I happen to have a Wilkerson refrigerated compressed air dryer that needs attention. It is a model that works by chilling compressed air, getting water to precipitate, separating the water and spitting it out periodically.
It runs, however it is not cold and does not seem to refrigerate anything. The motor inside its internal compressor unit runs, seemingly (shakes when starts up and continues to slow down for a couple of seconds after). The most obvious thought is that it is missing R-22 refrigerant.
You can see it here
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it was a local pickup item.
Would it be wise to just try to find a way (or someone) to recharge it with R-22? If it loses refrigerant, would it make sense to look for leaks? Another option to be considered is to just throw it away, but, I think, it is worth a look.
If an hermetic system looses its charge, there is a leak. Quite often it's in the tubing at a stress point, or corrosion at a swaged connection. But sometimes it's the waist seal on the compressor. Sometimes its the cer-met seal at the power connections. Sometimes it's just a rust spot that ate through.
If it's the compressor, it _might_ be worth replacing with another used hermetic compressor of the same size, but I wouldn't think it'd be worth a new one.
If there are service valves on the unit (unusual for hermetic capillary tube systems, but not unheard of), you can quickly make a lot of determinations about the health of the unit with just a set of manifold gauges. If not...
Run the unit. See if there's ANY sign of cooling at the evaporator right where the expansion valve or capillary tube(s) go into the evaporator coil. Even if a unit is darned-near empty of coolant, it will often get a little cold right at that point.
If not, it would still be worth installing one service valve on the low side. You'll know ASAP whether it's got refrigerant in it! If the system still holds pressure, it might be a defective valve in the compressor. You can tell by putting a gauge on the low side and running the compressor. If the pressure drops, the compressor is running (if there's refrigerant in it, it might drop as much as 50psi from equalibrium pressure). If not, Screwed again. If so, install a high-side valve, and try re-charging the unit. Or... you can use the super-heat method and do away with the extra valve and gauges (I recommend the gauges).
If you've gone so far as to replace the compressor, don't re-charge the unit without flushing the old oil (which can become acidified) and replacing it and the filter/dryer. The dryer doesn't have to be THE one for that unit. Just make sure it's got at least as large tubing fittings as the old one, and is designated for R-22.
This is a timely post. I was just wondering how one would recharge a hermetically sealed system.
Where would you get some service valves to add to a system?
I have done quite a bit of work with auto a/c systems, but not really that much with residential. The concepts pretty much carry over and I have the equipement to deal with them(vacuum pump, gauges, etc). I have a few things that have been hanging around that I would like to fix but wasnt' sure how to recharge them.
Related: As now R-22 is a listed refrigerent, what is an obtainable replacement that can be used? Supposedly propane is a drop-in, but the flammability is concerning. R-134a is also listed as a reasonable replacement(for certain apps). Any others?
For my particular app, I think R-134a would be ok as I don't need the low-end cold, but I am not sure what charge size to use. As R-22 is a high(er) pressure refrigerent than R-134a, I think it will take more refrigerent to reach similar performance. Am I right, or way off base?
OK, I have a refrigerant filter that I could possibly use, for that. Let's say, hypothetically, that I manage to install needed valves. How would I find R-22? Are there any places like maybe car repair places, thet could charge it with their R-22?
You could do that. It will be harder if it is not already provided with Schraeder fittings. Mine wasn't.
Of course, but they could be really hard to find, and even harder to fix.
I got one out of the dumpster at work. It needed a new starting relay on the compressor. Once I got that rigged with a similar relay from something else, it didn't seem to get very cold. I found out it needed to run a half hour before it got cold inside. It apparently uses a counter-flow heat exchanger so that it doesn't waste its effort cooling the air stream from the compressor, but recovers the "cold" from the outgoing air to cool the incoming flow. So, the only real work perfomed is condensing water. I ended up putting in more R-12 (that's what this model uses) but I don't know if it really needed it.
Mine has been working for nearly 10 year without any further attention!
People with a vehicle EPA license can't work on anything other than vehicles. For $19 you can get your own EPA certificate, then you can buy the refrigerant. That's what I did. I still have a few cans of R-12 left, so I haven't had to buy any yet using my card. I got the vehicle card, I should have spent a couple $ more and gotten the universal card. I still have a BIG can of R-22 for my home systems that will probably last until I no longer need it.
It almost sounds like it is trying to start and my be going off on the overload protector, then it could be the starting relay or a capacitor if it uses them. this business of it slowing down leads me to believe that this could be happening. and some rotory compressors do take some time to refrigerate like it was said it could take a 1/2 hr. or more.. an ammeter on the hot side would let you know if it has gone off on the over load it will usually make a clicking sound. hope I have not totally confused you I sure have confused myself. Ed ke6bnl
Any refrigeration guy can diagnose and fix it. Hankison and Wilkerson (I have a Wilkerson also) are the most common and they can bleed off. Depending on how you moved it..the compressor may...may have the pump filled with liquid. Let it set for 24 hours then try it.
Gunner
"A prudent man foresees the difficulties ahead and prepares for them; the simpleton goes blindly on and suffers the consequences."
Let it run a while and run some wet air through it, and see how much condensate it spits out. These are usually fractional HP compressors, they don't create ice instantly.
If you want to get service fittings on the refrigeration system to attach a gauge manifold and see what's going on inside, there are several options you can use - treat it the same as a window air conditioner, the factory doesn't install any service fittings but they do eventually need servicing...
If you don't want to vent the existing charge there are several nifty fittings that either clamp over the line (just like an "Icemaker Kit" tap) then a piercing element pops a hole in the main line.
(Diversitech "Quick-Tap" series.)
The more reliable ones are soft-soldered on as a saddle to make a tee, they don't have an O-ring seal to deteriorate over time. They use the sealing cap to drive the core with the piercing tip home, then the edge of the tee tubing swages over to hold the core in permanently.
(Diversitech "VLC-*" series, fill in the star with the size of the main-run tubing.)
If it turns out it has already leaked dry, then you can open up the factory tubes where they pinched the tubing shut and brazed the end, and install regular brazed-on service fittings. Silver-braze compound and an Oxy-Acetylene or Air-Acetylene torch.
If it has a capillary-tube metering orifice, the charge amount is very sensitive. Don't mess with "Adding a little", you need to totally evacuate the unit and then fill with the exact amount needed with the refrigerant bottle on a digital charging scale.
We had a similar dryer that crapped out and all it needed was a replacement Klixon bimetallic temperature switch. Digging out the foam insulation to access the switch was a real pain.
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