Hydronics High Five

Hydronics High Five

By John Vastyan
Special to Contracting Business

Hydronics High Five
Sensible layouts and the use of high-performance hydronics products show the heating and cooling power that can be packed into a small space.

It wasn’t long ago that the hydronics industry was stuck in time. Replacement business ruled the roost. Today, the hydronics industry has emerged from its extreme makeover. It’s now characterized by the emergence of new equipment and market conditions that have driven manufacturers to new levels of excellence.

Without question, market forces — especially the push for higher energy efficiencies, and demand for equipment to go where no equipment has easily gone before — are driving the pace for new and innovative hydronic solutions.

The newest generation of hydronic equipment, such as condensing technology that extracts heat from condensate within the system, has pushed boiler combustion efficiency into the 95% to 99% range. Or, consider the new generation of geothermal and watersource heat pump equipment, availing 400% and 500% system efficiency. That’s smart use of energy.

With efficiency performance like this, building owners are paying attention. When an installer can calculate a three- to four-year payback for new equipment, there’s real incentive to install new technology. Though residential work has taken a hit, the commercial market remains relatively strong. And higher energy costs have fueled interest in all things green.

With that as the context for a forum on what’s new and exciting in the hydronics industry, we asked several hydronics experts to contribute to a discussion about what’s shaping the industry. What they told is that high performance hydronic heating and volume water heating depends on the interrelationship of five key facets of the hydronic heating system: system efficiency, green heat, information exchange, the system in context, and heat distribution.

System Efficiency
How effectively the heat source relates to the total system is determined by its capacity to deliver heat. The common term is “to size to the load.” Also, total system performance is greatly enhanced when the equipment works at peak performance – with energy consumption happening at the highest levels of combustion efficiency – at all levels of heat demand.

According to Bill Root, vice president of sales and marketing, Laars Heating Systems Company, an important factor in system efficiency is sophisticated controls that sample changes over time and “learn” the responses of the system to changes in conditions such as heating load, outdoor air temperatures, and firing stages of the boiler or boilers).

“And, of course, there’s modulation or staged firing versus on-off,” says Root. “This illustrates the giant strides the industry has made during the past couple of years. Modulating and staged fired boilers reduce fuel consumption by sizing to the load so that the amount of heat produced by the system precisely matches the need.”

Piping and pumping are also key factors in building an efficient system. The most efficient boiler in the world can’t make an entire system efficient if the system is not piped and pumped correctly.

“Condensing boiler technology is one of the key factors for the dramatic increase we see in boiler/ water heater system efficiency,” adds Root. “Condensing boilers are built to encourage the formation of condensate within the system, to extract that heat, and to withstand the corrosive nature of the liquids that form there.”

However, efficiency is only one of the advantages of installing these systems. Application of the boiler can play an even more important role.

“Condensing boilers’ tough resistance to thermal shock and the ability to accept low return water temperatures puts them in a category of their own and opens up many new possibilities for high-volume, cold-start systems. One example is commercial snow melt systems,” says Mike Chiles, president and general manager, Watts Radiant. “A condensing boiler takes very low inlet temperatures in stride – in fact, the lower temperature of incoming water (or a water/glycol mix as is usually the case), the higher the combustion efficiency of the boiler.”

Green Heat
“Green” water heating equipment is another facet to the high performance equation. “Today, when this topic is discussed at industry roundtables, we look at emissions – NOx, CO, CO2 – with the real desire see lower levels of pollutants that endanger our atmosphere and harm indoor air quality,” says Root.

Ultra-efficiency is another measure of green. Commercial watersourced heat pumps and just-released, high temperature geothermal systems (with exiting temperatures of 145F) can provide coefficients of performance of 4 and 5, meaning 400% and 500% efficiency.

According to John Bailey, vice president of sales and marketing, ClimateMaster, green-minded contractors can choose from new lines of high-temperature water-to-water heat pumps that use HFC-410A zero-ozone depletion refrigerant.

“The new systems are available in a range of sizes in 50Hz and 60Hz voltages with ground loop efficiencies 25% higher than current units on the market,” he says. “The systems are rated for water loop heat pump, ground loop heat pump and ground water heat pump applications.”

