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#1
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HVAC question: Honeywell Wi-Fi thermostat
I want to install a Honeywell RTH8580WF Wi-Fi thermostat in place of an
existing Honeywell thermostat, but there is no C wire connected to the existing thermostat (which may explain why we have to keep replacing batteries in it) and no "Spare" wire that could be connected to C at the HVAC unit and at the thermostat -- even if I could get at the furnace: these are rented premises. I've read that it's possible to use an external 24V transformer, but Honyewell tech support just told me in a chat that that's possible only for 2-wire heat-only systems.; is that true? There are posts and YouTube videos that seem to suggest otherwise. This is a 4-wire gas and A/C system. Advice? Perce |
#2
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HVAC question: Honeywell Wi-Fi thermostat
Percival P. Cassidy has brought this to us :
I want to install a Honeywell RTH8580WF Wi-Fi thermostat in place of an existing Honeywell thermostat, but there is no C wire connected to the existing thermostat (which may explain why we have to keep replacing batteries in it) and no "Spare" wire that could be connected to C at the HVAC unit and at the thermostat -- even if I could get at the furnace: these are rented premises. I've read that it's possible to use an external 24V transformer, but Honyewell tech support just told me in a chat that that's possible only for 2-wire heat-only systems.; is that true? There are posts and YouTube videos that seem to suggest otherwise. This is a 4-wire gas and A/C system. Advice? Perce Interesting I run across this subject at this time. I had the igniter R&R'd on My heater yesterday. I too have a honeywell thermostat that I thought was giving up, but turned out to be the igniter. $175.00 later My heater works again. :') |
#3
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HVAC question: Honeywell Wi-Fi thermostat
I've read that it's possible to use an external 24V transformer, but Honyewell tech support just told me in a chat that that's possible only for 2-wire heat-only systems.; is that true? There are posts and YouTube videos that seem to suggest otherwise. This is a 4-wire gas and A/C system. Advice? Perce You may be able to connect a new external 24V transformer to the new thermostat terminals R and C. Connect the existing R wire to the R terminal as well. The thermostat will draw power for itself from the R and C connections to the new transformer. I give no guarantees that this is right, find some other confirmation. The phasing of the new transformer relative to the old one __may__ be very important. Connecting wrong may do damage. This gets complicated, but should be possible. m |
#4
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HVAC question: Honeywell Wi-Fi thermostat
On Tuesday, February 21, 2017 at 5:07:04 PM UTC-5, wrote:
I've read that it's possible to use an external 24V transformer, but Honyewell tech support just told me in a chat that that's possible only for 2-wire heat-only systems.; is that true? There are posts and YouTube videos that seem to suggest otherwise. This is a 4-wire gas and A/C system. Advice? Perce You may be able to connect a new external 24V transformer to the new thermostat terminals R and C. Connect the existing R wire to the R terminal as well. The thermostat will draw power for itself from the R and C connections to the new transformer. I give no guarantees that this is right, find some other confirmation. The phasing of the new transformer relative to the old one __may__ be very important. Connecting wrong may do damage. This gets complicated, but should be possible. m Much simpler and less risky solution..... Can you hook up a WiFi controlled table lamp, placed under the thermostat. When you want the heat turned down, turn the light on. etc. m |
#5
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HVAC question: Honeywell Wi-Fi thermostat
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#6
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HVAC question: Honeywell Wi-Fi thermostat
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#8
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HVAC question: Honeywell Wi-Fi thermostat
On 02/21/2017 11:16 AM, I wrote:
