Help with selecting my new wifi thermostat

Jerry_Z · August 24

I am looking for a new smart Wi-Fi thermostat that I can use remotely when I am away from my home.

I live in a small 1200sqft ranch, one level, one zone, 1970’s house in Northeastern part of the country.

Currently my home setup has two separate thermostats: one for heating and one for central AC.

HEATING: Weil-McLain Oil Burner with hot water baseboards. This is a single zone system that is original to the house. I have an old 7-day simple programmable thermostat for this. It has no “yellow” wire and it runs on two AAA batteries. Two wires going to the thermostat.

Central AC: Goodman Outside Unit installed couple of years ago. Compressor is outside and Blower/evaporator is in my attic. It is also single zone setup with air vents in ceiling. It runs on a separate simple 7-day programmable thermostat that uses 2 AAA batteries. This unit also has heat pump in it, but I do not intent to use it, so it does not need to be set up on my thermostat. Only the cooling system.

I wonder if I could find a Wi-Fi smart thermostat that I could connect both systems to it instead of having two thermostats.

I like Honeywell due to the company reputation and simple no fee apps for Wi-Fi connection. Would Honeywell RTH9600WF Smart Thermostat be able to do this task or do I need something else? I am very handy with electrical projects so I don’t mind running any additional wires or redoing anything that would be needed.

Any suggestions would be appreciated!

jesmed1 · August 24

I love the two ecobee thermostats I installed on our two boilers a few years ago. Remote control via Internet through their website dashboard is free. And there's a free mobile app called beestat.io that is also very useful.

I can't speak to running a separate AC unit, but I believe that is possible. You will need 24VAC from somewhere. I used a separate plug-in wall wart transformer in the basement, with the wires run up into the wall to the ecobees. You may also need some relay isolation. I am not the expert on that, so do your research. @EdTheHeaterMan here is a thermostat wiring guru, so maybe he can help you. I am just a very satisfied ecobee homeowner.

pecmsg · August 24

ecobee and Honeywell both make what you want

why do you have to change the temperature settings so often?

ratio · August 24

I use the Honeywell 8000 series (one step down from the 9000 series), it's available as a direct-to-Wi-Fi version if you will never need a wireless remote sensor or a Redlink wireless version that will accept wireless sensors, but needs a Redlink gateway to get onto teh internetz. It should be able to run both your heating and cooling without anything extra, they are built with separate contacts for heating and cooling, including separate R terminals (red wires), that come with a factory jumper for normal use. Just remove the jumper & land the R & W from the boiler on the Rh & W terminals. The AC will connect to the Rc, Y, G, & C terminals, the last being the common from the air handler low voltage transformer, which is what feeds the thermostat. It's required for most wireless thermostats, the 8000 is one.

You'll want the TH8321WF for the straight Wi-Fi version. The Redlink version is TH8110R, the gateway is IIRC THM600.

I dislike the feel of the Ecobee screen, but YMMV.

EdTheHeaterMan · August 24

HEATING: Weil-McLain Oil Burner with hot water baseboards. This is a single zone system that is original to the house…

Central AC: Goodman Outside Unit installed couple of years ago. Compressor is outside and Blower/evaporator is in my attic…

@Jerry_Z this is usually very simple. how close are the two thermostats to each other?

You connect any of the thermostats that include a R and Rh. or Rc and Rh to the air handler. this way Rc may be labeled R on some smart thermostats.

Then test the AC system to see if it works with the new thermostat. After the test is successful then you add the wires to the boiler to the smart thermostat like this:

Once that part is done, you can test the boiler operation from the new smart thermostat. This will work 90% of the time. If this does not work for you, then an isolation or heat relay may be needed to get your boiler to operate.

The setup instructions for the thermostat will tell you how to program the thermostat for 2-transformer (air handler & oil burner control) operation. This is usually in the installer setup menu of the thermostat.

I have liked Nest, but they can be problematic for some folks. Just ask @pecmsg . You cannot go wrong with the Resideo (formerly Honeywell) line of smart thermostats. I have also worked on Ecobee thermostats successfully. Just be sure you get one that has both R terminals.

R for cooling is the transformer that operates the thermostat on most brands of thermostats. R for heating is just a switch for the boiler when configured properly, and the two transformers do not cross-connect when properly wired.

The Honeywell RTH9600WF may no longer be available. That may be a Big Box store model number. If available, that should be a perfect choice. There are many 9000-series thermostats to choose from.

HVACNUT · August 24

Honeywell/Resideo has new models out. The RedLink models have more options. Ideally you're going to merge the thermostats into one so make sure there's a seperate Rc and Rh. A few months ago I was sent to a job to merge heat and cool thermostats with a customer supplied H/C WiFi thermostat. It was a Nest with only one R terminal.

This morning I went to survey for 3 WiFi thermostats for a new client. Existing is Honeywell Pro 6000 looking. I pop one off and THERE'S NO WIRES! I check the second floor Wireless. Basement? Wireless. And the EIM's at the furnaces. "Ma'am, you need an electrician. Call us when we have wires."

