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Refrigeration gauge set © D Friedman at InspectApedia.com Refrigeration Gas Test Gauge Q&A-2

How does refrigerant flow through a heat pump?
Does refrigerant get consumed or just leak?

  • POST a QUESTION or COMMENT about how to hook up and use an air conditioner, heat pump, or other refrigeration equipment refrigerant gas pressure test gauge

Air conditioner & heat pump refrigerant test gauge FAQs set #2.

This article series describes the connections, use, and reading of a refrigerant gas pressure test gauge set.

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Refrigeration Charging / Testing Gauge Q&A-2

R-22 refrigerant and air conditioning test gauges (C) Daniel Friedman

Recent questions & answers about refrigerant test gauge use, connections, charging ports, posted originally

at GAUGE, REFRIGERATION PRESSURE TEST - be sure to review the procedures and advice given there.

How does refrigerant flow through an A/C or heat pump?

When checking automotive AC system does the high pressure side flow through into the low pressure side as a cycle? On 2018-07-20 by Ralph Mcdonald

Explanation by (mod) -

In simplest terms, starting at the "high side"

  1. refrigerant leaves the compressor outlet as a high temperature, high pressure gas,
  2. is condensed to liquid refrigerant,
  3. is metered through a metering device or TEV
  4. into an evaporator or cooling coil, where it
  5. expands into a gas,
  6. and that state change cools the coil (expansion from liquid to gas absorbs energy and thus heat),
  7. the coil then cools air blowing across the coil, and
  8. that lower-pressure gas moves on to the "low side" of the system where it
  9. returns to the compressor suction side inlet.
  10. where the compressor compresses the refrigerant to a high pressure gas

 

Does refrigerant get used-up or does adding gas mean that there's a leak?

Does added gas mean that there is a leak or does gas get used up? On 2017-05-15 by Anonymous

Answer by (mod) - there is a leak

Thanks for asking that Anon as many people may get fooled by a technician who's not good at explaining why she chose to just add refrigerant to an air conditioner or heat pump system.

1. Refrigerant does not get "consumed" in an air conditioning or heat pump system. The refrigerant is circulating in a gas or liquid form (changing state between those) in a sealed system. The key word is "sealed".

2. If refrigerant is "lost" from an air conditioning or heat pump system then there is a leak.

3. leaks are not "standard", not "normal" and certainly not desirable: leaks of refrigerant contaminate the environment, cause the equipment ultimately to stop working, and overall increase heating or cooling costs.

4. the best solution when refrigerant has leaked out of a system is to find and fix the leak, then re-charge the system with the proper refrigerant quantity.

5. However some HVAC techs find that the cost of taking the time and trouble to find a leak can be so costly compared with just adding refrigerant that if an air conditioner or heat pump refrigerant leak is so small that the system will work for a year or two between charges their customer prefers to keep doing that. In my view it's not a very nice solution, and this approach, in the hands of a less scrupulous air conditioning repair company can change their business into something like a milk route: just drive around and deliver refrigerant to our customers on a regular basis.

How do I find the amount of refrigerant by using a manifold gauge?

How can i test the exact value of the recharged gas in the Refrigrator system by a manufold gage ? Thank you Zeleke Ayalew from Ethiopia On 2017-11-17

Explanation by (mod) - how to hook up a test gauge set

Zeleke,

The procedure for connecting a test gauge set to a refrigeration system is described in the

article GAUGE, REFRIGERATION PRESSURE TEST

You'd follow that procedure and then record high side and low side pressures when the system is running as well as after it has been shut down long enough for the system pressure to be equalised.

However only air conditioners, heat pumps, and most commercial refrigeration systems are factory-equipped with gauge ports. A residential appliance like a refrigerator or freezer usually does not have those ports installed.

Those connectors can be added on a residential appliance and are often done-so during repair or during a compressor replacement.

