I have a simple round heat only thermostat that is brand new out-of-the-box. It will not turn my Williams wall heater on. I have switched red and white wires, no luck. When I jump the wires together, the furnace clicks on. This is the second thermostat I have tried. Any ideas on this?
JPM
That?s a power stealing thermostat
Would need to add a bleed resistor to make it work
Better off getting a rectangular mechanical thermostat
Would need to add a bleed resistor to make it work
Better off getting a rectangular mechanical thermostat
There is no battery. The packaging says that it is compatible with gas forced air. I have use this with other in wall furnaces. That?s why I am so confused. I?m not even sure where I can pick up one of those old-school rectangular ones. This is about his old school as I thought I could get 
I appreciate your comments and help on this.
I appreciate your comments and help on this.
Honeywell makes a cheap CT31 mechanical thermostat/tstat and Home Depot has them.
You may have a millivolt system with that wall heater and a 24 volt tstat has a heat anticipator resistor which causes it to not work.
This basic one should be OK.
http://www.homedepot.com/p/Economy-Heat-Cool-Manual-Thermostat-CT31A/100400017
You may have a millivolt system with that wall heater and a 24 volt tstat has a heat anticipator resistor which causes it to not work.
This basic one should be OK.
http://www.homedepot.com/p/Economy-Heat-Cool-Manual-Thermostat-CT31A/100400017
Make sure you scrape the wires down to bare shiny copper when putting them on. Millivolt systems use less than .75 volt and can be cranky and with bad connections won't work.
Sorry for the late update ... I noticed that the vent limit switch seems to maybe be stuck (the red reset button does not move when pushed). I am thinking that I am getting some partial interference (drop) at this switch, that combined with a small amount at the thermostat, that the system doesn't trigger ... I am basing this on what I have tried earlier.
My thought is to take the leads of the switch, hook them direct to each other, then test with and without thermostat to see if maybe the switch is the problem.
Does this make sense?
Thanks,
Bill
My thought is to take the leads of the switch, hook them direct to each other, then test with and without thermostat to see if maybe the switch is the problem.
Does this make sense?
Thanks,
Bill
First of all we need to know if it is a millivolt system.
Is there a fat thick as a pencil pilot generator in your pilot light. It is not a 1/8" thin copper thermocouple like in a old furnace.
It will have 2 wires coming from it that go to the gas valve.
If you do it may be weak and should be tested.
The button should not move unless it is tripped.
Is there a fat thick as a pencil pilot generator in your pilot light. It is not a 1/8" thin copper thermocouple like in a old furnace.
It will have 2 wires coming from it that go to the gas valve.
If you do it may be weak and should be tested.
The button should not move unless it is tripped.
Attachments
Ideally you want to remove the generator wires at the valve WHILE holding the valve knob down to PILOT to keep it from shutting off. May need a helper for that.
If you have a very old one it may have a standing pilot and no shut off and that is OK. Once you lose power when it goes out it is impossible to turn on the gas anyway.
Then you scrape the wire connectors down to bare metal and attach them to your DC volt meter using alligator clips on your meter leads or jumper wires with alligator clips. If you hold them in your fingers your body will absorb some the juice and give you a false reading.
If it is less than 650 millivolts replace it. It may work down to 600 but will be wonky and intermittent.
Also the pilot burner needs to be clean and you need to have a strong enough flame to heat it fully. Sometimes the orifice needs cleaning or the old ones had a aerated pilot burner and dust gets in the intake hole and messes with the flame. Blow it out or carefully dis assemble it if you can.
Lots of fun working with these finicky units.:biggrin2:
If you have a very old one it may have a standing pilot and no shut off and that is OK. Once you lose power when it goes out it is impossible to turn on the gas anyway.
Then you scrape the wire connectors down to bare metal and attach them to your DC volt meter using alligator clips on your meter leads or jumper wires with alligator clips. If you hold them in your fingers your body will absorb some the juice and give you a false reading.
If it is less than 650 millivolts replace it. It may work down to 600 but will be wonky and intermittent.
Also the pilot burner needs to be clean and you need to have a strong enough flame to heat it fully. Sometimes the orifice needs cleaning or the old ones had a aerated pilot burner and dust gets in the intake hole and messes with the flame. Blow it out or carefully dis assemble it if you can.
Lots of fun working with these finicky units.:biggrin2:
Ok, I did some poking around on my lunch break and discovered the CT87K does in fact use a battery.
Contrary to its appearance the CT87K is not the same thermostat used decades ago. Those thermostats used a coiled bi-metallic strip and a mercury switch. The new ones have replaced the mercury switch with an electronic sensor and switch.
According to other consumers, for some reason Honeywell does not tell you about the battery, not even in the user manual. Others reported they had to search the Honeywell web site. The battery is a lithium CR2450.
From anther reference I found the following that the battery is used when the thermostat is first powered and when there is a call for heat that last for over 4 hours. Then sort of goes to sleep. The battery should last over 10 years and is not field replaceable. It takes around 4 minutes to charge the capacitor and the capacitor will run the thermostat after that.
