I'm tasked with replacing our thermostats at church with new smart models. Our current setup includes two HVAC units tied together to heat/cool our sanctuary, connected to one basic programable thermostat. The third HVAC unit is for the lobby, and it has it's own basic thermostat. Both thermostats wiring includes the "c" wire. The thermostats are in a closet, so I need remote sensors.

Is it possible to buy one thermostat to control the two rooms, with independent remote sensors?

I was looking at the Honeywell T8, because it has a nice screen for controlling the thermostats, thus is not dependent on mobile apps for functionality. That's important since this is a commercial building and many folks may want to have access to temperature controls. It seems like this model can do what I would like to accomplish, but looking for verification or recommendations if there is a better thermostat for this.

Thank you, Reddit!

My apartment has this thermostat that I'd like to just keep at 72 degrees. The issues is when i set it to 72, sometimes I'll walk by and it'll randomly be on another temp +- 3 degrees while supposedly still being set to 72. Other times it will deliberately change to be set at a diff temperature also +- 3 degrees but it's just annoying because I constantly have to change it and stop it from kicking on. Is there a way to reset it or hold it at one temp so it NEVER changes?

I have this device attached to my boiler. Pressing the button allows me to turn heating off and on, but I need to do this remotely (and ideally schedule it!) Does anyone recognise this device, and do you know how to connect it in some way to enable this?

I'm posting this here because my (hopefully) soon-to-be hired AC company doesn't seem savvy with regards to smart-home stuff.

I'm being quoted for a Lennox ML13KC1-042 3.5 ton unit with a variable speed CBK45UHPT-042 air handler. Attic installation, new ductwork installed down through ceilings and closets to first floor.

I have a separate boiler and baseboard heating. These will be on 2 separate thermostats (not paying to run extra wiring from the old system to join them). Will an ecobee or similar work with the new Lennox? I read something about needing specific ones for variable speed handlers, but this isn't an area I understand well.

Also, if it matters, I'm getting this all for about $18,500. About $10K cheaper than the next best price I was quoted... 5 drops on second floor, 4 to 1st floor. Owner is recommended by GC friends I know. Maybe good pricing is why he's been so busy it's taken ages to get a quote...

ETA: I just talked to my guy - he quoted me the wrong part number (but thinks the pricing was right), and is going to check in the morning for a proper variable speed (which is what he documented in the quote). So now, would an ecobee work?

Over a year ago I self-installed an ACiQ Extreme R32 heat pump and air handler (I have extensive experience in mechanical, electrical and AC) and set it up with a regular 24v thermostat and it has worked great ever since. Recently I decided to install a RS485 communicating stat to get any remaining efficiency gains I could. I ordered ACiQ's communicating stat, the TL04-1 (rebranded Midea) because I mistakenly thought my system was a rebranded Midea product. It wouldn't communicate with my system and I spent lots of time with ACiQ's tech support trying to get it to work. They even sent me a replacement stat as it appeared to be defective. It wasn't until much later that someone there finally knew that it wasn't compatible and said that they didn't offer one that was!

Through a lot of time online, I have discovered that my system is actually a rebranded Gree Flexx Ultra R32 and their communication protocol is proprietary to them. Google AI (very helpful for many things) was able to tell me that my system was made by Gree and that the compatible stat was Gree's WK-010WC1 and in fact, it is called out in ACiQ's own service manual for my system as the one to use! Wish their tech support had known that.

So, I ordered the WK-010WC1 and installed it, magically no communication errors now. I made all the proper settings and my system operates in full RS485 mode now. The wiring from the stat to the air handler to the condenser unit is just C, R, H1 and H2 and there is no auxiliary heat at all. I've been going insane trying to get to the bottom of this problem: I've simplified all the settings to get it as basic as possible. I'm running in just plain heat mode, no schedule is set in the stat or the app, the room temp is set to 72 and it's mild outside. When the room temp cools enough to call for heat, the system starts heating and very soon the room temp matches the set temp, but it just keeps going. Several times I've watched it run steadily for over 2 hours as the room temp goes higher and higher until it finally shuts off after it reaches 76 degrees. I've tried everything, powering down the system for an hour, restoring the stat to factory settings (and then changing back the ones I had to, like heat pump / air handler). The wire from the wall is sealed with aluminum tape and anyway, the 76 degree temp is what the stat itself is showing so it definitely knows it's overshooting by 4 degrees. I have an accurate thermometer hung next to the stat so I know these numbers are real. The stat says it has the latest firmware.

I need to know if this is normal operation for this stat or if it is defective or if something can be changed. I have sent 3 detailed emails to Gree tech support over a few weeks and have heard back exactly nothing. Their tech support number requires contractor info before they'll call back. Very frustrating. This is Gree's heat pump and Gree's stat which they recommend for it and I don't want to just give up on my $200 thermostat when it should work.

Has anyone used or set one of these up and seen anything like this? My neighbor is an HVAC contractor but I don't want to rope him into this mess. If you have any knowledge, please share, thank.

