Accumulator Facts & Tips

Bryan teaches a class about accumulator facts and tips. He explains what they accumulate inside an HVAC system, covers some common problems, and gives some tips on how to use them.
Accumulators are designed to accumulate liquid refrigerant before that liquid can reach the compressor. Liquid should never get inside the compressor. When liquid floods the compressor, it washes out the oil. Many compressors are also refrigerant-cooled, and that refrigerant has to be a cool vapor, not a liquid.
Accumulators are more common in Carrier heat pumps because those systems have fixed-orifice pistons that don't control the superheat. Therefore, the accumulator is an additional safety measure when there is no control over the superheat in a wide operating envelope; it interrupts the liquid before it can affect the compressor. Although the accumulator can become liquid-locked and feed back, it's unlikely. Accumulators also prevent slugging. However, modern compressors are unlikely to slug due to their refrigerant-cooled nature. Slugging happens when liquid gets into the compression chamber.
Overall, getting liquid into the compressor in any capacity is undesirable because it starts foaming the oil and ejecting it from the compressor. The oil lubricates the compressor bearings, which keeps the compressor working for its entire lifespan; premature failure may happen if there is too much mechanical wear without the oil. When oil is ejected from the compressor, it also goes to the rest of the system and can get stuck in the evaporator coil when it gets more viscous.
The accumulator has a U-shaped tube with a small pickup hole at the bottom, which picks up oil. (Oil is heavier than liquid refrigerant and will sink to the bottom of an accumulator.) If that bottom port gets blocked, oil won't be able to get through and will get stuck in the accumulator, so it can't lubricate the compressor. Copper shavings, dirt, and carbon flakes may block that port. There is also a port near the top that stops the accumulator from becoming liquid-locked.
In some cases, oil also may not return to the compressor due to long line sets. Long lines require the HVAC/R technician to add more refrigerant, and special considerations need to be taken to make sure that liquid refrigerant doesn't migrate (or vapor refrigerant doesn't condense to a liquid in the compressor). These strategies include liquid line solenoid valves, hard shutoff TXVs, and crankcase heaters.
When we replace a compressor, we want to pay attention to the accumulator. Replacing the accumulator is perhaps the best practice, especially in a burnout situation, but the old accumulator can be reused if it's flushed and completely cleaned out. It's a good idea to dump out the accumulator and analyze the oil; a lot of contaminated oil indicates a lot of oil loss and could be a burnout. The accumulator is a good place to test the oil, too.
Charging a system with an accumulator is different from charging a system without an accumulator. Liquid charging could result in refrigerant going into the accumulator and getting cold, which makes it hold liquid refrigerant and indicate undercharge because the subcooling won't go up (even though the system could be overcharged). So, using a charging scale and giving the system plenty of time to equalize will help prevent that from happening. With labor, refrigerant, and callbacks being as expensive as they are, the small details matter.
It's also worth noting that motors and electrical parts often fail due to mechanical conditions, not electrical ones. So, burnout isn't always caused by lightning strikes, start capacitors that aren't taken out of the circuit, or over-voltage conditions.
Read all the tech tips, take the quizzes, and find our handy calculators at www.hvacrschool.com/.

[@Captain_Kdawg]

Good video. I knew the basic understand of the accumulator. But I can say I learned about the holes in the pick up tube today !!

[@nu-nu-ramen3326]

😂😂😂e😮😅

[@jasonjohnsonHVAC]

Tech tip....accumulators can and do leak....usually from the bottom. Don't forget to check them on a leak search

[@trevorjones559]

Yes. They have condensation nearly 100% of runtime, so if the paint is chipped on older equipment, chances are you're gonna find leaks. I've found them on the top also.

[@seandowns8828]

Changed 2 out last week bottom leaks

[@fre0nx675]

Almost always. Especially in heatpumps when they get full of dead leaves or muddy sand that holds water.

[@OcRefrig]

1) They leak up at where the factory connections are at copper to steel joint also. ( top of accumulator ) 2) also at Overtemperature Relief Plug in top area on Heatcraft units. ( see one of my videos if you don’t believe) 3) also at welds - top & bottom. Rust out. 4) bottom stud - as everyone is mentioning. 5) Factory paperwork says good life is 5-8 years on accumulator. After that all bets are off. 6) After welding in - I have started wire brushing & painting any burnt areas at top connections. Especially on marine applications.

