Dual Fuel Systems

Dual Fuel Systems describes any heating or cooling system that utilizes more than one fuel source. Most commonly, you’ll see a heat pump coupled with a fossil fuel burning appliance. We think outside the box and offer many types of dual fuel systems. We will couple solar with gas and wood with solar. We will use heat pumps with radiant systems and many other combinations, depending on your needs.

Often times, there is a mixture of systems within a home and that’s where Abacus can really help. Combinations of systems require special care with piping and control strategies to ensure comfort and high efficiency operation.

Many times, you’ll see multiple fuel burning appliances serving devices that could all be served by one appliance. If you have a gas furnace and conventional water heater, you still have the potential to retrofit a truly high efficiency solar thermal system into your home. If it is a whole system replacement, we have options to replace the gas furnace with a hydronic coil/variable drive air handler that is served by a water-heating source that also does your domestic hot water. If it is an existing high efficiency system, we can add a hydronic booster coil to supplement gas heating. These are ways to incorporate one water-heating source whether it’s a tank less water heater, a boiler or a solar thermal supplement system. By eliminating multiple fuel-burning appliances and serving all your equipment with one fuel burning appliance will greatly decrease fuel consumption.



  • FREE Lennox Healthy Climate Air Filtration System or 50% off Whole House Humidifier with purchase of new High Efficiency Furnace or Air Conditioning add-on
  • 25% off Tekmar TN4 Comfort Control System with upgrade of current boiler to High Efficiency Con-Mod BoilerThe combination of 1. Properly resizing the boiler to your home; 2. Upgrading boiler efficiency and; 3. Adding an intelligent Tekmar Control system has realized as much as 75% overall savings and optimum comfort for some customer! (not to mention proper system design)
  • 10% off Tekmar TN4 Comfort Control System to add to your existing boiler system for savings of up to 30% off your current fuel costs
  • Free Solar Site Analysis with HUGE Green Incentives available through December 2010 – Call Abacus to ensure your system is done right!
  • Free estimates and consultations/ education on your home or building’s mechanical systems