Honeywell Hydronic Programmable Heat Only Thermostat TL8100A1008


With the TL8100 there’s no need to carry multiple thermostats for different applications. It can be used to control 2-way zone valves, 3-way zone valves or circulator pumps in both line volt and low volt applications. It also offers special protection modes to prevent system seizures and to reduce callbacks. Easy to install, the TL8100 is exactly what you need to provide your customers with cost-efficient programmable control of hydronic heating systems…and much more!


  • 7-Day Programmable — Up to 4 periods per day to fit any lifestyle and help save energy.
  • Precise Comfort (+/-1ºF) — Maintains consistent comfort to the highest level of accuracy
  • Low Battery Indicator — Gives 60-day warning to replace batteries.
  • Installation Flexibility — Works with mV, 24V, 120VAC, and 240VAC heating systems. Rated at 5A resistive and 2A inductive load.
  • Pump Protection — Activates zone valves or pumps for one minute every 24 hours to prevent seizures and reduce callbacks.
  • Armchair Programming — Save time on the job with convenient programming by simply removing the faceplate from the base.


The TL8100 works in the following Hydronic applications:

  • Line volt circulators
  • 24 volt circulator relays
  • 24 volt zone valves
  • 120 volt zone valves

Not only is the TL8100 great for valve and pump control, it also does much more!

  • Electric heating up to 1200W@ 240V max.
  • Millivolt systems (e.g., gas fireplaces)
  • Gas, oil or electric systems
  • Hot air system with no fan control

Compatible Honeywell Zone Valves and Actuators

  • V8043 1000 and 5000 Series Zone Valves
  • MZV Series PowerTrak™ Motorized Zone Valves
  • MT4 Series Smart-T Thermal Electric Actuators