Harsch received her Certified Nurses Assistant license in 2004. Powered by 24-volt transformers that step-down 120-volt line voltage, the thermostats monitor room temperature and send ON-OFF signals to the furnace through small-gauge wires when temperatures drop below or rise above the temperature set by the user. Low-voltage thermostats are the most common type in residential forced-air systems. Stand at the thermostat while an assistant stands at the furnace. Low-voltage thermostats use small-gauge wires that are easy and safe for DIYers to work with. She attended Tarrant County College and studied English composition. Although some of these problems can also be caused by furnace issues, the thermostat is the first place to look if you notice one of three common problems: The vast majority of standard forced air furnaces or furnace/ AC units are controlled by low-voltage thermostat units mounted somewhere in the house, usually in a central location. Finally, reset the thermostat to your preferred setting. Our furnace … Installing the wrong kind of thermostat is likely to cause miscommunication and result in system failure. If your furnace stops working properly, it’s a good idea to inspect your thermostat’s wiring. You will have to look inside your current thermostat, and this is where you will more than likely be met with a series of numbers and letters. Loose or missing wire connections, and faulty or aged wires can cause your thermostat to lose its connection to your heating and cooling systems, thereby causing an interruption in service. Thermostat Screen. Heating or Furnace System. Proper operation of your furnace requires correctly matching your thermostat to your heating system. The furnace puts out erratic amounts of heat. Step 2 – Bring Out the Room Thermometer Check connections. Thus, many of the problems with thermostats involve the elements that are common to all thermostats: the temperature-sensing mechanism, the wires and their connections, and the low-voltage transformer. Before troubleshooting your thermostat, check to see if all filters are clean and all hoses to and from the units themselves are free of wear. 3. Ohm wires. First, set the thermostat to its lowest setting and use a soft brush or compressed air to clean the bimetallic coil. Introducing "One Thing": A New Video Series. Often the problem lies within the thermostat itself. Should you find a significant void in the wall behind your thermostat, try filling it with some insulation to curb the airflow. How old is it? Your thermostat may not be set properly. For systems that have more than one stage for cooling look out for wires that are attached to an “y1” and “y2” terminals. First and foremost, check to be sure it is set to “heat”. To achieve good comfort, you want long heat cycles. In fact, it's best to first rule out thermostat issues, which are often relatively simple to fix, before looking at the major furnace components. Does it mean that the thermostat "talks to" the pc control board in the furnace in a back and forth exchange of instructions? She has several years of experience in the home-improvement industry, focusing on gardening, and a background in group exercise instruction. The batteries in the thermostat may be dead. Some modern furnaces have a door switch that engages when the door is closed properly, thereby activating the entire system. If your furnace isn’t functioning properly and you’ve ruled out the usual suspects—like a dirty furnace filter or bad flame sensor—it may be that the thermostat is to blame. The furnace and ac have both been working like champs and the only maintenance I've done is changing the air filter. The thermostat measures the temperature in your home and directs your furnace to come on when the temperature falls to the level you've set. Here’s a look at a few of the most common thermostat-related furnace problems and their solutions. Dirty furnace filters. Stand at the thermostat while an assistant stands at the furnace. Comfort Features Personalized temperature control means you get the comfort you want when you want it. Also, check the battery to make sure it is fresh, if your programmable thermostat requires a battery. Check your thermostat to make sure it is in the "On" position. If your thermostat is broken, you don't have to shiver until the repairman can come or until you can get to the store to buy a new thermostat. If you suspect faulty wiring, tighten connections and replace wires as necessary, or consult with a knowledgeable HVAC professional. My thermostat is not communicating with my furnace. To ensure proper matching, consult with an HVAC professional or take your old thermostat with you when you’re shopping for