[@condor5635]

@@OcRefrig thanks for the wire brush paint it tip. My top area is rusty and needs that. It’s like 20 yrs old surprised it has not leaked already. I keep bottom of condenser clean of junk so that helps I guess. Thanks!

[@davidryder3374]

As an HVAC instructor, I appreciated your pain when you asked a simple question and nobody answered.

[@Boraxo]

Or an answer they just pulled from their behind.

[@enochian7133]

Mr Brian,thank you for these videos .For some of us studying online these videos are sooooo valuable! Your students are lucky to have you as an instructor.

[@lynncomstock1255]

Good job. One correction at 11:06 Liquid will end up in the compressor oil regardless of temperature difference because oil has a very low vapor pressure, and the refrigerant vapor migrates into the compressor oil to increase the vapor pressure of the mixture. (Think of the low vapor pressure of the oil as like a very slight vacuum. It takes quite a while for this to happen. Manufacturers asked that the CC heaters be activated before startup because the bulk of the refrigerant shipped in the equipment will always be in the compressor oil. This is also a reason why compressors have twice the minimum operating oil ensure that they have enough oil under widely varying conditions.)

[@632Harrison]

I give you two thumbs up my friend I have been a HVAC / Refrigeration technician for over 42 years

[@benkuxhouse787]

Nice video I’m a technician of 37 years and learned a few things. About the oil test I did a compressor replacement in freezer the compressor was $5000.00 alone Wholesale. Needless to say I came by a few times to do inspection of oil site glass and a few oil acid tests. as he said in this video which is correct commercial compressors can be very expensive

[@adamcox1809]

I'm considering entering the trade and the amount of information I've learned from this channel for free is incredible. Thank you so much!

[@jpstryker23]

just started this trade, thank you sir for putting this together in a concise explanation, im going to a school via our union in florida and these classes are helping fill some gaps where i dont fully understand at school. i love the animation, just seeing it helps tremendously.

[@TheBanaxel]

You sir are a honest contractor. Thank you.

[@nathanhurst5155]

Thank you so much for these work meeting videos and all the others you do. They are all awesome 👏

[@mathman0101]

Love the chit chat with the techs you have now that’s an employer who teaches and strengthens their employee training kudos to you all and for sharing that knowledge.

[@sparkyobrian6417]

love these videos, hvac terms are so different than my field, very interesting !!!

[@gorrillaback11109]

This video came at a right time. I wanted more knowledge on accumulators and this video was recommended on the algorithm.

[@VOTEREPUBLICANS594]

Now i have understanding of the accumulater , thank you !

[@samutokakece731]

thank you for awesome and informative knowledge

[@LheodaDjTechTv]

Watching and sending support thanks for sharing

[@larryproffitt4729]

Thank you for putting together this informative video.

[@Stuart68505]

Lots of helpful ideas. Thanks.

[@POlin-qs1um]

Great stuff. Coastal Nc area,Blackbeard Country. RustyTanks and Driers blow first,then Coils. A.c.r 30 Yrs. Sometimes I'll wrap a new Tank with black cork tar tape. It will never rust out. Ocean Salt galore. Life is a Beach! Great vids!

[@rafaarroyo5438]

Thanks!!

[@mohammadalshaikhhasan5091]

Thanks Brian, a good topic to attention. Replacing the accumulator requirs attention about the size. If you describe little about what could happen when installing a bigger size accumulator in the system.? Thanks again

[@Stuart68505]

Thanks lots of helpful ideas

[@MichaelSmith-pg6gi]

Excellent!

[@dalvindersinghmanku8243]

Good information regarding accumulator....i heard this types of leakage in bottom of accumulator.

[@vnesmuonnam]

Thank you

[@randyfalkosky8579]

very well done!!

[@MrGarcon98]

well done thank you

[@etherealrose2139]

Solid video.