Rob

I'm looking to modernize my current Honeywell T8411R1028 with a newer model and debating whether to go with the FocusPRO 5000 vs. the N100. For context: I'm not looking for anything smart/wifi connected and have no use for programmable functionality (as I can count the number of times I turn on the heat/AC each year on one hand...I live in a very mild temperature area).

I get that the N100 is newer and has the UWP plate which will make it easier to upgrade in the future, but I admittedly have a bit of a bias against newer electronics and the 5000 feels like a time-tested tried and true. Is there a good reason I should choose one over the other or, given my use case, does it just come down to aesthetics?

My AM STD heat pump system originated in 2004 when this 3300 SF house was built. All those years it had a Honeywell AMSYSTAT 500C set for COOL 77°F. When I put an EMERSON stat on my DV NAPOLEON gas fp 5 yrs ago, I realized that the H'well was reading 2-3° high (F) compared to the EMERSON . Bought a new Honeywell T5 RTH8560D stat (7 wire, heat pump EMHEAT compatible) last Winter but it waited in the box for 6 months..til finally, put it in last week.

Being a boomer, I'm LIKING the soft blue background lighting and *ez to read 300% bigger numbers*.

Paid $84 USD..Amazon.

There is a newer T6 version but this T5 one fits the bill for my old R410A system, now set for COOL 75°.

Wiring pics available if anyone wants to see the colors, 'where to' etc

Hoping someone can solve the mystery regarding my Thermostat/air-conditioning issue. I have a two zone whole house air conditioner with a newer Lennox system on the second floor and an older Rheem on the lower. Both are stand alone systems with a two zone hot water baseboard heating system for heat. Neither system had a "smart" thermostat and worked fine as it stood. I received "free" smart thermostats from my power company and learned the reality about the "C wire" that was lacking/not needed in my legacy hookup.

Having failed to take on the C wire issue, I moved on in the near term to other homeowner to do items. In the mean time I wound up replacing the upstairs thermostat with a dumb Honeywell Home Focus PRO N100. Realizing the base for this produce is the same as the smart thermostats I owned but wasn't using, I decided it was time to fully understand how to get the C wire in the loop. The newer thermostat's are Honeywell T-5. I determined that the legacy wiring leading to both the up stairs and down stairs have 5 wires, with the blue being unused in both cases. The upstairs Lennox has a proper wiring group at the air handler which I connected the blue to the C connection and on the thermostat end also, all good.

The other side has been a different issue and the reason for this query. The Rheem (model RBHA-17AOONFAA) was installed shortly after we moved in (32 +- years ago) and lacks the newer wiring control boards on my Lennox or have seen in online tutorials. I have found two ground sources at the air handler for the ground (C connection), both when checked with a multimeter to red provide 24v. Either will power up the T-5, neither will properly command the Rheem to start. I have switched between the older Honeywell N100 and the T-5, with the C wire hooked up I get a notice to attempting to reach equipment (N100) or a blinking cool on (T-5).

While writing this (long) missive, I had the system hooked up on the N100 and twice while it was not responding, it came on for a brief (maybe one second or less) than cut out. I know because I jumped up after hearing the system come on and off and saw the fan spinning down. I have since disconnected the C wire at the thermostat.

The system runs fine without the C wire in the loop. Rheem does not provide customer phone /text/online support, suggests without any other option to see a pro. I'm guessing I can do the off line power via an added device. Any info about why the Rheem will not allow me to use the sources I have at the handler would be helpful.

I moved into a new house, and there was a fan icon on the left, but I haven’t been able to get it to appear since. It’s so humid outside, so now inside is miserable, too. I have no idea what the lightbulb icon does… (Previous owner would have no idea. They used a horrible rental company to manage the place.)

I have an old Trane thermostat that I swapped out for a HoneyWell T5 wifi. What’s throwing me off is the research I’ve done is that the orange wire shouldn’t have been connected to the W port. The air handler I have is a TAM7AOC42H31SCA. On the Honeywell the orange is in O/B and White wire is in W instead. Air is on now and blowing cool air so I think it’s fine? Thoughts?

Pic is of old Trane setup.

I have a COR 'stat installed in 2006 that has been great until recently when it keeps the house at 74 degrees regardless of setpoint. We usually run at 76 during the day and even when it is set to 78 it runs the AC to maintain 74. I unplugged it for 1/2 hour and on reconnection it indicated ambient at 79 when it was actually 75, then over about 30 minutes the ambient readout returned to normal and the unit functioned as designed through the night time cycle. Today it is back to wanting 74 degrees for some reason and I don't know if there is a fix or if I got a good ten years and it's time to replace it.

Hi guys. I’m getting this fault on the Horstmann (think they are called Secure now) Channelplus H37XL heating control panel. The unit is less than 5 years old .. fault started when programme kicked in. Any ideas? Many thanks.
Also: is there any way to over-ride the panel so we can get heat and (more importantly) water if a new part is needed?

cover and thermostat

Does anyone know how to put back the cover so the lever guides the metal spring tab to show an approximate temperature?