new equipment. A surprising number of thermostat-related problems stem from problems with the power supply that operates the thermostat. Replace batteries correctly: display should come on. If there is more than one large strand, the wiring isn’t Nest compatible. Remove batteries and insert backward for five to ten seconds to reset thermostat. If your thermostat is connected to a furnace, check the furnace door. • Set System switch to Off. I bought the house in 2016. Change batteries to see if that solves your problem. When your furnace thermostat is not working, your furnace does not know if it needs to work to heat up your home or if it can rest. Get daily tips and tricks for making your best home. Check for any programming overrides on a programmable thermostat to confirm that the overrides are not impeding the thermostat operation. • Temperature limit setting is reached: range is 45°F to 88°F (7°C to 3TC). Therefore the thermostat will take a higher temperature reading than it … Check to see if your thermostat is properly programmed to heat or cool your home depending on the season. Contractor's Assistant: Where in your home is your Carrier thermostat installed? Look closely at the end of one of the thermostat wires. CC-U01 Thermostats Full-featured programmable communicating color touch-screen thermostat for any 3, 5, or 7 Series unit. Older mechanical thermostats, however, must be manually adjusted—ideally, using an amp meter to determine the proper setting. (Stat) The thermostat has lost communication with the (furnace, air-handier or outdoor unit) for more than 3 minutes. When a furnace does not work it may be caused by problems with the furnace or the thermostat. One minor difficulty is that that non-communicating thermostats contain up to 12 wires for the many functions possible—furnace, AC, second-stage furnace, second-stage AC, heat pump, heat pump reversing valve, blower motor, fan only mode, auxiliary heaters in heat pumps plus the c … These thermostats are called low voltage because they run off a transformer that reduces line voltage from 120 volts to a level somewhere between 12 and 24 volts, depending on the brand of furnace you own. This communicating thermostat communicates via a 4-wire Modbus protocol and will only operate as a stand-alone thermostat with the Aurora Control System, or as a zone thermostat (not the MasterStat) in the IntelliZone2 or IntelliZone2 24V zoning system. Have triple checked the most obvious and wiring at both ends. Thermostat – If your thermostat isn’t properly functioning, your furnace won’t respond in the correct manner. Even when a thermostat is controlled wirelessly by a smartphone, has sophisticated programming to automatically shut on and off, or is controlled wirelessly by a smartphone, the principles are still the same: Low-voltage wires inside the thermostat send control signals to the furnace through small-gauge wires when the thermostat's inner mechanism senses the room temperature has moved outside the user setting. The thermostat will auto recognize Please consult the thermostat feature chart for a complete summary of all features by model, or the Thermostat Brochure for complete details. Does the Lennox G71MPP modulating furnace communicate with a Comfortsense 7000 in the same fashion? Have changed out the new Aprilaire for another exact model. 2. Check Thermostat Placement Then, set the thermostat to its highest setting and clean the coil again. The furnace cycles on and off more frequently than is necessary. Check Thermostat Communication With The Furnace. If the thermostat is set properly, turn it up a few degrees to see if that makes a difference. She writes mainly home improvement, health and travel articles for various online publications. It seems to me like my unit isn't communicating with the thermostats? It has a variable gas valve and so on. Or does it sound like something else? If your furnace fails to turn on when it should (or if it turns on when it shouldn’t), an inaccurate temperature reading may be the culprit. Turn off the breaker to your furnace. Cecilia Harsch has been writing professionally since 2009. If you have a battery-powered thermostat, make sure its batteries are working. Is your furnace firing up but not blowing heat as hard as normal? you can find details about these processes in the Honeywell programmable thermostat manual. thermostat that works with non-iComfort-enabled and non-Lennox® products Universal thermostat that works with non-iComfort-enabled and non-Lennox® products Works with premium Lennox® communicating equipment only. If it’s not shut properly, then the door switch will not activate the central HVAC system. Thermostat Functionality. Ensure