Hmmm, how about converting the system to chilled glycol? You'd have to replace the whole chiller, of course, but that could actually come out cheaper than the refrigerant you would need. If the piping is of sufficient diameter to support the required flow rate, it ought to work. You mentioned leaky shaft seals, so maybe you are replacing at least the compressor. Geez, shouldn't you be using a semi-hermetic, anyway?
Otherwise, a do-it-yourself conversion would require an evaporator/heat exchanger and a circulator pump. This would obviously save thousands of $, even with a relatively affordable refrigerant.
I would like nothing more than a shiny new machine, but it aint happening. The entire load of RS-45 refrigerant is about $40,000 $9.50/lb. Compressor seals are the most expensive parts (York doesn't embarrass easily), but to tal parts cost will be under $8,000 to put the whole thing back in "pretty good" shape. Compare that to a 30 ton chiller, evaporator, pumps, 55,000 fe et of pipe, 420 yards of concrete, etc, etc. I wish.
The only guy who worked on this system in the last 20 years died last month. We did have pretty extensive talks in the past couple of years, though. But he took all his knowledge to wherever lies beyond.
three or four previous contractors/maintenance/service people who left the re and get whatever else bad news they found out about the needed repairs.
th. We did have pretty extensive talks in the past couple of years, though. But he took all his knowledge to wherever lies beyond.
Oh, I have a pretty good handle on the "needed repairs." The problem is dec iding which to do now and which can wait a while. Obviously the leaks need to be fixed. As I think I said, the compressor shaft seals are dripping oil , so they're a no-brainer but they eat up a LOT of money in parts (Someone' s making big bucks at York). The valve stems all need repacking, some of th e flanges need tightening, the gauge tubing all needs to be replaced, 3 of the 6 gauges (suction, discharge, oil for each of two compressors) are inop erable, and most importantly, the relief valves (two of them) are probably the originals from 1980. They should be replaced every 5 years. They both s how signs of leakage. I have taken one of them off and it's full of gunky s ludgy oil & dirt from being 6" off a very dirty floor.
I got a couple of the kids who work there to clean up the floor (if you're adding 20 gallons of oil a year, the oil must be going somewhere - in this case, most of it was on the floor turning to oil mud), and it made a huge d ifference in everyone's attitude about the project. Instead of felling like it's a disaster area, it now looks like a reasonable facsimile of a mechan ical room.
I really took on this project thinking I was only going to update the contr ol and monitoring system (that's my specialty). Things kind of spiraled fro m there.
When you're up to your neck in alligators, it's hard to remember that you c ame to drain the swamp.
So, I got to thinking that there might be a better place than AGL, Praxair or Aigas to get the nitrogen or Argon. A couple of minutes with google turn ed up a welding supply / gas supply about a mile from my house. They will r ent a 330cf cylinder for $4.00 per month and fill it with nitrogen for $29 or argon for $65.
This is way cheaper than I would expect to pay at any of the big shops, and couldn't be much more convenient. A huge bonus.
This is way cheaper than I would expect to pay at any of the big shops, and couldn't be much more convenient. A huge bonus.
========== Once it holds a vacuum I'd make a rough estimate of the volume with dried compressed air, then a better one by evacuating it and filling from a nitrogen tank nearest the estimated cf capacity. The (absolute) pressure drop in the cylinder and the rise in the piping give you the volume ratio. The more the gauges change, the better the resolution.
What I was thinking, without knowing whether it would work, was to use the EXISTING pipe in the floor for a glycol system. Now, maybe the pipes are just too long for the glycol to flow through, but with 55,000 feet of pipe, it seems there is PLENTY of surface to absorb heat. But, maybe the glycol would need a lot of short pipes between manifolds, and the Freon system has fewer, very LONG pipes, as it is absorbing heat by evaporation.
But, yes, the ONLY way it would make sense is if the existing pipe in the floor could be used as is.
And, you can likely find a used but good 30 ton water-water chiller quite easily on the used market. I'd start at HGR surplus. When you are talking about $40K of refrigerant plus expensive repairs to a belt-driven compressor which is certain to start leaking again sometime, it seems like a good idea to look at alternatives. 30 tons is just NOT a great big chiller.
That's a good one, but it requires that you know the actual cf in the tank first. I have no idea how accurately that gets measured when tanks are filled.
The refrigerant pipes in a typical rink are about 10 or 11 miles long (seriously), and are (sometimes) 5/8 OD thinwall steel, but that's a variable. ====================================================================================================
Just as a sanity check when you do the pressurize with nitrogen test, I get a volume of 72 cu ft or 2039 L for 10 miles of 1/2" ID tubing. At STP, 0 C and 101 kPa nitrogen has a density of 1.25 g/L so at STP 72 cu ft would weigh 5.62 lbs (I'm ignoring the difference between room temperature and STP for this estimate :-)). If you start at atmospheric pressure you would need
3x72 cu ft = 216 cu ft to reach 44.1 psig which should be completely safe since the vapor pressure of R22 at 75 F is 132 psig. So you will need at least a couple of tanks of nitrogen on hand to be safe, and a refrigeration scale that can do 0.1 lbs at the weight of a full tank of nitrogen with regulator should let you get an answer in the 5-10% range. Have fun.
========================= Yes, I tend to practice an experiment cheaply to find issues with my equipment and technique, before making careful measurements. I no longer have access to recently calibrated lab instruments and the motley assortment of surplus I have at home doesn't all agree too well.
However my flea-market 1970's Fluke 4-1/2 and 5-1/2 digit bench meters are still within spec when measuring a 10V calibration standard.
The reference IC is really an AD584. Its hand-written label indicates that it measured 10.00222V on an Agilent 34401A at 21C in 2015. My Fluke 8800A (no cal?) shows
10.0017/18, the Fluke 8600A (1995 cal) shows 10.002V.
I've got 300cf of nitrogen in one big tank, an accurate temperature sensor buried in the concrete and a scale that's good to 1% or so at the weight of this tank.
And thanks, I do expect this to be at least a little fun.
I WORKED for Praxair, and my extra special employee discount was .69c per day tank rental, and .55c cf for argon.
Needless to say, passed on THAT fine deal. Quit the company, too:(
Aigas to get the nitrogen or Argon. A couple of minutes with google turned up a welding supply / gas supply about a mile from my house. They will rent a 330cf cylinder for $4.00 per month and fill it with nitrogen for $29 or argon for $65.
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