Frequently-asked questions about how to add or replace air conditioner or heat pump refrigerant:
Questions & answers about refrigerant charging procedures using a gauge and refrigerant canister and other equipment.
This article series describes the procedures for charging an air conditioner, heat pump, refrigerator, freezer, or similar equipment - how does an HVAC service tech put the proper amount of refrigerant into the system?
Green links show where you are. © Copyright 2017 InspectApedia.com, All Rights Reserved.
These questions & answers on charging HVAC equpment refrigerants were posted originally at REFRIGERANT CHARGING PROCEDURE - home
[Click to enlarge any image]
On 2017-10-31 by (mod) - Can you charge a heat pump air conditioning many split below 75ﾟ
Generally yes, Tim. Particularly, it's safer easier to charge on the low side.
Also see REFRIGERANT DIAGNOSTIC FAQS
On 2017-10-30 by Tim
Can you charge a heat pump air conditioning many split below 75ﾟ
On 2017-10-31 by (mod) - how can I tell how many pounds of freon the mechanic is charging me for
The technician should be using a weight-scale or other charge metering device to know the charge voume but often they don't. Instead the tech will add refrigerant by monitoring the temperature of the suction line at the compressor/condenser.
In that case you're paying whatever they decide is their "standard" or guesstimated charge. The tech should make clear ahead of time how they're going to bill you and for what.
On 2017-06-23 by sonny
how can I tell how many pounds of freon the mechanic is charging me for
On 2017-06-22 0 by (mod) - Ive been told to recover from high side then low side collect the rest through vapor
You only need tho charge from one side, installing the proper charge quantity.
On 2017-06-21 by Anonymous
If you want you can give answers here to.my email from Gary email is email@example.com thanks
Ive been told to recover from high side then low side collect the rest through vapor my question and might be stupid beacuase im a student in Hvac in.
my last class but Igot alot of head knowledge but verry little handd on my question when charging a unit do you want to start from low tp high side or high side first or can you do them both same time ive herd of the pull push or push
my question is whats thecorrect way to charge a systym and if you ever herd of the pull push systym please explain that I here its alot faster im not even sure im saying it right
I lnow this much I learned alot in school well alot to me and I worked with this idiot contractror just to get the hands on and he was doing everything wrong that I learned I.now time is money but this guy never recovered the refrigerent he just hooked up the hose and dumped it in the air no recovery machine then he just pulled a vacum lol
is this common out there and even worse did not ever get super heat subcooling readings lol anyways back to.my question what the right way to charge a system as far as do you charge from low side or high side first and whats the right and fast way of doing it
also what do you usually want your evaporator temp reading at for airconditioning when I was working with that guy the evap temp was usually between 34 f to 38f also should there be about a 20 degree delta t drop from your return to your supply
nether words if its coming in at 75 should your supply be around 55 degrees thats.my last class air distribution sorry for all the questions but j want to get it right needless to say im not training with that contractor any.more.my choice thanks guys
On 2017-02-05 by Anonymous
WHAT IS THE CORRECT POSITION THAT THE FREON TANK SHOULD BE TAKEN TO DOWNLOAD THE GAS?
On 2016-06-01 by (mod) -
Liquid in the receiver and gas on the low side
On 2016-05-31 by Abhishek
Where is the refrigerant position when system is still or is stopped?? Is it in liquid state or vapor state??
On 2016-05-09 by (mod) - To avoid sending liquid refrigerant into the compressor techs might charge on the low side
That's an interesting idea, Henry but I am afraid it might get confusing.
To avoid sending liquid refrigerant into the compressor techs charge on the low side (which swaps positions when you change from cooling to heating) and use a charging device that forces the measured liquid to enter the low side suction line as a gas. There are both charging device heaters and cylinders that change the measured liquid to a gas as it passes through.
On 2016-05-09 by Henry
To prevent the liquid 410a goes into the compressor, is it a good method to charge 410a in running heating mode if the split air conditioner with heating pump?
