I had a Goodman GSX140181 1.5 Ton 14 SEER Air Conditioner R-410A installed with a Goodman CHPF3636B6 3 Ton Horizontal A Evaporator Coil installed by a contractor. It came as a kit, along with a Goodman TX2N4A Kit 1.5-2 Ton R-410A Thermal Expansion Valve. Note that it's a 3T evaporator and a 1.5T condenser. That's the way the kit came, and it was priced well, so although the tonnage is different, it was sold as a kit, to be installed together, and was supposedly the way the manufacturer intended for 1.5T worth of cooling to be delivered.

The contractor installed the system and it's cooling nicely, but later I found out that he did not install the TXV (it's still in the box, in the attic). When I asked, he said it was not necessary because he used the piston/orafice that was shipped with the condenser unit. I saw that piston, which was in a bag, stapled to the condenser unit.

Although the system is cooling fine, and I'm getting about a 12 to 14 degree F temperature drop, I'm wondering about efficiency, long-term reliability, warranty, etc.

What's the difference between a TXV install versus an installation with the appropriately sized piston? Will it effect efficiency, reliability, warranty, or anything else? Is it worth the trouble to evacuate, install the TXV, and recharge?


I believe he used an orifice, the correct size orifice will function fine in the system but the txv may be able to increase the efficiency. An orifice just meters the flow of refrigerant, the txv actually regulates the flow or throttles the refrigerant to maintain a constant temp in the evaporator. Yes a larger evaporator is quite common you would never want a smaller one but larger will be fine as long as it is not icing up. I have done both and had both. orifice controlled less possible failures as 1 less active component, TXV slightly lower cost to run but usually cost more up front. If you wanted the txv in the system we would recover the refrigerant into a tank that’s a bit bigger than any bags I have seen, remove the orifice install the txv place the control bulb on the return side of the evaporator solder back up pump down and recharge the system with the refrigerant that was removed. It can take the better part of a day and I usually use the orifice on low seer machines (below18) and would in this case because your coil is larger you may not recoup the extra cost.

  • Yes, I think his/my term "piston" is the same as "orifice". Any idea of the magnitude (percentage) of the efficiency gain with TXV? Probably a small gain, given your comment about how the TXV cost (about $80 in my case) is enough to tip the scales on payback. – Dale Aug 26 '20 at 22:26
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    On a 14 seer system that is a hard guess when you get over 18 that’s where they really look to make a difference in the curves. I have a ice maker that I have to replace the valve on it is much larger and a small failure of something not sure but luckily the valve stuck open so I was able to use the pressure controls to cycle the machine as this particular valve is coming from Germany with a 6 week lead time. Really not sure what caused to stick the system is only ~3-1/2 years old and it failed when they need ice every day. – Ed Beal Aug 26 '20 at 22:48

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