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Mod/Con Boiler Technology
Modulating/condensing, gas-fired boilers (ModCons), meet my goals for nearly every hydronic heating system, new or retrofit: safety, reliability and efficiency. If we add to this integration, we can talk about investing in ultra-high combustion AND system efficiency. Lets start with a gas-fired appliance at say, 98% thermal efficiency and use this superior heat source to supply water for bathing, heat for floors, walls, ceilings, sidewalks, driveways, pools, furnaces...well you get the idea. Mod/cons are a perfect match for CAST IRON RADIATORS. System efficiency comes from engineering distribution and control systems that optimize a particular boiler’s capabilities. In the not-so-distant past, the reliability of high efficiency boilers was an issue and the service industry's lack of experience with high efficiency equipment made for sparse and sometimes poor system design, installation, service and maintenance. This is still true to a degree, as you will find if you try to secure a bid to install a new high efficiency boiler. In short you will probably receive 6 bids all proposing an 82 (federal minimum) to 86% AFUE boiler (this is low efficiency). They will also be within a few hundred dollars of one another and probably won’t include a computer generated heat loss analysis, options for domestic water heating or outdoor reset. These otherwise knowledgeable contractors will inform you that high efficiency or condensing boilers are "too expensive", "unreliable" or they require "too much service". This was the case with some units and particular installations of the past, is no longer the case. By the way, your local gas provider is neither trained or qualified to design, install or service a high efficiency gas-fired appliance.
This is a new day. In Europe wall-hung gas-fired water and space heaters are commonplace. In Germany condensing technology is more than 25 years old! In the United Kingdom it is now mandatory to install condensing boilers in new construction and retrofit. Today most domestic boiler manufacturers offer condensing boilers (7 manufacturers offer 95 AFUE boilers!) most of which utilize European design and/or manufactured components. Many thousands of condensing boilers are operating in the US. In fact I recently serviced one of the first condensing boilers still working since 1990! Mod/Con boilers stand-alone in the level of sophistication they bring to any heating system. Early condensing boilers like the ones I sold and serviced in the 80's and 90's would condense (that is, reduce the stack temperature from say 550 degrees Fahrenheit to 100°F) only when installed properly in an appropriate heating system. Today a microprocessor is used to regulate the burner and produce the lowest water temperature necessary to replace the heat lost by your home. This low water temperature keeps the boilers condensing (and running) as much as possible. Operating like cruise control on your car, the boiler senses the outside air temperature and ramps the boiler operating temperature up and down with the weather. This is called OUTDOOR RESET and the combination of outdoor reset, condensate energy recovery and burner modulation has made the Mod/Con boiler the unmatched energy saver for space and hot water heating. Today there is a Mod/Con that will work with any hydronic system and improve performance, comfort and efficiency. P.S. Most Mod/Cons can be set on the floor, hung on a wall, use plastic pipe for intake air and chimney and are nearly silent while operating!
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