Thank you so much. I spent 2 days Googling after I found I needed a C wire. I have an older furnace & you showed me what I needed to do. Keep making videos. Stay healthy.
I have a hydronic boiler with a 24 volt transformer powering 2 Honeywell zone valves. I have a extra unused green wire at my thermostat. Can I connect green wire to C terminal on T stat and then bring green wire to common side of transformer to power up my wifi Honeywell RTH9585WF T stat? THANKS IN ADVANCE!
I have along with the red and white a black wire that is hooked up to the G terminal in the furnace.i'm also installing a wifi thermostat that requires 24V. It doesn't seem to matter if the black is hooked up to the thermostat or not.Could I move the black on the furnace terminal to the C terminal and then to the C on the thermostat providing the C has 24V ?
Hey Gray. I was diagnosing a lennox single stage furnace under a year old. It had Nest thermostat it had the common. Furnace would work for 20 mins go off all that. Long story short I put a honeywell thermostat on and the furnace worked fine. This was their 3rd nest before I put the honeywell on. I was later told by the other company that it needed a new gas valve to work with the nest. I am confused as it worked fine with the honeywell. Now it works fine with a new gas valve and nest apparently. I am very confused. The board, and pressure switch were changed and still had same problem with nest.
The problem with Nest is that it uses solid state switching and power stealing, which Nest tries to "lipstick on a pig" by calling it power sharing. This means that by design it never fully stops the current flow while off, and doesn't fully pass the 24v sine wave while on. IMO all Nest units need a common wire and a relay isolation board installed whether they seem to work without them or not.
Back in the 1980s, when the first electronic thermostats came out, we were changing them out all the time until we started installing isolation relays to separate the electronics in the thermostat from the electronics in the furnace controls. Honeywell and White Rodgers figured that out many years ago and changed their thermostats to use mechanical relays inside the thermostats. That stopped all the problems. I also agree with Daniel Armstrong and his isolation relay. My advice: Go with Honeywell or White Rodgers. GFM
My thermostat is a normal Honeywell FocusPro 5000 with the common wire hooked up. I got it from the bins at the Goodwill outlet store. I was previously using a hardware store Honeywell. My favorite feature of this stat is that it locks out the cooling for 5 minutes when it senses a loss of 24v, IE it works as a power failure anti-short cycle timer to protect the compressor.
@@grayfurnaceman Thank you. One more question if you don't mind, my new thermostat says to jumper the Y to the G at the furnace if I move my G wire to use as the C. I only have heat not AC nothing is connected to the Y. My only 3 wires being used are R, W and G. Hope that made sense.
Question, I have a heat pump will run perfectly when jumping out R, Y, O, & G. When I hook up a digital stat using a common wire to power the stat the unit kicks on and immediately kicks out. When I remove the common wire from the stat and power the stat with 2 AA batteries it also runs perfectly. Its that common wire being hooked up that's the problem. I have to hook up a Nest stat which is, as you know, only powered by the unit. Tech support threw up their hands and say they don't know. I pulled all the hair out I can spare, lol.
I have the same problem. Im using a braeburn tstat with wifi and zone control board. Everything works fine until i connect the c wire to the tstat. Then the tstat turns off... when i disconnect the wire and runs on battery everything works. Its sad because i can not use the wifi function. The system is a lennox heat pump, braeburn thermostat, honeywell zone controller and two 24v transformers (one internal for the heat pump and another one for zone controller). The tstats are connected to the zone controller.
hey quick question on thermostatic expansion valves? where you have liquid charged sensing element and liquid cross charged sensing element. when do you choose between the two of them?
so the EIM module still has advantages over wifi. control humidifier, dehumidification, DAT and RAT delta charts, alerts. oD temp and humidity. but this gets closer.
Question... I had a licensed HVAC guy install a new 7/8" line set and 4 ton evaporator coil at my residence. The new line set is approximately 30 feet. I noticed that he did NOT use a micron gauge, and he vacuumed the line set for approximately 15 minutes before releasing the charge from the New 4 ton unit. It only ran for approximately 5 minutes, he said that he would have to come back on a warmer day to charge the system. would it do me any good to pump down the system and do a proper leak test and vacuum and re- release the refrigerant?? Or do I need to Evacuate the system and start completely over??
If the evacuation was not complete, it will do no good to pump it down, as the refrigerant will be contaminated. The only way to be sure is to replace all refrigerant, leak check and evacuate. That said, you need to consider if it is worth the cost. The evacuation was not properly done, but the line set and coil are new and should be reasonably clean. GFM
Thanks for your Reply. I decided to Recover all the refrigerant and start over.. I ordered Everything I needed from Amazon last night. The Testo 550, a Recovery Machine and tank, Hoses, digital Psychrometer, refrigerant and a Lot more other stuff I will need. It was NOT cheap, But now I can service my unit Properly .. Thanks again.
