Does variable-speed system require TXV?

[JoeSix]

I'm wondering if a TXV is required to prevent floodback to the condensor when you have a variable-speed blower (specifically when using the dehumidifying features of such systems like a period of slower fan operation at the beginning of the cooling cycle).

In this case the condenser is a 2.5 ton XL1200 and the furnace is a Trane TUD080R9V3. I'm pretty sure it's a 3-ton Trane evaporator coil also.

(Long story: Builder lost original coil during remodeling project and replaced it with a new one. I'm not sure if the original one was installed with a TXV or not but they definitely didn't put a TXV on when they replaced the coil and I'm trying to be sure this isn't a problem.)

[aircooled53]

I need model # of coil to answer if it came with TXV.

Most Trane dealers do put txv's on variable drive systems.

[pstu]

My dealer installed a similar VS furnace, AUD080R9V4 in the American Standard line, on each of my 2 AC systems. One had a TXV added on his recommendation, but he did not inform me it was a must. The other is a rather old Intertherm system due for replacement in the next year or two. It does not have a TXV. If this is mal-practice then I would like to know too.

Best of luck -- P.Student

[JoeSix]

Originally posted by aircooled53
I need model # of coil to answer if it came with TXV.

Most Trane dealers do put txv's on variable drive systems.

I don't think the original coil was a trane coil, so if it had a TXV then it was added by the contractor who installed it. (The original coil model number was HCC-17HH52236, which doesn't look like a Trane number to me). It was originally installed about 4 years ago.

Sorry for a dumb question, but you would presumably see the TXV in the liquid line just outside the coil, yes? (or do they make them integral with the coil now)

[millerman]

TXV's are always the better way to go.