Sanity check on maintenance

[RyanHughes]

okay, I'll ask about just not having it, or removing it. I'm guessing they put them on all the systems as part of their standard install... but who knows.

So, how do they test for a clog, per se? Just going by temp rise across the drier, and assuming everything else is fine, it must be clogged, so close off the lines, drain them down, remove the drier, and replace? (then recharge the system). I'd assume they're not going to care what it's clogged with and therefore not know why it clogged in the first place?

I'll make sure to insist on nitrogen.

I'm assuming that there's little chance the system is low on charge given the symptoms (and numbers)? Just trying to avoid extra costs here...

Oh, and are they going to have to replace the built-in one as well, since they're "opening" the system?

In my opinion, (not a fun task, but) at this point, take out both and put one after the liquid line shraeder valve (where the second one is). And braze with Nitrogen...

[staze]

duplicate of below.

[staze]

k. I shall report back... anyone else with input, please please! Also, just went out and checked, and indeed, there are two filter driers (one on the LL as it heads to the house, and one inside the side panel on that same side (blue)).

I do notice things like this: http://sporlanonline.com/240-10-2.pdf that suggests two driers. But that seems to only be for simple non-reversible ones, which I'd guess the built in one is, and the external one says it is. =/

Or this: <Links to other HVAC forums are not permitted> that does indeed say a second is silly.

Would I have ANY case at all arguing that if the external one is clogged, that they should fix the system for free since it shouldn't have been installed anyway?

[catmanacman]

on trane units the subcool in heat mode depending on the unit can run as much as 40-45 degrees and still be ok,the super heat should be less than 20 im betting on a bad outdoor txv ,the unit has a 10 year part warranty what is the serial number

[beenthere]

okay, I'll ask about just not having it, or removing it. I'm guessing they put them on all the systems as part of their standard install... but who knows.

So then what ever is in the system that is causing the external to clog. Will just clog up the internal later.

[Brent Ridley]

I do notice things like this: http://sporlanonline.com/240-10-2.pdf that suggests two driers. But that seems to only be for simple non-reversible ones, which I'd guess the built in one is, and the external one says it is. =/

Read the first sentence of the second paragraph.

The diagram you have is for installing 2 single flow (one way) LLFD on heat pumps.

No need to do that if you have 1 bi flow (two way) LLFD on heat pumps.

[staze]

on trane units the subcool in heat mode depending on the unit can run as much as 40-45 degrees and still be ok,the super heat should be less than 20 im betting on a bad outdoor txv ,the unit has a 10 year part warranty what is the serial number

Not terribly comfortable with posting serial numbers on a forum. The unit was purchased in 07, so it's still under warranty for parts then. Was there any known issues with the txv around that time?

[staze]

Read the first sentence of the second paragraph.

The diagram you have is for installing 2 single flow (one way) LLFD on heat pumps.

No need to do that if you have 1 bi flow (two way) LLFD on heat pumps.

yeah, got that. so the general consensus seems to be there shouldn't be two filter driers....

[staze]

And the winner is: catmanacman

There's nothing wrong. According to the tech, subcool really only matters (in heat mode) if it were REALLY high or low. He just measured, and it was about 20. Can't recall what he said the superheat was, but he said it was fine.

No real temp difference across the driers (he did say that if he were to replace them, he'd just remove one, and replace the other). Figured the previous measurements were due to the probe the other tech was using, or just fluctuation (even while he was measuring it, it would raise and lower a degree or two between measurements).

Also checked the caps, and they seemed fine as well.

Thanks everyone! If any of this sounds crazy, let me know...

[staze]

on a side note, does the XL15i have a recip or scroll compressor? just curious.

[RyanHughes]

on a side note, does the XL15i have a recip or scroll compressor? just curious.

Reciprocating 1.5-3 ton. Scroll 3.5-5 ton. Same holds for all single stage R410a heat pumps in Trane's current residential line.

Thanks for the update.

[staze]

I have a 2.5ton, so reciprocating. Got it.

Thanks!

Ryan, does his explanation seem reasonable?

[Brent Ridley]

Staze,

You cannot accurately determine correct charge in heat by using superheat and subcool.

Superheat and subcool can only be accurately used in cool mode above 55 degrees (on Trane).

Trane/American Standard has a chart in their service facts. That chart is used as a way to check the charge in heating. This is what your contractor should've been using.