Heating and cooling is a balance of science and equipment functioning together in various applications — such as hydronics. Although hydronic science dates back to ancient Rome, the equipment and techniques used by technicians have reached a level of sophistication unrivaled by its previous iterations. The boiler, a key component of a hydronic system, has changed as well. No longer warming the baths of Roman citizens, modern boiler applications are designed for comfort and efficiency. The proper installation and maintenance of boilers does not come with cookie-cutter schematics and instructions. There are, however, a small army of those willing to help technicians provide and maintain the best possible boiler for hydronic systems.
Technicians have the opportunity to address both efficiency and reliability when installing boilers, according to Catie VanWormer, PE, LEED AP, engineering manager, Packaged Boiler Systems, Cleaver-Brooks. She said that technicians looking to address efficiency should pump away from the boiler; install in a primary-variable-flow arrangement; and install automatic isolation valves on multi-boiler installations to prevent flow through non-firing boilers.
“As for reliability, technicians should ensure venting is properly installed, and also flush the piping system before operating the boilers,” VanWormer said. “Removing any old sediment is especially important in a retrofit system. Often, new pumps and boilers will improve flow to areas of the system where sediment has settled, and this can damage a new boiler.”
According to her, technicians should use stainless steel UL1738 for CAT IV-approved venting material that is correctly pitched to remove condensate; and condensate traps should be installed where needed.
System efficiency is also affected by the size of the boiler chosen.
“Great heating contractors know how to size boilers properly by completing accurate heat loss calculations,” said David Hansen, product manager, U.S. Boiler Company. “This practice helps equipment run more constantly, with less on-off short cycling and wear and tear.”
Hansen noted that all properly selected residential boilers are sized to replace the heat lost on the coldest days of the year.
“They will run constantly on those days,” he explained. “On more moderate days, properly sized non-modulating boilers will start/stop less frequently and run longer than oversized boilers that will short-cycle.”
Other installation tips come from Tim Kiely, regional sales manager, Raypak Inc. He said that paying attention to service clearances as well as clearances to combustibles is imperative.
“Pay attention also to installing the proper sized pumps to provide adequate flow rates for the installed boiler,” Kiely said. “A boiler should be installed with the proper sized piping based on the flow rate of the equipment.”
Like other HVAC equipment, boilers must be maintained once installed. Boiler manufacturers provide specific maintenance tasks in their equipment manuals for technicians to follow, but remembering four specific maintenance time frames can help a technician ensure optimal system performance.
The minimum maintenance for most boilers is annually. Every year, boiler manufacturers instruct owners to have the boiler system shut down and thoroughly cleaned. Depending on the type of boiler, this process could include opening the access doors to expose the fireside of the boiler; cleaning all blower fans; cleaning tubes and tube sheets; checking and adjusting combustion air settings; cleaning the condensate neutralizer and replacing the media; removing and cleaning the burner; and ensuring that all of the electrical connections are tight on the control panel.
Hansen said that even though heating equipment is often relegated to a dark part of a basement or garage, it should never be neglected.
“Yearly preventive maintenance is recommended for all boilers,” he explained. “Specific tasks vary and are documented in manuals. High efficiency gas condensing boilers contain more numerous and precise components that are worth an external and internal inspection every year.”
Kiely said that there are some monthly steps to be taken as well in order to keep the boiler running efficiently.
“Every month, technicians should clean or replace the air filter for the incoming combustion air,” he said. “There should also be a visual inspection of boiler operation.”
VanWormer further suggested that semi-annual water samples be taken and compared to manufacturer recommendations. She also said that checking pump alignment on all the base-mounted pumps in the boiler room should be coupled with resetting combustion using a combustion analyzer for reading O2, CO, and NOx emissions.
BOILER TRENDS AND FUTURES
Current boiler trends have technicians engaging flow rates, controls, and monitoring options that have changed the market and will likely continue to do so in the near future.
“Varying flow rates on modulating boilers are becoming more and more popular,” said Kiely. “If the flow rates do not match up with the required input, this condition can cause erratic operation of the system and could cause harm to the boiler heat exchanger. Solid engineering is a must.”
VanWormer added that variable flow primary systems are becoming more prevalent for hydronic systems and operate on the principle that one set of pumps will distribute water to the entire system, including the boilers and all heating coils.
“In this scenario, the entire system is exposed to variable flow, enabling it to benefit from lower flow rates and energy savings at reduced loads.”
Controls and monitoring options are companion trends that have grown increasingly pervasive in the HVAC industry.
“Boilers are entering an era of refinement to fit the needs of customers,” said Aaron Weaver, East Coast commercial sales manager, Raypak Inc. “This is being driven by the Internet of Things, as we love the connection to everything. Colleges, schools, owners, contractors, even engineers all want to ‘see’ the boiler plant in operation at various stages of the project.”
Weaver, known in the company as The Boiler Guy, said that he is also expecting to see the electric boiler make a comeback in certain areas of the country.
“These areas don’t have enough gas due to aging infrastructure or for environmental reasons,” he said. “This will drive the industry to develop new boiler products for that market segment.”
With the change in fuel availability in certain regions, Weaver expects that, with the abundance of natural gas and new networks of pipelines being installed, natural gas boilers will replace more oil and coal boiler plants.
As the future of boiler technology continues to develop, Hansen said that technicians will likely see newer products that may perform better and more easily for higher value.
“Boiler marketers and designers continue to chase ways to increase product reliability and reduce fuel costs,” he said. “They prioritize efforts to simplify and shorten installations and spare homeowners the inconvenience of service calls. Future adaptive gas combustion technology will save installers combustion set up time and let them install new boilers in basements with factory precision.”
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