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Budreaux · Nov 16, 2005, 07:36 PM

Hi,

I have hooked up the thermostat (replaced an old analog Honeywell unit) and had the same wiring as the one on this post
https://www.askmehelpdesk.com/...ead.php?t=14531
(ie on the old unit, the blue wire to the Y terminal and a yellow jumper wire from the Y terminal the back of the unit - current wiring on the RTH230B is White to W, Red to Rc/RH, Green to G, Blue to Y).

Anyway, everything seems to work fine. The fan control works, the AC comes on when switched to cool and the furnace comes on when switched to heat. My problem is no matter what I set the temperature to, the unit comes on and does not shut off. Even when the desired temperature has been overshot by 10 degrees (ie unit set to heat, desired temp 70, actual temp is 80 and the unit is still on). I have brand new batteries in the unit.

Is it possible I have wired something wired wrong, or do I just have a defective unit?

Any help would be greatly appreciated.

Thanks,
Dave

labman · Nov 16, 2005, 08:38 PM

The thermostat is simply a multiple pole switch. Depending on the mode, it switches power from the transformer, red, R, to W, Y, or G. When the heat or cooling reaches the set point, it switches to off. If the heat quit when the old thermostat shut the power to W off, it should when the new one does too. Does the furnace have a B or C terminal? One of the pair of wires out to the A/C compressor should be connected to it. If you have 24 volts AC between the W and B or C when the temperature at the thermostat is above the set point, the thermostat is definitely not working correctly.

I don't know why the blue is connected to the Y instead of yellow, but as long as you have the same wire connected to the Y at both the thermostat and furnace, the A/C should work. Electricity can't tell what color the insulation is.

If this is a duplicate, it is a duplicate. My original may have gotten lost when the question was moved, or my be on the original forum. Fortunately not only did I write the answer in NS 4.8, but Klipper saved it for me to repost.

Budreaux · Nov 16, 2005, 08:55 PM

Labman,

OK, your post got me to thinking. I never really tested the thermostat to see if it was functioning properly (turning heat on and off). So I took the thermostat off the base and tested it for function. It was working properly turning the heat on and off (tested with ohm meter between the pins for Rc/Rh and Y) depending on the desired temp and the actual temp. This unit also has a little icon that shows when the heat and a/c is on (this also turned on and off properly). I then put the unit back on the base and switched it to heat. The unit, which made a distinct click while testing, did not come on and the heat icon did not display yet the furnace turned on.

I now believe I have a problem somewhere with my wiring. Is it possible that the thermostat has a small level of current leakage when it is turned to heat (or cool) that is turning on the furnace (A/C)? I'm not really sure how to test for this (I know enough about electronics to be dangerous while not really understanding all the principles behind it). Perhaps this info may help you in pointing me in the right direction.

Thanks,
Dave

Budreaux · Nov 16, 2005, 09:15 PM

Ok, after my last post, I started checking things again. I spoke with my father-in-law and he mentioned the jumper on the back. I have a gas furnace, and the jumper was set (per the instructions) to HG. To test a theory, I moved the jumper to HE (the supposed setting for an electric furnace). I set the switch to heat and... nothing. Exactly what I was looking for. I set the temp to 80 and the furnace came on. I let it run for while, then set the temp to 65. The furnace shut off.

It appears things are working properly. I didn't think the jumper would have an effect on the function of the unit, but apparently it does. Maybe my furnace is wired incorrectly, or may the jumper setting is set-up wrong, but either case, this works. The only down side to this is that the blower starts as soon as the furnace starts (no delay). Other than that, it is working properly.

Thanks for your help Labman, sometimes I just need a little prodding to get me going in the right direction.

Later
Dave

labman · Nov 16, 2005, 09:43 PM

Is it labeled a voltage stealing thermostat? Here I am giving advice on things I have very little experience with and don't quite understand how they work. You have one terminal of a transformer connected to red wire to the RH and RC. The thermostat then switches it to W, Y, or G which are connected to the other side of the transformer through the coil they activate for the functions. In order for the thermostat to power itself from the transformer, it must feed power back to the other terminal somehow. Some thermostats use a fifth wire connecting B or C terminals. I figure the others use a low enough voltage to power themselves to flow back the W wire, but not enough to activate the gas valve. I think the batteries are only to preserve the program when the power is off.

I would make the same voltage check I suggested in my last post, but look for even a small voltage between W and B or C, perhaps even a half wave from a DC power supply.

Having figured out some things on my own from my own furnace, I got started on simple things here. For lack of anybody better, I keep getting drawn into things I know less and less about. As I have learned more and more, I manage to help people figure their problems out. Be interesting and helpful if you report back what you find. The one I really like is the one guy after I suggested the control board in his furnace was bad. He took it out, took it to work, and found and replaced a 25 cent capacitor that was bad.

Budreaux · Nov 17, 2005, 05:15 AM

Thanks labman for your help. I actually figured out the problem before you got a chance to respond (see my last post above).

Dave

labman · Nov 17, 2005, 06:45 AM

Does the blower run afterwards to cool the furnace down? If not, I would do some more checking. Also, is it a higher speed using the HE jumper?

Budreaux · Nov 17, 2005, 01:44 PM

The blower does perform the "cool down" of the furnace after the furnace shuts off, so the thermostat that controls the blower is working properly. I have not noticed a difference in blower speed.

