heat pump stupid question

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Old 01-27-03, 05:37 AM
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heat pump stupid question

while going to school I work part time as maintance, during my first heat pump check. I hook gauge to what I thought was low side. The unit was in heat cycle. I got high pressure out of unit. Then when I switch to cooling it was normal. please explain.
 
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Old 01-27-03, 06:06 AM
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brownbagg:

I'm not really sure what "normal " is.

I don't want to burst your bubble, but you should not be tampering with a sealed system unless you are properly trained and licensed.

A "heat pump check" that you could do would be to check the filter in the airhandler, fan condition and cleanliness, belt condition and tightness, air handler general condition and cleanliness, refrigerant line security and look for places of possible vibration damage.
Outdoor unit general cleanliness and condition, condenser coil cleanliness and fin condition, fan motor operation, frost accumulation and defrost operation.

This would be considered normal maintenance.

BTW, the pressure will change when the unit changes from heat to defrost.
 
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Old 01-27-03, 06:32 AM
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I agree with GregH on knowing what to do before doing it but I think I understand what you mean. I bet the eyes bulged out of your low pressure gauge too.

On a heat pump the low side reading is taken at a port that is not fixed to either line outside the unit. It is not on the service valve either. You should find the low pressure port somewhere near the lines but by itself coming through the cabinet. The reason for that is that in heat mode, the large tube is the high side and you would not be able to check suction pressure without another port. I hope that makes sense.
 
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Old 01-27-03, 10:01 AM
bigjohn
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With a heat pump split system you can't call the large tube the suction line like you were thinking. It is the VAPOR line. During the cooling cycle suction vapor flows thru it from the indoor coil to the compressor and it is part of the low side. During the heating cycle, hot gas vapor flows thru it from the compreesor to the indoor coil and it is part of the hgh side.
 
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Old 01-27-03, 02:22 PM
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hey I was just during what my boss tells me to do, I did not mean doing maintance, I work as maintance at a apt complex and my boss in helping me learn A/c told me to hook to this one heat pump. I just do not want to seem stupid and tell him I begg the gauge without asking someone that cannot fire me. and yes there was a third port on this unit.
 
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Old 01-27-03, 03:45 PM
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It's OK we won't tell your boss. There will always be a third port on a heat pump and that is always the suction port. It comes right off the compressor, or close to it.

And don't feel like we were reading you the riot act. I eas told once by an instructor that you lose 1/2 oz. of refrigerant every time you hook up to the high side. Even with no leak, everyone will need a charge sooner or later. I now use the hoses that keep the liquid in the hose when it is unscrewed and put it back in the low side before disconnecting that hose.

Make sure you recalibrate that low side gauge if it is not zeroed out already.
 
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Old 01-27-03, 04:08 PM
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refrigerant loss

KField is right, but its alot more than 1/2 ounce, if the gauges are empty it's more like on the order of 4 ounces. Most units today have fixed orifices for a metering device. These units are critically charged. If you must connect your gauges, precharge them with refrigerant, purge any air, (the system is screwed if you didn't, it'll take time, but copperplating and acid is on its way, along with a high head pressure if enough air is in the system), the secret is NEVER connect gauges unless you have to. You can tell alot by feeling the piping.
As mentioned before, the two lines are the discharge line and liquid line during heat mode, suction line and liquid line during cooling mode. Heat pump charges should only be checked in the cooling mode, preferably in June. A weighed charge is the best way to go, if you must charge a system.
For maintenance, keep the air filter and belts changed before they get bad, oil any motors that have oilers, keep both coils clean (wash annually if you can), that is all you can do to keep things operational. Uses your senses...
 
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Old 01-27-03, 04:13 PM
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Smile

brownbagg:

The refrigeration and airconditioning trade is very rewarding and its nice to hear of someone new getting involved with it.

There is however a right and wrong way to learn.

I'm not sure on what basis you got your job, so I can't say what you might have told your boss you knew.
If your boss knows you don't know much, he would be personally responsible for any screw-ups that may happen, including injuries, and should be beside you during the checks he asked you to do.

The EPA requires certification to work on this equipment, but you would be allowed,provided your boss is licensed and certified.

Is he?
 
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Old 01-28-03, 05:24 AM
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The basic that I statred with was, swimming pools, electrical, painting carpet,etc. I have alway had a intrest in A/C there is not an A/C school wiyhin 200 miles from here. The boss want me to learn these residental a/c unit so he can have every weekend off, let me be on call. I really do not want on line schools, they want more money than I make. I hold a unvirsel certicate. That part not the problem, It is the general trouble shooting with each brand of unit. the hands on part. Theory easy.
 
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