Ordering and installation

Converting to tri-energy does not effect warranty on your existing heating appliances. The multi-stage electric plenum heater is installed in the main warm air heating duct downstream from the heat pump indoor coil, near the furnace. Because heating ducts have a different layout for each house, the preferred location, dimensions, and heating capacity of the plenum heater is determined by our expert during an onsite visit. After signing the purchase order and receipt of down payment, it typically takes 2-3 weeks for completion of engineering drawings, approval process and manufacturing before the equipment is installed. Installation and testing of the tri-heat equipment typically takes 1 day to complete. During fall and heating season the lead time following receipt of order may increase depending on the work load.


Tri-energy heating system layout.

Fig.2 above shows the tri-heat system layout for a typical installation. The plenum heater is installed downstream from the heat-pump indoor coil. The outdoor temp. sensor signals the amount of heat required to compensate for building heat-loss at any given time. The return duct sensor detects when the thermostat is in nighttime “setback” mode.

The 3-FLEX tri-energy controller is wired to the furnace, heat-pump, plenum heater and house thermostat. It directly controls all 3 heating devices, extracting maximum efficiency and comfort based on prevailing thermostat heating cycle and actual building heat-loss. During heat-pump defrost cycles, the plenum heater supplies “measured heat” to temper cold air influx, without interrupting the defrost cycle.

By allowing the heat-pump to run uninterrupted for extended periods of time,

its output efficiency is optimized, while wear & tear on the outdoor unit

moving parts due to mechanical stress during colder days is reduced.

When the thermostat is set to “E-heat” the 3-FLEX controller is effectively locked-out.

Allowing the house thermostat to directly control the furnace and fan.


3-FLEX tri-energy greatly improves the duty–cycle and output efficiency of both

 heat-pump and furnace. The results is drastically lower home heating costs

rivaling that of geothermal, but at a fraction of its upfront cost.



Heat-pump capacity and ductwork air-flow considerations

Use a qualified heating contractor

When in the market for a heat-pump, homeowners can spend considerable time researching different

brand names for the highest efficiency, reliability, features and of course finding a heating contractor

that will do the job for the lowest price. Instead time is more wisely spend, finding a reputable

heating professional with the tools, knowledge and willingness to make a house call, determine

specific requirements and limitations before proposing a suitable heat-pump for the job.

      Failing this important step can set you up for a string of problems down the road.

Insufficient air-flow

Insufficient air-flow is the most common cause of compressor failure.

The heat-pump capacity should match to the furnace fan and ductwork CFM air-flow capacity.

Ignoring this rule, and over-sizing the unit can lead to incomplete heat-transfer which can lead

to indoor evaporator coil icing, reduced efficiency and pre-mature compressor failure.

Under-sizing the heat-pump (to much air-flow) leads to cold drafts when in heat mode.

Ductwork modifications.

Residences constructed before heat-pumps became popular often have smaller sized ductwork suitable

for “high intensity” fossil fuel furnaces capable of raising the warm duct air temperature to 50-55°C.

A heat-pump by comparison produces “low intensity” heat, increasing the warm air duct temperature

to 25-35°C only. When converting to dual-heating, ductwork modifications may be required to increase

airflow volume of the lower temperature heat, in order to satisfy demand.


To much heat-pump capacity.

For dual-heating systems the heat-pump capacity should be balanced between winter heating and summer cooling demand. For the northern regions of the continent, cooling/dehumidifying demand is generally

less than for heating. Over-sizing a heat-pump to reduce furnace use is “false economy”, even when

furnace fan and ductwork are adequately sized to deliver increased CFM and air-flow.

An oversized heat-pump can “short cycle”. This occurs when it turns on/off frequently during milder

winter weather and summer cooling, creating unwanted humidity and temperature swings reducing home comfort. An oversized heat pump spends to much time in startup mode, reducing operating efficiency while increasing wear & tear on moving parts, especially the compressor.


Furnace fan speeds.

The blower speed /CFM requirements are determined by the delta T factory specifications of furnace and

heat-pump. Furnaces for dual-heating operate on 2 different fan speeds. High for heat-pump, medium

during furnace operation. Increasing the fan speed to accommodate a larger seize heat-pump can create

other unwanted site effects including increased fan and duct airflow noise.


Clean the furnace filter at regular intervals …

Failing to clean or replace the furnace return duct air filter on a regular basis leads to reduced airflow

leading to house temperature fluctuations, furnace overheating and over-temperature shutdowns and

heat-pump compressor damage. All leading to eventual equipment failure.



Get more out of your dual-heating system!

switch to tri-energy.

What makes dual-energy heating expensive to operate ?

The common problem with dual-energy is that as it gets colder outside, the heat-pump can no longer keep up with the house thermostat demand for heat. As a result the “expensive” fuel furnace kicks-in to raise the falling house  temperature — even when “cheap” electricity at the low DT rate is still available.

How Tri-energy works.

Tri-energy solves this problem by adding (to the existing heating system) a special 3-Flex control unit and variable electric plenum heater that acts like a small electric furnace (see fig.2 below). The heat-pump and electric element heater combination now ensures that the house stays warm and comfortable down to -12°C, taking full advantage of the low DT rate. Only after the orange “expensive  electricity” warning light has turned-on the fuel furnace kicks-in.

At today’s energy prices heating with an oil furnace is nearly 4x more costly compared to a tri-energy heat pump + electric plenum heater combo.

This number drops to about 2.5x when a gas furnace is used. Because the furnace is only used below –12°C it adds only marginally to your total seasonal heating cost. A small price to pay to enjoy a low electricity rate all year long.



Fig.2  Tri-energy heating system layout.