the thermostat is set on the appropriate setting -- "Heat" or "Cool." Have a buddy stand near the furnace and listen while you adjust the thermostat from “LOW” to “HIGH.” If he or she hears a sound, the problem is probably with your furnace. Change Thermostat Batteries. If your furnace is not within shouting distance from your thermostat, use walkie-talkies to communicate. Make adjustments where necessary. Dirty air … Move the thermostat to heat. Thank goodness it is much less expensive to replace a thermostat than your central heat and air unit. Take a picture with your phone or digital camera of the wiring inside the thermostat to show how they connect. A dirty thermostat can cause erratic operation and sudden system failure. If they are dead, the thermostat cannot communicate with the furnace. To address this issue, remove the cover from your thermostat and gently clean its interior components—including the bimetallic coil and switch contact surfaces. Make sure it is securely attached to the wall and no wires appear loose or frayed. The Spruce uses cookies to provide you with a great user experience and for our, How to Troubleshoot a Low-Voltage Thermostat, 8 Common Problems With Conventional Gas Furnaces, How to Troubleshoot Electric Ignition Furnace Problems, How to Adjust a Thermostat's Heat Anticipator, How to Install a Line Voltage Thermostat for a Baseboard Heater, Understanding the Terminal Letters on a Thermostat, How to Troubleshoot a Gas Furnace That Produces No Heat, Choosing the Right Thermostat for Your Furnace, How to Wire a Line-Voltage Thermostat for a Baseboard Heater, How to Light the Standing Pilot Light on a Gas Furnace, How a Furnace-Mounted Home Humidifier Works. If your heating is not working, it's probably due to issues with the following: Air Flow. Although some of these problems can also be caused by furnace issues, the thermostat is the first place to look if you notice one of three common problems: Your furnace stops producing heat. If fault persists, then cycle power. ABCD or 123) There is an Equipment Interface Module (EIM) board present at the equipment-level bridging your thermostat and furnace Thermostat Wiring. A broken furnace or central air conditioning can be expensive to replace, but before you blame the failure on your systems, troubleshoot your thermostat instead. Fault clears after communication is … Your furnace supplies 24 volts AC to most wireless thermostats, via an internal power supply, and fed to the thermostat via the wiring that connects furnace to thermostat. When the door is not shut correctly, the door switch is not depressed and cuts power to the thermostat. Turn off the power for the furnace and air conditioning systems by switching the appropriate circuit … Loosen the screw label “R” or “Rh” and the screw labeled “W.” Remove the wires from beneath the screws. Check your thermostat to make sure it is in the "On" position. Most common issues with thermostats can easily be fixed if you know what to check for. This is more common when the thermostat is mounted on an exterior wall, but it can also occur on interior walls if there is air movement from a basement or attic. You can also try resetting the thermostat by turning it on and off. The access door on the furnace is open or not fully shut. Systems with remote sensors - While the Sensi thermostat may be compatible with this system type, it will not be able to gather data from existing remote sensors Proprietary or Communicating Systems - The Sensi thermostat can’t communicate with serial protocols, although some proprietary HVAC equipment can be wired with standard HVAC wires If your furnace stops working after a new thermostat is installed, it's quite possible that the wrong type of thermostat has been installed, or that its wiring has been connected improperly. Because the thermostat operates on low voltage, there is no risk of electrocution. Solution 1.8.1 This device, called a heat anticipator, tells the thermostat when to turn off the furnace burners. The thermostat is in the kitchen on the first floor. General advice is to not keep the thermostat in the immediate vicinity of the boiler, especially if the boiler is in a small room or enclosed space, because it is likely to be warmer in there than other areas of the house. If the furnace does not turn on, the furnace needs repair. This is usually a good thing because thermostat problems are usually easier (and cheaper) to correct than problems with the furnace itself. Raise the thermostat heat settings slowly. Even modern high-tech wifi or "learning" thermostats operate on principles similar to the classic older dial thermostats. Modulating furnace has many stages, and the real advantage