Nordyne dry units

[BaldLoonie]

Found out today that the scroll in them is coming with POE oil in it, not mineral oil as you'd expect. Idea behind that is using R407C instead of much more expensive R22. That gas is approved by Nordyne for warranty purposes. But we're back to the old POE and mineral oil issue. Local tech rep says blow the he!! out of things with nitro or even use an RX11 flush. Of course that adds cost to the job and most dry unit jobs are wanting bottom dollar. But then you could save by using 407C and not worrying about oil.

One of our guys went to a class on refrigerants recently. He was told that Copeland may be shipping replacement 22 compressors with POE in them. Wonder how they'll identify them and any procedures they'll want done. Cornfusing.

[hvaclover]

My Nordyne guy didn't know until I told him about your post. said he has so many r22 units from last year he's not sweating the coming of the POE units but would find out about it and get back to me.

Baldy, what's 407C going for in your area?

[mark beiser]

POE and mineral oil are completely fine mixed together in any ratio, hell, throw some AB oil in there too, it doesn't matter, there are no ill effects from mixing them from a lubrication or chemical compatibility standpoint.

The issue with mineral oil in R-410a systems is that mineral oil is not miscible in HFC refrigerants, so any that makes it out of the compressor may not return to the compressor, and will tend to settle out in areas with low refrigerant velocity, like the evaporator coil, and cause a reduction in capacity.

POE and mineral oil are both miscible with R-22, so there is nothing to be concerned about.

Copeland has been shipping HCFC refrigeration compressors with POE oil in them for more than a decade. Mineral, POE, and AB oils have been getting mixed in refrigeration rack systems for a long time now, with no ill effects.

[BaldLoonie]

The tech rep told me what they were selling 407 for but I can't recall right off. Quite a bit less than 22.

So, Mark, no special procedures then? No flush? Just hook up the unit like always?

[mark beiser]

So, Mark, no special procedures then? No flush? Just hook up the unit like always?

Yeap, there really is no bad juju between mineral and POE oil, it has been mixed in HCFC refrigeration systems for years.
POE oil is actually a better lubricant, just don't get water in it...

The issue with HFC refrigerants is purely due to mineral oil's low miscibility with them.

[cuchulain]

I agree with mark. We took a class this winter and the instructor informed us that one reason that 22 uses mineral oil, is that when it was first being produced the mineral oil was cheaper then the poe and it just stuck. 22 and poe oil will mix with no problems involved, but as mark pointed out 410 will not mix with mineral very well due to the miscibility.

[Ron223]

Great information! A close friend got shafted and stuck with a dry unit set in place and walked away from. I've been trying to find an alternative solution to using 22. So can I flush the system and use 407? And do I still use the same procedures with it in ensuring proper SH and SC? Are its characteristics the same? I've only worked with 22 and 410.

[chaard]

Why if R407c is available and cheaper, then the MFR's aren't just shipping dry R22 units with R407c? I'm assuming the new dry R22 units contain POE oil. I'm reading a Bristol bulletin from 1995 about retrofitting an R22 system to R407c. That's 17yrs ago. What's the hold up.

[mark beiser]

That's 17yrs ago. What's the hold up.

There is a significant capacity loss, and about 11º of glide, so the refrigerants in the mixture leak at significantly different rates.

[SBKold]

In the tech manual online for duponts MO99 drop in they actually recommend blending in 10-25% Poe oil in with total mineral charge.

So is this another confirmed source documenting no ill effects blending them?

[ga-hvac-tech]

There is a significant capacity loss, and about 11º of glide, so the refrigerants in the mixture leak at significantly different rates.

Please correct me if I mis-read... 407C is similar to 410; After a % of the charge leaks out, it is better (or necessary) to remove the entire charge and recharge with virgin? Do you know what the %'s are for 407C and 410 (roughly)? THX!

[mark beiser]

Please correct me if I mis-read... 407C is similar to 410; After a % of the charge leaks out, it is better (or necessary) to remove the entire charge and recharge with virgin? Do you know what the %'s are for 407C and 410 (roughly)? THX!

Yes, if there is a small leak in a system using R-407c, the composition of the blend will change. The amount of change depends on the size and location of the leak, how long it has been leaking, etc..

The composition of R-410a won't change enough to worry about it, basically ever, as it only has about 0.3ºF of glide.
If you were to start with a full drum of R-410a, and top off a number of systems by vapor charging with the drum, the composition of the blend will have changed by less than 1% by the time you get to the last bit of refrigerant in the drum.
Outside of a lab that has tightly controlled conditions, and lab grade instruments, you would not be able to detect a difference in the performance.

[ga-hvac-tech]

Yes, if there is a small leak in a system using R-407c, the composition of the blend will change. The amount of change depends on the size and location of the leak, how long it has been leaking, etc..

The composition of R-410a won't change enough to worry about it, basically ever, as it only has about 0.3ºF of glide.
If you were to start with a full drum of R-410a, and top off a number of systems by vapor charging with the drum, the composition of the blend will have changed by less than 1% by the time you get to the last bit of refrigerant in the drum.
Outside of a lab that has tightly controlled conditions, and lab grade instruments, you would not be able to detect a difference in the performance.

THX Mark!

And all this time, I have been charging 410 as a liquid because I thought it would be 'out of balance' if I charged gas. Probably will still charge liquid though...