Honeywell RTH9580WF Internet Thermostat, being snapped onto wall plate.
A Honeywell not turning on heat can happen for many reasons. A faulty Honeywell, a broken heating system, power losses, damaged wiring, et al. Here, we list some of these causes, and offer repair tips to solve these no-heat issues. First, we look at what might have happened with the Honeywell itself. Then we explore the furnace issues that can also cause no heating at all. Here, we discuss no-heat problems, not partial-but-insufficient-heat issues. These address the case when you get no heating at all. But they do not cover the cases where you get some yet not enough heat.
The temperature display seems to show that the current room temperature never reaches the set heating temperature. Yet the heat never turns on. So in this case, the display offsets may be too high. That is, the unitacts as if the current indoor temperature is higher than it really is. And when the t-stat thinks that the room is warmer, it will not turn the heat ON.
Consider this.
Now the Honeywell calls for heat when the temperature it reads drops below 74 degrees. But a +3 degree offset means that the actual temp must fall to 3 degrees below 74 to get heat. So though you set the temp to 74, you won’t get heat until the actual room temp falls below 71. Now in apartment buildings, a room on the upper floors might easily hold at 71 degrees. So you may rarely or never feel the heat working if you set to 74.
Decrease the display offset temperature. This helps assure that the temp reading shows as closer to actual room temp. Plus, an accurate display reading helps prevent the situation where you heat does not come on enough. We suggest that you avoid setting the temperature offset to more than one degree either way (+ or – offset).
Or, just turn up the set temperature. In this scenario, let’s say you want your place to heat to 74 degrees. But with the +3 degree offset, you’ll need to turn the temperature higher than you desire. So you’ll have to set it to 77 degrees to get that 74 degrees actual temperature.
The screen looks blank or dark. No readings or status messages appear. Further, the furnace heater does not run. Plus, you hear no humming at the furnace. But for non intelligent t-tats you may no power loss indication, except that their backlights don’t glow. Yet the effect is still the same, no heat turning ON. That is, that the furnace never runs, no matter the setting.
Honeywells often get power right from the furnace system. So, check that all furnace systems are getting electricity. Often there’s a single circuit breaker that feeds the furnace. Then there’s another that feeds the outside compressor unit in HVAC arrangements. So verify that all these breakers are ON.
Furthermore, the heating and cooling subsystems often get electricity from separate circuit breakers. So, the Honeywell could glean power from either one, although usually not both. A power outage in either system could cause Honeywell not turning ON heat. By checking that the heating control circuits have power, you’ve ruled out this cause of power loss. In this way, a faulty cooling system can make the heating system fail too.
If the heating problem happened when you installed a new unit, you may have wired it the wrong way. Perhaps you’ve reversed the W and Y wires. This would run the cooling stage though the unit is actually calling for heating. Other symptoms may arise too. These depend on which wires and how many of them you have connected to the wrong terminals.
Check for correct wiring at both ends of the cable. At the Honeywell, affix all wires to the right screw terminals in the mounting plate. Then, do likewise at the furnace. Seek help from a professional heating technician if you feel insecure matching these wires up with the right terminals.
Poor leveling on older thermostats can affect how well they respond to room temperature changes. Those early models used a bi-metal spring to sense temperature. Manufacturers would affix a mercury switch to the outside end of that spring. Then, as room temperature rose and fell, the spring changed size. This caused its outer end to move back and forth in accordance with temperature changes. This in turn tipped the mercury switch ON or OFF, to bring room temperature nearer to the set temperature.
You needed proper leveling for this tipping to occur as designed. Indeed, if tilted too far off of plum or the horizontal, the heating system might never turn on. In this case, the mercury inside does not make the contacts as it should when the room gets too cold.
Now you may still have a mercury and bi-metal thermostat. If so, then you should replace it with a current all-electronic model that has no moving parts. Today’s Honeywell models have more accurate sensors and many more features. Plus, modern t-stats work well, no matter how far off of level you install them. They’ll turn on the heat correctly in the house, no matter their position. Mount them on their sides or upside down. Or, let them dangle by the wires (although we do not recommend this). But the point is that they will regulate your heat well, in any position.
If you cannot upgrade from an older models, then try drilling new mounting holes. To do that, remove the screws and wires if they get in the way. Then re position the unit over the new holes. Finally, drive the screws into those new holes. Use wall anchors in these holes for a stronger hold.
If your t-stat is not too far out of level, try loosening the screws that hold it to the wall. Then, slide the unit toward level. Then, mark the wall with an erasable pencil. Next, while holding the Honeywell in that marked position, tighten the screws again. Finally, use an eraser to clean off any visible wall markings.
You can set the temp way lower than the ambient temperature in your home. During moderate days outside for instance, you might set the heat temperature to 72 degrees. But if you live in a tall building, your apartment may never fall below 72 degrees. Thus, your heat may never come on.
The solid copper wires in the cable can break if flexed or bent too much. Or, maybe the installer stapled the cable with too much pressure, and shorted out the individual conductors in that cable.
This issue normally appears during testing only. But sometimes, this problem may not show up for decades. Plus, settling of wall beams can flex these stapled wires. So, after many years, this flexing can wear wire coverings, causing faulty or no heating.
Replace the cable between the Honeywell and furnace. Avoid tightly stapling the wire, and don’t fasten it more than you must for a secure installation. Lay it loosely.
Now and then with smart thermostats, a snap of static electricity near the Honeywell, can freeze the touch screen. Also, a power surge in the home’s electrical system can do this as well. Then too, the data shown onscreen no longer updates. Further, the heating system may not come on. No matter how far from set temperature the room temperature is, the heating system may not run at all.
When this no heat problem happens, try rebooting the Honeywell. Turn off its power for ten to twenty seconds. Then switch it on again. This power cycling is a literal snap with many models. Why? Because they can detach from furnace power without having to unscrew them. Just unsnap them from wall plates. Then, wait a few seconds. And finally snap them back into place to reboot. Or, if your t-stat does not come off of the wall easily, power cycle it at the breaker box. Doing this reboots the unit.
Certainly you might see Honeywell not turning ON heat, when it’s not currently n heating mode! On our smart thermostat, we can set it to either heating mode, cooling mode, or OFF. If OFF, you won’t get heat. Nor will any cool air flow from your registers in Cool mode.
Set the t-stat’s operational mode to Heat. On our t-stat, we do this in the System tab. We show that screen pictured above. Just tap the Heat option and press Done to make the new setting effective. You should soon thereafter feel some heat.
For a HDD not spinning, getting the data off of it is impossible. This…
Keeping your backups up-to-date is perhaps the best HDD making clicking noise fix for desktop…
Just got an HP laptop into the shop, and according to the customer, it's internet…
Just got an HP laptop into the shop, and according to the customer, it's Ethernet…
Now and again, we've noted that the touch screen responsiveness on the iPod Touch MC011LL…
Follow these reboot Echo Dot 2 if you wish to reboot this speaker. In fact,…