Trane XV80/XL16i/803 wiring setup problems

[eswells95]

I’m going to apologize up front about the length of this post. Info from this forum has me concerned about my install (wiring/setup in particular). In May 2007, I had the following system installed:

XL16i Heat Pump 4TWX6036B1000AA
XV80 100k TUD100R9V3K
RXC036S3HPD coil
TCONT803 tstat w/Outdoor temp sensor
Aprilaire M-700 Power Humidifier
Aprilaire 2200 Media Filter

As I've been thinking of replacing my 803 t-stat with the IAQ, I've been reading this forum and trying to learn more about my system/watching how it performs in it's 1st cooler weather.

Everything seems to be working on the heat pump correctly (at least at moderate outdoor temps in the 40's and upper 30's) from my layman's perspective. It seems like it’s running the Comfort-R ramp profile. Heat pump kicks on, warms up for a minute, then the fan kicks on with warm air at registers. Fans kicks to higher speed after another 8 minutes or so.

Now as temps have dropped below freezing, I think I notice problems (like not getting to 2nd Stage with my gas furnace!!). Specifically, here’s what I’ve noticed:

1) When outdoor temps are below my compressor lockout, aux heat is called (shows up on t-stat) and gas furnace starts up. But it never gets to Stage 2. I stuck a thermometer in the supply vent (there's a 3-inch wide black fabric material between 2 pieces of duct just above the furnace burners and I had seen previous HVAC maintenance crew test temps there) and got supply temps around 108 last night with 67-68 degrees house temp. I’ve waited down there for 30 minutes and I never heard it kick to 2nd stage or saw any rise in supply temp.

2) When I change the t-stat to Em. Heat, the burners come on and I get about the same 1st stage supply temps (~108 w/67-68 inside temp). After about 10 minutes, the 2nd stage gas does kick on and I notice higher air flow and supply temps increase to 120-123 (w/same 67-68 inside temp).

3) The aux heat has come on even when the outside temps are above the compressor lockout setting (currently 30 degrees). I didn’t notice this until outside temps started getting down to the low 30’s. Is this because aux heat is coming on during a HP defrost?

I’m attaching some pics of the furnace board wiring and dip switches (install pics in separate post). From what I can tell here’s the settings:

Dip switches:
1 – off , 2 – off, 3 – off, 4 – off, 5 – on, 6 – on, 7 – on, 8 – off

From what I can gather, this would make the settings: 3 ton unit, 400 cfm/ton, Comfort-R is on, and Normal heating airflow (950cfm/1300 cfm for 1st/2nd stage). I’m not sure what the difference is between 7 on, 8 off and the factory setting of 7 off , 8 on.

The wiring looks like it’s close to the wiring diagram on page 5 of the HP install guide (my contractor actually used the Figure 15 schematic from the TCONT803 install instructions after I noticed they were following the Figure 14 instructions which I think are for a multi-stage (non-scroll) heat pump like the XL-19i).

There are a couple of things that I have noticed (good and bad):

1) The R to BK jumper (W14 ) has been cut.
2) There is a wire connecting R to O on the furnace board.
3) YLo is isolated on the furnace board.
4) I don’t see any wire connecting W1 to W2 on the furnace control board.
5) W2 only has one wire connected and that heads to the T-stat. Figure 15 shows this connection is to the T-stat at X2 versus the W2 connection in Fig 5 of the HP install guide (that may not be a real distinction).
6) Notes in the HP install guide say “X2 must be connected to variable speed air handler terminal W3, as shown, for proper indoor air flow during the defrost cycle”. I don’t see a W3 terminal on the furnace board. Is that a problem?

My questions/concerns:

1) Don’t W1 and W2 need a connection? Is this why I’m not seeing 2nd stage on gas furnace in regular aux heat?

2) What is different with Em. heat that allows it to get the 2nd stage call after 10 minutes?