+grayfurnaceman do you have any idea how to adjust the cycle rate on a honeywell 5/1/1 t-stat? I have figured out how to get reduce the cph in heat mode, but can't adjust cooling mode. unit is short cycling in cooling mode
I am also in a situation where I want to install a wifi thermostat without a C-wire from the existing wiring. As I tried to connect the wire to the low voltage transformer, I discovered that the voltage across the terminal was only 19V. Initially I thought that the transformer was bad. But after searching the model number (EM57580), I found that the transformer was a 18V transformer.! The service manual for my furnace (GMP-150-5) only make references to 24V. Do you think that I should replace the transformer even though it has worked 20+ years?
gfm. i havent watched the entire vid, but I did a nest not too long ago. the tech support told me i didnt need the common wire. however, it did not work without it. just two cents there.
I am going to repeat the answer I gave below so you know. Back in the 1980s, when the first electronic thermostats came out, we were changing them out all the time until we started installing isolation relays to separate the electronics in the thermostat from the electronics in the furnace controls. Honeywell and White Rodgers figured that out many years ago and changed their thermostats to use mechanical relays inside the thermostats. That stopped all the problems. I also agree with Daniel Armstrong and his isolation relay. My advice: Go with Honeywell or White Rodgers. GFM
That's confusing on some Trane unit's I've seen. They sometimes use "B" as common. I see you had a "B" and a "BK". I'd be second guessing myself on that one.
Thank you so much. I spent 2 days Googling after I found I needed a C wire. I have an older furnace & you showed me what I needed to do. Keep making videos. Stay healthy.
ty
My RC wire is hooked to my common terminal can I hook my common wire to that also? Thanks
I have a hydronic boiler with a 24 volt transformer powering 2 Honeywell zone valves. I have a extra unused green wire at my thermostat. Can I connect green wire to C terminal on T stat and then bring green wire to common side of transformer to power up my wifi Honeywell RTH9585WF T stat?
THANKS IN ADVANCE!
Go for it.
GFM
My thermostat is hooked up to a primary oil controller with terminals that read t and t3 2 1 what should I connect the c to
Your system does not have a C. You will need to install a transformer with an isolation relay for the oil burner.
GFM
@@grayfurnaceman okay thank you
I have along with the red and white a black wire that is hooked up to the G terminal in the furnace.i'm also installing a wifi thermostat that requires 24V. It doesn't seem to matter if the black is hooked up to the thermostat or not.Could I move the black on the furnace terminal to the C terminal and then to the C on the thermostat providing the C has 24V ?
Not if you have air conditioning. The G terminal is used in cooling.
GFM
No I dont have air conditioning so should be ok, thanks for the quick reply!
Hey Gray. I was diagnosing a lennox single stage furnace under a year old. It had Nest thermostat it had the common. Furnace would work for 20 mins go off all that. Long story short I put a honeywell thermostat on and the furnace worked fine. This was their 3rd nest before I put the honeywell on. I was later told by the other company that it needed a new gas valve to work with the nest. I am confused as it worked fine with the honeywell. Now it works fine with a new gas valve and nest apparently. I am very confused. The board, and pressure switch were changed and still had same problem with nest.
The problem with Nest is that it uses solid state switching and power stealing, which Nest tries to "lipstick on a pig" by calling it power sharing. This means that by design it never fully stops the current flow while off, and doesn't fully pass the 24v sine wave while on. IMO all Nest units need a common wire and a relay isolation board installed whether they seem to work without them or not.
Back in the 1980s, when the first electronic thermostats came out, we were changing them out all the time until we started installing isolation relays to separate the electronics in the thermostat from the electronics in the furnace controls. Honeywell and White Rodgers figured that out many years ago and changed their thermostats to use mechanical relays inside the thermostats. That stopped all the problems. I also agree with Daniel Armstrong and his isolation relay. My advice: Go with Honeywell or White Rodgers.
GFM
My thermostat is a normal Honeywell FocusPro 5000 with the common wire hooked up. I got it from the bins at the Goodwill outlet store. I was previously using a hardware store Honeywell.
My favorite feature of this stat is that it locks out the cooling for 5 minutes when it senses a loss of 24v, IE it works as a power failure anti-short cycle timer to protect the compressor.
Do you think that the customer will have the same issue with the nest and new gas valve?
Virtually all electronic thermostats do that.
GFM
I have an older Lennox and it has a T not a C is that the same?
Oil or gas?
GFM
@@grayfurnaceman Gas
@@grayfurnaceman Lennox G-20 Series
@@BLomedico The T is common.
GFM
@@grayfurnaceman Thank you. One more question if you don't mind, my new thermostat says to jumper the Y to the G at the furnace if I move my G wire to use as the C. I only have heat not AC nothing is connected to the Y. My only 3 wires being used are R, W and G. Hope that made sense.
