Heat Pump ?s

[jamesgangnc]

I've done a fair bit of my own hvac work. I replaced a couple of gas furnaces and one split ac. I'm building a new garage with living space above it out at my lake house. I picked up a "slightly" used goodman 1 1/2 ton heat pump compressor off craig's list. It was installed as part of an attic conversion that was never completed. While the seller was moving out of the house the low side line was damaged and it lost charge. Fast according to the seller.

The guy didn't know enough to shut the valves. Instead he hacksawed off the lines. Folded the small one over and stuffed a piece of foam in the big one. I cut them off with a pipe cutter, closed the valves, and blew them out with compressed air. I was worried that I probably did not get all the copper filings from the hacksaw so I opened the valves and blew the lines out again via the third tap. (The one that is used to check pressure during heat mode.) I didn't get a lot of air to move through it though that way so I doubt I blew out any more filings.

So I'm worried that there still may be some copper filings in the lines. What else can I do?

I'm also a little worried that it may have lost some oil when the low side was broken. There doesn't seem to be any easy way to drain and refill the oil though.

I won't be installing it from a few months. I'd like to go ahead and vaccum it down. Can I do that via the third tap? I'll fill it with some r22 after I vacuum it.

[ilbebauck]

Using R11 in liquid form makes for a very good solvent in cleaning out a contaminated system but youll have to get someone in the Trade to get some for you ; its not available for Consumers. Short of that, I would first vaccuum out the lines as best you can then replace the liquid line filter drier which may have come with the Heat Pump unit already installed, or, add an external Bi-Flow type just outside of the unit in the liquid line once you are installing the Unit . You can add a small amount of Refrigerant Oil for the compressor via the open Suction Line , so when the system is put into operation (cooling mode) , it will suck the added oil into the crankcase of the hermetic compressor ; id find out the total oil capacity for that specific compressor and add 10-15% of the total capacity it is supposed to contain . Use the correct oil -- it doesnt take 10w30 Oil ! Its a special oil formulated for A/C compressors.

[Stormin Mormon]

CY: yes, those are good skills to have.

I'm building a new garage with living space above it out at my lake house. I picked up a "slightly" used goodman 1 1/2 ton heat pump compressor off craig's list. It was installed as part of an attic conversion that was never completed. While the seller was moving out of the house the low side line was damaged and it lost charge. Fast according to the seller.

The guy didn't know enough to shut the valves. Instead he hacksawed off the lines. Folded the small one over and stuffed a piece of foam in the big one.

CY: Compressor oil absorbs moisture from the air. When you go to reinstall, you should vacuum the system to 500 microns, and leave the vacuum pump running at least an hour. Also, please install an ovesize filter drier, as you may have a lot of moisture trapped.

I cut them off with a pipe cutter, closed the valves, and blew them out with compressed air. I was worried that I probably did not get all the copper filings from the hacksaw so I opened the valves and blew the lines out again via the third tap. (The one that is used to check pressure during heat mode.) I didn't get a lot of air to move through it though that way so I doubt I blew out any more filings.

So I'm worried that there still may be some copper filings in the lines. What else can I do?

CY: Liquid and suction line filter driers comes to mind.

I'm also a little worried that it may have lost some oil when the low side was broken. There doesn't seem to be any easy way to drain and refill the oil though.

CY: That's right, there is no easy way.

I won't be installing it from a few months. I'd like to go ahead and vaccum it down. Can I do that via the third tap?

CY: How about cap the lines, and then vac through the usual service ports?

I'll fill it with some r22 after I vacuum it.

CY: Well, enough R-22 to keep air and moisture out. 30 PSI or so should help.

[The Daring Dufas]

Blowing compressed air into the unit was a little bit of a bad move. People in the HVAC and refrigeration trades use dry nitrogen for internal clean out along with a suitable solvent for coils detached from the compressor. Compressed air can carry moisture into a system when blown through it. R11 isn't used as freely as it once was because it kills the poor defenseless little ozones. I use a product called CF-20 Internal Coil Cleaner available at many HVAC supply houses and it's available without any special permit:

You would have been better off leaving the valves closed and flushing out the pipe stubs with freeze spray which is basically a freon mix of some sort or even dust blaster which will blow the stuff out and leave no residue. The low side line being pierced would not cause an appreciable oil loss from an un-powered unit. Because of the compressed air introduced to the system you will need to pull a deep vacuum on the system. The warmer it is when you do it, the better it will pull out the moisture. Of course a good sized liquid line dryer like a C-163 Sporlan which is a 3/8 flare dryer which makes for easy replacement. I always add a sight glass with a moisture indicator to all the systems I install. You can get one that will screw right on to the C-163 and and attach to the tubing with a flare fitting. Heck, HVAC work isn't rocket surgery, Storman Norman does it. *snicker*

TDD

[The Daring Dufas]

OOPS! Dumb ass attack, the liquid line dryer will have to be a biflow type because it's a heat pump. It works when the refrigerant flow is reversed.

