Did my AC service guy overfill my system?

[brianfox]

Hello,

I recently had my residential AC units serviced. I bought the house new 6 years ago, and both units are Bryant. I had them serviced because my 3 1/2 ton blew its capacitor. The other unit is a 2 ton. During the service, refrigerant levels were checked and I was told they were low.

An hour later, I was told that 8 LBS of refrigerant was added to EACH unit.

The thing is, now each time either unit turns on, the compressor is very loud for about 1/2 second - very loud buzzing. It was always quiet before. It especially happens if the unit was off for 10 minutes or so. I also HEAR what sounds like swishy/hissy sound above my head. When I hear this happening, I am in a corner room on the 2nd floor. The compressor is on the other side of the wall, on the ground floor. It doesn't sound like gas escaping, but rather flowing through a pipe. This swishy/hissy sound happens for about 3-4 minutes after startup and then the entire system becomes silent - except for the fan of course. This sound is happening on BOTH units, and never happened on either before the service.

From what I have read online, this is symptomatic of liquid slugging, where the system is overfilled to the point where refrigerant is compressed into liquid form, especially right after the system turns off.

Now, I have to say, the system IS cooling much better than before, so I suspect it was really a bit low on refrigerant...but 8 lbs each?

The way I justified it to myself was that this was a new installation in a tract house, and the whole street was initially charged at the same time. If all units were undercharged, then it makes sense that both units were equally low.

Do my symptoms sound like overcharge?

[green jumper]

Depends on the size of the unit, distance between the condenser and evap, and efficency of the unit of how much refridgerant is needed.

If its cooling better i'd say no its not out of the ordinary, but you dont have any data in your post to prove otherwise.

Loud is subjective and pipe noise from flow of refrigerant happens. Likelehood of general contractor not installing and charging a system right is high.

[amd]

Adding refrigerant is not part of normal maintenance - either there's a leak, they weren't charged properly to begin with, or your service tech has no business working on HVAC equipment.

Chances are that it's all of the above. :rolleyes:

[catmanacman]

i think you got ripped off as i find it hard to believe a 2 ton would hold 8 lbs and if they were still cooling the 3.5 ton would not take that much either.

[davefr]

I think the tech. is either defrauding you or an error was made. (ex: miscommunication??) Are you sure it wasn't .8 lbs/ea or a total of 8 lbs for both?

8 lbs of refrigerant added to each a 2T and 3.5T unit mean't either they were both nearly bone dry at the outset and couldn't have possible performed even close to normal OR they are now grossly overcharged. How long is the lineset for each system?

If 8 lbs was really needed, they both have major leaks that should have been investigated.

I'd call the owner of the company and investigate further. This just does not sound right. If he doesn't fess up that there was a simple miscommunication or paperwork error then get another tech. out to double check everything because your system could be at risk if it's grossly overcharged.

I would leave them off unitl this is resolved.

[wahoo]

As earlier posted, sounds like you either have a "wag" figure (wild ass guess) on the amount of Freon put into your systems, or both systems would have to have been nearly dry. Seldom have we seen a system even hold 8 lbs. of freon (maybe a HP 4ton or larger) if it was bone dry. Has your system been regularly checked by a qualfied servicetech? Something does not sound right. Did you see a scale on the job (to weigh in the charge)? Check into this, as something is fishy!

[heaterman]

Total system capacity is figured using the factory charge information listed on the condensor plus any extra refrigerant needed for additional line length over the standard allowance which is normally 15' of line. At any rate, 8# is alot to be added for systems of this size assuming they were working prior to the check up. If they are in fact over charged, that can be bad. For peace of mind a second tech opinion might not be a bad idea.

[brianfox]

Thanks for the advice, all.
The service receipt shows 8lb refrigerant per system. They were in fact cooling nicely before and after the charge, but had never been serviced in the 6 years. He said it took more refrigerant than he originally thought because the evaporator is a good 40-50 feet away; the lines run up two stories and then across 2/3 of the house. As mentioned in the thread, this was a glaring piece of info I left out.

I will follow up and find out if the system is overcharged.

[davefr]

He said it took more refrigerant than he originally thought because the evaporator is a good 40-50 feet away; the lines run up two stories and then across 2/3 of the house. As mentioned in the thread, this was a glaring piece of info I left out.

I will follow up and find out if the system is overcharged.

The correction factor for refrigerant line is +.6 oz/ft assuming 3/8" diameter and +1.2 oz/ft if it's 1/2" diameter.

If your line was 75 feet total assuming curves and bends then that's an additional 2.25 - 4.5 lb of refrigerant above and beyond the system's initial factory charge.

[gary_g]

What were the superheat and subcooling after the addition of refrigerant, and how do those 2 numbers compare to the mfr's specs?

[danielworkerbee]

I would also be very upset. Did the tech write down any of the data for the before and after of the refrigerant addition ?

Please do not 'assume' the worst of the tech, just call the service manager about the service and ask if he would review the invoice and possibly schedule a senior tech to re-check the charge level at "no cost".

[DGIO-Not]

Very late joining this one but I was wondering what was included in the servicing? We never ever asked if coils had been cleaned (albeit not convinced all is right but still we seem to be all over the map with what is considered diagnostics and service, seeing notation of 6y without maintenance.)

I agree this needs to be escalated within the company, it is just plain odd two (2) systems requiring exact amounts of refrig. I do realize, the HO does not know how well the system could work when serviced properly, but I am still constantly amazed at the number of techs who will go through the trouble of putting gauges on plugged systems and add refrigerant. It just seems like a hard way to earn your paycheck if you ask me.

[skizot]

Look at the stickers/nameplates on the outside unit. They will show the factory charge amount. Most likely that amount includes 15 feet of lineset. davefr mentioned the correction factor of 0.6 ounces / foot for 3/8" diameter lineset (probably what you have). (50 - 15) * 0.6 = 21 ounces (1.3125 lbs.) in addition to what it says on the nameplate.

I've got a 3.5 ton unit, and the factory charge (includes 15' worth of lineset) for it is 111 ounces, or 6.9375 lbs. As others have said, it sounds like the unit would have had to have been almost bone dry to need 8 lbs. of refrigerant.

[BlackMountain]

8 lbs in each unit would mean they both were almost empty. Have em come back out and double check charging chart to make sure not overcharged. If they both needed 8lbs, then a leak search is in order. Sounds fishy.

[tincup51]

I would also be very upset. Did the tech write down any of the data for the before and after of the refrigerant addition ?

Please do not 'assume' the worst of the tech, just call the service manager about the service and ask if he would review the invoice and possibly schedule a senior tech to re-check the charge level at "no cost".

Maybe the tech ment 8oz. ea. unit.

[Twilly]

Twilli says was it 8 lbs of gas or 8lbs of liquid?