I'm not knowledgeable on the WiFi side. I assume there's no wireless WiFi thermostat because they'd be vulnerable to hackers? Maybe distance is a problem, like Bluetooth?

ratio · August 24

The radios use lots of juice when they transmit, wifi even more. Batteries wouldn't last very long.

meycou · August 27

I have an ecobee thermostat, works great, and with BeeStat you can track the performance over time to see how your system performs.

@HVACNUT mentioned a wireless Honeywell, I just looked it up, seems to be they have some thermostats that work with an Equipment Interface Module. Honestly very smart, maybe the days of running low voltage are over, and you can place thermostats wherever you want.

ratio · August 27

The Honeywell thermostats that communicate with an EIM are the Redlink models. You'll need a Redlink gateway, and you'll still need two conductors to the thermostat for power if you go with the 8000 or 9000 series, AFAIK the 6000 model that @HVACNUT mentioned is the only one that's completely wireless.

Jamie Hall · August 27

Just a minor comment here. What, exactly, is your plan B when — as happened here last month — your power is out, your wi-fi is out, your internet is out, and your cellphone coverage is out? A home generator (not a battery — power was out for a week) keeps the lights on and the freezer cold, but… ALL your wireless whiz-bangs are dead.

Happens about once a year around here, and this isn't country.

Jist askin'

jayvath · August 27

You're describing a common problem where there are not enough wires between the thermostat and the HVAC equipment. The most common solutions are:

Pull new wires from the thermostat to the equipment. This usually involves drilling holes and touch up painting or repainting in finished areas. Expect to pay for at around 4 hours of labor unless you're able to pull the wire yourself.

Purchase a thermostat designed to use 2-wires or special adapters that send multiple signals over a wire.

Wireless thermostats with batteries and the risk of dead batteries.

The tekmar Invita WiFi Thermostat 564 uses 2-wires to provide power and up to 8 signals from the thermostat to the HVAC Interface Module or HIM (tekmar equivalent to the Resideo EIM). The HIM operates the relays to switch the boiler and AC on. Since your boiler and AC are located in separate locations, you're going to need to pull a new wire from the mechanical room to the attic. Hopefully this is less work and less disruptive than pulling a new cable from the thermostat location to either location.

PhilKulkarni · August 27

A word of caution while wiring…

I had a central air installed last year which has its own 24v xformer. All worked fine until I turned on my steam boiler and that blew the fuse on the central air. When the boiler stat calls for heat, the boiler’s xformer powers the R/W circuit shorting the central air former. All I did to power both units from a single xformer -the central air one, was to disconnect the thermostat wire on my Peerless. It is easy to get these xformers out of phase. I have Sensi wi-fi stats everywhere.

ratio · August 27

The Rc and Rh terminals are made for the instances where there is a heating transformer and a cooling transformer. The Rh makes with the W terminal (or terminals, for multi stage) and the Rc makes with the Y's and G. Electrically, they're separate once the factory jumper is removed. Not all stats have this, but those that were designed back in the olden days when AC was an add on do.

Most dual-transformer stats power themselves from the Rc transformer, meaning the C or common has to come from that transformer as well, but not all do so check the paperworks carefully.

HVACNUT · August 28

https://forum.heatinghelp.com/discussion/comment/1902751#Comment_1902751

Only one R terminal at the thermostat? The two transformers shouldn't need to be "in phase". They shouldn't have anything to do with each other. You need an isolation heat relay at the air handler. Or a new thermostat with seperate Rc and Rh.

EdTheHeaterMan · August 28

https://forum.heatinghelp.com/discussion/comment/1902751#Comment_1902751

This will not happen if you wire the thermostat correctly. If, however, you have a thermostat that has only one R wire terminal (there are some out there) then you need to add a heat relay to the air conditioning system. It is very simple.

Then add a 2-wire connection from the AHU to the boiler to operate the boiler.

When this design is used, the power to the AHU must remain on all year. This is important to know because, for some reason or another, some owners feel the need to kill the power to the air conditioning system at the end of the cooling season. This practice will render the thermostat without any power to operate the boiler. If it is a split system you can kill power to the outdoor unit but the AHU in the attic needs to be powered.

PhilKulkarni · August 28

I see your point Ed. However, I found that my Rc and Rh wires were joined somewhere, not at the thermostats, and my central air xformer is capable of powering all the stats. So I powered both units from that xformer which took a 3 mins of my time- a bit more than I thought. Now the Peerless xformer powers the feeder, the ignition, the vent and the LWCO.

pecmsg · August 28

The t-stat is the only location you would have RC / RH

Jamie Hall · August 28

https://forum.heatinghelp.com/discussion/comment/1902811#Comment_1902811

https://forum.heatinghelp.com/discussion/comment/1902812#Comment_1902812

And if they are joined somewhere else, do yourself a favour and find the location and fix it. They should NOT be, and it is probably at best a 50/50 lucky chance that that arrangement hasn't blown one or both transformers.

Help with selecting my new wifi thermostat

Comments

Categories