New scroll compressors within the units make it possible to generate leaving water temperatures of up to 145F (63C) even at ground loop minimum temperatures.

Information Exchange
How well does the heating unit act as part of a system in terms of both accepting and responding to external sources of information? “Information exchange” refers to the heating system’s ability to both receive external information (such as outdoor air temperature, instructions from a building automation system, and system zone information) and to send information back to the building automation system (such as inlet and outlet water temperatures, operating cycles, fuel consumed, pump operation, etc.).

This communication ensures the system is operating not only properly, but optimally.

The Heating System In Context
Of course, what exists beyond the heating system’s jacket and piping will affect overall system performance. Consider circulation, control solutions and heat distribution. New technology and intelligent system design are the key players here.

One of the most important facets to optimal circulation for hydronic systems is for installing contractors to match a pump’s performance, or flow characteristics, to the specific job that it needs to perform within the system.

Tony Radcliff, product technology manager, Grundfos Pumps Corporation, explains that a single-speed pump has one performance curve – a measurement of head (in feet) and flow (in gallons per minute) – and operates at that level only for a particular condition. Multi-speed circulators offer a much broader range of performance. With the flick of a switch, various speeds can be chosen, easily changing head and flow to meet the specific needs of the system.

For more sophisticated needs, there’s variable flow. New variable flow circulators on the market offer a broad performance range with flows from 10 to 170 gpm, and can automatically adjust their performance to meet demand and save energy. These circulators “learn” what works best for the system, and continually change their settings to provide the temperature and comfort required. This translates to substantial savings on running costs.

“Three-speed and variable-speed circulators offer us great control and versatility,” says Tim Rosen, P.E., a partner in the plumbing and mechanical contracting firm, Concept Mechanical, based in Avon, CO. Rosen says that he always does the math, calculating heat loss, flow rate, and pressure drop for each pump.

“I use this information and the stated pump curve to select the proper pump for each load,” he explains. “In the past, we might have three or four different pump models on one job, all selected to match the exact needs that we’ve determined. With multispeed or variable speed pumps, one pump does it all.”

Heat Distribution
The hydronic industry’s renaissance is, in part, due to the reemergence of the radiant heat industry. In the commercial sector, large radiant heat systems place unique demands on a heating system. According to Chiles, these systems were historically characterized by cold starts with long boiler run times, high water volume, high mass, cooler required supply water temperatures, and short boiler cycle-times when the mass was at temperature. In other words, all the ingredients for a boiler’s worst nightmare.

Of course, large radiant systems require a boiler or boilers with high output. A key advantage today, however, is that when the thermal mass of a floor or heated surface has reached temperature, shorter and less frequent boiler cycle-times are required. Better yet, a boiler system with modulation permits the heating, and later heat-maintenance of the heated surface. Either a fully modulating burner or the lead-lag staging of boilers, allows a system to meet ever-changing load requirements for optimal system efficiency. Another option is to add mass to the piping system to increase boiler run times during periods of low demand. For this, water tanks can easily add mass to a piping system.

“Snowmelting systems pose a different challenge: high demand and high mass with extremely cold water/glycol temperatures,” adds Chiles. “Here, the challenge is not short-cycling of the boiler. Thermal shock happens when freezing return-water temperatures come crashing into the heat exchanger in a long, hard, cold start.”

Fortunately, the new generation of condensing boilers takes this brutal jab in stride. Many modern boilers are not susceptible to thermal shock, due to the materials of their waterways and heat exchangers. Others can be easily protected from thermal shock with the use of a boiler bypass, which mixes hot fluid with the cold system return. This allows the user to meet the manufacturer’s minimum return temperature requirements. The bypass can be built to operate automatically, with the addition of a control system, or can be a manual, fixed-temperature type.

Any way you look at it, this is an exciting time for contractors and manufacturers to be involved in the hydronics industry. And as good as it is now, the technology will only continue to improve, so stay tuned.

John Vastyan is a freelance writer based in Manheim, PA.

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