recirc loop ok can't add branch

Discussion in 'Plumbing Forum, Professional & DIY Advice, Tips & ' started by den, Jan 14, 2007.

  1. den

    den New Member

    Messages:
    6
    Currently have a hot water recirc loop to master bath. Grundfos pump is attached to hot water return line (upside down) and tee'd between the water supply check valve and expansion tank at the HWH. That works ok. When I put a comfort valve between the hot & cold water under the kitchen sink it has no affect.
    Kind of acts like a check valve is somewhere in the system, more than likely I don't understand the concept. Florida house, so cold water plumbing is either coming up thru the slab or hidden in the wall which prevents me from visually checking beyound the hwh connections

    Anyone have some advice
  2. jimbo

    jimbo Plumber

    Messages:
    8,997
    Location:
    San Diego
    You are mixing apples and oranges. The existing recirc loop is circulating water at a fairly low volume. There is very little DP on the hot line, not enough to open that Comfort crossover valve.
  3. den

    den New Member

    Messages:
    6
    Jimbo

    Based on your input I guess I need to put a small recirc pump under the sink
    ie: autocirc1 from Laing??

    Den
  4. jimbo

    jimbo Plumber

    Messages:
    8,997
    Location:
    San Diego
    I would not recommend mixing a recirc loop and a retrofit pump. I would check with grunfos on the Comfort system and ask them if there is any way to make that work alongside a dedicated recirc loop.

    I guess a Laing under the sink maybe would be transparent to the recirc loop, but I am not positve about that, either. Possible unforseen issues.
  5. den

    den New Member

    Messages:
    6
    Sent E-mail to Grundfos

    Thanks again for the input.

    Sent an E-mail to Grundfos ==

    Den
  6. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,285
    Location:
    Cave Creek, Arizona
    comfort

    I install the comfort pump on the hot water outlet as usual, (not at the return lines connection to the tank), with the comfort valve under the sink. You may need a spring loaded check valve where the dedicated recirculation line connects to the heater to prevent chatter.
  7. den

    den New Member

    Messages:
    6
    not much room

    All the examples I have seen show the pump location as you describe.
    Since this pump has been in place for about 8 years it seems the reason
    it was installed on the return line was that the installers did not leave
    themselves enough room to attach the pump between the hot water outlet
    pipe and the wall. Outlet pipe makes and immediate 90 deg. turn at top of
    tank then enters wall within 8 to 9 inches. FYI on the return line before it
    goes into the pump is a spring valve. If it is possible to relocate pump per
    your suggestion would that create more DP than the way it is currently .
    "Jimbo" thought they may be a chance of conflict between the dedicated
    loop & the cold water recirt. Your thoughts.

    Thanks,

    Den
  8. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,285
    Location:
    Cave Creek, Arizona
    pump

    You are confusing apples with oranges. The pump was put where it was because that is the proper location for the original circulation system. NOW, you are adding that "orange" and for that the pump has to be on the heater's outlet, because you are creating a 'hybid" system and for that you have to let the Comfort system be the primary one and your original circuation system, ride on its coat tails. It will work, but only the way I have described it.
  9. den

    den New Member

    Messages:
    6
    HJ - don't shoot me

    I am only attempting to get hot water to the kitchen sink quicker - and
    I tried the comfort valve because of a suggestion by the local plumbing
    supply shop. Do I have two options? One: Purchase a comfort system
    pump and have it installed as you described (not good at sweating pipes) . Two: Put a autocirc1 type pump under the kitchen sink (this I can do).

    DEn
  10. solsacre

    solsacre Plumber

    Messages:
    70
    Location:
    Arkansas
    You've got to visualize the system under the floor. It is a loop. you are working on a branch of that loop.... withiout more exact info we can't help you on, if this will work.

    Use your mind's eye... will this extra pump work or ad problems.....


    a rec pump adds no pressure, it only creates flow........:eek:

    will the two pumps create flow that is complementry, or will there flow clash.?

    It's in the exact application that will see a solid system.

    good luck

    dances-with-pumps
  11. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,285
    Location:
    Cave Creek, Arizona
    pump

    You can do it either way. The Comfort pump does not use soldering if your heater is connected with corrugated flexible supplies. It fits between the heater and the supply pipe. You get a better pump with this system than the small one with the AutoCirc type installation. If you use the Comfort pump remove, or at least unplug the present circulation pump.
  12. den

    den New Member

    Messages:
    6
    Thanks to all

    Jimbo, HJ, Solsacre

    Thanks all for the help. Let you know the outcome.

    Jimbo - I was a ping jockey (sonar) on a destroyer USS Damato
    in the early days of the nukes. Never had much luck
    picking you guys up.

    Den
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