Dedicated Heat Recovery is not a new topic. In 2003 ASHRAE published an article detailing the technology and advantages of dedicated heat recovery chillers (DHRC) – see link below. However, these systems become increasingly beneficial with the advent of modular chiller design, and a packaged controller capable of staging the compressors based on the lower of the two loads. Therefore we are able to constantly maximize the amount of heat recovery while never creating excess cooling or heating that cannot be utilized in the system.
Dedicated heat recovery machines work by taking the heat normally sent to the atmosphere via the condenser water & cooling tower and instead they re-use that for heating needs inside the building. We’re able to do that by working the compressors harder and increasing the leaving condenser water temperature up to a usable temp such as 140 °F. This hot water can be used for VAV reheat, domestic hot water, snow melt, process heating – and the list goes on. DHRC should be considered for any application (new or existing) in which there are substantial run hours with simultaneous heating and cooling loads.
A proper energy analysis should be administered to understand the simultaneous loads throughout the year. At that point, we are able to review just how large our DHRC load is, and how many run hours we can expect. Finally, a payback analysis should be conducted. In general – we tend to see paybacks in as little as 2 to 3 years.
In summary, DHRC should be weighed as an option whenever you have simultaneous heating and cooling loads. Please contact NEAP with any questions on this topic and we’ll be happy to answer them.
ASHRAE Publication - DHRC
Multistack DHRC Catalog
VME II Info