Smart thermostat issue

charliechicago

Hello to all,

I've been a member here for a while but never posted under this category so apologies in advance if this question has been asked.

I'm working on an ecobee thermostat that until now has worked for three years with no problems at all. Its attached to a three zone EWC zone board. My thermostat is attached to zone 2 and another thermostat is attached to zone 1, nothing on zone 3. On a call for heat the zone board itself is not registering a call for heat. Meaning the green LED that should light up next to "zone 2 open" is not lighting up and nothing is being initiated.

1- If I jump out R and W at the thermostat the board registers the call for heat, opens the damper and the heat works.

2- If I take the thermostat wires off the EWC board and then jump out R and W on the board, the heat works in the same manner as above. But if I jump out R and W with the thermostat wires still connected, heat does not work.

3- If I disconnect the zone damper wires from the board, the heat does not work.

4- If I disconnect zone 1 thermostat wires, zone 2 (my zone) does not work.

5- If I move the thermostat wires and the damper wires to the spare zone (zone 3) heat does not work.

Wires are 18 gauge and three years old. I had a similar issue with a nest that had worked for a while but the wires were 20 gauge and old so I chalked it up to that.

Any suggestions? Thank you.

Mark N

Have you tried switching the thermostats on zone 1 and 2? See if the problem moves with the thermostat.

Jamie Hall

Does the Ecobee have an external constant power source ("C wire")? If not, my guess is that the tiny internal battery has died.

Mark N

The EWC zone board has a C terminal for all 3 zone thermostats

LRCCBJ

1- If I jump out R and W at the thermostat the board registers the call for heat, opens the damper and the heat works.

2- If I take the thermostat wires off the EWC board and then jump out R and W on the board, the heat works in the same manner as above. But if I jump out R and W with the thermostat wires still connected, heat does not work.

The above statements are fundamentally impossible. Jumping R and W on the board eliminates he thermostat from the equation.

I'd like to call it a bad thermostat but I cannot with the above data.

jesmed1

If the board has misbehaved with two different thermostats, isn't it more likely the problem is in the board?

EdTheHeaterMan

I am seeing something here by your language used

"My thermostat is connected to zone #2"

Am I to understand that this is a multi-family building with at least 2 zones and your zone is zone #2 and someone else is living in zone #1 (or there can be someone else living in zone #1)?

If so, can I assume that you are not the owner of the HVAC system and someone else (like a landlord) is responsible for the maintenance & operation of the system?

Say that is the case.   There is a possibility that some work was completed without your knowledge and that is about the time you started having problems with your system.  The technician that worked on the system at that time may not have had access to your unit.  The technician may not know that you have a smart thermostat.  That technician may have reversed some wires on the zone control panel and you need to double check that your thermostat is properly connected Thermostat R to zone panel R.  Thermostat W connected to zone panel W and thermostat C is connected to zone panel C.   

Your statements

1- If I jump out R and W at the thermostat the board registers the call for heat, opens the damper and the heat works.

This means that the system works and the trouble is in the thermostat or the connecting wires.

2- If I take the thermostat wires off the EWC board and then jump out R and W on the board, the heat works in the same manner as above. But if I jump out R and W with the thermostat wires still connected, heat does not work.

This means that the system works and the trouble is in the thermostat or the connecting wires. with the possibility that the Com wire has been reversed causing a short circuit.

3- If I disconnect the zone damper wires from the board, the heat does not work.

This tells me that the zone damper has an end switch the brings on the equipment. Without the damper wires connected, the end switch does not bring on the equipment.

4- If I disconnect zone 1 thermostat wires, zone 2 (my zone) does not work.

This means that the system works and the trouble is in the thermostat or the connecting wires.

5- If I move the thermostat wires and the damper wires to the spare zone (zone 3) heat does not work.

This means that the system works and the trouble is in the thermostat or the connecting wires.

The test you did not perform is the one that will eliminate the connecting wires as the cause of the problem. That test would be to go to the thermostat and remove the thermostat from the wall and connect the R and the W wire at the thermostat location with the thermostat not connected. If the system works then the problem is in the thermostat. if the system does not work then the problem is in the connecting wires.

charliechicago

Thank you for all the responses. I actually spend a decent amount of time phrasing my questions so they are clear and thought out because I know its not easy to diagnose in this manner but its not always easy and I regret any confusion and I will try to respond to all of your points.

This is a singe family house with a furnace/ac coil that has two zones. The customer states and I believe her, that no one has worked on the unit since it was installed. (three years) The one important thing I forgot to mention is that I swapped the thermostat from the problem zone (zone 2) with the thermostat from the working zone (zone one) They are identical thermostats. Zone 2 continued not to work and zone 1 worked, so it does not appear to be a thermostat issue.

The thermostats are both correctly wired from the board with R,C,Y,W and G

When I said that I jumped out R and W at the thermostat my intention was that I took the thermostat off the wall, took R and W off the back plate, connected R and W and the system worked. So it does not appear to be a wiring issue.

With all the wires connected at the thermostat and at the board (like it was before I arrived) when I jump out R and W at the board, the board is not registering a call for heat. But when I take the thermostat off the wall and them jump R and W at the board the heat works. So the board seems to be OK.

