A thermostat basically just energizes the individual circuits (G (fan), W (heat), Y(cool) ) which in turn (via the furnace controller) powers a relay which provides line voltage to the actual units (like the fan or A/C. In the case of heat, it instructs your furnace to open the valve supplying gas).

My home furnace is currently controlled by a programmable Honeywell thermostat, but it regularly thrashes the furnace by turning the furnace on for just ten or twenty seconds. It seems that the thermostat will register a one-degree drop in temperature for a few seconds, turning the furnace on, but then switch back up to the previous temperature ...

It's also possible the onboard fuse of the furnace control board blew. If the breaker is not tripped, it's possible that the coil wires in the transformer or the thermostat wires are damaged. You'll want to start by doing a continuity test on the R and C wires, to insure they are intact and not damaged.

2021年12月2日 · So you have a furnace with no C terminal and a thermostat with no Rc terminal. That's a royal pain. Nest documentation suggests you TRY running without a C wire. If the thermostat can leech enough power off the R-W connection to keep the battery charged without the furnace detecting it is doing so, you'll be ok. The only way to know is to try.

2015年10月31日 · 1. The furnace blows hot air only in "FAN" mode. 2. When the mechanical thermometer is switched to "AUTO", I could hear the click sound from the unit, however the FAN does not start blowing the hot air at all. According to the professional, it seems to be caused by the defective heat sensor/thermostat on the furnace unit.

2017年12月28日 · Problem: Furnace came on as usual in the morning but failed to shut off after the set temp on the thermostat was reached. The house temp (as measured on the thermostat) reached about 10 degrees higher than the set temp and hot air was still blowing out of the registers. Thermostat: Inexpensive (Honeywell), programmable thermostat

2021年2月11日 · UPDATE: The thermostat is a Honeywell model TH6210U2001: The pins connect to the base plate which connects WYGR wires to the furnace and air conditioner (separate units). The furnace is a Jonson AirEase 80 Plus.

Check with the furnace manufacturer, and all local codes before attempting this procedure. Make sure the breaker for the furnace is OFF before you begin. Make sure the breaker for the furnace is OFF. Start by removing the access panel on the furnace, and locating the thermostat wires. Remove the wire from the G terminal, and connect it to the C ...

Replace the 20VA 24VAC transformer with a 40VA version (40VA HVAC control transformers are utterly bog standard) and then tap C at terminal 6 on the furnace's control terminal block, using a 24VAC SPST relay to allow the thermostat to control the electric side.

My current furnace controller doesn't have a C terminal, but the current thermostat wire has 2 unused wires (black and blue) what's the best way to do this? On the 24V side of the transformer there is: 1 Red Wire 3 Blue Wire - 1 Blue is ground - 1 Blue goes to gas valve - 1 Blue goes to furnace controller