No Power Light

[jlamberth]

Just installed the new HA-30403 SKU Wireless Thermostat & Receiver Combo. My power light flashed once then went off. I have 24VAC at the thermostat between R and W, but no light.

The heater comes on regardless of the temp settings and ran the temp up to 78 while it was set to 68...I am thinking the receiver is bad.

Any suggestions?

UPDATE - I have been experimenting with this device most of the weekend. I found that the connector on the receiver is somewhat tempermental. I finally got it to "light up". It seemed to work fairly well last evening. I only had one instance where it did not cut the heater off and I had to intervene.

It was operating in the program mode. When I awoke this morning, the program temp was set for 68, but the house temp was 62. I carried the thermostat within a couple of feet of the receiver so I could observe what was happening and it would turn on and immediately turn back off when the signal was sent.

The thermostat was only about twenty feet from the receiver during the night (upstairs/downstairs). I have now reinstalled the old thermostat and everything is back to normal.

Do you think the receiver is bad??

[thuor]

So i'm assuming that now the power light on the receiver is on solid right?

As for the difference in setting between the actual temperature and when it comes in thsi might have to do with the programmed deadband (hysteresis) value in the thermostat. See page13, 15 and 16 of the manual here on how to change the deadband setting: http://www.rfwel.com/kc/pdf/P474-1100RF20OM.pdf. Also just in case you have more than one thermostat talking to the receiver remember that this setting will only have an effect for only the thermostat programmed as UnitID#1.

Also what type of HVAC system do you have and are the DIP switches on the receiver set correctly. Check out the install manual here if you don't have it handy: http://www.rfwel.com/kc/pdf/T1100REC...nstallRev3.pdf

[jlamberth]

Yes, the light is on solid now. The programmed deadband is 2. I only have the one wireless thermostat and it is programmed as Unit ID #1. My HVAC is a Trane XE 60 which is a standard gas heater. I do not have airconditioning, so this is not an issue. All DIP switches are set to off. I even experimented with changing the house code per the instructions.

As explained in my UPDATE from the original post, what would cause it to turn on and immediately turn off before the furnice lights? It was doing this repeatedly while the thermostat was set to 68 and the temperature was at 62 with a deadband of 2.

[thuor]

Thanks for rulling out potential interference with a co-channel thermostat as well as RF range issues. This now suggests either a faulty receiver or that it might have to do with the amount of power sourced by the furnace to control the receiver. Actually this is explained on p16 of the install guide although it can show up differently depending on how your tstat is wired up.

How many wires do you have on your wall to connect the thermostat? Did you originally have jumpers on the original thermostat you took out? When you measured 24VAC between R & W was this with the thermostat receiver hooked up and running?

R is the main power supply to the thermostat when calling for heat needs to transfer this voltage to W for the burner and/or G for the fan motor relay so depending on the load could pull down R to where you start to see either a dim display or no display. The solution as explained is to sink that current using a weak resistor to the transformer common terminal if available.

If you only have a 2-wire system you will need to get a separate external 24v relay and 24v step down transformer to drive this relay directly.

[jlamberth]

I have two wires, red connected to R and black connected to W. With the face of the receiver off, I tested the current between the two with a volt meter and it was 24VAC.

There is not a separate wire for the fan relay. There is a jumper between RH and RC on my old thermostat, but nothing else connected to RC.

I have not noticed any dimming of the display. If the old thermostat seems to run the furnice and fan just fine, wouldn't this indicate that there is not a significant "pull down" on the power?

[thuor]

Workaround for 2-wire gas heat w/ wireless tsat receiver

This is the problem. If you have a 2-wire system this thermostat/receiver cannot work for you as-is. You need to get a relay to drive the furnace board and the relay is controlled by the thermostat. See p9 of the receiver/install guide or checkout this forum post that addresses this issue: http://www.rfwel.com/forums/showthread.php?t=620

The idea is that Red and Black on your furnace needs to be closed (short-circuit) when you are calling for Heat. So what this workaround does is that it closes the relay switch using W from the thermostat. You then need to have a 24VAC reference input which drives the power on the thermostat "R" and the common of this reference input is then the common to the relay.

The problem you are seeing is because "Red" for you is NOT a power input but one end of the furnace board relay switch which is why you see it lose power and which is why you need to have an additional 24VAC, 200mA reference supply.

[jlamberth]

I've done a little research elsewhere on the Internet and it makes sense to connect the C terminal to complete the circuit on the receiver.

Wouldn't this deliver the proper voltage?

[thuor]

I thought you didn't have a C terminal on your furnace board? C is the common and if you are only have two wires Red and Black C would be floating so it doesnt help to connect anything to it.

The problem you are having is that you need a circuit that will close the path between Red and Black. For other furnace wiring this is accomplished by connecting W1,0,B terminal on the thermostat to W on the furnace and R to R. If you measured the potential difference between Red and Black with heat on it should be close to 0v but what you have now is that these two are not on the same circuit path. Think of a simple switch. One end is 24vac. if you apply 24vac to the other end you still get an open circuit (transient current due to finite resistance of the switch will make it appear that it was trying to turn on). So what you need is a relay that can actually provide electrical contact to the two switch terminals under the control of W.

[jlamberth]

Okay, I am ready to purchase the relay and related components shown on page 9 of the manual.

I have had this thermostat for two weeks now and I would really like to get it working!!

[thuor]

Here is the link to get it: http://www.rfwel.com/shop/?target=pr...roduct_id=1679

Let me know how it goes and thanks for your patience.