Hydronics Vs. Air: Radiant Cooling

By Greg Cunniff, Applications Engineering Manager, Taco, Inc.

In comparing hydronic chilled water and VRV/VRF systems, a new emerging factor for the chilled water side of the equation is radiant cooling. Radiant cooling is an exciting feature that avoids some of the challenges with space cooling distribution common to both types of air conditioning systems.

Comfort cooling is dependent on cooling coils and fans in the form of fan coil units or heat pumps along with filters (in the case of critical areas high efficiency filters). In lower end systems lower performance grills and air diffusers are commonly used, which can aggravate the comfort problem by dumping cold air on occupants. A radiant cooling system, however, avoids these problems since chilled air is not distributed through an air distribution system, as described above, but rather by a combination of radiant and natural convection. This only serves to improve IAQ.

Radiant cooling systems are now coming of notice here in the U.S. and design engineers are turning to them to achieve high comfort levels. Radiant cooling, like most hydronic-based applications, is common in Europe, but the trend line here in the U.S. is encouraging. There are a number of domestic radiant cooling manufacturers around today with successful installations.

At Taco’s Milton, Canada operation we have installed a chilled beam system to cool the office and training areas during the summer months.

Chilled Beam installation at our Taco’s operation facility in Milton, Canada

In this application active chilled beams were employed along with chilled ceilings to supplement. Together they work to reduce fan energy by a factor of 10, since the only air circulation that’s required is from the DOAS. This system supplies just enough treated, dehumidified outdoor air to slightly pressurize the building, negating natural infiltration of humid outside air. Like its counterpart, radiant heating, the market for radiant cooling will only grow larger in the years ahead, now that use of 100-percent DOAS is understood to be an effective remedy for the dehumidification issue previously associated with radiant cooling.

One Response

  1. The biggest issue with hydronic cooling is sweating pipes. In high humidity areas this is a very big issue and can lead to mold growth and rotting materials. Excess water runoff has to be the biggest priority.

    At my vacation home I have hydronic cooling and a ground loop in a low humidity environment and it works great. Once the water warms up in my home I have it go through a heat exchanger where it prewarms my hot water just before it enters my hot water tank.

    When it’s really hot out the humidity is low as there is a direct correlation between temperature and humidity. I have temps of 100 and humidity as low as 4%. I don’t have to worry about sweating pipes.

    At my primary home I use a ground loop and just go through my A coil that I converted to water. It allows for sweating and will catch that and pump it outside. Then the furnace turns on and blows the cold air throughout the house. Being in a high humidity area this is the most economical solution.

    I use a Taco 007 pump and could get by with a much smaller one but the Taco 007 is so much cheaper than the smaller ones.

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