When I disconnected the zone damper wires I know that the heat will not come on. My intention was just to isolate the zone motor from the board to make sure it was not interfering with the board function. Even with the zone damper wires disconnected the board is not registering a call for heat.

What I don't understand is that the thermostat, wiring and board have all been proven to be ok but when the thermostat is connected the zone does not work.

Thanks in advance.

HVACNUT

1- Jumped R and W at the thermostat sub base. Heat worked.

2- Removed R and W from zone panel thermostat (not equipment or system) terminals and jumped R-W zone panel thermostat terminals. Heat worked.

C- Jumped R and W at the zone panel with the thermostat connected to the sub base and heat DID NOT work.

4- Its the thermostat.

You said you had a Nest previously and worked about the same amount of time? Is the zone panel using a dedicated 40 va transformer as it should, and not the system transformer?

yellowdog

@charliechicago

What I don't understand is that the thermostat, wiring and board have all been proven to be ok but when the thermostat is connected the zone does not work.

Doesn't this statement tell you everything you need to know?

jesmed1

The common element in the fault is that the thermostat must be connected (and I assume drawing power from the board through the C wire) for the fault to occur.

When the thermostat is NOT connected and therefore NOT drawing power through the C wire, the board works fine.

This points to an internal board problem that prevents the heating circuit from working properly when the thermostat is drawing power from the C wire.

Try measuring the voltages at all the board terminals under two conditions: (1) with the thermostat connected and drawing power from the C wire, and (2) with the C wire disconnected. If you see a difference, that supports the theory of an internal board problem that won't allow the heating circuit to work when the Tstat is drawing power from the C wire.

Mark N

@charliechicago swapped the thermostats and the thermostat from zone 2 worked in zone 1, but the thermostat from zone 1 didn’t work in zone 2. Maybe the issue is the zone 2 thermostat base.

charliechicago

Thanks for the responses.

I'm going to test all three theories.

1. To look if there is an external transformer as HVACNUT suggested.
2. To measure voltages at jesmed1 suggested
3. To see if it's the sub base as Mark N suggested.

Jamie Hall

Have you tried one other simple test? Swap the wire connected to R at the thermostat with the wire connected to W at the thermostat. Then try it…

Yes, I know. The red coloured wire should be connected to R and the white coloured wire connected to W. Electricity is colour blind… so it isn't the colour of the wire which matters, it's what it's connected to.

jesmed1

Jamie, I think I see where you're going with that idea. But if the R and W had been incorrectly reversed somewhere, the ecobee wouldn't be getting power, would it? The fact that the ecobee does get power seems to suggest that R is correctly supplying 24 VAC from the board, and C is returning it.

So if the OP now swaps R and W, the Tstat will not be drawing power. At which point, jumpering R and W at may in fact make the zone work, similar to the Tstat being unplugged from its base, when OP said jumpering R and W worked.

So swapping R and W may have the same effect as removing the Tstat entirely, because it will no longer be drawing power from the board, letting the board work when R and W are then jumpered.

Jamie Hall

Got a point there… just one other thing to check, though

charliechicago

So I’m pretty sure I figured out the issue. First I checked for an external transformer which it had. Then I checked voltages with and without thermostats connected and they were ok. switched back plates but did not help. Then I removed w at the thermostat and I took an extra brown wire from the thermostat wiring that wasn’t being used (it’s a six wire and five are used) and attached it in place of w and the ac came on. Quickly shut it off. Presuming it’s shorting wires but continued troubleshooting a little. Took brown wire off and took y from thermostat and stuck on w. No heat. Pulled g off thermostat and put on w and no heat. At some point I checked voltage at EWC board from y and g to common with y and g off at the thermostat and w back on thermostat and had voltage. So at this point I was pretty sure it was crushed/shorting wire. I put everything back, but left y and g off at the board and heat worked. I think voltage coming back to board at y and g was keeping heat off.
Thanks everyone.

EdTheHeaterMan

Back on January 2 @EdTheHeaterMan Wrote:

The test you did not perform is the one that will eliminate the connecting wires as the cause of the problem. That test would be to go to the thermostat and remove the thermostat from the wall and connect the R and the W wire at the thermostat location with the thermostat not connected. If the system works then the problem is in the thermostat. if the system does not work then the problem is in the connecting wires.

January 6 @charliechicago replied:

Then I removed w at the thermostat and I took an extra brown wire from the thermostat wiring that wasn’t being used (it’s a six wire and five are used) and attached it in place of w and the ac came on. Quickly shut it off. Presuming it’s shorting wires but continued troubleshooting a little. Took brown wire off and took y from thermostat and stuck on w. No heat. Pulled g off thermostat and put on w and no heat. At some point I checked voltage at EWC board from y and g to common with y and g off at the thermostat and w back on thermostat and had voltage. So at this point I was pretty sure it was crushed/shorting wire. I put everything back, but left y and g off at the board and heat worked. I think voltage coming back to board at y and g was keeping heat off.

Looks like a new wire may be in your future. I hope it is an easy one to snake a new wire to.