I want to install a Honeywell RTH8580WF Wi-Fi thermostat in place of an existing Honeywell thermostat, but there is no C wire connected to the existing thermostat (which may explain why we have to keep replacing batteries in it) and no "Spare" wire that could be connected to C at the HVAC unit and at the thermostat -- even if I could get at the furnace: these are rented premises. I've read that it's possible to use an external 24V transformer, but Honyewell tech support just told me in a chat that that's possible only for 2-wire heat-only systems.; is that true? There are posts and YouTube videos that seem to suggest otherwise. This is a 4-wire gas and A/C system. Advice? I have now gained access to the HVAC unit, an ancient Singer, and can see the C terminal, but the 4-conductor wire bundle to the thermostat (there's a separate 2-wire to the outside compressor unit) goes up through the ceiling of the utility room and is either plastered around or caulked around, so there is no easy way to use it to pull a 5-wire bundle to replace it -- and who knows whether it's stapled to the joists in the roof space? There is a G wire connected to both the furnace and the Tstat, which I understand could be repurposed as a C wire but at the "cost" of no longer being able to control the fan on its own. But they also say about checking with the local building code, so I guess that's what I need to do. Perce |
#9
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HVAC question: Honeywell Wi-Fi thermostat
On Tuesday, February 21, 2017 at 7:34:19 PM UTC-5, Percival P. Cassidy wrote:
On 02/21/2017 11:16 AM, I wrote: I want to install a Honeywell RTH8580WF Wi-Fi thermostat in place of an existing Honeywell thermostat, but there is no C wire connected to the existing thermostat (which may explain why we have to keep replacing batteries in it) and no "Spare" wire that could be connected to C at the HVAC unit and at the thermostat -- even if I could get at the furnace: these are rented premises. I've read that it's possible to use an external 24V transformer, but Honyewell tech support just told me in a chat that that's possible only for 2-wire heat-only systems.; is that true? There are posts and YouTube videos that seem to suggest otherwise. This is a 4-wire gas and A/C system. Advice? I have now gained access to the HVAC unit, an ancient Singer, and can see the C terminal, but the 4-conductor wire bundle to the thermostat (there's a separate 2-wire to the outside compressor unit) goes up through the ceiling of the utility room and is either plastered around or caulked around, so there is no easy way to use it to pull a 5-wire bundle to replace it -- and who knows whether it's stapled to the joists in the roof space? There is a G wire connected to both the furnace and the Tstat, which I understand could be repurposed as a C wire but at the "cost" of no longer being able to control the fan on its own. But they also say about checking with the local building code, so I guess that's what I need to do. Perce I doubt local building code, which would be the electrical inspector, would give a rat's ass if you gave up the fan wire on a thermostat. Do you ever even use the fan by itself? I've played around with my fan switch a few times over decades, but never found a real use for it. Re-purposing that would be my first solution, assuming you're OK with any liability if the landlord claims you screwed up his furnace, etc. Adding the additional transformer, in a rental property you don't own, if you tried to do that here in NJ, it's illegal because you'd have to wire it in and you can't do that on a property that you don't own or on a property that you rent out, unless you're a licensed electrician. Come to think of it, I'm not sure what the official position is on doing thermostat wiring, though I'm sure lots of people do it in properties they don't own. |
#10
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HVAC question: Honeywell Wi-Fi thermostat
On 02/21/2017 08:11 PM, trader_4 wrote:
On Tuesday, February 21, 2017 at 7:34:19 PM UTC-5, Percival P. Cassidy wrote: On 02/21/2017 11:16 AM, I wrote: I want to install a Honeywell RTH8580WF Wi-Fi thermostat in place of an existing Honeywell thermostat, but there is no C wire connected to the existing thermostat (which may explain why we have to keep replacing batteries in it) and no "Spare" wire that could be connected to C at the HVAC unit and at the thermostat -- even if I could get at the furnace: these are rented premises. I've read that it's possible to use an external 24V transformer, but Honyewell tech support just told me in a chat that that's possible only for 2-wire heat-only systems.; is that true? There are posts and YouTube videos that seem to suggest otherwise. This is a 4-wire gas and A/C system. Advice? I have now gained access to the HVAC unit, an ancient Singer, and can see the C terminal, but the 4-conductor wire bundle to the thermostat (there's a separate 2-wire to the outside compressor unit) goes up through the ceiling of the utility room and is either plastered around or caulked around, so there is no easy way to use it to pull a 5-wire bundle to replace it -- and who knows whether it's stapled to the joists in the roof space? There is a G wire connected to both the furnace and the Tstat, which I understand could be repurposed as a C wire but at the "cost" of no longer being able to control the fan on its own. But they