There are some opportunities that come along for homeowners that seem to good to be true, and most of your parents and grandparents can tell you if it looks this way it probably is.  But, how about quick return on your investment that will continue to save money for the life of your boiler?  This is what an outdoor reset control will do for them.  Add the feature of a more comfortable home and most people start asking: What is the catch?  The catch is the technician needs to not only sell this product, but install it correctly and educate the customer on the new use of the boiler.

    When installing an after-market outdoor reset control on a non-condensing boiler, be sure to keep the minimum Return Water temperature above 115F.  Most recommendations state 120F to avoid condensing on the sections and in the flue.  The installation of said control will save an estimated 15% of the annual fuel costs!  The same percentage in AFUE as the difference between an EnergyStar boiler versus conventional.

Example Boiler Heating Curve

      Next, make sure you educate the homeowner on how to operate the new boiler control.  This more energy efficient option provides the minimum amount of heat to match the load based on outdoor temperature.  Common sense can tell us we don't need 100% of the capacity unless we are at, or below the outdoor design temperature.  In MA this design temperature is likely around 0F.  The boiler temperature is generally set for 180F, this is the maximum the boiler operates at to meet the heat loss on a design day.  But, when it is warmer outdoors you don't need 180F water anymore, and you can be more comfortable by turning that temperature down.  Unfortunately, this makes your programmable thermostat almost obsolete.  You see, a large set back with a thermostat (more than a couple degrees) will take hours, even a full day, to recover if using an outdoor reset controller.  I see this a lot when homeowners replace a boiler with a tax credit eligible option and never get the education needed on the operation.

     I have heard arguments regarding increased electrical consumption since your circulator will now run for almost infinite periods of time.  Luckily, our Manufacturer friends have thought of this and developed some amazing pumps over the last couple of years.  Most of these ECM pumps will operate at minimum 50% less than their counterpart PSC pump.  To put it into friendly terms, instead of approximately 84 watts, these new pumps can range from 9-42 watts depending on load.  As more zones turn on, the pump will need to speed up to maintain the gallons per minute (GPM) or temperature differential settings.

     That all being said, I would recommend installing both of these: an outdoor reset control and ECM pump on any boiler without one!  It is not a code requirement, but it probably should be.  Have a Domestic Hot Water Indirect?  They have a priority setting for that.  Can't run the sensor wire outdoors in the mechanical room?  There are wireless versions that are now cheaper than the traditional controls!  Don't live in fear of your customers saying no - and put the inventory on your trucks!  It will amaze you how fast they move, particularly when you start offering Utility Rebates for most Natural Gas customers in RI and MA (sorry, no pumps in MA)!  When installing the parts, including markup and labor costs, the total job can run around $900 or so.  When the RI natural gas customer can receive $325 in rebates, this drops the payback period to about 2 years!  Depending on fuel usage, payback could be sooner.  Without rebates for Propane and Oil applications, this makes the payback approximately 3 years on a boiler that may be in for another 15 years?  That is an incredible amount of fuel & electrical savings, plus comfort.  So, what's the catch?

http://excessair.blogspot.com/2013/02/outdoor-reset-ecm-pumps.html

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Comment by Christopher Morin on February 12, 2013 at 6:24pm
Thanks for the suggestion Bob, I first heard about this from my local Lennox Rep. some 15 years ago - in fact I think he even wrote a few articles on the application. In theory this could be a poor man's outdoor reset, particulalry for a non-condensing boiler. Although the theory seems bulletproof, I worry about the lack of control regarding comfort in a poorly sealed/insulated home. Has anyone out there actually put this to use? I have to admit, I was always worried about the potential "call-back" and never put this into practice...
Comment by Bob Blanchette on February 12, 2013 at 4:25pm

Could the 2nd stage of a 2 stage stat not be used to increase temperature of the boiler as needed? Stage one engages the circulator, stage 2 increases the temperature in the boiler until the house warms up. Water temperature would never have to be any warmer than needed to do the job other than meeting the 120 degree minimum for condensation issues. During mild weather the circulator would cycle the 120 degree water, during cold weather the circulator would run constant and the 2nd stage of the thermostat would increase/decrease boiler temperature as needed.

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