3) The 1st stage temp rise (~40 degrees) seems a little low from what I can tell in the airflow/power tables in the furnace install guide (51 degrees). Is that a concern? With 2nd stage from Em. Heat the supply temps rise another 12-16 degrees (total temp rise ~52-56 degrees close to the furnace install tables of 56). Does that sound normal or is there some problem with the 1st stage supply temp rise? I’ve seen some variation in the 1st stage supply temps and maybe they are lower at times because of a defrosting, cooler coil that’s between the furnace and my supply vent thermometer? Would the supply temp of the furnace running during/just after a defrost cycle be lowered when compared to running in regular non-defrost times?

4) Are the times I’ve noticed the aux heat running at outdoor temps in the low 30’s (above the compressor lockout temp setting of 30) likely a result of a defrost cycle. Is it normal that aux heat (gas) comes on during the defrost cycle? What controls this process? Is the lack of me seeing a W3 terminal on the furnace board a problem? Is there a better way to setup what happens during a defrost cycle?
5) Is anything with my current wiring, etc causing harm to my system? Should I turn it off? Put it only in Em. Heat mode? Turn up the compressor lockout temp so as to more likely avoid the defrost cycle (I don’t understand the defrost process and controlling it at all). Does this situation warrant an immediate call to my HVAC installer?

Any other comments/suggestions/answers/advice on my setup/wiring is much appreciated. If I hadn’t been considering the IAQ replacement and reading this great forum, I likely would never have even noticed these issues.

Thanks for everyone’s help on this forum.

[dbb1]

4) I don’t see any wire connecting W1 to W2 on the furnace control board.
5) W2 only has one wire connected and that heads to the T-stat. Figure 15 shows this connection is to the T-stat at X2 versus the W2 connection in Fig 5 of the HP install guide (that may not be a real distinction).

I'm not a pro (as you know), but I wonder about the two wires going to W1. It would make sense for one of them to go out to your heat pump, so it can force aux heat on during defrost. Can you figure out where the other one goes?

Since your tstat can't do both stages of your furnace, there definitely should be a W1 to W2 jumper. The fact that Em. Heat cycles through both stages suggests that jumper exists. I can't understand how the same thing wouldn't happen under normal aux heat conditions if your runtime is long enough.

[second opinion]

Any chance you could take a couple of more showing a little lower and on the install closer shot on the air cleaner it looks like a gap on the furnace side. And one of the top compartment of the furnace.

It is miswired I cant tell were the white wire on y is going and W1

[dbb1]

It is miswired I cant tell were the white wire on y is going and W1

I don't see a white wire on Y... I do see one on common. I reeeeealy hope that isn't a white jumper between common and W1.... If it is, then as soon as your HP goes into defrost............

[mark beiser]

The 803 thermostat can only run 1 stage of your gas furnace in a dual fuel setup like you have.
The only way to get 2nd stage with the furnace is to have a jumper wire installed between W1 and W2 in the furnace. With them jumpered, the furnace will run in first stage for 10 minutes, then go to 2nd stage until the call for heat ends.

The Vision Pro IAQ thermostat will control both stages of your heat pump, and both stages of your gas furnace.

[Senior Tech]

Don't let this turn into a step by step or it will go away...

[dbb1]

Don't let this turn into a step by step or it will go away...

I think the OP is just trying to find out if he has a problem that warrants calling back his installer.

[eswells95]

I'm probably about as far from a DIY candidate as you can find on this forum. In any case, I won't be touching any wiring.

I am trying to find out if I have a problem (pretty sure that something's not right) and if so, try to find out what to tell my installer when I call and how urgently I need to get him out here.

I'm attaching some additional pics per 2nd Op's request. Here's what I would really like to understand.

I can watch the 2nd stage of the gas furnace kick in 10 minutes after the 1st stage ignites IF the 803 t-stat is set to Em. Heat. The sound is audible and the air supply temp rises 6-10 degrees.

