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wheres your head?

t4t4 Member Posts: 6
what happens if you use a pump that has to little head


  • t4t4 Member Posts: 6
    wheres my head

    correction -too little head
  • ZmanZman Member Posts: 3,516
    edited February 2013
    It doesn't move enough water

    The new taco valves work well.

    It sounds like you have circulator problems. Please descibe the application.

    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • heatpro02920heatpro02920 Member Posts: 991
    edited February 2013
    Look at the curve?

    So say your pump is rated at max-15' and 15gpm, with a straight curve {I know that is an oxymoron} you will have 14gpm at 1 ft of head, 13gpm at 2, 12gpm at 3 and so on on until you get to 15+ where you will have 0 gpm... So to answer your question you will have little no no flow at maximum or higher head pressures...

    I had a local pro call me with a service call a while back that had 3/8" pex on a DHW circulation loop that ran up to the third floor {a long way away from the water heater} and wouldnt circulate, he tried 2 new pumps and couldnt get the water to circulate when the aquastat called, I installed a DW 009 and it worked perfectly.... There too much head for that 006 and it pumped 0gpm.... Most heating systems are under 7ft of head, Thats why 007s are popular they have a long even curve that doesnt break until around 10ft of head and starts at over 20 gpm, so it will wok with a ton of different system..

    Look up the graph for the taco bumble bee that has a straight 15/15 curve...
  • pipekingpipeking Member Posts: 252
    i thought

     that when recirculating water, the hight of the system doesn't affect the head of the pump, it's the pipe and fitting resistance that affects head pressure of a reciculating pump? this is because the hight of the system (system head) is applied to the pressure of the system by the auto feed or street pressure. then u have "zone head" which is only affected by resistance, not pressure. am i saying this right? 
  • SteveSteve Member Posts: 486
    Not to hijack this tread


    Quick question How come 3 speed Circulators do not seem popular in this country

    When I worked in Europe (late 80,s early 90,s)

    Grunfos 3 speed was all we used

    Most of those systems were open vented Maybe that's the reason.
  • SteamheadSteamhead Member Posts: 11,378

    we don't want people fooling with them. 
    All Steamed Up, Inc.
    "Reducing our country's energy consumption, one system at a time"
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
    Baltimore, MD (USA) and consulting anywhere.
  • heatpro02920heatpro02920 Member Posts: 991
    I have used many 3 speed circs

    For hydronic residential heating the taco 007 has been the "go to" circulator for a long time, it comes as OEM with most every FHW boiler {except a buderus and just a handful of others}. it has a long curve and meets the needs of a lot of the residential systems....

    As for the 3 speed circs, I find 1- customers just turn them up to high anyway 2- they cost a little more {obviously adding to the price is never good} 3- on most residential systems you are not going to show a huge difference in performance between the 3 settings....

    Now if you add a simple delta t circulator, then you can get obvious gains and your system will operate better...

    I just see the 3 speeds good for keeping 1 circ on the truck that can replace 3 different models, but since they seem to only replace the 007, I figured why bother... And If you are doing a new install you are going to obviously know your head and gpm needs and buy the correct circ for the job when you buy the boiler...

    But anyway them are just my thoughts, I want variable speed controlled by an ODR, duct sensor{hydroair}, or supply/return sensors not a switch no one is ever going to change...
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