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Service Centre

Frequently Asked Questions (FAQ)

Q: Why does the compressor not operate in heating mode?

A: The BULLDOG™ is an energy efficient hybrid heat pump which does not require compressor operation for heating. The BULLDOG™ unit utilizes a hydronic hot water coil for heating. The hot water can come from various sources such as heat rejected from other heat pumps operating in cooling mode, a boiler system, and/or a geothermal unit with our Compax Modular Chillers.


Q: What is the proper operating temperature?

A: The BULLDOG™ can safely operate in both cooling and/or heating mode with supply water temperatures from 85°F/30°C to 125°F/52°C.


Q: My thermostat is not bringing on the BULLDOG™ heat pump? This is one of the most common service issues.

A: The BULLDOG™ is a Hybrid Heat Pump and will not operate properly if the thermostat is set to “HP” (heat pump) mode. It must be programmed for electric or gas heating.


Q: Why does my BULLDOG™ heat pump take so long to start once the thermostat is calling?

 A: Most programmable thermostats have an adjustable time delay (1-5 minutes) built into the thermostat program, and the BULLDOG™ heat pump has its own built in time delay of 10 minutes.

Helpful Hints

Home Owner Guide

Service Troubleshooting Guide

Flash Code Diagnostics

Commission and Start up

Commission and start up form

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