[@Cpt_bike_riders]

Struggling with a iced up accumulator. What can the problem be? This helps alot on clearing things about accumulators

[@duanecarroll4375]

I wish I could post a picture of 2 accumulators in an industrial setting. I had one that was for the cooler, and one for latent heat of fusion feeding a turbo ice maker. Had gravity fed vacuum tubes also. Some knarley rotary screw compressors let me tell you

[@ELECTRICMOTOCROSSMACHINE]

Very cool.

[@rachida3904]

Good 👍

[@Nab-Asn2803]

Thank you for domistraion, can I install acumelater in havc 6 ton that has recipating compressor inoder to protect my compressor in long run life of compressor

[@carldurham5879]

Accumulator sizing on variable speed compressor systems are critical and the same pipe sized accumulator must go in place if it is initially installed

[@davidpanyj]

Amazing 😊

[@morisuesue5019]

Should you replace the reversing valve when replacing the Compressor.

[@mushtaqahmad7897]

Nice video

[@scott5654]

👍🏻👍🏻 Thanks, Excellent as usual ‼️ I never knew oil could be bad and yet not look bad, as in black, or smell bad, as in burnt. I learned something new.

[@daveeckmann9568]

I took a compressor class by Copeland one time and they said the oil in a compressor should look new the same as it went in..."this is not an internal combustion engine...there is nothing inside the system to make it dirty" if its black it has been overheated/burnt.

[@loveyoutoo7081]

شكرا

[@condor5635]

This explains accumulator well. I had asked the question about what that cylinder was next to the compressor. Now I know. Mine is also a Carrier which I think you mention uses them a lot. The top junction looks like rusty and corrosion. I think I will wire brush and paint it. Thanks for the great video

[@JeremyChan]

thanks for the great info!

[@mitbbs]

Is it normal to have a sweating accumulator in a hot humid day? I found a pond of condensation water under the outdoor unit. Thanks!

[@ryanmullins715]

Just changed a compressor tonight,only to find a bad accumulator,I changed drier,contactor,dual cap,braised with nitrogen,had a feeling accumulator was bad knew I should have replaced it to,now have to recover and either flush or replace accumulator,thought it was mechanical but nope

[@alaminmiah5291]

Good Sir

[@markbowker5936]

GREAT INFO! THANK YOU

[@arealmaintenanceandrepairl1103]

Do ac only have accumulators I had one with some sort of cartridges on the liquid line not filter dryer

[@MdArshad-nn2do]

😊 Nice 😊 video 😊 sir 😊

[@wacoodude6567]

Does the accumulator always need to be have liquid refrigerant to return oil to the compressor? FYI when running in Heat Pump at really low temps, the density of liquid refrigerant can be more than the oil (depending on refrigerant and oil combination) causing oil return issues.

[@Pennconst101]

I would love feedback on this: probably five or six times in the last 15 years I’ve gone back on heat pumps and found them drastically overcharged however the overcharge is not immediately apparent. I’ve checked systems letting them run 30+ minutes only to go back a week later and find them off on high pressure And then proceed to recover sometimes more than 3 pounds. These are systems that are more than five years old and the question becomes how in the heck have they been running the whole time?! The only commonality is that they are all heat pumps so I presumed the accumulator has been acting as a receiver.

[@Brokefootchuck]

Did you remove all the refrigerant and weigh it back in? Or did you go by the manufacturers literature (pressure curves, subcool charts etc)?

[@brianlittle717]

Great video. I learned a couple things. Should super Heat be measured on the suction line entering the accumulator, or should it be measured as it enters the compressor? And that’s a good point about crankcase heaters. Is there a reason the CCH is more common on a recip than it is a scroll?

[@michaelwhitaker7764]

Reciprocating compressors have crankcase heaters more often because slugging can bend the valves in the compressor

[@brianlittle717]

@@michaelwhitaker7764 I guess that makes sense. So you’re saying it’s harder to damage the scroll from cold oil?

[@lynncomstock1255]

@@brianlittle717 Not cold oil. Liquid refrigerant slugging. Scrolls are designed so that the compression chamber between the scrolls opens up (enlarges) whenever non-condensable liquid refrigerant or oil completely fills the compression chamber.