It is odd that the old thermostat caused the blower to delay prior to starting when the furnace turned on and the new unit doesn't, however, when the jumper is on HG the blower is delayed (it just never shuts off after it starts). Again, I am just guessing here, but could this be a current limiting function that starts the furnace and delays the blower on the new digital unit?

I tried to trace the wiring from each of the components (furnace transformer, a/c transformer, blower), but the wiring is such that it is difficult to follow. The blower control had about 6 wires coming out of it alone. The wiring at the heating transformer also spidered out to various other places, so I kind of just gave up.

Dave

labman · Nov 17, 2005, 02:55 PM

If you do try to sort out things some more, here are some basics that may help. Usually there is a 24 volt AC transformer in the furnace with the secondary winding connected to a red wire running to the thermostat and a blue wire, common, to the gas valve, A/C relay, and fan relay. From the thermostat there will be white wire to the gas valve, yellow to the A/C, and green to the fan. The thermostat is wired to switch the power from the red to the white, yellow, and green as needed with the blue completing the circuit. Most thermostats and furnaces have the contacts labeled R, B or C, W, Y, and G for the corresponding wire colors. It may be wired to have the A/C control wires return to the furnace and its controls and then a second wire goes to the A/C unit. Internal wiring may replace the green wire if the thermostat does not give you the option of fan only or continuous fan. Digital or programmable thermostats may need the blue wire connected to them.

I came across the niftiest gadget for trouble shooting, a voltage detector. They work through the insulation of wires. There are several brands. I have a GB Instruments GVD-505A, less than $15 at Home Depot. Touch it to a hot wire, and the end glows red. Find the doodad that lights it on one side, and not the other, and you have the culprit.

Budreaux · Nov 18, 2005, 05:42 PM

All right, I just checked the wiring, and all agree with your information above. I also pulled the thermostat down and checked it for function according to the jumper. When the jumper is on HE, the fan switch does not act the same as the old unit. When the jumper is on HG, the fan switch works exactly the same.

Like I stated earlier, when the jumper is on HE, the thermostat works fine (with the exception of the pre-heat). When the jumper is on HG, the furnace starts and does not shut off no matter what the temp is set to.

Oh well, I guess I'll continue to use the unit with the jumper set to HE. If anyone else has any suggestions as to why this is happening, I would greatly appreciate the help.

Dave

labman · Nov 18, 2005, 07:05 PM

I think the thing is defective. I would exchange it for another one.

[email protected] · Nov 19, 2005, 11:29 PM

:( I just bought this same unit, same problems. I will be returning unit to store for a different unit.

labman · Nov 20, 2005, 06:34 AM

Originally Posted by [email protected]

:( I just bought this same unit, same problems. I will be returning unit to store for a different unit.

I tried to reply to your private message, but it came back invalid user name. I prefer to work here in public. This is the answer I tried to send:

I doubt it. Maybe you need to carefully go through your installation or users guide or talk to honeywell. Remember, I don't have that wide of experience. I have been able to help many mainly figure out their own problems. Some areas here we have very strong people, but I am just doing what I can on thermostats for lack of anybody better.

I came here to answer dogs questions where I do have extensive knowledge, but have jumped in on stuff like this where nobody else is giving much in good answers.

chipper118 · Jan 2, 2006, 11:21 AM

I have misplaced my instructions on how to program this and can't find anywhere? Help! :) Kim

[email protected]

klmgb · Jan 2, 2006, 08:36 PM

Kim

I'm having the same problem, I have the instructions in Spanish I can email to you if you can translate, otherwise if I dig them up I'll let you know and I'm sure you'll do the same

Keith

chipper118 · Jan 3, 2006, 05:06 AM

A friend mine has the instructions- will get them this weekend - can't use the ones in Spanish - thanks :) Kim

Honeywellsux · Jan 26, 2006, 11:47 AM

I just registered to support Budreaux. I had the exact problem, down to the same colors of insulation on the wires, as Budreaux. I installed the RTH230B precisely as the instructions stated and the furnace just would not turn off unless and until the function switch was flipped from heat to off. I just tried his solution of changing the jumper switch from HG to HE, and it works! The only drawback is that the fan comes on the same time as the burner (which means 30 seconds of cold air at first) and the fan seems to stay on longer than it used to, but I can live with this.

Honeywell simply blows (pun intended, sorry). There is not one word of supporting literature on the website on the RTH230B, not even a placeholder. Honeywell has also failed to respond to an email desperately asking for assitance. Needless to say, Honeywell will not be getting another dime of my money.

Thanks Budreaux!

labman · Jan 26, 2006, 01:19 PM

It is a shame to see that from a fine old brand. They own Fram too. Fram oil filters are the worst on the market. For half the price, the Wal-Mart house brand is twice the filter. Sad thing is that the Pennzoil filter is a Fram painted yellow.

bulldog25 · Jan 30, 2006, 09:39 PM

:) Our furnace is blowing cold air and the thermostat is reading a temperature lower than the one it is set on. Is this an electrical wiring problem or do I need to change out the thermostat?

labman · Jan 31, 2006, 05:20 AM

I would go to the heating system and short the red and white thermostat wires together. If that doesn't start a heat cycle, the problem is with the heating system. It could be with the control board or the limit switches. Newer furnaces have a light that blinks a trouble code. If it is showing a limit switch code, I wouldn't bother with the test above.