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Preferred System Pump for ModCon Secondary Loop

BoilOver2 Member Posts: 38
I'm having trouble tracking a clear answer down to this, so figured I would ask this group. I'm looking to have a ModCon boiler installed (Lochinvar Noble) with zone valves and was wondering whether a delta p ecm pump is preferred (ex: Taco VR1816 or Grundfos Alpha2) or a delta t pump such as a Taco VT2218. It seems that some would say DONT use a delta T pump since that counteracts the mod cons control approach, but elsewhere others seem to actually recommend it. Thanks in advance.


  • clammy
    clammy Member Posts: 3,113
    a lot would depend on your heat emitters and how much temp control you would desire on zone loops. On my own mod con had a standard grundys 15 58 and switched to a wilo ecm pressure differential pump for both a panel rad and staple up zone both running the same low temp Noticed better control on radiant temp meaning tighter 10 td through the whole cycle and a bit of a wider td on my panel rads being its set at a lower head I use the pd pumps for zones and td where I want to try to maintain a set td across my loops hope that helps. Of course on the boiler it has a fixed speed pump over all I can’t complain gotta the wilos for a song and dance being most of the guys at the supply gawk at any pump over 100 bucks I got them for a little bit more then a007 so I brought a few and have been using no issues yet but keep your eyes open for magnetite particles related to steel piping and spend some $ on a good maginetic separator it’s cheap insurance and good custermer relations peace and good luck clammy ps others may think differently but it been working for me
    R.A. Calmbacher L.L.C. HVAC
    NJ Master HVAC Lic.
    Mahwah, NJ
    Specializing in steam and hydronic heating
  • Ironman
    Ironman Member Posts: 7,379
    With zone valves, you want a delta P.
    Bob Boan
    You can choose to do what you want, but you cannot choose the consequences.