Honeywell TH1100DV1000 vs Honeywell RTH8500D: Heat-Only Simplicity or Full Scheduling

The Honeywell TH1100DV1000 and the Honeywell RTH8500D are both Honeywell thermostats, but they solve different problems. The TH1100DV1000 is a two-wire, heat-only digital thermostat built for straightforward heating control. The RTH8500D is a seven-day touchscreen programmable model that requires a C wire and manages both heating and cooling on a schedule.

That single split — heat-only versus full programmable system control — is the decision this comparison covers. The short version: the TH1100DV1000 suits a simple heating setup and a tight budget, while the RTH8500D suits a home that wants weekday and weekend scheduling for a full HVAC system. The detailed read follows, dimension by dimension.

Honeywell TH1100DV1000 Pro-Digital 2-Wire Heat Only

Product Type: Digital thermostat
Control Scope: Heat only
Wiring: 2-wire
Series: Pro-Digital
Display: Digital
Price Tier: Budget

The TH1100DV1000 is the kind of thermostat that gets installed and then forgotten, which is the point. Its two-wire design means it drops into the wiring that older heating systems already have, so a replacement does not demand a new cable run through the wall. The digital display gives setpoint control without the guesswork of a mechanical dial.

The Pro-Digital label points to a unit aimed at straightforward, reliable heating control rather than app connectivity or multi-stage scheduling. Buyers who heat with a boiler, a baseboard system, or a single-stage furnace and who do not need cooling control are the natural audience. It is also the obvious pick for anyone replacing a failing thermostat on a budget.

Trade-off: A heat-only, two-wire unit cannot run air conditioning or fan-only circulation, so it is the wrong choice for any home that needs cooling control from the same device.

Check the Honeywell TH1100DV1000 on Amazon

Honeywell RTH8500D 7-Day Touchscreen Programmable Thermostat

Product Type: Programmable thermostat
Control Scope: Heating and cooling
Wiring: "C" wire required
Programming: 7-day
Display: Touchscreen
Color: White
Price Tier: Premium

The RTH8500D is a full-featured programmable thermostat with a seven-day schedule and a touchscreen interface. Seven-day programming means each day of the week can carry its own schedule, which suits households with irregular routines or a home office that needs different comfort hours than the rest of the week. The touchscreen replaces physical buttons with on-screen controls.

The "C" wire requirement is the detail that shapes the buying decision. A common wire supplies steady power to the thermostat, and homes without one may need to run an additional wire or use an adapter before the RTH8500D will work. Buyers with a modern HVAC system and a C wire already in the wall get the full benefit of the scheduling and touchscreen controls.

Trade-off: The C wire requirement can turn a simple swap into an electrical job, and the premium price is hard to justify for a home that only needs basic heating control.

Check the Honeywell RTH8500D on Amazon

Side-by-Side Specifications

Attribute	Honeywell TH1100DV1000	Honeywell RTH8500D
Product Type	Digital thermostat	Programmable thermostat
Control Scope	Heat only	Heating and cooling
Wiring	2-wire	"C" wire required
Programming	Not a programmable schedule model	7-day programmable
Display	Digital	Touchscreen
Color	Not stated in name	White
Series	Pro-Digital	RTH8500D
Price Tier	Budget	Premium

How the Two Thermostats Compare

The comparison turns on four dimensions: what the thermostat controls, how it is wired, how much scheduling it offers, and what it costs.

Control scope. The TH1100DV1000 handles heat only, so it has no role in cooling, fan circulation, or a combined system. The RTH8500D controls heating and cooling together, which makes it the only option of the two for a home with central air. For a heating-only property, the extra capability of the RTH8500D goes unused.

Wiring. The two-wire design of the TH1100DV1000 makes it a direct replacement for older heating wiring. The RTH8500D needs a C wire, and a home without one faces extra work before installation. Buyers should check the wire bundle behind the old thermostat before ordering, because that single detail decides whether the RTH8500D is a drop-in or a project.

Scheduling. Seven-day programming is the RTH8500D’s core advantage. A household with a predictable weekday routine and different weekend habits can set separate schedules and let the thermostat manage the transitions. The TH1100DV1000 offers setpoint control without that scheduling layer, so comfort changes happen at the wall rather than on a timer.

Interface and price. The touchscreen on the RTH8500D is easier to read and adjust than a basic digital display, and the premium price reflects the added programming and touchscreen hardware. The TH1100DV1000 keeps costs down by doing one job with simple controls. Neither approach is better in the abstract; the question is whether the home needs what the extra money buys.

Which Should You Buy?

Choose the Honeywell TH1100DV1000 if the home has a heating-only system, the existing thermostat uses two wires, and the goal is a reliable digital replacement without extra installation work. It also suits a rental, a cabin, or a garage heater where scheduling and cooling control add nothing.

Choose the Honeywell RTH8500D if the home has both heating and cooling, a C wire is already available behind the current thermostat, and the household wants a seven-day schedule with a touchscreen interface. It is the stronger pick for a primary residence where comfort hours vary across the week.

Buyers who are unsure about the wiring should check the thermostat cable first. A C wire in the wall removes the main obstacle to the RTH8500D, while its absence makes the TH1100DV1000 the simpler path.

FAQ

1. What is the main difference between the Honeywell TH1100DV1000 and the Honeywell RTH8500D?
   The TH1100DV1000 is a two-wire, heat-only digital thermostat. The RTH8500D is a seven-day programmable touchscreen thermostat that controls heating and cooling and requires a C wire.

2. Does the Honeywell RTH8500D need a C wire?
   Yes. The product name states that a "C" wire is required. Homes without a common wire may need to run one or use an adapter before the thermostat will operate.

3. Can the Honeywell TH1100DV1000 control air conditioning?
   No. It is a heat-only thermostat, so it cannot run cooling or fan-only circulation.

4. Which thermostat is better for an older heating system?
   The TH1100DV1000 is the more natural fit for older heating wiring because its two-wire design matches what is already in the wall.

5. Is the Honeywell RTH8500D worth the higher price?
   The premium buys seven-day scheduling, a touchscreen, and heating plus cooling control. That value depends on whether the home has a C wire and needs those features.

6. Can either thermostat be installed without professional help?
   Both are typical DIY replacements for a compatible system, but the RTH8500D’s C wire requirement raises the skill level. Buyers who are unsure about wiring should consult a qualified HVAC technician.

7. Which one suits a rental property?
   The TH1100DV1000 suits a rental with heating only, where simple controls and a low price matter more than scheduling.

Bottom Line

For a heating-only home with two-wire wiring, the Honeywell TH1100DV1000 is the straightforward, budget-friendly choice that installs without extra work. For a home with both heating and cooling, an existing C wire, and a routine worth scheduling, the Honeywell RTH8500D is the better fit and the stronger long-term buy.