What you wanted to know in 2022
By Bob “Hot Rod” Rohr
By far and away the question I was asked most frequently in 2022 is: How can I keep my energy costs down with rapidly rising fuel costs? On the hydronic chat rooms, the question is worded more along the lines of increasing the boiler efficiency. Bottom line … the most frequently asked question is a great one, with lots of answers for you to pick and choose from. Consider the savings from the increased efficiency against the upfront costs. Also, add into your calculations that using energy efficiently is good for the soul, and the planet.
WHAT ARE THE OPTIONS?
While cleaning and adjusting the boiler may pick up a few percentages of efficiency, it may not show up as a huge fuel savings. Most condensing boiler manuals suggest a yearly cleaning and combustion analysis, but I doubt the majority of boiler systems are serviced yearly. This would include attaching a proper combustion analyzer to check and confirm and document the settings.
With mod cons, or, really, any fuelled appliance, they are what they breathe. In dusty regions and high pollen areas, expect to see the “mouse turd” residue when you open mod cons up. That is the blend of byproducts of combustion mixed with the air borne contaminants. You essentially have a vacuum cleaner pipe sticking out the building. Even bugs that get close will be inhaled. Many of the manufacturers have “how to’’ videos online for proper cleaning procedures. Have extra gaskets on hand, possibly a spare flame rod, or other consumables when you are servicing hydronic systems.
An accurate combustion analyzer is a must for dialing in high efficiency equipment. Take a class on how to use and decipher the results. Any fuelled boiler would be a candidate for a combustion check. Leave a printout on the equipment or keep the results in a cloud folder for reference.
ELIMINATE EFFICIENCY HIT
Short cycling really puts the hurt on equipment efficiency. Studies have been done on the efficiency hit you can expect from a short cycling boiler. I know of no official number for a short cycle. The number in the industry seems to be a minimum of 10 minutes of run time each time the boiler fires. A huge step towards boiler efficiency was the introduction of variable output rate boilers, known to most of us as mod cons, which is a nickname for modulating, condensing boilers. While the condensing function can get you an efficiency boost, don’t ignore the importance of the modulation. The more closely we can regulate the output to match the load, the less the cycling. This helps not only with fuel consumption, but lessens the wear from stop and go operation on gas valves, relays, fans, and other system components.
About 10-1 seems to be the lowest turn down to be able to maintain a stable flame. Hopefully we see a time where we could turn down to a few thousand BTUH output. I’d like to see the boiler fire on the first call for heat and modulate all through the heating season, never shutting down, maintaining a perpetually-fired condition. Think Olympic flame
ADDRESS THE STRUCTURE
So, we have addressed the efficiency of the appliance, whatever type it may be, and upgraded the distribution system. Now, what next? At the end of the day the best money you can spend in the quest to keep fuel costs affordable is to address the structure. The cost to keep a building warm is directly related to how well the building keeps the heat inside.
A heat load calculation on the building as it stands, or before it is built will give you an idea of how much fuel and money it will cost to heat. On new construction, at the least, insulate and seal to building or energy codes. Go beyond the minimum if you can, as it is a gift that keeps on giving: the efficient shell.
For existing buildings and homes, you have some energy audit options. The load calc needs to reflect some necessary assumptions, of course, since the walls are closed up. An infrared camera walkaround will get you a good picture of where the heat energy is escaping, and possibly even show a roof or siding leak. Another big and often overlooked variable is infiltration. This is perhaps the biggest energy thief. A sound investment would be weatherstripping to control leaks around the framing members, windows, etc. A blower door test will calculate how much a building leaks. In some areas your utility provider may offer this service. They have skin in the game to lessen loads on their resources. Or find an energy audit person or company that will perform all of these tasks: the load calculation, infrared scan, and blower door test.
In our last home I had a crawl space and I sealed the rim joist connection, and also used some of the underslab radiant insulation tarp product to cover the walls and dirt floor. I could immediately feel the difference on our feet as we sat in the living room during winter months. Drafts were eliminated and fuel was saved.
A few cans of expanding spray foam goes a long way to sealing a leaky home. The low hanging fruit is where the bottom plate contacts the footing or foundation. As the wood framing shrinks, gaps open and the wind blows through, taking your energy dollars along with it!
Keep in mind you do want some air changes for a healthy home, so don’t hermetically seal your home or building. ASHRAE has guidelines for ACH air changes per hour to maintain a healthy space. Humidity control will be a part of the equation, also.
If you are starting with a clean slate, I’ve found homes with radiant heat systems can run a few degrees cooler on the thermostat setting and be comfortable. With any hydronic or steam emitters, you are warming the objects in the space as opposed to blowing warmed air around. You can sometimes retrofit hydronics. Panel radiators are a great retro option.