also say about checking with the local building code, so I guess that's what I need to do. Perce I doubt local building code, which would be the electrical inspector, would give a rat's ass if you gave up the fan wire on a thermostat. Do you ever even use the fan by itself? I've played around with my fan switch a few times over decades, but never found a real use for it. Re-purposing that would be my first solution, assuming you're OK with any liability if the landlord claims you screwed up his furnace, etc. We've hardly ever used the fan on its own. I may be the only person that's ever done it; I doubt too many people know it's an option. We have a ceiling fan anyway, if we need to move the air around. Adding the additional transformer, in a rental property you don't own, if you tried to do that here in NJ, it's illegal because you'd have to wire it in and you can't do that on a property that you don't own or on a property that you rent out, unless you're a licensed electrician. Come to think of it, I'm not sure what the official position is on doing thermostat wiring, though I'm sure lots of people do it in properties they don't own. The 24V transformer I have is a plug-in one: https://www.amazon.com/Elk-TRG2440-2.../dp/B0007N5LJK so no wiring-in required. Perce |
#11
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HVAC question: Honeywell Wi-Fi thermostat
On Tue, 21 Feb 2017 17:11:41 -0800 (PST)
trader_4 wrote: Do you ever even use the fan by itself? I've played around with my fan switch a few times over decades, but never found a real use for it. So no one else can either...do keep up there in the rear. |
#12
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HVAC question: Honeywell Wi-Fi thermostat
On 2/21/2017 7:18 PM, Percival P. Cassidy wrote:
On 02/21/2017 05:06 PM, wrote: I've read that it's possible to use an external 24V transformer, but Honyewell tech support just told me in a chat that that's possible only for 2-wire heat-only systems.; is that true? There are posts and YouTube videos that seem to suggest otherwise. This is a 4-wire gas and A/C system. Advice? You may be able to connect a new external 24V transformer to the new thermostat terminals R and C. Connect the existing R wire to the R terminal as well. The thermostat will draw power for itself from the R and C connections to the new transformer. That is what I had in mind. I have the thermostat sitting on the bench at present powered from the 24V transformer connected to the R and C terminals but not to the HVAC unit. That seems to work fine. With the Wi-Fi hotspot two rooms away, the thermostat shows a decent signal strength and I can change settings from my smartphone. I give no guarantees that this is right, find some other confirmation. The phasing of the new transformer relative to the old one __may__ be very important. Connecting wrong may do damage. I thought of that. Am I right in assuming that I would connect one wire from the transformer to either the C or R terminal, leaving the other wire from the transformer disconnected, then check for zero Volts between that unconnected wire and some other terminal (which one?) on the thermostat rather than 48 Volts? This gets complicated, but should be possible. Perce Given the price of the thermostat and the risk of damaging or destroying either the thermostat or the furnace control board (even more expensive), perhaps a few phone calls to reputable, experienced HVAC contractors in your area are worth the investment, even if it involves a house visit by one of them? |
#13
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HVAC question: Honeywell Wi-Fi thermostat
On Wednesday, February 22, 2017 at 8:39:49 AM UTC-5, Peter wrote:
On 2/21/2017 7:18 PM, Percival P. Cassidy wrote: On 02/21/2017 05:06 PM, wrote: I've read that it's possible to use an external 24V transformer, but Honyewell tech support just told me in a chat that that's possible only for 2-wire heat-only systems.; is that true? There are posts and YouTube videos that seem to suggest otherwise. This is a 4-wire gas and A/C system. Advice? You may be able to connect a new external 24V transformer to the new thermostat terminals R and C. Connect the existing R wire to the R terminal as well. The thermostat will draw power for itself from the R and C connections to the new transformer. That is what I had in mind. I have the thermostat sitting on the bench at present powered from the 24V transformer connected to the R and C terminals but not to the HVAC unit. That seems to work fine. With the Wi-Fi hotspot two rooms away, the thermostat shows a decent signal strength and I can change settings from my smartphone. I give no guarantees that this is right, find some other confirmation. The phasing of the new transformer relative to the old one __may__ be very important. Connecting wrong may do damage. I thought of that. Am I right in