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Thread: Coping with capacity problems..
12-27-2009, 08:23 PM #1
Coping with capacity problems..
I have a fairly new customer who has an old walk-in cooler with two sections and each section has a Singer MN/ LPL 160-1 evaporator that has 5 fans(Might be 6?)...And 1-1/2 ton R12 C valves.
The units in the basement are AHA7511AXF air cooled..
I was there in the summer trying to cope with the high head pressure problems.Somewhat I got them going back then.
Today while I was there to replace one of the C/U motors I looked into the systems again.And tried to figure out my next step when the compressors start going bad.
The basement has a very good exhaust fan by the units and a good intake on the other side of the basement..I know the issue is more then warm ambient air.
I was thinking about offering them water coils for each units,but then the apparent sizing problem gave me a second thought.The condensing units are only close to a ton..I can't give exact dimentions of the box but I can say this much that the insulation is very poor on the very old box.And there is a heavy usage.(Maybe I can guess the size of each sections as being 8*8*7 or so,I know it's not that big..)
I am planning to put larger capacity C/U s once the compressors start going.Maybe at that point I will add or convert to water cooled.
But here is what I am wondering.While the compressors are still pumping during hot summer days could I reduce the load on the compressors by disabling one of the evaporator fans?( I actually did it on one of the evaps this summer.)
Also there is a freezer box attached to the end of the cooler box,the C/U of which is in the same location with the cooler C/U s.I entered the box to look behind the evaporator.The whole bottom half of the coil was covered by aluminum foils,possibly by the previous service company.They must have tried to cope with the same problem in the same fashion.
I just wanted to discuss the temporary measures that can be taken in this kind of problems.(Poor box insulation,undersized condensing units,high ambient..)
Like I said above, my permanent solution will be increasing the C/U size and making them water cooled ( 2 ton coil for each each unit.)
12-27-2009, 08:55 PM #2
12-27-2009, 09:30 PM #3Regular Guest
- Join Date
- Apr 2002
- San Diego
There is nothing you can do at this point. It's in the customers hands now. He needs to upgrade and he knows it. "Jimmy rigging" only works for a while. And to answer your question. Yes, removing a evap fan will reduce the load.
Maybe this new customer is a new customer for a reason. He sounds like a cheap skate.
12-28-2009, 01:09 AM #4Professional Member*
- Join Date
- Nov 2009
- Richmond, working under tarps
midseat the suction service valve.
12-28-2009, 06:08 AM #5
with new units, your still leaking like a siv out of the box. Like throwing money right out the window.
New box and units is what I would try to convince them of.
I wonder why your looking at water cooled. I suspect you are because these units can not keep up and run high head. Follow me on this.
The box has degraded further and further. Heat transmission into the box is greater now than in the past. You once had a nice tight box with properly sized condensing units. But over time these units have become undersized due to the increased load from the box degrading and allowing much more heat in."The only real security that a man can have in this world is a reserve of knowledge, experience and ability." Henry Ford
12-28-2009, 07:09 AM #6
12-28-2009, 07:13 AM #7
your first concern is not a concern. Building a walk in box is like putting lego's together. It's very easy. It's very very easy. Unless it's a low temp box and the floor has to be treated.
You do have to have some minor carpentry skills with true and square but I assume your intelligent and so I believe that would not be a problem. I quite honestly am always fascinated how some guys can screw it up. It's hilarious.
The second concern is only valid after they have declined.
How do you do a proper load calc when the load is degrading infinitely? Thats like asking you to do me a furnace and ac in my new house, but I fail to tell you that every year I intend to cut a big hole in my wall for a yet another new garage door. How long before the ac and furnace you put in is now undersized.
Makes it tough to roll the dice and deliver a job that will perform for them. It's their dice to roll just make sure your informing them of the caveats."The only real security that a man can have in this world is a reserve of knowledge, experience and ability." Henry Ford
12-28-2009, 07:37 AM #8
Unless water is free, your better off with air cooled. Water cooled equipment is more expensive to buy and if they have to pay for water more expensive to run. It's more expensive to maintain too unless you install a very good water filtering system. Even then your gonna have to acid bath them.
Some may say the KW consumption in higher ambient will offset KW consumption due to the fixed head pressure. I dunno. Maybe there is some merit to that. Just not a big fan.
I am not a big fan of water cooled units because what I hate the most is, I can't see how fouled the condenser is. I can measure I suppose but I can not see it. Air cooled, for the most part you can. There is a place for water cooled in refrigeration but only if air cooled is not applicable. This of course is my opinion. Plus to clean a water cooled condenser can be a real PIA."The only real security that a man can have in this world is a reserve of knowledge, experience and ability." Henry Ford
12-28-2009, 01:39 PM #9Professional Member
- Join Date
- Mar 2003
- Cochrane, AB
12-28-2009, 05:41 PM #10Professional Member*
- Join Date
- Jun 2005
- Las Vegas NV
The AHA7511 and the LPL160 is not an ideal match for a typical cooler. At a 90 ambient the evap TD would be about 8.9. Your hotter ambients would decrease this TD even more.
A 2HP R-22 unit would be a better match.
The existing unit is not undersized for a 8x8x8, it's actually oversized unless the box is in terrible condition.
12-28-2009, 10:21 PM #11
12-28-2009, 10:46 PM #12
I like to do light work.I don't like to find a helper for one job or two and not know what to do with him after.Everything I do for the last 5 years is geared towards one small man..My customers know that.I am not crazy about making another 10 or 20 G a year and go out of my way.Maybe I am complacent or tired.I think if I were in my 20s my opproach would be different.A lot of times I get a rush of service calls that I have hard time keeping up with.So I can't dedicate a full day or two for one customer.That's why I am always looking for more specialization ideas.For a while I fancied with the ultra low temp equipment.Looked into it seriously.Met two guys in my area.One is out for health reasons.The other one is almost out from old age.The old guy still keeps touch with me,and I do too.But I don't think that's the way to go either.Maybe the ice cream parlor equipment could be it.In May 2010 Carpiciani-usa is giving a 4 day training if there are sufficiant number of applicants.
So for this customer,if it gets that bad,I will hand them over to someone else for the new boxes.
Thanks for the encouragement though.
12-29-2009, 05:46 AM #13
wanna, I completely understand. This is exactly where I found myself so frustrated when I was in business. I had a heavy industrial commercial background, and the work that gravitated my way was this type and I found my little one man band getting myself involved in work that I as a one man horsepower show could not do. Just did not have the guys.
I don't think too many guys could understand what you said and know what that means in reality. I do. I really do. It's actually harder in my opinion to stay small. You have to often walk away from work you can;t get done because of the size of the job.