[@brianlittle717]

Is that the same thing as when it bypasses at 625psi? And how does the chamber get full of liquid? I know some liquid will go through it if it’s frozen up or when you’re charging it but that’s not a full chamber is it? It should be able to handle that. And if there’s a suction trap and it fills with oil then it might get a big gulp from that once in a while. But how does the crankcase heater prevent a full chamber of liquid if it’s not the oil we are worried about?

[@michaelproust7891]

Could you explain why a system fault could be exacerbated by the client running the interior ambient higher.

[@gyrgrls]

I've always chased my aspirations, but I never really accumulated much.

[@Elisummit845]

🤣🤣🤣🤣 are you friends with TY Branaman? Lol

[@John..556]

I had a Rheem heat pump Freon leak and bad compressor. Figured leak was in indoor coil.. customer decided better solution to replace compressor. So I did, 1 month later I discover the new comp is dead. So i warranty it out. But I notice there’s 0 oil in the compressor. I thought wow no wonder it roasted. Then I put the other new one in pressure test is ok. But I know it’s leaking so I ignore it. Pull my vac and I’m seeing tons of vapor exhausting. So I start looking at my joints. All good. Then I lean on the accumulator and hear the hiss of death. That accumulator had cracked on the bottom and the oil and rust would semi seal it and it had leaked all the oil out underneath it but you couldn’t tell because it ran under the condensing unit… rheem is not my fav system lol. And I cut the accumulator out and straight pipes it works perfect now lol

[@AaronPowellvox]

Watching these videos with peanuts in the background and waiting for them to give you the right answer is sooooooo grueling. It’s why I never liked school. Just get to the point! Sheesh. I love the information and am grateful but I wish these videos were edited.

[@WickedIllusion1]

Can someone expand on the 'hard start kit' part... If I have a presently well working system should I not add one? I was led to believe recently that even on a properly functioning system ( mine is a 9 year old Rheem, in SE Michigan) that a hard start kit is an "upgrade" and would likely extend the life of the compressor....

[@hvacmisadventures]

Yeah you can add one. It would be best if they all just came stock with them but that would be expensive and people don't wanna pay for that

[@irham9856]

👍👍👍

[@CapsCup2012]

Serious question - why do we charge liquid into the suction line if liquid is bad for the compressor?

[@emptech]

It's nice if we know the refrigerant capacity of a system, but we don't always. We tend to look at superheat on a cap system and subcool on a TXV system, but the manufacturer doesn't always give those numbers, so we use ball park numbers. I learned from others that while the system is running properly, the accumulator should be filled to about 2/3's of it's capacity. Like others, I've flashed it with a torch and then used a thermal camera to look at the liquid level, some will put their hands on the side and feel the liquid line. You didn't mention any of this, is it a wives tale? I'm rebuilding a wine celler control system, will have to charge it by the gage readings, but it does have an accumulator. A method I used one time, measured the volume of the accumulator, then calculated 2/3, got that number, then found the density of the refrigerant, and once charged by the numbers, then added enough refrigerant to fill the accumulator to 2/3, did I over-do it? Always appreciate the videos - Jim

[@ooklathemok7322]

You do not charge a Refrigeration circuit by filling the accumulator. I believe you might be thinking of a receiver. These are 2 different components that do 2 different jobs. By design a well balanced system with an accumulator will not have any refrigerant in it. When a TXV is used it's job is to control superheat. A fixed orifice if charged correctly will rarely bring saturated refrigerant to the accumulator. But due to system operating parameters a heat pump or low temp refrigeration system could have saturated refrigerant returning to the accumulator. Mainly because of frost or ice on the evaporator. It is common to fill a receiver to 80-90% capacitor for condenser flooding, when teamed up with a head pressure control valve aka headmaster. Receivers are common on Refrigeration units. I hope this helps

[@wigginsryan0]

I'm in Orlando. How can I find this course and take this course in person?

[@UQRXD]

I am one to install a suction and liquid line filters. I heads off a lot of problems.

[@Elisummit845]

They say not to install a suction dryer only after a burnout.

[@indiantraveller194]

Good

[@Barracuda48082]

Q. How to size an accumulator on a system that should have had one..?

[@pb5640]

Knowledgable guy but this is known in education circles as a talking head. I’m glad you added the pictures and illustrations which helps undo the boring talking head. I don’t think the students in the classroom had this advantage.

