Procedure for Repairing Heat Pump Leak
A service tech is coming by today to replace a muffler in my heat pump. That's where the dye was after the dye test. I also expect him to pull a vacuum and replace the filter drier. Am I missing anything? What is the proper procedure that you would follow given this situation? I want to make sure he is doing a good job because I don't want anymore callbacks (and I'm sure he doesn't either). Thanks in advance.
If the FD is inside the unit, move it to the outside.
You already know about nitrogen when brazing, hopefully he does too.
Weigh in charge. And test in all modes possible for the days OD conditions.
Thanks Beenthere. He brazed using a mix of acetylene (?) and oxygen. He charged the system in cooing mode using a superheat measurement. The filter drier that was installed (outside of the unit like the last one) is a copper-spun one that looks different from the old Parker filter drier.
Everything seems to be working fine, but he showed me how my compressor was working harder than it should be, drawing around 19 amps when the maximum is around 22, on a tool that measures amps (I don't know what it's called). He said this is probably due to my mismatched system and/or the fact that the compressor has run without ample refrigerant. I understood. He said the compressor could be on its last legs or it could run like this for longer. Any opinions?
Did he take a wet bulb measurement of your ID temp, to determine what the superheat should be.
The high amp draw could be from the mismatch, or an over charge. Or as he says, from running starved for refrigerant.
Did he take an amp reading in both heating and cooling mode.
PS: Its called an amp meter.
He used his gauges to convert the pressure into a degrees Fahrenheit and subtracted the temperature reading from the suction line. I can't remember whether or not the amp reading was taken in heating or cooling mode, but I do believe it was just one mode he took it from. What is a wet bulb? Your experienced input is really appreciated, thank you.
Outdoor unit: PH10JA042-C (from 2004)
Indoor unit: Lennox CB26UH-042-R (from this past summer)
What people warn about is coming true now. It looks like the compressor's life is being shortened considerably, especially with all that's happened lately. I'm sure I'll have to take the consequences of the mismatch at some point down the road. I hope to keep this system maintained down the road, however. With all that the full service agreement has covered, I can't really imagine having a problematic system like mine without one.
Also: Tonight I switched my thermostat back to a program to not waste the benefit of a programmable thermostat. The most I have the thermostat dropping in heat mode is 2 degrees (70 -> 68, 68 -> 70). The auxiliary heat probably shouldn't have to come on too long to make up this difference, but I will have to monitor it. I'm going to play with it to see if it's worth, economically, to use a program schedule versus a permanent hold at 70. Auxiliary heat is nothing new to me as of late. Do you think a 2 degree drop at night is bad?
Then he checked what the superheat was. He didn't charge by superheat, since he didn't check what it needed to be.
Wetbulb, is basically the lowest temp water will evaporate at under the current conditions of the area it is being measured in.
There is a chart he should have compared that reading to, in order to know what superheat to charge to.
The conditions for today could have called for 5*, or for 17* superheat.
I doubt your system is charged right.
He said 14 degrees was the superheat (50-36, so 36 was the PSI converted to degrees Fahrenheit). I guess I'll have to call this company back out. Maybe next time they can put a service valve back on one of the ports (not a service port, there's one just above where the refrigerant lines go into the system that has a small capillary tube connected to it (I'm sure you know what I'm talking about).
Sometimes I wish people like you could service my heat pump! To be honest, as much as I think this service tech is a good guy, I don't think he'll understand anything about a wet bulb measurement. He didn't seem to know anything about flowing nitrogen while brazing (see above post for his method). This is actually supposed to be a good company for the MD/DC/VA area and I have neighbors who use them. It's scary to think other systems besides my own are being charged this way.
It seems like it's been a while since I've actually had a functional heat pump for a decent period of time...
IMO he can't get an accurate charge in cooling based on superheat if there is snow on the ground(exaggerate). If he comes back he just needs to check the head pressure in the heating mode. Make sure all the vents are open and the filter is clean, let the system run for 15 min., check head pressure. There might even be a cheat sheet for this procedure inside the door of the HP or in the installation manual. It will tell you what acceptable readings it should have. Then schedule your technician to come back this spring and check the superheat or sub cooling on a hot afternoon. Otherwise he must remove the charge and weigh it in and add or subtract for the length and diameter of the liquid line. Again IMHO
Originally Posted by RyanHughes
BTW did he remove or did he isolate the charge when he replaced the muffler? Did he pull a vacuum?
Seems like he should have weighed the charge in and then adjusted for the mismatch and a long lineset if it is unusually long. He should have used nitrogen while brazing and for a leak check after the repair was done. Did he even have nitrogen on the truck. It would have been good to blow nitrogen through the system before pulling the vacuum too.
oxy acet is the torch type.
The nitro has to be flowed through while he is brazing.
Many techs are not taught this. So it may not be his fault for not using it, he may not know any better. He's probaly doning it the best he can, by what and how he has been taught to do.
Can't weigh in the charge on a mismatch system and expext it to be correct, since there is no weigh in chart for it.
now lets see how long it holds freon!
freon must be old timer, (brand name) refrigerent thats what i teach my students haha.
hard to charge in cold weather in cooling mode. scale is about the best way or charging cylinder and then guess for over sized coil or longer line set.