assuming that I would connect one wire from the transformer to either the C or R terminal, leaving the other wire from the transformer disconnected, then check for zero Volts between that unconnected wire and some other terminal (which one?) on the thermostat rather than 48 Volts? This gets complicated, but should be possible. Perce If your ability level is such that you understand what I meant by checking the phasing, and you get the phasing right, then it should work. Note, if it is a wall wart type transformer, and you plug it in the other way round, the phasing will change... so make sure it is set the right way and can't be changed. I had an idea, if you connect the new transformer in series though a car brake light bulb, if there is any problem, the bulb will light and burn out protecting everything else. If the connections are correct, the current will be low and the bulb will not light or be very dim. I'd keep the bulb in the circuit. I'm talking about connecting the bulb on the 24V side, not the primary. good luck... let us know how it goes m |
#14
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HVAC question: Honeywell Wi-Fi thermostat
[snip] I have now gained access to the HVAC unit, an ancient Singer, and can see the C terminal, but the 4-conductor wire bundle to the thermostat (there's a separate 2-wire to the outside compressor unit) goes up through the ceiling of the utility room and is either plastered around or caulked around, so there is no easy way to use it to pull a 5-wire bundle to replace it -- and who knows whether it's stapled to the joists in the roof space? [snip] I remember a 2-piece electronic thermostat that solved that problem. One piece was in the room with the HVAC unit, and the other (with the temp sensor and controls) on the wall. The 2 were connected with 4 wires (a power pair and a data pair) like USB. However, I don't know anything about where you'd get one. -- Mark Lloyd http://notstupid.us/ "The state (the U.S. Constitution) has not the right to leave every man free to profess and embrace whatever religion he may desire." [Pope Pius IX] |
#15
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HVAC question: Honeywell Wi-Fi thermostat
On 02/21/2017 07:11 PM, trader_4 wrote:
[snip] I doubt local building code, which would be the electrical inspector, would give a rat's ass if you gave up the fan wire on a thermostat. Do you ever even use the fan by itself? On some systems, Y is connected only to the outdoor unit, and needs the G wire to run the fan. I've played around with my fan switch a few times over decades, but never found a real use for it. Have you tried using cooling with G disconnected? Re-purposing that would be my first solution, assuming you're OK with any liability if the landlord claims you screwed up his furnace, etc. [snip] -- Mark Lloyd http://notstupid.us/ "The state (the U.S. Constitution) has not the right to leave every man free to profess and embrace whatever religion he may desire." [Pope Pius IX] |
#16
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HVAC question: Honeywell Wi-Fi thermostat
On 02/22/2017 07:15 AM, burfordTjustice wrote:
On Tue, 21 Feb 2017 17:11:41 -0800 (PST) trader_4 wrote: Do you ever even use the fan by itself? I've played around with my fan switch a few times over decades, but never found a real use for it. So no one else can either...do keep up there in the rear. I used to know someone who ran the fan all the time. Also, as in my other reply, not using the fan switch isn't always the same as having the wire disconnected. -- Mark Lloyd http://notstupid.us/ "The state (the U.S. Constitution) has not the right to leave every man free to profess and embrace whatever religion he may desire." [Pope Pius IX] |
#17
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HVAC question: Honeywell Wi-Fi thermostat
On 02/22/2017 10:54 AM, wrote:
[snip] If your ability level is such that you understand what I meant by checking the phasing, and you get the phasing right, then it should work. Note, if it is a wall wart type transformer, and you plug it in the other way round, the phasing will change... so make sure it is set the right way and can't be changed. I had an idea, if you connect the new transformer in series though a car brake light bulb, if there is any problem, the bulb will light and burn out protecting everything else. If the connections are correct, the current will be low and the bulb will not light or be very dim. I'd keep the bulb in the circuit. I'm talking about connecting the bulb on the 24V side, not the primary. good luck... let us know how it goes m Would the thermostat work with DC? Then there'd be no phase problem. -- Mark Lloyd http://notstupid.us/ "The state (the U.S. Constitution) has not the right to leave every man free to profess and embrace whatever religion he may desire." [Pope Pius IX] |
#18
