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Case Study

Petrie’s Landing Tower II – Luxury Condos

Tower II

Petrie’s Landing Tower 2 is a 145 unit, 15 storey luxury development in view of the beautiful Ottawa River. This project was one of the 1st Hybrid Heat Pump Systems this builder has developed in the Ottawa Region, but it is not the last! Tower 1 was designed using a traditional heat pump loop, also supplied by Longhill Energy, but after design discussions with the Engineer and Owner, the project team decided Tower 2 would benefit greatly from the advantages of Bulldog Heat Pumps. This builder now has 5 buildings and over 500 units furnished with Canadian made BULLDOG HEAT PUMPS!

About the Project

Owner: Brigil

Mechanical Engineer: M & E Engineering

Mechanical Contractor: NuHorizon Plumbing & Heating Inc.

Equipment: 150 InnKeeper & HomeKeeper Vertical Stack Heat pumps with Fluid Cooler

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The BULLDOG Heat Pump System is a novel combination of two traditional commercial HVAC building technologies.  The system combines conventional water-cooled air conditioning and hydronic space heating, all in one package.  A BULLDOG unit operates as a fan coil in heating and a water-cooled DX unit in cooling.  The compressors do not operate in the heating mode.  They can cool or heat any space at any time of the year.  Instead of a refrigerant reversing valve for heating, the BULLDOG unit diverts the loop fluid to a hydronic heating coil located inside the unit.  This loop fluid varies in temperature depending on outdoor ambient conditions.  As the ambient temperature gets colder, the fluid temperature is increased.

“No other heat pump does more, with less. Quieter, uses less electricity, modulating heat, lower heating costs and more…”

Operational Comparison of the BULLDOG and Reversing Heat Pump

What are the mechanical operational differences between a BULLDOG Heat Pump and a Reversing Water Source Heat Pump (WSHP)?

  • In the cooling mode, both systems operate the refrigeration components as water-cooled AC units.
  • In the heating mode, a Reversing WSHP uses the refrigeration system (compressor -evaporator – condenser) in order to absorb heat from the fluid loop.
  • The BULLDOG System uses a simple hydronic coil to absorb heat from the fluid loop in the heating mode.

Do the building systems have the same components?

  • Yes. There are boilers, pumps and

fluid coolers/cooling towers for either system.

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Fluid Cooler Benefits 

-Low RPM fans for low noise.

-Minimal maintenance with no Winterization Required!

-Fan staging for reduced energy consumption

-Lower initial cost vs cooling tower

-W-Bank layout for reduced footprint

While not as efficient as some evaporative forms of heat rejection, Bulldog Heat Pumps are designed for efficiency at elevated loop temperatures.

What internal components are different in the units?

  • A WSHP has a Reversing Valve while the BULLDOG unit does not.
  • A BULLDOG unit has a hydronic coil, while a reversing WSHP does not.
  • A BULLDOG unit has highly effective condenser.

Do the two systems operate differently?

Both systems can either heat or cool any space simultaneously at any time of the year.

The BULLDOG system will make use of warmer loop temperatures in the winter heating season since it operates as a simple fan coil. In the spring, fall and winter, the BULLDOG system will follow a simple water temperature reset schedule based on ambient conditions just like any fan coil system. Any BULLDOG unit that is called upon to operate in the cooling mode in the winter season will be able to do so.

Where does the heat come from for either system?

The heat comes from the same source for either system. Meaning, the heat comes from the fluid loop. The heat contained within the fluid loop comes from the heat of rejection of the cooling units or from the boiler plant or a combination of both or even from a geothermal field. The heat always comes from the fluid loop.

A WSHP system has a COP of 4 to 5. What is the COP of the BULLDOG system?

If the BULLDOG system had a COP it would be extremely high. Meaning, if we were to consider the kW input (fan motor only) and the heat output of a fan coil we would get a very high COP (in the range of 28+). However, we cannot use the term COP when referring to a fan coil. The simple fact is that a BULLDOG unit does not require compressor power input in order to absorb waste heat from the fluid loop. That does not change the fact that a fan coil can make use of waste heat from units operating in the cooling mode.

How much of the heat does the compressor deliver with a Reversing WSHP?

In doing work the compressors generate extra heat (called heat of compression) and it ends up in the air stream as useful heat. Approximately 25% of the total delivered heat comes from the compressor. Therefore, 25% of the heat delivered with a WSHP is electric heat.

How much heat does the BULLDOG system deliver from the compressor?

None (the compressors are not required for the heating mode)

If the BULLDOG system does not provide any heat from the compressors, how does it make up that portion of the heat that comes from electricity with a WSHP?

The BULLDOG system will make up the 25% heat from the building’s heat source, which is where 75% of the heat originates from with a WSHP.

Is it better to heat with electricity or with Natural Gas?

Electrical compressor heat will typically cost 3 to 5 times more than heat obtained from Natural Gas boilers.

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Boiler  Fluid Cooler, Cooling tower- PumpsYESYES
Reversing ValvesYESNO
Heat from electricityYESNO
Uses compressors in coolingYESYES
Uses compressor in heatingYESNO
Makes use of waste heatYESYES
Capable of simultaneously heating and cooling anytimeYESYES
Places heating components on same loop as heat pumpsNOYES
Places Make Up Air unit on the same loop as the heat pumpsWith limitationsYES

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