here is that it can go as low as 30%. This unit was estimated to be installed in 2013. If this supply becomes intermittent, noisy, drops or raises in voltage significantly, the thermostat WiFi connection will likely fail. Aprilaire Communicating Thermostat vs Lennox GHR32V Furnace [ 8 Answers ] Lennox furnace doesn't work after changing out thermostat to an Aprilaire model 8870 communicating thermostat. Drafts coming from the wall cavity behind your thermostat may also cause inaccurate temperature readings. it will kick on if I power down the thermostat, and then turn it back on, or if I flip the switch on the furnace, and sometimes it will work just fine on its own - there is seemingly no reason why sometimes it appears to be working and sometimes not. The furnace puts out erratic amounts of heat. A smart thermostat can help you save up to 23 percent in annual heating and cooling energy costs, and track energy use for a better understanding of how much you spend. What Is a High-Temperature Limit Switch on a Furnace? Experts recommend that thermostats be located close to the air return ductwork to allow for the most accurate temperature reading possible. The thermostat should emit a clicking sound and the furnace should also make a sound. My honeywell thermostat and furnace are not communicating normally with each other, and I haven't done anything different to make this happen. You may need to pull one out of the connector to check. This is not just the fan that spins slower but the burners as well. On older mechanical, non-digital (analog) thermostats, there is usually an electrical resistor device—a small metal tab—mounted in the center. Your thermostat must be matched to your heating system based on the type, capability, and capacity of your furnace. Sometimes, faulty or aging wiring, dust accumulation, extreme temperature changes, and other issues can cause your thermostat to malfunction, so that it can't properly communicate with the furnace and regulate the temperature of your home. To begin fixing your heating, continue to the Air Flow section. Temperature display does not go lower than 45°F (7°C) or higher than 88°F (31°C) during programming. When it is not functioning properly, it can cause your furnace to cycle on and off more frequently than is necessary. If the furnace does not make a sound, the thermostat is not sending a signal and needs to be replaced. How to Test Whether a Thermostat Is Sending a Signal. If your heat anticipator is improperly set, it will require an adjustment. Twist the ends of the wires together. Here are the things you need to check and what you can do if this is where the problem originates. and which manufacturer does it best. Turn on the furnace breaker. If you're unsure whether or not your current thermostat is communicating, there are a couple of things to look for: Your current thermostat has non-standard terminals (ex. Remove the cover from the thermostat to expose the wiring. Ensure the thermostat is set on the appropriate setting -- "Heat" or "Cool." Check to ensure that your thermostat is installed in the proper location—away from outside doors and windows and heat sources such as fireplaces and radiant heaters. The furnace is a Carrier 58GFA. This simple step is often overlooked. Furnace powers up but will not ignite. Sometimes, giving the heat anticipator a light push in both directions is enough to solve the problem. When your heater fails to come on in the winter and your air conditioning will not cool during the summer, you may think your heating and cooling systems are broken. Most new thermostat units are compatible with heat pump thermostats, baseboard heater thermostats, furnace thermostats and boiler thermostats. You’ll need to identify if your home is fitted with 1 Stage, 2 Stage, Direct Line Voltage, 24mV, or Zone heating and cooling to determine which thermostat … What to Look For When a Luxaire Furnace Is Not Working, How to Test the Thermostat on a Gas Furnace, Don Vandervort's Home Tips.com: How to Test the Thermostat, How to Know Your HVAC Ignitor Has Gone Bad, The Fan Won't Start on My Outside AC Unit, Help for When a Central Air Conditioning Unit Quits Working. If not, your thermostat is likely malfunctioning. [Indicated unif\ has not communicated with thermostat for more than 3 minutes. Exposure to direct sunlight, heat emissions, and outside temperatures will give your thermostat an inaccurate reading, thereby triggering your furnace to turn on and off when it shouldn’t. If the furnace comes on, the thermostat is not sending a signal and needs replacing. To achieve that, the modulated furnace needs a “special” thermostat. 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