Click here to Find a Contractor in your area.
Welcome! Here are the website rules, as well as some tips for using this forum.
Need to contact us? Visit https://heatinghelp.com/contact-us/.

Variable speed pumps

Simply RadSimply Rad Member Posts: 165
I installed a Grundfos Magma 32-100 pump for a full house radiant floor system and I am amazed how little energy is used to distribute so much heat! The system is currently pump 16 [email protected] 13' and is ONLY using 63 watts!!!!!!! This is incredible. These pumps are huge energy savers considering I am using continuous circulation distribution. The home is 10,000 ft2 with a heat loss of 160,000 btus. Amazing to think an old school 100 watt light bulb uses more energy than the system pump. Also, something to consider is the fact I have been using the Viessmann Vitocrossal CU3A medium mass boiler that I use direct pumping. Meaning, the pressure drop is so low, non restrictive and has 20 gallons of storage, that I am using one pump for the radiant floors and one for the DHW. Super simple and highest efficiencies since there is no mixing the return water....direct return. I love this boiler and system

Cheers Jeffrey
Jeffrey Campbell

Comments

  • kjb1057kjb1057 Member Posts: 1
    Right on! Your a very smart individual
  • hot_rodhot_rod Member Posts: 14,425
    Nice work!
    It's nice to have access to all that data also.

    I sent you a couple PM about that radiation sensor, not sure you received them?
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • ShahrdadShahrdad Member Posts: 19
    Jeffrey, how many BTU's does your Vitocrossal have? I have a 123 year old house with an old gravity system and a 1970s cast iron boiler (196,000 BTU output), and I'm considering changing to the Vitocrossal. Could you tell me more about your system? I have cast iron radiators that are lukewarm most of the winter and the house stays very comfortable. I know the biggest Vitocrossal 300 CU3A has an intake of 199 BTUs, which at 95% efficiency should be an out put of around 190K BTUs. I think that should be enough for my old house, but not totally sure. I see contractors installing huge boilers for houses way smaller than mine in my neighborhood, and I don't want to go that route.
  • Jamie HallJamie Hall Member Posts: 14,945
    It might be better, @Shahrdad , to start your own thread. Your question isn't really about variable speed pumps, after all, but replacing a boiler -- a very very different project.

    That said, you are clearly guessing at what size boiler you might need. There is only one way to determine that: do -- or have done -- a Manual J heat loss calculation for the house. Slant/Fin has a very nice calculator here: https://www.slantfin.com/slantfin-heat-loss-calculator/ which is remarkably accurate -- and easy to use.

    You are quite right in thinking that too big a boiler isn't a good idea. In fact, it is a financial catastrophe. Do it right.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England.
    Hoffman Equipped System (all original except boiler), Weil-Mclain 580, 2.75 gph Carlin, Vapourstat 0.5 -- 6.0 ounces per square inch
    ShahrdadRich_49
  • Robert_25Robert_25 Member Posts: 274
    I installed Grundfos Alpha circulators in my system this fall.  I have been very surprised at how little power they use.  I think lots of systems are over pumped.
Sign In or Register to comment.

Welcome

It looks like you're new here. If you want to get involved, click one of these buttons!