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Old 06-17-2012, 08:36 AM   #1
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Stopping a leak


People,

Trying to help a friend- hes ben told from his ac guy that for $100 he will inject some stop leak to plug up pin holes in his aluminum evaporator(?) in air handler. Is this a good idea? The ac guy said he had to put in 3 lb of R22.

Thanks!

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Old 06-17-2012, 08:43 AM   #2
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Stopping a leak


I am not a fan of that stuff, it can and will clog the metering device in some cases so why chance it?

I'd pump down the unit and nitrogen pressure test the lineset and/or use a leak detector to actually find the leak, then repair it if possible. I say if possible because if the leak is in the evaporator than he's going to need a new one.

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Old 06-17-2012, 09:05 AM   #3
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Stopping a leak


Thnaks, Doc. But where is this metering device located? What is it/what does it do?

Lets say, in 1-2 yrs he needs a totally new air handler- is this device in the air handler or in the outside unit?
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Old 06-17-2012, 09:19 AM   #4
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Stopping a leak


In the evaporator coil, where the heat extraction during refrigerant saturation occurs.

If this is an electric air handler than the evaporator will be in the same casing as the blower and electric heat strips. If this ia gas furnace than the evaporator will be in it's own case, seperate from the furnace.

Follow the copper lines into the unit. Remove the one side panel of the case where the lines enter the evaporator and you'll see the metering device. It could either be a piston (sits inside of the line and is non mechanical as in nothing opens or closes in it) or a thermostatic expansion valve which does open and close via line temp.


Hold on, I'll find a few pics.
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Old 06-17-2012, 09:21 AM   #5
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Stopping a leak


Piston.


Txv.
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Old 06-17-2012, 09:28 AM   #6
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Stopping a leak


The metering device breaks down the pressure on the refrigerant, from high pressure liquid going into the evaporator to a much lower pressure saturated (both liquid and vapor) refrigerant on the other side of the metering device. As the refrigerant travels throughout the evaporator it's slowly all changing state to pure vapor as it picks up (extracts) heat from the air travelling over the evaporator coil, as well as pulls moisture from the air during this procedure. By the time the refrigerant leaves the evaporator it should be all vapor, If not, there is something wrong with the system.
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Old 06-17-2012, 09:30 AM   #7
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Stopping a leak


How old is this aluminum coil your friend has.
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Old 06-17-2012, 09:45 AM   #8
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Stopping a leak


i have used it as a last effort on a old system to buy them the rest of the season. i dont like it either. if the found the leak in the evap, then replace it.if system is old then it might be time to replace it
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Old 06-17-2012, 09:55 AM   #9
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Stopping a leak


Quote:
Originally Posted by beenthere View Post
How old is this aluminum coil your friend has.
Ohhhh, I get it- its the same as an expansion valve in a car, right? Im very familiar with those. yes, I have heard about that problem- sealants clogging TEV's.

Now, beenthere, the system is ohhh, about 1989-1990 ish old.
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Old 06-17-2012, 10:02 AM   #10
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Stopping a leak


12 to 13 years old.

If its a heat pump. Now would be a good time to thing bout getting a whole new system.

If straight cooling only. A new indoor unit. So that when the outdoor does go. The indoor unit can be converted/converted back to R410A. So tht he/they don't get stuck buying a dry R22 unit. And having to deal with expensive R22 recharge top offs several years down the road.
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Old 06-17-2012, 04:39 PM   #11
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Stopping a leak


1990 is 22 years old. you got your money's worth. replace it

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