of Jan. 1st 2010. I need a higher cfm pump to get the 500 micron draw on new installs. It seems to take too long with my 6 cfm,2 stage pump. I was told the JB-DV285N pump is a good reliable unit.

RoBoTeq

If your 6 cfm pump is not pulling below 500 micron evacs in a timely manner, there is something wrong with either the pump, your lines, connections or something in the way you are evacuating. Are you changing the pump oil regularly and keeping the oil level correct?

smpha8

My 6 cfm pump is the problem. Its 12 yrs. old now and while pumping a 4 ton system down (condensing unit,lineset and coil), I let it run for about 90 minutes. I checked it then at 460 microns and came back 30 minutes or so and it was 395 microns. I turned it off and checked the oil,connections, etc. I started pumping it down again and it only took 20 more minutes to reach 500 microns. I didn't change oil or anything else but let it cool off before I ran it again. My local distributer said when it warms up after running for a while is when the seals in the pump start to fail on older pumps. I think I'll just get a 7 cfm 2 stage and use it for all my applications. I do change the oil after all repair or contaminated system pump downs and might let it go several times before changing oil if I use on an install job. Do you have an opinion on a good pump? Thanks! Steve Meyer (master hvac contractor) in Louisville Ky.

RoBoTeq

I do pump oil changes pretty much the same way. I have always used Robinaire pumps, but I'm sure there are other good ones.

mechanicalDvr

I have always had good luck with Robinaire as well. I bought a pretty expensive Yellow Jacket pump a while ago and it seemed to have leaking seals from the get go, it was fixed twice under warranty and leaked again, it's now a door stop in my garage.

RoBoTeq

That's a shame. Yellow Jacket makes quality products in many other products.

Could have been a bad unit or even one of a bad batch. I have a piece of crap Honda lawn mower, and I know that Honda makes good mowers.

henny

I currently have 4 pumps. I'd rate them in the following order:

Yellow Jacket
JB
Robinaire (the older style)
Harbor Freight (don't laugh, I don't use it for HVAC)

I thought I read that Robinaire is now manufactured in China.

RoBoTeq

What isn't made in China any more? I'd be afraid of having another child for fear he'd come out Chinese

mechanicalDvr

Well as long as he didn't have heavy metals in his blood you'd be ok.

RoBoTeq

Reminds me of Mr. Wong who's Chinese wife had a Black baby. Mr. Wong decided to name the baby Sum Ting.

DuMass

DVR… I don’t know if this could be related the issue you’re having with your YJ pump, but it’s just something to check on if you haven’t already, as it could be why it’s not pulling down properly.
There was an omission in the YJ users manual that was supplemented with a red toe tag in the box for the older SuperEvac pumps.
The thing with YJ, at least with the older 6 CFM SuperEvac, is that the oil level has to be checked and adjusted after you start the pump. If you change the pump oil and just fill it to the line in the site glass, it’s not full. You need to run the pump and add oil until it is up to the fill line in the site glass with the pump running.
Hopefully, this is all that's wrong with it.

DuMass

[quote=RoBoTeq;972]There are several reasons to not evacuate too fast or too deep. Too fast can freeze vapor molecules which then causes them to take longer to evaporate by sublimation. quote]

I may be all wet here, but I seem to recall that keeping the gas ballast valve open longer could also help prevent a larger CFM pump from pulling a system down to quickly, as well as it’s intended function, that being to help prevent contamination of the pump oil from moisture in the system being evacuated.

RoBoTeq

[quote=DuMass;1308]I've only ever used the gas ballast valve to open for easier startups and to close on shut down to relieve pressure. Outside of that, I haven't thought much about the function of this device.

beenthere

1 CFM per 7 ton, is all you need.

If your current pump is worn out. Still don't need a larger one. One of the same size will pull down faster then your worn out one.

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