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HVAC question: Honeywell Wi-Fi thermostat
On 02/22/2017 07:55 PM, Mark Lloyd wrote:
I doubt local building code, which would be the electrical inspector, would give a rat's ass if you gave up the fan wire on a thermostat. Do you ever even use the fan by itself? On some systems, Y is connected only to the outdoor unit, and needs the G wire to run the fan. Honeywell does have "official" instructions for repurposing the G wire, and they say to jumper G and Y at the HVAC unit. I've played around with my fan switch a few times over decades, but never found a real use for it. Have you tried using cooling with G disconnected? No. Re-purposing that would be my first solution, assuming you're OK with any liability if the landlord claims you screwed up his furnace, etc. [snip] |
#19
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HVAC question: Honeywell Wi-Fi thermostat
On 02/23/2017 08:59 AM, Percival P. Cassidy wrote:
On 02/22/2017 07:55 PM, Mark Lloyd wrote: I doubt local building code, which would be the electrical inspector, would give a rat's ass if you gave up the fan wire on a thermostat. Do you ever even use the fan by itself? On some systems, Y is connected only to the outdoor unit, and needs the G wire to run the fan. Honeywell does have "official" instructions for repurposing the G wire, and they say to jumper G and Y at the HVAC unit. That ought to work, as long as Y is available at the HVAC unit. At the unit I was talking about earlier, Y ran within a foot so connecting it to G should be doable. BTW, I did add an electronic thermostat to that unit, using a wire from C. [snip] -- Mark Lloyd http://notstupid.us/ "The certainty with which a religious belief is held is usually in direct proportion to its absurdity." [Rev. Donald Morgan] |
#20
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HVAC question: Honeywell Wi-Fi thermostat
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#21
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HVAC question: Honeywell Wi-Fi thermostat
On Saturday, February 25, 2017 at 3:31:57 PM UTC-5, Tekkie® wrote:
posted for all of us... I've read that it's possible to use an external 24V transformer, but Honyewell tech support just told me in a chat that that's possible only for 2-wire heat-only systems.; is that true? There are posts and YouTube videos that seem to suggest otherwise. This is a 4-wire gas and A/C system. Advice? Perce You may be able to connect a new external 24V transformer to the new thermostat terminals R and C. Connect the existing R wire to the R terminal as well. The thermostat will draw power for itself from the R and C connections to the new transformer. I give no guarantees that this is right, find some other confirmation. The phasing of the new transformer relative to the old one __may__ be very important. Connecting wrong may do damage. This gets complicated, but should be possible. m I don't understand what phasing would do with an AC transformer? -- Tekkie It wouldn't if there was only ONE transformer. What PPC wants to do is power a new wifi thermostat that requires power, with another transformer that's in addition to the existing HVAC one. That's because to get power at the thermostat you need a common return wire to the HVAC transformer and his wiring does not have that wire or a spare one. In that case, phasing probably matters. At least I would not attempt it without knowing they are in phase. An alternate approach, re-purposing the fan wire was suggested and that would be my solution. |
#22
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HVAC question: Honeywell Wi-Fi thermostat
On 02/23/2017 09:59 AM, I wrote:
I doubt local building code, which would be the electrical inspector, would give a rat's ass if you gave up the fan wire on a thermostat. Do you ever even use the fan by itself? On some systems, Y is connected only to the outdoor unit, and needs the G wire to run the fan. Honeywell does have "official" instructions for repurposing the G wire, and they say to jumper G and Y at the HVAC unit. I've played around with my fan switch a few times over decades, but never found a real use for it. Have you tried using cooling with G disconnected? No. Re-purposing that would be my first solution, assuming you're OK with any liability if the landlord claims you screwed up his furnace, etc. I re-purposed the G wire and jumpered G to Y at the HVAC unit, and all is fine. Of course, the new "smart" thermostat is still learning how far ahead of time it needs to turn on the heat for it to be at the desired temperature at the right time. It makes life much easier. And I can grant access to the thermostat settings for other users; e.g., someone may have a previously unscheduled meeting and can set the temp. to be comfortable by the time the meeting starts. Perce |
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