Regular Guest
I will be going back tomorrow for the 2nd time on a new install and would like some help from you pro's!
I sold a client a 2 ton R22 air handler to go with his 2 ton straight cool XL14i condenser and we mistakenly installed a 3 ton R410 air handler (Trane) and had a call back for not enough cooling the next day. We then replaced the air handler again with the correct size but still using the R410a expansion valve. When I questioned why not replace the expansion valve I was told by management that it will work fine and no need to replace valve. And now after a few days later I find out I am going back and I have a feeling that my problem is going to be that the valve should be replaced to use R22. As I don't really know why other than its wrong. What can I tell my management to explain why it's wrong? And if it is ok to do I will just drop my argument and move on.
Thank you in advance for your help.
God Speed, Jim. We'll miss you - 2-26-23
It will flood the evap. The pressure in the evap is not high enough to counter the charge in the bulb. The pressure in the external equalizer is what pushes back against the bulb charge. Opposite happens when you use an R22 TXV on an R410A system, it under feeds.
Global Moderator
It is going to be the valve. That was made clear by everyone in your last thread on the job.
Regular Guest
Thank you for the answer, i appreciate it.Originally Posted by beenthere
Regular Guest
I expected an answer like this as well. I realize it won't work correctly but I wanted to know why it won't work correctly. The reason for the new thread was to make it clear to me and drop all the other stuff about the job. So thank you for the useless and obvious info and for taking the time to dig and point out that there was another thread, that really helped!
Professional Member*
Did you install a Trane Hyperion AHU? If so, check the EEV board. There is a dip switch to swap from R410A to R22. No need to change the whole valve or stepper motor.
Change the switch, cycle the power, and restart.
Regular Guest
Honestly I can't tell you that yet but I am going there in a couple of hours and find out but i believe it is going to be the GAM air handler. Thanks for the input I will check it out.
Member
What we have here is as failure to communicate.
Professional Member
lol. Some men, you just cant reach
Professional Member
I bet the 3 ton ah would have worked by simply changing the txv to r22. The route taken seems backwards to me
Professional Member*
+1.
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Professional Member*
+2
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Regular Guest
Seems the problem is the length of the line set. Measured the line set at 375 foot with 10-12 foot vertical rise. Found the liquid line at 67 degrees at the air handler. Spoke with Trane tech support and be said max 200 feet. He said without moving the condenser closer the only other thing I could try is lowering the fan speed which I did and it did help but not a lot. Explained that to the client and of course he gave me "we'll the original system worked fine" so now we are moving the condenser if the lowered fan speed does not work. And the Trane tech support said that having a smaller evap coil is actually helping me.
Regular Guest
Yes it is that kind of air handler and it was set for R22. Thank you
Global Moderator
This is confusing. The first post in the thread said you have the right size, 2 tons, but still a 410 TXV. That sounds like a GAF2. But above, you saying you have a TAM4, GAM5, TAM7 or TAM8 with an EEV and it is set for 22?
Obviously the lineset is outrageous but hard to argue with "it worked before". What kind of temp drop did you have on the liquid line when it is 67 indoors? What did it leave the condenser at? Did you check superheat? If it is a 410 TXV, beenthere says it would be flooding the coil so superheat would be zilch. If it is an EEV set for 22, you shouldn't be too far off on superheat unless low on gas or starved for gas.
Professional Member
375 feet is outrageous. would have walked from that job. Have work on units with 225 that lost compressors like crazy due to oil not returning fast enough to compressor. good luck. if you have the old air handler might look at fixing what ever was wrong with it and reinstalling it.
out of curiosity was the old unit fixed orifice? if so i would pull the piston in it and see what it was use it compared to what the unit would have come with to give you an idea of what adjustments may need to be made to the expansion valve.
Regular Guest
Honestly I don't know what type of metering device was in the original air handler I did not look at it that much to remember. I opened up the unit to find oil all over the place and the system only at 70psi with the system not running, so I said to myself the evap coil is leaking and moved on.
And I knew the air handler was a long ways away from the condenser but really didn't think about how long it was and that it would have an effect on the system like that. I knew it had a liquid line solenoid at the A/H and a suction line accumulator at the condenser so I guess I figured all is well. Shame on me I know.
Regular Guest
That was me assuming, I apologize for that
It was never 67 indoors that was the temp of the liquid line in the attic at the air handler.
When I arrived it had a 6 degrees of subcooling and I don't know without looking at a pt chart or my gauges right now how much super heat I had but I can tell you that the suction pressure was 70 and the suction line temp was 87 degrees.
I looked at the data plate of the condenser and it read 10 degrees of sub cooling so I started to add refrigerant and the head pressure did rise and the liquid line temp at the condenser fell. I stopped and started scratching my head and took a temp difference across the evap coil and it was 10 degrees. I decided to call a few other techs and was told "I dunno". I called tech support and that's when he basically laughed and was like "seriously how long is the line set?" And proceeded to explain why it won't work and to try to lower the fan speed. After I lowered the fan speed the suction line temp fell to 58 and the suction pressure of 85 and I had 14 degrees of subcooling. That's when the client arrived and I explained the problem and gave a solution. And quickly packed up and continued to run more calls as I was extremely way behind schedule and management was on my butt to get going.
Professional Member
when there is really long line set it normally is stepped down like a truck line on ductwork 7/8 to 5/8 to 1/2 to the air handler. you lose capacity the entire way. the liquid line solenoid sounds like a pump down system to me is it pumping down? what brings on the compressor, a pressure switch? is the accumulator aftermarket? i have seen accumulators installed with very long line sets. also assuming it is a pump down system with that long of a line set i am thinking that the expansion valve would not settle down and run at a constant number for a while after startup like 30 min just guessing with that.
Professional Member*
Post some numbers. We can better understand what is happening and provide better advice with more info.
More info = More knowledge.
Suction Pressure? Head Pressure? SH? SC? CFM? Delta? Indoor wet bulb? Indoor dry bulb? Outdoor ambient?
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