I recently purchased and installed a Honeywell WP6500 WiFi thermostat and thanks to Stack Exchange, got it up and running. I have a house in New Hampshire, which I use occasionally during the winter. I do not like to keep heat on in the house all winter as I may not be there for 2 to 3 weeks. When I set the thermostat to maintain the house at 41°F it works fine. However, if I set it to the heat off position, at some point it stops communicating with the router, and I cannot turn the system on or raise the temperature. It can get 5 to 10°F in the house. I have tried on many occasions to get some answers from Honeywell as to, is there a temperature at which the thermostat, stops communicating with the router, and if there is, can it be overridden.
At what temperature does a WiFi thermostat stop sending a signal to the router
heatinghvacthermostat
Related Solutions
It's a balancing problem, fairly typical for a one-zone heating system spanning an entire house.
Mind you, I'm a bit concerned with a setup that kicks on the A/C in heating season - being from a primarily heating climate, we typically have a "winter/summer" or "heating/off/cooling" mode switch either on the system/boiler/furnace or on the thermostat to prevent that sort of foolishness. If it's REALLY so hot in winter or cold in in summer that we want to change the mode, WE choose to change the mode, rather than leaving it up to a machine to decide.
Presumably you have forced air heat, since the same system is cooling. One approach to improve balance is to run the fan more to distribute air around the house and balance temperatures even when heat is not being delivered. A more basic step is adjusting the airflow to different parts of the system for heat delivery that more closely keeps things even - but if the same system is cooling this may be difficult to get balanced in a manner that works well for both, since heat rises and cold air sinks, left to itself.
The system may be oversized (so it quickly heats or cools the location of the thermostat, and then shuts off the fan, rather than running a large percentage of the time when it's cold out), but all systems are prone to being somewhat oversized much of the year in order to be large enough to heat on the coldest days and cool on the warmest days.
A good HVAC professional may well be worth talking to in order to tune your system as best it can be tuned. Moving to continuous circulation (perhaps at a lower fan speed) seems like it might be needed in this house to reduce stratification, at a guess. The only major downside if your system is not too noisy will be the electric bill for running the fan.
As a quick stopgap, examine your thermostat to see if it has a "fan" switch, typically with two positions - Auto (blows only to heat/cool) and "on" or "Continuous" - if the switch exists and is wired correctly, that should put the fan in continuous circulation mode - but you may want to alter the system to make that quieter and/or more efficient with a lower speed or even an entirely different fan/blower. And it may still need to be balanced to work better.
No problem.
First, the furnace must be designed to have an external millivolt thermostat. A millivolt thermostat is a very simple creature, it has 2 wires going to it, and it shunts those to call for heat.
Second, the smart 'stat will need a 24V power supply. This is available from any $15 thermostat transformer, such as many designed to mount in junction box knockouts or on the cover of a junction box. The 24V wires go to R and C on the smart 'stat. It goes without saying, this smart stat will not work with the power out.
The smart 'stat cannot directly talk to the millivolt furnace. However since a millivolt 'stat simply shunts the two wires, a relay can be used to shunt those same two wires. The NO contacts of the relay go to those two wires. The coil winding of the relay goes to W and C on the smart 'stat.
And that's it.
Now one more thing. A wonderful feature of most millivolt furnaces is that they are able to run normally when the AC power is knocked out. It's the difference between shelter in place, or needing a hotel room. ** Now, the smart stat will lose its 24VAC when the AC power fails, so it will not be able to command the relay to turn on. For that reason, leave an analog millivolt stat in parallel with the relay. Set it to 40F so it stays out of the way, then when you need it, you can set it to your desired temp and it will shunt the wires and make the furnace kick.
** Difference between your pipes freezing or not. (As if anyone would install a millivolt furnace in the snowbelt, ha ha, they are all used in Florida and California of course. You can't even buy them in the snowbelt, nobody carries them and your HVAC guy doesn't know what they are).
Best Answer
You're looking for a specification called the operating temperature range of the thermostat or router or both. This is the temperature range within which the manufacturer states that the device will function correctly.
For consumer electronics like these, it's typically from 0°C (32°F) up to about 60°C (140°F) to 70°C (158°F). So if you turn the heat to off, the ambient temperature in the house will drop below that range, and the thermostat will stop working properly.
There should be a specifications page in the manuals for the thermostat and router that will tell you their minimum operating temperatures. Keep your house above the upper of those temperatures and you should be OK.