Operation High Efficiency: Condensing boilers play well with others
How high can you go?
With efficiency rates for condensing boilers in the high 90 percents, where does product development go from here? Manufacturers are looking at features that optimize the potential of condensing units, streamline the installation process, as well as make integration into building automation systems less complicated.
“We see that the focus is shifting from individual certified boiler efficiencies to the total installed efficiency of all equipment in the boiler room. The quest: how to optimize boiler operation with the other components of a heating installation,” said Chuck O’Donnell, director of marketing, Laars Heating Systems.
“A key facet of that is to match distribution flow rate to boiler modulation. As a boiler modulates down to more efficient levels based on heat load, a variable speed pump should be used to match the loop’s flow rate. For commercial systems, the Laars Vari-Prime system ensures that the boiler always remains in phase with the flow rate of a variable speed pumping system. This optimizes both boiler efficiency and pump electrical use.”
“We have achieved upper 90 percent efficient boilers and it would be a marvel to get near 100 percent, but every far-reaching goal has its limitations,” said Brian Fenske, specialty channel marketing manager, Navien. “It is time for the industry to use the high-efficient product offerings available and apply them in an attainable high-efficiency operation. What happens is the high-efficient boilers are being installed in situations that won’t allow or rarely hit its efficiency potential.
“Many manufacturers are providing adjustable boiler operation parameters that are rarely used or adjusted for the particular systems. In addition, there is a long ways to go to get the majority of hydronic designers and installers to create a system that is beneficial for the application of 90 percent plus AFUE boilers available today,” Fenske said.
Economy as a Variable
In addition to high-efficiency equipment, Lochinvar is leading the charge with advancements in control technology, said Jeff Vallett, segment market manager for the company. The next generation boilers feature smart controls that simplify serviceability and streamline operations for all parties involved. For example, Lochinvar’s CON·X·US remote connectivity platform, which is available on the FTXL Fire Tube Boiler and our KNIGHT Boiler family, allows most smart devices to be linked with compatible SMART SYSTEM boiler controls from around the corner or halfway around the world.
“Using a wired or wireless connection, CON·X·US offers the ability to log in to a boiler, monitor its current status and modify operational settings from a remote location. For example, the user can view the current outdoor air temperature at a connected boiler’s location, track the target reset temperature when there is a call for heat and ensure outdoor reset is being utilized properly. CON·X·US will even send a text message or email if an issue with its operating status arises. One contractor even told us there are so many advantages to having CON·X·US remote connectivity that it’s like having another employee in the field.”
The demand for high-efficiency products really depends on the state of the economy, “people having money to invest upfront for the equipment and if there are state or local utility rebates,” said John Kopf, senior product manager, Weil-McLain. In certain cases, local utility rebates can pay for half to 75 percent of the equipment. “Second, there is the potential for lower operating costs with boilers that can modulate down in response to lower demand for heat. You’re getting your return water temperature lower and lower, and that improves efficiency.”
“Standard efficiency” is anything less than 90 percent, Kopf explained. Anything 90 percent and up is considered high efficiency. ”The DOE introduced a new rule in 2012 requiring manufacturers like us to research to bring the standard efficiency up to 82 percent. Utility rebates typically kick in when you’re at about 90 percent. In my opinion, realistically, I think 94 to 95 percent is the goal; you can get 98 and 99 percent in certain artificial conditions, but not in everyday situations.”
The most important feature of the condensing boiler is the efficiency, Kopf said. “Condensing means they operate at about 90 percent so users save with the initial cost, based on the utility rebate, and second, there is the savings from lower operating costs. However, we have seen customers going back to standard efficiency cast iron boilers because they have longevity, such as churches and other private spaces. Government and educational verticals look for efficiencies, for green solutions; and they look for rebates, Kopf added. “So, naturally they tend to go more for condensing high-efficiency boilers.” Building usage also impact system choice. If a space use is sporadic rather than constant, different demands are presented and different solutions available.
“For example, in process applications where you have to keep temperatures steady, it’s not a good application for a condensing unit, because you would be operating at the maximum design at probably the lowest efficiency point,” Kopf said. “When the application is comfort heating, you may want to consider condensing because there is only three to five percent of time throughout the heat season when the boiler will be operating at full load.”
Focus on Hydronics
What are the “new” features on condensing boilers that are now taken for granted? New and recent features include fully integrated on-board controls that can control multiple boilers, auto-rotate the lead boiler if the original lead boiler fails, and easy connections to building automation systems, O’Donnell said. “These are features and capabilities that are now included that, in the past, would require multiple, external control systems.”
Today’s consumers and contractors are now expecting boilers to deliver high-efficiency operation, so that’s no longer viewed as a new feature but really a standard for a modern boiler, Vallett said. “Otherwise, there is enough differentiation between manufacturers’ products that unique features are still important difference-makers in the buying decision by contractors.”
Contractors appreciate pre-configured controls, easy express setup, and plug-and-play operations, Weil-McLain’s Kopf said. “Nobody wants to go to the job and troubleshoot and troubleshoot, because time is money. For condensing boilers, preconfigured controls are quite important. There are controls where you can get express set-up and everything is pre-loaded at the factory. “At the job site, the installer would enter the date and model number, and the controls are ready to go. Pre-configured controls are becoming more important for boilers with advanced features, such as multiple boilers, modulation, sequencing and communications between boilers and with building automation systems.”
Kopf said contractors also need to be aware of venting arrangements so they can deal with challenging installations. Common venting is another optional feature for multiple boiler installations, he said. “If you have eight boilers, you don’t want to have eight pipes going through the wall, because you’ll have to have eight openings. Instead, you can have all eight boilers vent to a common vent dock, a manifold or plenum, then this goes to a common vent through the wall.
“When you have multiple boilers, boiler rotation is becoming pretty much standard, Kopf added. You run boiler number one for a certain number of hours, then switch to boiler number two, and so on. Manufacturers offer this in four-, eight- and 16-boiler options.”
Smaller and lighter wall-hung high-efficiency condensing products have changed the way some installation companies bid and schedule their work, Navien’s Fenske said. It’s very common today to see boiler installation company’s pre-pipe boiler panels to simplify and shorten the time required to install or perform a boiler change out.
“Navien’s boilers appear to follow the norm of about four to five percent of our boiler products being applied in radiant applications,” Fenske added. “This remains to be a vastly untapped hydronic application arena that shows the largest growth potential for residential and commercial boiler applications. Our past year’s heavy boiler growth has been in the rapid expanding combi boiler segment. With the recent introduction of our NHB series boiler into our residential/light commercial offering, we expect great successes with our full-rounded water product offerings.”RJ