If the t-stat is set to normal Heat, I DO NOT see that 2nd stage gas kick in after 10 minutes or anytime later.

Has anyone experienced this before or have any guess/info that I can share with my installer?

FWIW, there is no obvious wire connecting W1 and W2 at the furnace board. The only wire obviously connecting 2 terminals on the furnace board is between R and O.

In the Notes in The HP install guide has a note that says “X2 must be connected to variable speed air handler terminal W3, as shown, for proper indoor air flow during the defrost cycle”. I don’t see a W3 terminal on the furnace board. Is there a W3 somewhere on the furnace board? Is that a problem? Is that defrost control taken care of in some other way?

From looking at the wiring diagram that I think my installer used (Fig 15 from the TCONT803), it shows X2 on the HP going to W1 on the furnace board(not W3 like on the HP instructions). Is that a possible source of my problems?

Nothing else looks obviously wrong with the wiring, but I can't see to any connections at the T-stat and HP.

Thanks for any help you can provide.

[second opinion]

The unit needs the jumper between W1 and W2. Schedule Shannahans to come back out next week. I need to attend a couple of wrestling tournaments but I will E-mail to your profile a list of corrections. Ignore the W3, the three stage gas furnace is not ready for release yet but soon.

[eswells95]

Thanks Second Opinion. I'm still trying to understand how I'm getting to 2nd Stage in Emergency Heat after 10 minutes, but not in Regular Heat Mode. Any help is appreciated.

My e-mail is in my profile (minus the *comments*).

Thanks again.

[mark beiser]

Thanks Second Opinion. I'm still trying to understand how I'm getting to 2nd Stage in Emergency Heat after 10 minutes, but not in Regular Heat Mode. Any help is appreciated.

My e-mail is in my profile (minus the *comments*).

Thanks again.

The wire currently hooked to W2 in the furnace is probably connected to X2 in the thermostat, so it is getting powered when you switch the system to emergency heat, but not when the system is in the normal heating mode.

[eswells95]

Thanks Mark.

That's what's in the schematic (TCONT803 install instructions) that I think my installer used to setup my system (X2 on T-stat to W2 on furnace).

Is that the correct setup? Emergency heat does go to 1st stage for 10 minutes before going to 2nd stage. If my contractor adds the W1 to W2 jumper on the furnace, will my regular heat then work the same way (10 min on 1st stage then go to 2nd stage) as Emergency Heat? Is the current setup causing any damage to the HVAC hardware?

I'm actually beginning to wonder if I won't like my current setup, even if my installer didn't intentionally mean for this to be my setup. Given that I don't have the IAQ (still wondering about getting it) to "really" control the staging on the furnace, maybe this is a reasonable "poor man's" approach.

Here's my thinking and I'd love to here your comments:

1) With 803 T-stat, I set the balance point (#0350) so that only the heat pump will run down to 30 degrees (HP seems to heat my house pretty well and only switches to aux/gas during defrosts).

2) Below 30 degrees, my normal mode aux/gas heat will work with no HP operation. Right now it's only using 1st stage gas (probably incorrectly!). But I think the 1st stage on my gas furnace (~52K BTU) can heat my house until it gets fairly cold outside (maybe to around 15 degrees?) because it's probably oversized given what I've read on this board.

3) When it gets really cold (say below 15 degrees), I can manually switch to Emergency Heat mode and then it will run, like it does now, on 1st stage for 10 minutes and then on 2nd stage (~80K BTU).

This is definitely not as good as the IAQ would control the staging on my furnace from what I've read. But at least I could run longer 1st stage cycles (more comfort) in moderately cold weather (15-30 degrees) which I couldn't do otherwise with the 803 stat.

Do you think it's worth trying out for a while this winter and seeing how this setup works out for us? Or should I call my contractor to get it setup normally/correctly because my current setup could be causing damage or problems?

Thanks for everyone's help and advice.