Hot answers tagged

3

The documentation for your furnace, calls for a switch rated at 0.90" wc. Using a switch with a lower rating, means that the switch may be closing without the proper inducer air flow. If you called the tech out because the furnace was not working, you may have a problem that was preventing the switch from closing. By putting in a different switch, the ...


3

According to the wiring diagram for your system (i.e. Figure 2 in the linked PDF) -- the yellow wire on the 24VAC side is the C wire (it's the wire that goes to the compressor but not to the 'stat in the diagram). Just incorporate the green wire from the thermostat cable into the nut with the yellow and green wires in it on the 24VAC side, and you'll be set!...


2

I have a Lennox too and I hate the filter situation with a fury of 1000 suns: It's just sitting in the furnace against the return duct - previous owner left a VERY dirty one taped with aluminum tape that took me a long time to peel. I've been using masking tape. One of these days I'll find time to fabricate a filter box to sit between the return duct and ...


2

I will assume it is indeed a failure to ignite problem. The way it works is your circuit board puts out about 5 milliamperes through to your flame rod. When there is flame the electrical signal jumps the flame and the ground completes the circuit back to the board. If it doesn’t read approximately 5 milliamperes back to the board it assumes there is no flame ...


2

As I commented, my G16s have a hardwired power switch on the side. Or as others suggested, you should figure out which breaker controls the furnace circuit, and turn it off. (You should not have to shut off the main unless you are working inside the panel box itself) But after looking over the wiring diagram for my G16, it does seem that the door switch ...


1

If you have a filter in the return air grille, that's likely the only one in this system. Nobody wants to climb into their attic just to replace an HVAC filter, so when a furnace or air handler is installed in the attic these filter grilles allow placement of the filter in a more accessible location. In fact, according to page 6 of this spec sheet for that ...


1

I have this exact same furnace (30+ years old) and very similar messy nest of wiring. As user76730 noted the yellow on the 24V side of the transformer is the key. In your photos, this is the left most wire nut that is pointing up with 2 yellow wires and a green attached. I had a spare blue thermostat wire from my old Honeywell mercury blob setup that was ...


1

Posting the correct response to my own question in case any other novices are looking for the same info in the future: The wires on the left side of the thermostat (ALL the way left, between the mercury bulbs) are not coming from the wall; they’re just part of the old thermostat and aren’t needed with the new one. Also (for Paul, mainly), the wires ...


1

It appears that you have a thermostat that is designed to control a standard split-system heat pump. However, the wiring color code does not follow what I would call a conventional design. The control wiring for these heat pumps are fairly sophisticated. You may want to consult a Lennox dealer for help. Or a standard HVAC dealer for help with the control ...


1

It sounds like the system is not actually "cooling". It sounds like it trying to dehumidify. An A/C system actually is a dehumidifier by its design. If the Temp of the residence is satisfied, and the A/C is still running, try turning up the humidistat higher. if the system turns off and returns to normal, then that is the issue. if it keeps running, then you ...


1

Under proper conditions the burner flames could roll out causing a fire and damage to your furnace should the flue become partially clogged. Engineers spent a lot of time and testing to determine the proper switch for the furnace. It is fine to use after market parts but they must have the same rating and design characteristics.


1

Alright, I figured out why it wasn't working. Had nothing to do with ACC not having a lead. I was looking at my setup closely and noticed that only 2 wires were coming up from the motor, but it needs 3. I noticed that there was a wire coming from pin 3, but it was crimped and didn't run to the motor. So I looked at the speed table and decided I wanted to ...


1

Check that the gas supply is okay. Maybe someone fiddled with the gas valve. Maybe there is a gas leak outdoors. Verify that another gas appliance is working correctly. Check the space between the pilot light and its themopile or thermocouple. If the flame is not heating the sensor, the pilot light is supposed to be cut off to prevent gas accumulation. ...


1

Modern residential systems frequently have the filter located at the return-air grill. Look for the large grill where blower air is pulled in from the house; if the grill has small latches and hinge tabs, where it can swing open, it is probably designed to have a slim furnace filter installed behind the grill.


1

Before I get into this, I should say that if you paid a professional HVAC company to fix your furnace and they replaced the draft motor 1 month ago, you should call them and tell them they aren't finished yet. If they told you it was fixed and it isn't then there should be a guarantee you can call them on, if there isn't than you should hire somebody else ...


1

Using a single HVAC unit with zone dampers is pretty well-established and can save the trouble of having multiple separate units. Some things to discuss with your salesman (and if s/he doesn't have detailed answers, ask for someone with detailed knowledge): If your cooling needs will often only require one zone or the other (i.e., daytime downstairs, ...


1

Just like the installation manual clearly says: This unit is not equipped with a filter or rack. All G40UH(X) filters are installed external to the unit. Which means it is installers responsibility to implement filtering system, Lennox has nothing to do with it. Here's the 2 rules of thumb (all, not just Lennox): If furnace is located in the basement ...


Only top voted, non community-wiki answers of a minimum length are eligible