Honeywell / Resideo FocusPRO 6000 programmable thermostats (TH6110D, TH6220D, TH6320U): quick sheet

Covers: FocusPRO TH6000 series programmable thermostats: TH6110D (1 heat / 1 cool), TH6220D (up to 2 heat / 2 cool conventional or 2 heat / 1 cool heat pump) and TH6320U (up to 3 heat / 2 cool heat pump). The model number is behind the battery holder. Common SKUs seen in the field include TH6220D1028 and TH6110D1021.

Single sourceBrands: Honeywell Home / Resideo3 components

A pro-channel, battery-or-C-wire programmable stat with separate R and Rc terminals, a factory R-Rc jumper, Aux/E/L terminals on heat pump models and a numbered installer setup. Most service calls are setup mistakes after a swap: wrong system type, O/B set the wrong way, cycle rate left on the default for the wrong equipment, or a two-transformer system with the jumper left in.

Safety first

Low-voltage work: kill power at the HVAC equipment before rewiring so you do not blow the 3 A fuse.
If the old thermostat is labeled 120 or 240 V, or has heavy wires with wire nuts, it is line voltage and this stat cannot replace it.

How it works

Power comes from batteries, a C wire, or both. C is optional when batteries are installed; with a C wire the batteries act as backup.

R and Rc are joined by a factory jumper for one-transformer systems. On two-transformer systems (separate heating and cooling transformers) the jumper is removed, R goes to the heating transformer and Rc to the cooling transformer, and C must come from the cooling transformer.

On heat pumps, O/B drives the reversing valve. Installer setup chooses whether it is energized in cooling (O) or in heating (B). Aux and E are separate terminals on the TH6220D (jumper them together if there is no separate emergency-heat relay) and combined on the TH6320U. L gives a constant output in Em. Heat, used to switch Resideo zone panels.

Installer setup (press and hold two keys until the display changes) sets system type, changeover valve, fan in heat (equipment-controlled for gas/oil, thermostat-controlled for electric), cycle rates per stage, manual or auto changeover, Adaptive Intelligent Recovery, °F/°C, compressor protection, 5-2 or 5-1-1 scheduling, and the heat and cool range stops.

There is a built-in installer system test that turns each stage on and off from the thermostat. Compressor protection is bypassed during that test, so do not flip the compressor on and off quickly.

Components & tests

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Official manufacturer documentation

Always confirm values against the tech sheet for the exact model.

OnCall Tech is a reference tool for trained technicians and can make mistakes. Always disconnect power and confirm with the manufacturer's documentation before you work. © 2026 OnCall Tech. Original content; not a reproduction of any manufacturer document.Generic part photos (not of this brand): Air-source heat pump outdoor unit beside a house in the snow by PeterEastern, CC BY-SA 4.0

Diagnostic guides for this appliance

Guide · Thermostat

Thermostats: alerts and wiring codes vs real equipment faults (Nest, ecobee, Honeywell, communicating systems)

Smart-thermostat alerts are inferred from temperature and runtime trends, not read from the equipment. Google says its System Health Monitor is not a substitute for an HVAC diagnosis. Some thermostat codes are about the thermostat's own power and wiring: Nest E and N codes in one family mean it lost power it was drawing through a call wire, often fixed with a C wire. The equipment fault itself is on the furnace board LED, the outdoor unit or, on communicating systems, in the wall control's service menu.

7 steps ~20 mineasy

Guide · Thermostat

Thermostat cycle rate (CPH) settings: matching the setting to the heating and cooling equipment

Many Honeywell/Resideo and similar digital thermostats use a cycle-rate setting (cycles per hour, CPH) instead of an adjustable heat anticipator. The number tells the thermostat how often it is allowed to cycle the equipment at about a 50% load. A setting meant for an electric furnace on a steam boiler gives short, inefficient firing; a steam setting on a forced-air furnace gives big temperature swings. Check the system type, then set heat, auxiliary/emergency and compressor cycle rates to match the equipment. This is a settings job: no wiring changes and no gas work.

5 steps ~15 mineasy

Guide · Thermostat

R, Rh and Rc: when to keep the jumper and when a system has two transformers

Most forced-air systems have one 24 V transformer at the furnace or air handler, and R and Rc are tied together (a factory jumper or an internal link in the thermostat). Some homes, usually a boiler or older furnace for heat plus a separate air handler or add-on AC, have two transformers: one for heat on Rh/R and one for cooling on Rc. Joining two transformers through the thermostat can blow fuses or burn transformers. Decide which you have before landing wires, and pick a thermostat that supports separate Rh and Rc when there are two.

5 steps ~30 minmoderate

Other thermostats manuals

Manual · Thermostat

Google Nest Thermostat (2020, mirror face, no ring): quick sheet

Google Nest Thermostat launched October 2020 (model G4CVZ, sold as GA01334-US and color variants). Not the Nest Learning Thermostat (3rd/4th gen) or the Nest Thermostat E, which have their own sheets/notes.

9 components5 common failuresGoogle Nest

Manual · Thermostat

ecobee3 lite smart thermostat (EB-STATE3LT-02 and Pro EB-STATE3LTP-02): quick sheet

ecobee3 lite retail (EB-STATE3LT-02) and contractor/Pro version (EB-STATE3LTP-02). Now listed as discontinued by several distributors but very common in the field. ecobee Premium/Enhanced have their own sheet.

9 components5 common failuresecobee

Manual · Thermostat

Honeywell Home T5 / T5+ Smart Thermostat (RCHT8610WF, RCHT8612WF, RTH8800WF): quick sheet

Honeywell Home / Resideo T5 Smart Thermostat RCHT8610WF (no C-wire adapter in the box), T5+ RCHT8612WF (ships with the THP9045A C-wire adapter) and RTH8800WF retail variant. T6 Pro, T9 and T10 have their own sheets.

7 components5 common failuresHoneywell Home, Resideo