To make sense of the pressure readings that you obtain you need to know

- the specific refrigerant in the system, such as R22 or R410A

- the ambient temperature

- the gauge readings


Using a gauge set just on the low side

Hi there. Thank you for this extensive guide, I am studying it. I am a DIY'er and I totally appreciate that I shouldn't attempt to connect a split AC unit on my own but I want to give it a go anyway.

I totally understand the risks involved but I think I can make it!

I am sourcing a vacuum pump, pipes and flanging tools.

Once everything is there and connected I will need to create a vacuum in the line, open the gas taps on the unit and hope that the engineer who decommissioned the unit left the gas in the condenser unit!

I only have one question so far. The test gauge manifold has High and Low gauges.

My outdoor unit has two taps and ONE service port on the LOW pressure side.

Where is the High pressure service port?

Do I need it?

In the end I do not have any gas (R410a) so I will only hope that gas is already inside and check the pressure when the unit is running but I am a little confused by that.

The unit is a 7Kw Fujitsu, outdoor unit is AOYR24LCL. I do appreciate your help on this! :)
Cheers! On 2017-11-10 by Tony

Comments by mod (Daniel Friedman)

Tony you can see my gauge set above on this page.

The reason we use a high side gauge is to check high side pressure - as part of a diagnostic routine.

Some techs charge systems from the high side using liquid refrigerant, as that's much faster than low side charging. It also is riskier and requires more expertise and care in my OPINION.


I thought we always charge refrigerant just on the low side

You said" do not send liquid refrigerant into the low side of a refrigeration system

But i read at another website that you charge the system: If you add refrigerant, you add it to the low pressure line as a gas

I thought we always charge from the low side (blue line) and i thought all refrigerant comes in gas and not liquid form

thank you 2017-07-04 by Anonymous

Opinion by (mod) -

Not quite. Refrigerant in the can is a liquid. Depending on the equupment used by the tech, a system can be charged by adding gas to the low side or liquid to the high side of the system.

I prefer the low side charging as safer.


Is it technically possible to add refrigerant without a gauge set

I know I have a leak can I put in r410a feron in unit with out checking gauges On 2017-06-12 by Ruben

Answer by (mod) - yes but watch out

Ruben

If you are asking if it is technically possible to add refrigerant without a gauge set, yes of course, though adding an unknown quantity, especially to a system in unknown condition could damage the equipment.

Consider that we don't find and fix a refrigerant leak in a building air conditioning or heat pump system we are basically continuing to dump refrigerant into the atmosphere - illegal, harmful to the environment, and wasteful.

There are "stop leak" products that can be added - with mixed reviews and mixed success - or not success, as those too might clog a refrigerant metering control component and thus damage the system.

 

Explain how a frost free refrigerator works vs a bad heating element on a frost-free refrigerator

Wouldn't it be nice if AC Heat Pumps exhibited a readout of the unit when it runs low of gas so that owner can get adequate service before complete failure?

Actually I have a question. I have been told that a frost free refrigerator is frost free because of a heating element used to melt ice on the evaporator in the freezer compartment.

'Well, my frost free refrigerator is still frost free because my heating element went bad and I disconnected it. If you know how a frost free refrigerator works, please enlighten me. Thanks. On 2016-12-30 by ALVIS JENKINS

Explanation by (mod) re:

Alvis

Your suggestion sounds perfectly reasonable, though the idea turns out to be more of a challenge than one might imagine.

A/C and heat pump equipment does not consume refrigerant. The system is hermetically sealed and the same refrigerant should stay in the equipment for its lifetime, barring mechanical damage that causes a leak. So we're not looking for something like a fuel tank gauge that's found on a car.

Your comment on frost-free equipment is spot on.

Heaters keep frost-prone surfaces such around a freezer door or on the freezer internal surfaces either warm enough to not form frost/ice OR a timer periodically runs a de-frost cycle. In the latter case on older refrigerators you'll find a drain into a pan below the refrigerator/freezer.

The pan catches the meltwater and lets it slowly evaporate into the environment.

If you disconnect just one heater element, say for a door, the unit may still have its internal defrost cycle working.

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