Heat recovery occurs when we extract the heat from a chiller to use in an application rather than wasting or dumping it outdoors or into a geoloop. Heat recovery is available with air to water units as well as water to water units. If a building has a cooling load and a heat recovery chiller we will use heat recovery any time there is a call for heating and cooling at the same time. This is free heating which provides tremendous energy savings and greatly lowers the carbon footprint as fossil fuels are not used to produce the hot water anytime we are using heat recovery.
Heat recovery is available in different capacities typically 25-40% or 100%. 25-40% is called a desuperheater and 100% is called total heat recovery. Heat recovery is only available when there is a cooling load and there is a call for heating at the same time. It is heat recovery not simultaneous heating and cooling as some manufacturers call it, and I state this as there are units that can provide true simultaneous heating and cooling with any amount of heating and any amount of cooling whenever you need it. When there is a call for both the simultaneous unit will provide heat recovery.
A simple example is a 100 ton chiller with desuperheater. When the chiller is providing 100 tons of cooling the desuperheater will provide 40 tons or 480,000 Btus of free heat. If the load drops to 50 tons the amount of heat recovery from the desuperheater drops to 20 tons or 240,000 Btus. If the chiller has no cooling load there is no heat recovery available, so no cooling no heating. The same is true for 100% heat or total heat recovery, as the load on the chiller drops the amount of heat recovery drops proportionally. A true simultaneous unit will allow you to have up to 100% heating even if there is no cooling. Read more about heat recovery here.
Heat recovery is available anytime a chiller or heat pump is in cooling mode. The heat that is typically rejected to the outdoor ambient or to a geothermal loop etc. is passed through a refrigerant to water heat exchanger and the heat is recovered to be used where it is needed. The refrigerant is passed through a heat exchanger before being sent to the condenser and when a pump is activated as there is a demand for hot water the refrigerant gives up its heat to the water through the heat exchanger rather than sending it to the condenser to be rejected to the atmosphere or a geo loop.
There are some controls involved along with valving etc but it is a pretty simple solution. As it is such a simple solution is is an easy way to provide a more efficient HVAC solution to building owners, manufacturers etc.
The advantage of heat recovery is that the heating energy is free. No need to pay for heat when you have a cooling load, and we lower our carbon footprint along with our negative effect on the environment. Imagine that we are able to save money and save the environment, this has to be a win, win situation.
The energy savings while proportional to the size of the chiller can be dramatic. We have seen applications where 3 large heat recovery chillers operate year round providing almost 9 million btus of free heat to the building 24 hours a day 365 days per year. The energy savings are tremendous as is the effect on the environment. Use our Heat Pump Calculator to calculate potential savings of using our equipment versus alternatives.
Some applications will use 100% heat recovery and some will use a desuperheater or 40% heat recovery. If you have a 100 ton chiller you will receive 12,000,000 Btus per hour of free heat when the chiller is operating at full load. You may use this heat when required but if the need for free hot water drops the chiller will automatically reject the heat to the ambient or geothermal loop.
A desuperheater will provide up to 720,000 Btus per hour of free heat when the chiller is at free load. It is important to know that if there is no cooling load there is no free heat.
Heat recovery chillers are being used in many applications such as:
These applications are prime as they tend to have year round heating and cooling needs. As energy management becomes more of a topic of conversation we will see heat recovery being used in more and more applications including residential, commercial and industrial. We should be using heat recovery in our homes for free domestic hot water when we are in cooling mode, in commercial applications wherever cooling is used as there is almost always a need for hot water weather it be for process, domestic or cleaning. Click here for our Case Studies.