[@zerwell47]

The last I looked, refrigerant is heavier than oil...therefore oil floats on it. (7:33) not as stated. But, good video anyway.

[@dhronpatel9158]

Same thought here

[@Mapdotgolf]

So if we don’t want refriger

[@Mapdotgolf]

So if we don’t want refrigerant in systems, does that mean pumping down a system is bad for it?

[@sjsz06]

Are there any videos that don't act like a school asking questions as though you have already been given the info, but just relay the information? I like the info, but am way past going to school (I'm 74).

[@fre0nx675]

Someone told me those old TRANE orange compressors (Easter egg) had internal accumulators

[@cacangfishing9905]

Accumulator prak tips

[@Ihscout1069]

Wish Lennox would use an accumulator and get rid of the outdoor txv

[@nehorayneemani1039]

Why did you mention accumulator with heat exchanger???

[@jessehanecak2241]

I am not an experienced technician and I am far from what I see as an expert but I understand that electrical issues are almost never lightning strikes. I guess my question is, is this really a common thing? I wouldn't have expected it to be.

[@lynncomstock1255]

Many years ago, compressor manufacturers claimed that a majority of compressors returned under warranty were not failed. I expect the same is true today because of incompetent technicians.

[@brendaggiegigem6742]

​@lynncomstock1255 and $$$ grab. I just had a unit in trouble Trane 2 stage where it cycled on and off quickly several times until Thermostat (Nest) error coded E107. Wiring issue. 1st tech came, and diagnosis was compressor on 7yo unit. Over $2k under warranty to replace it. I'm not tech or hvac trained, but ?wiring code =compressor? 2nd tech came and troubleshooting couldn't figure it out initially. He jumped it past thermostat and compressor worked fine. His diagnosis is thermostat bad. Replaced thermostat with original b4 Nest installed and working fine. Saved me $2k and found a new customer. Honesty drives profits through happy customer referrals. Glad to hear you, sir. training student techs to replace the contactor and do preventive to keep from having another call back in 2 weeks/months.

[@tomconner5067]

Liquids can't be compressed

[@Zerofukstogive]

The funny thing about skilled trades is that you can master one and be really good at it but you can't balance both. I've met plenty of people in my day that claim to do both but they are never masters of both. They chose one or the other but they will always say they know both. Stick with one trade and master it. I can pick up on a person that "pretends" to know it all. It's bullshit. I'm a card carrying plumber in ohio and I don't pretend to know hvac. I worked in hvac for a year and a half and I still don't pretend to know how to service hvac. It takes over 5 years to become a good tech in either trade. Stick to one and master one. It's easy to pretend to know both if you know how to talk but in reality you are just doing both and hoping those certified employees don't ever mess up.

[@Mr.body1917]

😂😂

[@The-LongRoad-Home]

I've never had a compressor and probably done hundreds I have come with a new wiring harness🧐

[@hvaciqguy2655]

BECAUSE A COMPRESSOR CANT COMPRESS LIQUID!!! Can’t someone just say that??? For F@CK sake… I would have to avoid these little get togethers… and YES WE DO talk JUST LIKE THAT in THIS-HOUSE…🤣😂 poor Brian…

[@hvaciqguy2655]

Then one day I’d be walking past, hearing Brian’s explanation n think to myself, wait, I didn’t know that…

[@tomlewis632]

I always hated those damn steel accumulators that would rust out and leak. Especially Carrier and their shit brands.

[@condor5635]

My carrier is over 20 yrs old. I am happy with it overall. Changed contactor and cap myself and also installed 5-2-1 recently. Copeland scroll compressor. Happy overall

[@tomlewis632]

@@condor5635 Its funny because all of my training is from Carrier. In Florida, the A/C gets used for 10 to 12 months out of the year. Over the years for me, the average seemed like 7-10 years Max. Back in the day, before they got bought out by Trane, I saw General Electric ⚡️ units over 25 years old still running.

[@condor5635]

@@tomlewis632 - I guess I’m extremely lucky then

[@charlesfleming742]

⁰p

[@fwily2580]

Asking questions as a method of teaching is not teaching. It’s just a bad conversation.Right?

[@HVACS]

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