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Question DetailsAsked on 7/29/2016

how long you wait to detect a leak after a dye is put in HVAC?

my HVAC is 2 years old, installed in winter of 2014 and in the first summer 2015 nevr kicked in, was recahrged then and I was told the new quipment was probably sitting longer and so low on freon and recharged..Worked taht summer agin this summer same issue...had to be recharged again. The tech put in a dye as well to detect any laeks and told us the unit has to run couple of months to detect any laeaks..Question is , how long the unit be running to detetct leaks after the dye had been put in?..Aprreciate your help!

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Depends on the extent oif leakage - a good sized leak that will drain a unit down in say a month or less might be visible in hours or a day - I once saw the dye appear within minutes on a valve casing crack that was draining the unit in a week or so. One that requires annual refills with several pounds or more of refrigerant might take a few days to a week or few to show up, so commonly they say they should come back in a month or two if the loss rate is not high. Also, some leaks occur onloy when the unit is running at max pressure, other (commonly fitting leaks) may leak even when the unit is off - so a longer wait time obviously makes it more likely it will have leaked and been stained by the time he comes back.

Key thing is not to go so long that the unit is getting low on refrigerant and overworking or overheating, or risking damage to the compressor from lack of lubrication, (which is transported around the system by the refrigerant), so if the unit starts laboring or running significantly longer periods of time in a cycle to cool down (in generally the same ambient conditions) shut it down until fixed.

First tech who said it was low because it sat (presumably he meant in storage/warehouse) was fresh from a swim in your pool - i.e. all wet, and did you a disservice. If the same tech for all these (or same company) I think they owe you a free recharge. If the unit came in pre-charged - with the gas already in the outdoor unit as some do (especially package units for mobile homes and such), then some gas might have leaked out a leaky cap - but when the system was installed the system should have been topped off to correct pressure at that time - so any leaked-off gas would have been topped up then - and should not have leaked off since then. Barring a distinct fitting or coil leak, most A/C units should not leak off more than a pound or less every few years due to minor leakage at threads and diffusion through the tubing - and many units run 20 or more years without needing topping off.

The problem is the law was very specific about having to fix significant leaks in commercial systems and spelled out just how big a leak is allowed before it has to be fixed, but while it states it is illegal to intentionally or knowingly discharge refrigerant (with a couple of specific test and charging losses exceptions), it did not specifically state for residential systems that it is illegal to recharge a leaked-down system without first finding and fixing the leak - even though a leaked down system = leak = knowlingly recharging a system with a leak = knowlingly and willfully discharging refrigerant. Even though the EPA has made clear that refilling a leaking system is a violation (and has heavily fined several contractors and pulled their licenses for it) a LOT of HVAC contractors take that lack of crystal clarity in the law as a loophole and just recharge systems without even looking for a leak - which makes them money in coming back and recharging the system for commonly hundreds of $ a pass, which is no favor to the homeowner.

You can certainly look around the system yourself (though might or might not be easy to access the evaporator coil yourself) for signs of the dye at any time - maybe once a week, and then call the tech back to fix it at that time without waiting the couple of months - especially if the dye is bleeding out and leaving any trail or spray of dyed oil, rather than just a single spot of color which might be a minor leak which is not the one causing your major gas losses. Of course, find out how to detect it - some are red or orange or green or blue dyes. At least one you use a black light to look for the leak (which is really finding the organic oil as much as the dye) - which you can get cheap at Amazon, and of course works best at night or in substantial shading.

Answered 3 years ago by LCD

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