QUESTIONS
ANSWERS
What, exactly, is a Munchkin boiler?
It’s basically a higher-tech water heater with double the efficiencies and capabilities, with very little water storage. It can create a lot more heat in a very small space, with probably four times the life expectancy of a water heater.
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Why should I go with a boiler instead of a cheaper, simple water heater?
Because the cost of operating a hot water heater could be more than double that of an efficient boiler. If you have a 2,000 to 4,000-square foot home, you’d need several water heaters to heat your radiant floors and then another one for domestic hot water.
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How efficient is a boiler?
Up to 95% efficient. The average water heaters is about 70% efficient (that means it actually burns only 70% of the natural gas or other fuel, with the remaining 30% going up in the air. But here’s what happens: You heat the water at 70% efficiency; then it cools off if you don’t use it right away. Then it has to be reheated — this cycle can go on and on. Some of the best boilers don't have any losses at all, because they're on-demand.
An average water heater for a small family, according to National Renewable Energy Laboratory, is about 30% efficient, considering standby losses.
A 95% efficient boiler with a super-insulated tank will lose only about 1/2 degree a day. So when you get the tank up to temperature, you’ll only use a minute amount of heat. (check ratings of tanks)
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How do I size my boiler?
To properly size the boiler, have the home evaluated for Btu needs. This is important because it’s easy to oversize your boiler, using a draw-from-the-hip estimate. With a boiler that’s too big for your needs, you not only spend more money upfront, but you also shorten its life, because it short-cycles more than it should. Short-cycling is what happens when the boiler starts, catches up real fast and then stops, so that the boiler spends all of its life starting, and not actually running. Fuel consumption is also higher with so much starting action.
You can figure out your home’s Btu needs using a comprehensive heat-loss calculation program, which will determine the Btu total you'd need to heat your home in the coldest conditions. A Btu is equal to the energy of a match, or the amount of energy it takes to raise one pound of water by 1 degree. Many contractors can perform a heat-loss calculation, simply from your house plans.
Once you know the Btu needs, size the boiler no more than 15 to 20 percent higher than whatever the Btu total is. For instance, if your home will need 80,000 Btus to keep it warm, an appropriate boiler size would be 100,000 Btus.
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Can I use a cast iron boiler or water heater?
We recommend strongly against cast iron, and the industry is agreeing more and more. Unlike stainless steel, cast iron deteriorates over time and fill the system with gunk. Cast iron boilers are often less energy efficient. So if you install a 100,000 Btu-boiler that’s rated at 70% efficiency, you’re getting the equivalent of a 70,000 Btu boiler, so it would be too small to heat a 100,000 Btu home.
Also with cast iron, the efficiency deteriorates over time. The production of a 5-year-old boiler, for instance, could be significantly less. The boiler may last 20 years, but it’s efficiency curve has bottomed out.
Comparing costs, a stainless steel boiler is more expensive, but it can be sized smaller. A cast iron boiler would have to be pumping out 120,000 Btu of heat to meet the needs of a 100,000 Btu home.
There are also other factors to consider. A cast iron boiler, for instance, has to operate at 180 degrees to reach maximum efficiency. Whereas, a stainless steel high-efficiency boiler can run much more efficiently at lower temperatures. Most in-floor heating systems can heat a well-designed home on between 100 and 110 degrees. A heating system with a cast iron boiler is often more complicated.
It is not efficient to heat water to 180 degrees, but mix it down to a lower temperature.
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Can I install a boiler heating system myself?
Because it’s hard to fix problems buried in concrete. It’s best to have a professional design and provide the system, because one or two components can destroy the system if they’re not correct.
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