134a discharge pressures

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I work on some old equipment (ice chests, from Leer). The older R-12 units used to run about 150 to 170 discharge pressure. The R-134a units run more like 225 to 250 or so. Anyone else seen this?
http://dodgeram.org/tech/repair/HVAC/R134a.htm
Some online checking shows that's about normal. Seems a bit unusual, after working with R-12 all these years. For the first few degrees, the temp F and the PSIG are about the same. But when it gets hot, the pressure takes off.
I can tell that getting used to 410a is going to take a while.
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R410a is like any other refrigerant... it has to be charged by superheat and subcooling. The only real difference is that the pressures are approximately 1.6 times higher than R-22..... other than that, there isn't any "gettin used to". But if you had gone to any of the R410a classes put on by manufacturers and supply houses, you would know this.
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I never said that I wasn't qualified or licensed. I never indicated one way or the other. I may have been at one time.
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On Sat, 19 Sep 2009 18:03:34 -0400, "Stormin Mormon"

Every time you open your mouth its shows you're not qualified and the last time I checked NY doesn't require a license which makes it easy for hacks like yourself.
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Ah, you're just sayin that to make me blush!
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Steve wrote:

How could any one miss those classes? They have free Pizza, pop, etc.

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Busy fixing other stuff. I'll have to check at the parts house one day soon.
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Stormin Mormon wrote:

I think it may be because 134a was developed to work most effectively in higher temperature applications. I can't wait for HFO-1234yf to replace 134a. I'm going to have problems remembering all those darn numbers and letters. Sir, I'm sorry to inform you that your refrigerator needs 2,3,3,3-Tetrafluoropropene. Let me get my environmental suit and breathing air tank. Hey, I get to charge more!
TDD
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I'm sure 134a works a LOT better at medium and high temp applications. Well, it keeps ice cubes cold enough. Sure was simpler when we only had four or five common gasses. Now, we've got a real nightmare.
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Stormin Mormon wrote:

Have you seen the new square and triangular shaped snap on connectors for the new refrigerants? The manufacturers are trying to make sure new and old refrigerants don't get mixed up.
TDD
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Not seen those. Never know, might be a good idea. Or, more gadgets to haul around. Offhand, I think it's bad idea for techs like me.
Thinking some more about 134a. When I start up the box, the inside can be 70F or hotter. The system is designed for evaporator temps more like 30F. So, the supeheat is way off the charts. Helps explain the high discharge temps.
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Stormin Mormon wrote:

In hot kitchens or in older stressed equipment, I charge them with R-416a. It runs a lower head pressure than R-12 or R-134a and can be used in place of either. I've had very good luck with it.
http://www.refimax.com/Page/5681/Products_-_R-416A.aspx
TDD
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Thanks for the ideas, and information. One parts house near me has that. I've used 409a with great success. Advertised as a direct drop in for R12, with same mineral oil. But the 416a is noticably cheaper. I'll try that next time.
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Stormin Mormon wrote:

Johnstone stocks it in 25lb cylinders and in the small 9.6oz cans. The screw on can adapter has left hand threads if I'm remembering correctly. I have a 25lb cylinder and haven't used the small cans in a long while.
TDD
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I used a small can of one of the R12 replacements that was specifically sold for use in household ref/freezer applications. I'm thinking it was 414A, but I wouldn't swear to it. Anyway, I just used a side puncture can tap and it worked fine. If you bought a jug of every single R12 supposedly drop-in that is on the market, you'd be hard pressed to fit them all in an empty service van-- definitely wouldn't fit in a Pinto, even a wagon. Larry
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On Sun, 20 Sep 2009 17:37:44 -0500, snipped-for-privacy@webtv.net (Lp1331 1p1331) wrote:

    You'd have some really nice jugs, though.
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I hear you, with the explosion of mixtures and blends. It's not like the old days. I've specialized a bit, and only carry a couple refrigerants in my work pinto.
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Stormin Mormon wrote:

I do kind of wonder why you are in HVAC in the first place. If you are a locksmith, there can't be much time for HVAC. 3 or 4 hours in rekeying cars in a Repo lot should net you around a $1000. One car opening would bring in $85 and upward. Nose opening safe deposit boxes for the bank is about 3 minutes each and $35 a box with a minimum of $350. a 5 minute job of impressioning a lock is $75. Recombinating safes for businesses is $150 each and takes about 6 minutes. Opening a home file/fire safe is $300. Opening a large Diebold would run about $1,000 to $2,500 each You can start at $10 grand for a full vault. Home openings run about $85.00 upward. You don't need the investment in equipment that you have for HVAC and you can haul most of the tools around in your pocket Or Pinto glovebox. Insurance and certification at ALOHA is very cheap in comparison to what we pay. Nobody cares how you got to the job. You can actually do calls on a bicycle. Locks don't change much and the Feds are not dictating your business and licensing is sketchy.

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For whatever reason, the locksmith biz doesn't make the phone ring enough to keep me alive. But, the ad under refrigerators repair helps keep me busy. I think your price schedule is a bit more than what I can get around here.
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Stormin Mormon wrote:

Do you have a yellow page ad and are you registered with ALOHA?

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