On 2015-08-12 by Drew F. - lot of good info
I'm not a professional, just an EPA cert. apartment a/c tech. And yes, there is a big difference between those who work on numerous different brands and makes on a daily basis, rather than some of us who have the same unit's throughout and get to know them well.
(Aug 1, 2011) Brian said:
what is procedure to evacuate most common home hvac system
Current regulations in Northamerica require that refrigeration systems that are going to be evacuated are first emptied of whatever refrigerant remains in the system - but that refrigerant is NOT vented to the atmosphere. It must be collected into a retrieval canister. There are two ways this is done.
Traditionally a vacuum pump is connected to a service port on the HVAC system and the output of the pump is connected to a receiving canister. The pump is run until there is a vacuum on the HVAC system for some specified interval then the receiving canister is closed and the pump shut off.
Currently there are also refrigerant receiving canisters that are sold already having been pumped to a vacuum. The canister can be connected to the service port on the HVAC system.
In either case a gauge set with appropriate connecting hoses and control valves would be used to make the connections between the HVAC system service port(s) and the receiving canister.
Following removal of refrigerant from the system, depending on the HVAC system size, a vacuum pump may be left on and running for minutes to hours to attempt to clean the system as thoroughly as possible of refrigerant, moisture, and debris. The reason we need to allow some time to pass is that the initial "vacuum" is incomplete. Some moisture may remain in the refrigeration system that can convert to gaseous form as the system warms up, thus allowing still more moisture to be removed in vapor state. On a home system this may be just an hour or three; on a commercial HVAC or other refrigeration system we might leave the vacuum running for 24 hours.
Finally, when the system is to recharged, the HVAC tech will normally also install a dryer/filter to help remove any remaining moisture or debris.
(Sept 12, 2012) Anonymous said:
How to transfer coolant from refill tank to fill yank on machine
(Oct 25, 2012) Anonymous said:
reza how charging gas
(Sept 29, 2012) Edrotman@aol.com said:
In measuring the level of r-22 in a central Ac, Does the level and amount of gas in the system vary in cool weather vs hot weather? I had a service technician tell me my system needed 4 pounds but when I asked another technician he said it showed low because it was too cool to get a proper reading. Whose right?
(Mar 21, 2013) Anonymous said:
what is the pressure when we put refirgerant in the system?
At the article links near page bottom where you find an article index and more reading suggestions check out
REFRIGERANT PRESSURE READINGS - separate article. You'll see that while the total volume of refrigerant in the system remains constant - a refrigeration system is a closed system with a fixed charge of refrigerant
- it is indeed the case that the pressure and temperature of the refrigerant on the high and low side as well as the apportionment of refrigerant volume between liquid and vapour states changes when the system is being run and at different ambient temperatures.
If you are asking about preserving refrigerant when disconnecting and moving HVAC equipment, I am doubtful. IN a conventional split system cut, move, and reinstall, the tech will need to pull a vacuum, clean the system piping and equipment after it's reconnected in the new location, then install refrigerant.
(Oct 15, 2012) Rob said:
Was wondering if yhere is an easy way to remove the air from a split system that has not been bled
The service tech needs to install a vacuum pump, remove refrigerant, pull a vacuum, remove all gas, air, and all possible moisture, install a new filter/drier, and then recharge the system. There's no shortcut that will remove "just the contaminating air" from a refrigeration system that was not properly charged.
Continue reading at REFRIGERANT CHARGING PROCEDURE - home, or select a topic from closely-related articles below, or see our complete INDEX to RELATED ARTICLES below.
Or see LOST COOLING CAPACITY
Or see REFRIGERANT PIPING GURGLING
Or see REFRIGERANT DIAGNOSTIC FAQS
Or see these
Or use the SEARCH BOX found below to Ask a Question or Search InspectApedia
Try the search box below or CONTACT US by email if you cannot find the answer you need at InspectApedia.
Also see REFRIGERANT DIAGNOSTIC FAQS
Use the "Click to Show or Hide FAQs" link just above to see recently-posted questions, comments, replies, try the search box just below, or if you prefer, post a question or comment in the Comments box below and we will respond promptly.
Search the InspectApedia website