Replies

1. Expert Member
   Dana Dorsett | Dec 09, 2015 04:51pm | #1

   Retrofit heat purge controllers/economizers for boilers are cheap & effective. The Intellicon 3250HW+ is cheap & effective heat purging economizer suitable for cast iron boilers, and has a good track record. There are other more sophisticated models out there with other functions, but it's not clear they work any better (or even as well.) It's DIY-able for those with some electrical skills. The greater the degree of boiler oversizing for the heat load the greater the fuel use reduction, but low double digit percentage savings are common.

   Retrofit outdoor reset controls for cast iron boilers is a mixed bag from an efficiency point of view, and will often short-cycle a boiler into lower efficiency, or worse- potentially destroying the boiler with return water that's too cool if not implemented correctly. It needs careful system analysis & setup, but they exist, and sometimes provide efficiency improvement.

   I'm not aware of retrofit ECM drive blowers for hot air furnaces, and would be surprised if they existed. There are many ways it could be problematic, unless the retrofit was designed and specified for particular models through the original manufacturerer.

   ECM drive circulation pumps for hydronic systems exist, and can cut the electrical power use in those systems dramatically. Some are programmable for setting the delta-T on a loop or progammable fixed flow rates, or programmed temperatures, etc. There's a variety out there- the Taco Bumblebee and Viridian series are pretty popular with hydronic designers, as are the Grundfos Alpha series. In the right hands with the right analysis the full system efficiency can often be improved, not just the power use portion. But even in the hands of DIYers a lot can be done with these smart pumps. (You still have to be able to read a pump curve, and understand the characteristics pumps you are replacing though.)

2. 
   wlarsen | Dec 10, 2015 06:05pm | #2

   Thanks!

3. 
   jj1 | Dec 10, 2015 06:47pm | #3

   Hi Whitney: actually replacement ECM furnace blower motors are available from two manufacturers: the Concept 3 (aka Fieldpiece LER motor) and the Evergreen IM model. Martin Holladay wrote a typically excellent summary at: https://www.greenbuildingadvisor.com/community/forum/mechanicals/20709/swapping-ecm-psc-fan-motor
   NREL has published a comprehensive summary and cost/benefit analysis of the Concept 3 at:
   http://www.nrel.gov/docs/fy14osti/60760.pdf
   NREL concluded that the typical $20 p.a. electricity savings provided an inadequate payback relative to the approx. $475 installed cost, unless of course the existing blower motor needed to be replaced anyway, or unless the homeowner used the furnace fan ON mode during all/most of the year.

4. 
   user-2890856 | Dec 11, 2015 08:08am | #4

   Dana , as usual hit many relevant points . Thermal purge is a very good technology , especially if you purge the leftover heat in the boiler to your water heater or a tank prior to your water heater . Nothing sucks up excess heat better than a big tank of water .
   There are many things that can be done with water based systems that are altogether less expensive than ripping out everything and replacing with something cheap . Whatever anyone does with these systems to renew them though , you must take a system approach , not just replace parts .

5. Expert Member
   Dana Dorsett | Dec 11, 2015 02:54pm | #5

   BTW: The Concept 3 / Fieldpiece LER retrofit air handler ECM motor is apparently no longer available.

   The Genteq Evergreen IM series are around, and can replace some split capacitor air handler motors at about $300 / pop (f.o.b. the distributor's warehouse, not the installed price.)