TDD

[Stormin Mormon]

After a long day of breaking refrigeration and AC units all over the tri county area, and leaving destruction in my wake. I come home.... to THIS!

"Why, you'd think they were all my wife!" Maj. Frank Burns, MASH 4077th.

[The Daring Dufas]

Neener neener neener!

TDD

[jamesgangnc]

The valves weren't closed when I got it so I figured the compressed air was not going to make much difference at this point. I don't have a nitrogen tank. My supplies are a vacuum pump, set of gauges, a can of r22. My brazing skills are sketchy so I try to minimize that. I'd like to have a nitrogen tank but so far I've gotten away without.

I'll go ahead and pump it down and fill it with r22. I'm guessing it's ok to do that using that middle tap?

It has a filter/dryer on the high side. I can add one to the low side. The guy moved it from one house to the another and kept it in a shed. So it got moved around a bit. I'm afraid that there may be some copper filings further down the low side line inside the unit that I can't really get to. What happens when they go into the compressor? Will they just end up sitting in the bottom in the oil? Or the switching valve? Are these things engineered anticipating that occasional small solid might get in? This is my biggest worry. The moisture I can get out with my vacuum pump.

[Stormin Mormon]

Since the system was opened for a period of time (longer than a few minutes), it's a good idea to install a BIG liquid line filter dryer.

[The Daring Dufas]

Around here it's dirt daubers/mud daubers and other flying or crawling critters you have to worry about when a pipe is left open. The little bit of copper filings isn't a big concern. The vacuum needs to be drawn from both high and low service fittings through the gauge set. If you're worried about moisture, why on earth are you not replacing the liquid line dryer? The dryer is the first thing to replace, just don't leave it open to the air for any longer than it takes to install it. Since it's a heat pump, it requires biflow or bidirectional dryers because the refrigerant flow is reversed when changing from heat to cool. If you're worried about trash getting into the reversing valve, the best thing to do would be to remove the section of large diameter tubing and clean it out. Make sure you wrap a wet rag around the reversing valve when using your torch near it. You can always cut the tubing a distance away from the reversing valve and braze it back together with a coupling. A lot of service techs are using a low temperature silver solder on HVAC equipment which doesn't require the use of oxygen-acetylene torches.

TDD

[jamesgangnc]

Sorry if I seem stupid here, but I can't pull a vacuum through the service valves without capping the lines can I?

Yes, I used silver solder on my regular hvac install at my primary residence.

[jamesgangnc]

Guess I should add it's not been so open that bugs could get in. It's just that the service valves were never closed. The high side line was folded over. A piece of the low side foam was stuck in the low side pipe.

[The Daring Dufas]

I assumed you were referring to pulling a vacuum after installation, not for storage purposes. If the pipes were plugged up in any fashion, there shouldn't be much moisture infiltration since there would still be mostly freon in the system. The dryer should still be replaced when it is finally installed. Since you have no nitrogen, R22 would be fine for putting a slight pressure on the unit for storage but when installed, it will still need a deep vacuum drawn on it. When me and my friends install a new system in the field, we pressurize it with nitrogen and leave it that way before ever pulling a vacuum and opening the valves for startup. If we don't leave the condenser because of the theft problem with new construction, we cap the line set and pressurize it with nitrogen until it's time for occupation. That way we have no surprise leaks such as those caused by other tradesmen putting a nail or screw through a pipe. The thing about dry nitrogen is that the static pressure is not going to change perceptively with a change in temperature. If you pressurize for a leak test and come back a week later when the weather has changed, the test pressure will be the same if there are no leaks.

TDD

[Stormin Mormon]

Yes, you'd have to cap the lines.

[jamesgangnc]

I gotta store it for a while. The garage/rec room is under construction at the moment. It's about done with the framing/ exterior. My back is shot so I had to hire a local guy to do most of that. I'm going to do the plumbing/electrical/hvac after he's finished. Then I'll get someone back in to do the drywall, my back's too bad for that as well. I picked this unit up because I've been collecting stuff off craig's list local materials for a few months now. If you know what you need and are not in a hurry it's a good way to get supplies cheap. Lots of new items where someone changed their mind or bought too many. This was $250 and johnstons wants $899 for it. Some risk on my part but hey that's life.

I'll pull a vacuum via the third service port and follow up with a little r22 into it.

I wouldn't mind having a nitrogen tank but a bargain hasn't come along yet :-)

[The Daring Dufas]

Keep looking, I found both of mine abandoned. Of course over the years I've exchanged them numerous times but I didn't have to pay that initial $135.00 or whatever it is now. I have two "Q" sized cylinders and I bought a good regulator which has the same fitting as an oxygen regulator but is for inert gas. Dry nitrogen is some very handy stuff to have around. I also have a gaggle of 20lb CO2 cylinders that are for soft drink fountains. Those are extremely useful when used with a high flow regulator for blowing out condensers, clearing drains, running air tools or inflating tires. I've found all manner of tanks in dumpsters and as door props. Darn, I have a bunch of propane tanks too. I'd make good terrorist.

TDD