How to recharge your heat-pump water heater (HPWH)

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Hello everybody, the only Nissan I ever owned was a 1975 280Z. I turned 70 yesterday and just wanted to share some old man wisdom. Bringing up the temperatures on the Geospring to figure superheat is kind of tricky. It is easier to look at the evaporator to "see" what's going on. If the lower tubes are becoming frosted and the higher tubes are dry, your unit is low on freon. If the tubes are sweating, but not all the way up, you are probably leaking some freon and the unit could use a charge. My Geospring seems to like about 40 psi on the low side after the compressor has been running for thirty minutes. At that point, all the tubes on both sides of the evaporator are sweating and the output air is very cold. Check the evaporator now and then to look for these tell tale signs.

Regards, Larry
 
Thanks for the tips, Larry! I'll look at those things next time I have the cover off.

BTW, the last time I recharged, I used the R139A with leak stopper and lubricant. I'm thinking perhaps I should just go with pure R139A with no additives next time to avoid adding too much oil. What do you recommend?
 
Hello RegGuheert, I have traveled the same road with "leak stopper" and it helped. The oil situation is more difficult to monitor. I have read where oil can become acidic and harm the compressor. There are those who do not recommend "leak stopper" for the same reason.
http://hvac-talk.com/vbb/showthread.php?611472-acid-oil-test-kit Some interesting reading. Also -
https://www.google.com/search?q=hvac+oil+test+kit&ie=utf-8&oe=utf-8 Everything in moderation, right? You meant to refer to R134a, correct?
Google "oil test kit in refrigeration" for more info. I am also going to use straight R134a and test the condition of my oil.

Regards, Larry
 
I know this post is old, just wanted to say the this has been the most informative location for info regarding this HPWH. I've been struggling to come up with a realistic solution to repair due to labor costs. GE sent me parts for free since I'm under warranty, but estimates for work came in around $500-$700.
Failure code F-C was displayed. Unit is 8 years old installed 2011.
I had about 5 psig of refrigerant in system. My T3a temp was about 10 F with T3b around 65 F.

I followed instructions with line tap valve and had some issues getting the unit to charge. Was very slow and only able to get the pressure to about 35 psig. T3a is now about 45 F with T3b about 70 F. No frost on coils and condensation up about 1/3 of the way, but I'm thinking something is still wrong since the charge was very slow and I can't get a full charge.

Regardless unit is working much better, so thanks for info!
 
Thanks for the info. I have a gen 1 GE HPWH, installed in 2010. Mine has worked fine the whole time, no issues. Funny to find good info here, only now happening to find it, now that I have come into a Leaf (just S, no heat pump...).

The water heater is installed in the basement next to the really old inefficient natural gas boiler, and I duct the electric dryer exhaust to the HPWH. I rigged an old mercury tstat, and a pot with the T2 (water temp) sensor. When the dryer or the furnace raises the temperature (waste heat available), it makes the T2 sensor read about 10 deg F lower, which causes the HPWH to run and catch the heat. Wife is happy with hotter water, and then the HPWH is less likely to run when there is not easy heat to get.
 
Hello RegGuheert. I found this post from 2015 with detailed instruction for recharging the refrigerant in my GE Geospring HPWH. If your are still out there I wanted to say thanks and ask for any additional input you have.
When I found the 2015 post I was very excited and proceeded to buy the required supplies and dive in. Unfortunately, I was unable to download the photo of the installation that you posted and I ended up installing the line tap valve on the suction side of the compressor rather than the discharge side. (the gauge on the recharge kit shows readings that reflect a vacuum ranging between 10 and 25 In WC). Before I realized my error, I forged ahead and added refrigerant. I believe I was successful in adding most of a 12 oz can. The good news is i don't seem to have caused any damage, but the FF error code still persists. I have another line tap valve and I am tempted to install it on the discharge side, check the discharge pressure, and perhaps add more refrigerant, but I am a little reluctant to make another penetration, and concerned about overcharging the system. I decided to slow down, take a hot shower, and reach out for any additional input before proceeding further.
 
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