Is it possible the thermostat was not left connected long enough to charge the capacitor?
Another issue may be the battery. Many devices that use batteries like this usually have an insulating strip to prevent the battery from running down during shipment. To use the product one usually just pulls out the strip. Although I could not find any information confirming this, considering you have had two thermostats that did not work yet the furnace kicks on when you connect the wires, my guess is either it was not connected long enough to charge the capacitor or the battery is not activated due to a non-conductive strip not being removed.
You could also try contacting Honeywell Customer Care at 1-800-468-1502
Contrary to its appearance the CT87K is not the same thermostat used decades ago. Those thermostats used a coiled bi-metallic strip and a mercury switch. The new ones have replaced the mercury switch with an electronic sensor and switch.
According to other consumers, for some reason Honeywell does not tell you about the battery, not even in the user manual. Others reported they had to search the Honeywell web site. The battery is a lithium CR2450.
From anther reference I found the following that the battery is used when the thermostat is first powered and when there is a call for heat that last for over 4 hours. Then sort of goes to sleep. The battery should last over 10 years and is not field replaceable. It takes around 4 minutes to charge the capacitor and the capacitor will run the thermostat after that.
Is it possible the thermostat was not left connected long enough to charge the capacitor?
Another issue may be the battery. Many devices that use batteries like this usually have an insulating strip to prevent the battery from running down during shipment. To use the product one usually just pulls out the strip. Although I could not find any information confirming this, considering you have had two thermostats that did not work yet the furnace kicks on when you connect the wires, my guess is either it was not connected long enough to charge the capacitor or the battery is not activated due to a non-conductive strip not being removed.
You could also try contacting Honeywell Customer Care at 1-800-468-1502
You cannot use a 24 volt tstat on a millivolt system which the OP has. Not enough volts to charge that capacitor.
It sounds like a power stealing thermostat and all of them have been troublesome/troublemakers and cr*ap. They use the W wire and run a small current thru it and the gas valve to the C on the other side of the valve.
However they can screw up modern circuit boards as they don't like seeing that signal.
With millivolt systems I use a cheap battery operated electronic thermostat as they just operate a simple switch that has no resistance to the millivolts.
I am not even sure if anyone makes a millivolt tstat anymore as there is not enough demand.
It sounds like a power stealing thermostat and all of them have been troublesome/troublemakers and cr*ap. They use the W wire and run a small current thru it and the gas valve to the C on the other side of the valve.
However they can screw up modern circuit boards as they don't like seeing that signal.
With millivolt systems I use a cheap battery operated electronic thermostat as they just operate a simple switch that has no resistance to the millivolts.
I am not even sure if anyone makes a millivolt tstat anymore as there is not enough demand.
yuri, I was just relaying the results of my research.
I do agree that the OP should dump the CT87K thermostat for a more modern and rubust one.
I do agree that the OP should dump the CT87K thermostat for a more modern and rubust one.
I appreciate your research. I did not know what was inside of it and don't sell it. Does not sound like a good idea on their part.:vs_no_no_no:
Sorry of the delay of update ...was away from furnace for a few days!
Tested as you indicated and got .53-.55 volts. I am looking and will purchase a generator as shown. No local stores carry (there is one but only sells to licensced individuals.
May take a couple days to get. Will update then.
I have learned quite a bit with this posting ... it will certainly help troubleshooting in the future.
Bill
Tested as you indicated and got .53-.55 volts. I am looking and will purchase a generator as shown. No local stores carry (there is one but only sells to licensced individuals.
May take a couple days to get. Will update then.
I have learned quite a bit with this posting ... it will certainly help troubleshooting in the future.
Bill
Most mechanical t-stats have a heat anticipator, it's a coil in series with the heating control circuit.
On a milli-volt system, you may have to bypass it or set it to the highest current. The higher that setting, the lower the resistance - on low current applications, needs more resistance to throw off the correct amount of heat.
In your case, you don't want any added resistance.
On a milli-volt system, you may have to bypass it or set it to the highest current. The higher that setting, the lower the resistance - on low current applications, needs more resistance to throw off the correct amount of heat.
In your case, you don't want any added resistance.
Yuri and others,
After two shipments that were lost, I finally got my generator. Placed in and doubled checked and tightened all the connections. Took about 5-10 minutes to heat up correctly but then was good to go. Furnace now fires ... using a Honeywell CT33A1009 thermo.
Thanks for all the insight. I really do appreciate you guys taking time out and helping someone like me.
All the best,
BT
After two shipments that were lost, I finally got my generator. Placed in and doubled checked and tightened all the connections. Took about 5-10 minutes to heat up correctly but then was good to go. Furnace now fires ... using a Honeywell CT33A1009 thermo.
Thanks for all the insight. I really do appreciate you guys taking time out and helping someone like me.
All the best,
BT
Yur Welcome:smile:
It does take a few minutes to warm up. You should test the new generator to see how strong it is.
It does take a few minutes to warm up. You should test the new generator to see how strong it is.
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