Question, I have a heat pump will run perfectly when jumping out R, Y, O, & G. When I hook up a digital stat using a common wire to power the stat the unit kicks on and immediately kicks out. When I remove the common wire from the stat and power the stat with 2 AA batteries it also runs perfectly. Its that common wire being hooked up that's the problem. I have to hook up a Nest stat which is, as you know, only powered by the unit. Tech support threw up their hands and say they don't know. I pulled all the hair out I can spare, lol.
I have the same problem. Im using a braeburn tstat with wifi and zone control board. Everything works fine until i connect the c wire to the tstat. Then the tstat turns off... when i disconnect the wire and runs on battery everything works. Its sad because i can not use the wifi function. The system is a lennox heat pump, braeburn thermostat, honeywell zone controller and two 24v transformers (one internal for the heat pump and another one for zone controller). The tstats are connected to the zone controller.
hey quick question on thermostatic expansion valves? where you have liquid charged sensing element and liquid cross charged sensing element. when do you choose between the two of them?
Simple reply. Cross charged valve will operate over a wider range of temps than valves charged with the refrigerant used in the system.
GFM
thanks for the information.
so the EIM module still has advantages over wifi. control humidifier, dehumidification, DAT and RAT delta charts, alerts. oD temp and humidity. but this gets closer.
Question... I had a licensed HVAC guy install a new 7/8" line set and 4 ton evaporator coil at my residence. The new line set is approximately 30 feet. I noticed that he did NOT use a micron gauge, and he vacuumed the line set for approximately 15 minutes before releasing the charge from the New 4 ton unit. It only ran for approximately 5 minutes, he said that he would have to come back on a warmer day to charge the system. would it do me any good to pump down the system and do a proper leak test and vacuum and re- release the refrigerant?? Or do I need to Evacuate the system and start completely over??
If the evacuation was not complete, it will do no good to pump it down, as the refrigerant will be contaminated. The only way to be sure is to replace all refrigerant, leak check and evacuate. That said, you need to consider if it is worth the cost. The evacuation was not properly done, but the line set and coil are new and should be reasonably clean.
GFM
Thanks for your Reply. I decided to Recover all the refrigerant and start over.. I ordered Everything I needed from Amazon last night. The Testo 550, a Recovery Machine and tank, Hoses, digital Psychrometer, refrigerant and a Lot more other stuff I will need. It was NOT cheap, But now I can service my unit Properly .. Thanks again.
on the first transformer there was no R or C labelled. so how would you know which is which? thanks.
It does not make any difference as long as the one that goes to the C terminal is also connected to chassis.
GFM
@@grayfurnaceman this is my exact set up. Unfortunately it's still not working even when I tried connecting to either side of the transformer.
said red and white wire, but had the green and white bent up, that pesky colorblindness.
still educational for many :)
Sure was.
GFM
if the C terminal is grounded to the chassis, would i be able to use it for wifi thermostat? thanks.
+grayfurnaceman do you have any idea how to adjust the cycle rate on a honeywell 5/1/1 t-stat? I have figured out how to get reduce the cph in heat mode, but can't adjust cooling mode. unit is short cycling in cooling mode
just watched your video on electric thermostats. going to make sure the senor is clean
I am also in a situation where I want to install a wifi thermostat without a C-wire from the existing wiring. As I tried to connect the wire to the low voltage transformer, I discovered that the voltage across the terminal was only 19V. Initially I thought that the transformer was bad. But after searching the model number (EM57580), I found that the transformer was a 18V transformer.! The service manual for my furnace (GMP-150-5) only make references to 24V. Do you think that I should replace the transformer even though it has worked 20+ years?
Replace the transformer.
GFM
gfm. i havent watched the entire vid, but I did a nest not too long ago. the tech support told me i didnt need the common wire. however, it did not work without it. just two cents there.
I am going to repeat the answer I gave below so you know. Back in the 1980s, when the first electronic thermostats came out, we were changing them out all the time until we started installing isolation relays to separate the electronics in the thermostat from the electronics in the furnace controls. Honeywell and White Rodgers figured that out many years ago and changed their thermostats to use mechanical relays inside the thermostats. That stopped all the problems. I also agree with Daniel Armstrong and his isolation relay. My advice: Go with Honeywell or White Rodgers.
GFM
Thank you for the information.
thank you for making videos. not all Wi-Fi thermostats are compatible to your Wi-Fi router
Very interesting video, can't wait to see next part, thank you Sir!!! 😊😊😊
modern technology, thank you ...
Welcome
GFM
That's confusing on some Trane unit's I've seen. They sometimes use "B" as common. I see you had a "B" and a "BK". I'd be second guessing myself on that one.
Yeah they can drive you nuts.
GFM
Your videos are so informative!
first comment?