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Thread: Refrigeration 101
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16-08-2009, 10:55 AM #1
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10-09-2009, 11:36 AM #2
Re: Refrigeration 101
Hi All;
enjoy the site, I'm a sparky working on hot water heat pumps and have a couple of questions regarding fundamentals.
We were called to a fault, the outlet from the TX valve was frosting up. The fridgie explained that the TX valve was the problem.
The unit was working fine, the reported fault (rattly). Both pressures LP and HP were a little low, there was some oil but no leaks could be found. I suggested topping up refrigerant, it was explained that doing this would only put more refrigerant into the TX outlet (and frost it up more).
I have read some posts about checking superheat temp in the fault finding of a TX, not sure how this is done. If someone could give me advice on checks to carry out if TX valve outlet frosts up (including adjustment) I'd appreciate it.
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10-09-2009, 01:14 PM #3
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Re: Refrigeration 101
Frosting of valve outlet at air-con unit could indicate at problem, but at refrigeration unit that is normal. What is that unit used for?
The unit was working fine, the reported fault (rattly). Both pressures LP and HP were a little low, there was some oil but no leaks could be found.
How much low, we need numbers?
We also need temperatures of air in and out of evaporator and condenser to tell if pressure is low or not.
Also we need pipe temperature at evaporator outlet, compressor inlet, condenser outlet.
I suggested topping up refrigerant, it was explained that doing this would only put more refrigerant into the TX outlet (and frost it up more).
If measurement say that subcooling is low, than refrigerant is missing in condenser. It could be leak or restriction on low side. If you have oil spots and nobody before is not added refrigerant you are probably short of refrigerant.
If you have sight glass, than you will be having lot of bubbles in glass.
I have read some posts about checking superheat temp in the fault finding of a TX, not sure how this is done. If someone could give me advice on checks to carry out if TX valve outlet frosts up (including adjustment) I'd appreciate it.
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13-09-2009, 09:24 PM #4
Re: Refrigeration 101
Hey Gary
How would you determine the correct refrigerant charge in a water cooled system when water flow is controlled by a water regulating valve and it depends on head pressure to regulate. Say we are working with R404 and condenser water temp. of 50F?????
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14-09-2009, 08:02 AM #5
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14-10-2009, 11:03 AM #6
Re: Refrigeration 101
Hi, I'm new to all this. have found the forum amazing usefull, having been sent on a couple of basic courses, which mainly teach you all the legislation, then left a static sight with no guidense or help. I have a slight confusion which is probably easy to resolve. After reading the guide to calculating superheat and subcooling (which made alot make sense) I use my companies service sheets to record the information needed, but instead of asking for liquid line temp. and press. they ask for discharge temp, press to be recorded. I would have assumed discharge would suggest after the compressor, are they the same thing or is this more likely because the sheets are incorrect. This probably seems like I'm being pedantic but untill I found this forum it was causing me all kinds of confusion.
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19-01-2011, 05:51 PM #7
Re: Refrigeration 101
Hi Gary ,
I havn't been a member long and am currently in an apprentaship in the trade, i have about 6 months experience and things are clicking into place for a newby if that makes sense ha. I just want to say that your postings are brilliant and are helping me alot. Looking forward to reading some more many thanks
Ben
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