Receiver Basics

Receivers, which we sometimes call “liquid receivers,” are components that store refrigerant. You'll see it on everything from small self-contained refrigeration units to very large commercial and industrial systems.

Many new techs who are used to residential air conditioning confuse receivers with accumulators. It's an understandable error, as they both contain liquid refrigerant. However, you'll find the accumulator on the suction line before the compressor; it prevents liquid from entering the compressor. On the other hand, you'll find a receiver on the liquid line after the condenser. That's because it stores liquid refrigerant that doesn't need to be in circulation for the current heat load.

The liquid receiver stores refrigerant when the system is operating at less than its maximum heat load. In general, systems with receivers are designed so that the receiver can hold the entire system's charge and still be no more than 80% full. That design allows you to pump down the entire system charge into the receiver without the danger of creating hydrostatic pressure; that refers to very high pressures resulting from full liquid expansion. (That's the same reason why we should only fill recovery tanks up to 80% full.)

The multi-position service valve at the outlet of the receiver is called a “King valve.” It can be used for refrigerant circuit access, and it may be fully front seated (turned clockwise) for pump down.

Because a receiver has both liquid and vapor present inside, many techs argue that the refrigerant cannot be “subcooled” in the receiver. The truth is that while the refrigerant that interacts between the liquid and vapor at the top of the receiver is at saturation, the refrigerant below the liquid line can be and usually will and should be subcooled.


One response to “Receiver Basics”

  1. I have a reciever Oz. An ice machine that’s 6.8liter or 229 oz capacity. Mfg recomened charge is 250 oz. With my head Master and 4 lbs extra for cold Ambient Temps, does this not exceed reciever limits? Mfg tech says I don’t know, put in a fan switch & forget head aster. But it’s still bypassing and trying to flood condenser. What is right

Leave a Reply

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.

Related Tech Tips

What Willis Understood 
I've been reading a book called Cool: How Air Conditioning Changed Everything, and it got me interested once again in the history of air conditioning and refrigeration. Like many things, the people who are credited with “inventing” are the ones dogged enough to make an idea commercially successful, not the idealists forever tucked away in the […]
Read more
Condensate Switch Controversy
Condensate overflow prevention devices or float switches, as they are often called, are such simple devices that you wouldn't think there would be much room for controversy. In my experience, there are few areas of the trade where technician and installer preferences and opinions vary greatly. Let's start with some float switch basics. Float (condensate) […]
Read more
Vacuum Pump Oil
This article is written by Sal Hamidi, founder of, an innovative manufacturers representative agency that promotes great HVAC/R products through training and media. You can reach Sal at   If we are going to discuss vacuum pump oil, it's important to understand what it is first. Most HVAC application vacuum pumps are rotary […]
Read more

To continue you need to agree to our terms.

The HVAC School site, podcast and daily tech tips
Made possible by Generous support from