Best WiFi thermostat? | NO C wire needed | ST55 Thermostat

One of the most common questions we get asked about wifi thermostats is whether there is an option for systems that don't have a c wire. We have several options for homes that have an existing 4 wires, because you can use a Ecobee or Nest thermostat with a power extender. But for boilers or simple 2 wire systems (heating only furnace applications) the ST55 Sensi product is a great alternative. In the event you'd like to purchase one, the links are provided below for your convenience.
Link to Sensi ST55 Wifi Thermostat on Amazon:
amzn.to/48exlOu
#commissionsearned #hvac #humidifer #furnace
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[@CommercialGasEngineerVideos]

Thanks for keeping us up to date with the latest and best tech.

[@TheHVACDopeShow]

Thanks for tuning in!

[@chachita176]

I really love the battery operated aspect of it which is why I decided to switch from the Nest to the Sensi ST55, but the Wi-Fi keeps dropping off despite that it was never a problem with my Nest and the router is only a few feet away. I’ve had to reconnect it at least twice a day in the last two days since I installed this thermostat. Furthermore, the app does not sometimes reflect what is actually going on at the thermostat itself, for example, it may be cooling, but the app looks like the thermostat is not doing anything and on standby. I hope Sensi somehow improves / updates this and I’d be all set.

[@daphnejakstis224]

The Sensi ST55 does, in fact, require a C wire. I purchased it because it was advertised as not needing one. The thermostat would turn the heat on as soon as it lost the WiFi signal, even for a second. My cable internet went out very briefly, and the thermostat started cranking the heat despite it being 94 degrees outside. When I contacted support, they informed me that it requires a C wire, even though their product descriptions say it does not. Here is what they told me "Thank you for contacting Sensi Technical Support. A common wire (“C” wire) is required on heat-only systems for both Sensi models. Without a “C” wire installed, the Wi-Fi connection will be intermittent to preserve battery power." They then informed me that I could have an HVAC specialist come out to run wires, which is what I was trying to avoid in the first place.

[@TheHVACDopeShow]

Good to know I didn’t realize that… we’ve put them on boilers and haven’t had this issue

[@daphnejakstis224]

@@TheHVACDopeShow@TheHVACDopeShow They will work until it loses WiFi. That is according to their own techs.

[@UlyssesM]

Works fine. On my electric furnace AC. Wifi drops sometimes but reconnects within a minute or so. No c wire

[@brandensmith161]

Also the C wire is required for HomeKit integration. This was why I bought this and strait up says it’s required to use on HomeKit.

[@DaveIngle1]

Northern Wisconsin is a great place to live! You need to convince one of your tech's that he's ready to open his own shop and head to the Mid-West! LOL

[@TheHVACDopeShow]

Houses are affordable up there by comparison that’s for sure lol!! I know Denver has gotten crazy, high cost of living. Will check with them and let you know!

[@UlyssesM]

Very informative

[@TheHVACDopeShow]

Glad it was helpful!

[@lakeweld]

I have a church with a hot water boiler heating system. Throughout the facility are 15 thermostats which control the heat output in the sanctuary, offices and classrooms. I would like to replace the old thermostats with the Sensi ST55 units. However, I am confused as you say that these units are compatible yet, with only the W and RH wires available, Emerson is saying that these units will not operate without a C wire on a heating only system. I had heard somewhere that Emerson is requiring the C wire to maintain WiFi connectivity. I have also heard that if you have a strong WiFi signal throughout the building (which we do), that the C wire isn't necessarily needed. Given the number of units I need to purchase, I want to make sure that I get the proper thermostat to do the job. Thank you for your advice.

[@TheHVACDopeShow]

I would buy one first to try it out I’ve seen them used without a c wire and WiFi so if that’s the case that’s surprising, thanks for the feedback I’m wondering if something has changed with the model. The Nest E3000 (frosted white looking thermostat) used to do that too but that model has since been discontinued.

[@kingmanzhang]

I just installed two for my home. Agree they are great. Although I still do not get where do they draw power from. Battery or the “steal” power as you describe?

[@TheHVACDopeShow]

That’s awesome! There is a built in battery and when there is no call for heat it uses the 24v power from the R and W wire to charge, and when the thermostat closes the circuit it uses battery power to close the circuit (very small amount of power) until it satisfies temp and then charges again.

[@BillieBetzold]

Can I use this if I only have a heating system and have no c wire either

[@TheHVACDopeShow]

Yes but it works with C wire too… but I’ve heard from some reports that the performance isn’t as good without a c wire for some reason, but in my experience it works

[@cardiackid48]

I am soon going to be looking at upgrading my system to a Daikin Fit...I do not have the C-wire on either of my thermostats in my house ..will this thermostat work with the Fit?

[@TheHVACDopeShow]

You only need 4 wires for a Daikin fit since it’s communicating… R and C and a 1 and 2 data terminals. So if you have at least 4 wires it will work or they can run a new 4 wire

[@TheHVACDopeShow]

You don’t need a 5th wire on a fit, you only need R, C, 1, 2, so 4 wires total and they can usually run a new wire if you don’t have one.

[@cardiackid48]

thanks I have the 4 wires just not the common wire...@@TheHVACDopeShow

[@jameslastname8165]

You said this can replace a two-wire system but then it says in the comments that you need four wires I'm confused

[@jeffreywright3499]

​@@jameslastname8165 I have not seen any Installation of the sensi st55 using only 2 wires. I think they should stop calling it a c wire and refer to it as constant power. I have 2 sensi thermostats hooked up and working good. One runs an oil boiler and the other a pellet stove. I was not able to get either one to work with only 2 wires. I used a separate power supply for 24v ac.