1. Home
  2. ⚡ Welding Forums
  3. Commercial chiller help and advice

Commercial chiller help and advice

This story would be funny if it happened to anyone else. Enjoy if you must, help if you can.

We are proud owners of a 40 year old York chiller. It is unique in the industry for having an electric block heater that resides in a well in the cast iron block of the compressor. The compressor will not start unless the oil temperature is high enough (the cast iron gets hot to the touch, probably ±140°) to prevent pumping Freon 11, a notorious solvent, through the bearings. The heater is about 8" long and 5/8"? made of stainless (no, I don't know what grade) with ceramic and a heater coil sealed inside. You would also need to know that due to controls, framing, and sensors the path to this well is about 20" away from anywhere you could have a drill motor. The well bore is horizontal. I did not have my bore gauges with me but a 3/4"? drill shank will NOT go in the bore.

The heater shorted and failed and in the process, apparently, welded itself to the bore of the cast iron well. The old heater is basically out, but the bore is not clean enough to let the new heater in. One of our technicians welded a 5/8 reduced shank to a

1/2" rod and launched into the bore. He made some good progress and then snapped the weld, he was able to get the drill back out. No problem, we had made up a 5/8 reamer on a cold rolled shaft for a previous similar problem on a different York. We had used it by turning it with a crescent on some flats. This guy decided that this would be too slow, so he chucked up the shaft in a hand held electric drill. DO I REALLY HAVE TO TELL THE REST OF THIS?

I was invited into this problem late Friday. There is about 1

1/2" chunk of broken off ream in this bore. The end of the piece of ream is 3 1/2" deep in the bore. The ream shattered at an angle. I was able to get a long thin screw driver into one of the flutes, but it is well jammed and I couldn't get anything to wiggle. It was decided not to deal with it until Monday due to Easter and an unusual cold snap.

I drilled a 1/4" hole through a 5/8 bolt to act as a drill guide. I left the head on to keep it at the face of the bore and have a stack of O rings to center it in the bore. I have a new package of taper length 1/4 cobalt bits that can just reach the back of the ream and drill about 3/4". I have a half dozen new 1/4" masonry carbide bits. I can turn the 1/4" bits with 2 Irwin speed bore extensions. We discussed a tap extractor, but I fear the ream is jammed far too tight.

Wish me luck. Say an extra prayer. Hurry up and give me some other advice. Rainy days and Mondays are bad enough on their own, I'm feeling challenged about tomorrow.

Reply to
DanG
Loading thread data ...

Good luck. Out of kindness to the others you will be working with in the basement tomorrow, don't eat too many boiled eggs today.

Steve

Reply to
Steve B

theChas,

As a matter of fact, I looked at that. The well casting does go through to the far side, though does not have a full "face" so knowing its center point is not straightforward. For any that do not know, Freon 11 is one of the expensive ones and this rig is full. There is a fitting threaded into the compressor ring that hangs down in front of the back side target. When I asked about removing that fitting, I was strongly discouraged, but I am impressed with your diagnosis. I would much prefer drilling the cast iron, I know I can do that. I have not said no to the possibility, but thought I would attempt the carbide masonry first. I was advised that the cobalt would not last long and might not work at all. I intend to really study the possibility of drilling the back side before attempting the reamer. Surely, that cast iron has some good "meat" in that area that is still well away from the Freon.???

Reply to
DanG

Can you access the other side of the cast iron block and carefully measure where the centerline of the bore hole is? Then carefully bore a small hole there where you could insert a punch to help assist in pushing the broken reamer back out.

Reply to
theChas.

Freon 11 is one of the expensive ones and this rig is full.

***************** If you can locate some empty Freon 11 tanks you can submerge them in a bath of rock salt and water and chill them. When connected to your compressor the freon will migrate and condense in the cooler tanks. After the units and the recovery tanks pressure has stabilized, one can then hook a vacumn pump up to the unit and remove the remainder of the freon, again pumping it into a chilled tank(s) with sufficient room to safely hold all the freon. Just make sure you don't overpressure the chilled tanks when pumping the unit down, and be sure to allow for expansion when the chilled tanks are allowed to warm up. Best method is to have some way to weight them as they fill. Now one can access the forbidden area.

. . . .when you get the broken tool removed, you then pump down the unit to as low as you can get in inches of mercuty, and then put the scavanged Freon

11 back in. Stateside one has to have a license to do this Freon handling.

. . . old time machinists have told me about using lime on heated bores to remove broken bolts ect. If you have an extra reamer identical to the broken stuck one, maybe you could manufacture a 'grabber' using the salvaged part from the broken one as a guide. This would have short strong projections, determined by the broken one, that could possibly grip the broken one to extract it. Usually, it seems, just a tweat is all that is needed to start to remove one of these. If the broken one ended up in just two pieces, then the salvaged piece silver soldered onto a handle may suffice.

If all else fails, one can contact an electrician or refrigeration person and have an external heater applied (within the safety circuit). Most likely the heater is there to insure there is no liquid near the compressor when it starts, so it doesn't blow its valves or heads. . . .Come to think of it, if the heater took the circuit breaker out when it shorted, you should be okay. If the heater just burnt out, and it itself, is not in the safety circuit, and the unit tried to start with a cold liquid logged compressor, the compressor may already be damaged . . . . It could be worse,,, it could be my problem..

Reply to
theChas.

PolyTech Forum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.