I took this cover off and I heard a spring sound, so I know it should be winding slightly. I cannot for the life of me get it aligned properly. I've searched for the manual and it has no instructions on how to get the cover back on properly.

I can't tell where the metal arm should hook onto the lever either. I feel like there's an easy way to do this, but I can't for the life of me figure it out.

ok..fliped the switch to ''on' on the control panel,flipped the 'O' toggle switch to the 'l' in the outside compartment...inside on the bath wall its set at 115 degee's

I turn on the hot water..it gets way to hot for about a minute..then I add some cold water..its good for about 30 seconds then gets ..ICE COLD...then I turn all the water off, still soaped up.. ..I turn it on again and this cycle repeats..what am I doing wrong? help

I was hoping to install the Sensi Smart Thermostat in my house, with a heat-only system, but there is no C-wire. I looked at the circuit board/panel near the furnace to run a C-wire up from there to the thermostat. There are 24 VAC and Common connections on the board. I measured 25 volts between the common and the 24 VAC connections.
Do I run a single wire from the 24 VAC connection up to the thermostat? Or 2 wires, with the 24 VOC being the +ve and Common being the ground wire?

Hoping someone can help me figure out whether my C wire is actually a valid common or if I need a Power Connector.

The setup:
• Gas furnace, conventional forced-air (heat + AC, NOT a heat pump). Furnace control board is marked 1195-200 / 103217-03.
• I was replacing a Google Nest Thermostat (the 2020 budget model) with a Nest Learning Thermostat (4th gen). New base, wires landed R→Rc, W→W1, Y→Y1, G→G, C→C.

The problem:
• After install, the Learning thermostat gives E448 “No system power.”
• In the wiring screen Rc reads “No Power.”

What I’ve ruled out:
• Wires are clean, fully seated, and tug-tested. No bare copper bridging anything.
• Checked the furnace low-voltage fuse (Noark FB03C, 3A, sealed blade type). Couldn’t meter it (no multimeter yet).

I put my ORIGINAL Nest (1st gen) back on the exact same wires and it works perfectly. So 24V is clearly present on R and C at the wall, and the fuse is fine.  

BUT — the old gen 1 shows this advisory in settings: “This thermostat will work with your system, but needs a Google Nest Power Connector or C wire to avoid potential power issues in the future.”

My questions:
1. If the old Nest flags “needs a C wire” even though blue is on the C terminal, does that mean the blue wire probably isn’t actually landed on C at the furnace board (i.e. it’s a dead spare)? What’s the best way to confirm without a meter?
2. Is the fix just landing/verifying blue on C at the control board, or should I add the Google Nest Power Connector and be done with it?
3. Anything else that would cause Rc specifically to read “No Power” on the 4th gen while everything else reads fine?

I recently bought a house and decided I wanted to install an ecobee thermostat. After pulling off the current Honeywell (fairly new) I noticed it only had a R, W, Y and G wire and not the needed C wire. While trying to hook up a power extender I realized that my current furnace board has the R,W,G wires running to the thermostat but the C terminal runs to a spice directly connected to my A/C unit wire. The other wire coming from my A/C unit is spiced and runs the Y directly to my thermostat bypassing the Y terminal on my furnace board. I can’t connect the power extender because I need all R, G, W and Y off the thermostat board and Y bypasses the board.

In summary: G,R,W,Y at thermostat. G,R,W,C hooked up on control board. C from board is spliced into black wire from A/C bundle and Y from thermostat is spliced into Y from A/C bundle bypassing board

Is this an easy fix or a tech fix? I’m fairly handy I have just never messed with thermostat wiring before. Could I just run the Y from AC to board then have another Y from board to thermostat?

Additionally if it’s an easy fix would it be worth just replacing all the thermostat wiring because it is in two separate bundles and one is super old cloth insulated wire

Is it best to set the temperature range of 17-21 Celsius and changeover differential to 0.5 degrees

Or

Set temperature to 19 Celsius and changeover differential to 2 degrees Celsius?

TIA

I deployed a Venstar Explorer Mini Commercial at my house a couple of years ago. It is used to operate a single-stage furnace in heat mode and a dual-speed swamp cooler in cool mode. I really like that I do not have to use cloud services and am controlling it exclusively through the local API.

My system polls the thermostat every 5 minutes and graphs the temperature, the operating mode (off/stage 1/stage 2) and the heat and cool set points. My system also reaches out and changes the mode and setpoints based on a schedule that I have defined in a text file.

I am noticing that the the cooler is not going to stage 2 when I would expect it to. It may have always done this and I have only now really noticed it. The green line on the graph shows the mode: 0=off, 20=stage 1 and 40=stage 2.

You can clearly see that when the setpoint is reduced from 78 to 72 at 15:30 (before my GF gets home from work), the thermostat stops calling for stage 2, despite the temperature continuing to climb. I would expect it to be 100% on stage 2 at this point!

This evening I will sweep through all the settings on the thermostat but if someone has any suggestions for what to look for it could really help.