The Wall
Forum / Gas Heating / head loss for mono-flo
  • Post a Reply to this Thread

    head loss for mono-flo (9 Posts)

  • cyrus_pinkney cyrus_pinkney @ 4:05 PM
    Contact this user

    head loss for mono-flo

    I am attempting to calculate my feet of head to decide whether or not I need to use a P/S system for my new boiler setup. I have never calculated it for a mono-flo type of piping layout. I am hoping some of you fine people could assist me in this.

    I have a single loop (for now) serving my entire home (see plan attached and here). Do I calculate the entire system as a single number or should I only calculate the longest half of the loop?

    I am contemplating installing radiant heat in the basement and am wondering if that will impact whether I'll need P/S also.

    As always, thank you.
  • R Mannino R Mannino @ 7:25 PM
    Contact this user


    speed # 1 on the 15-58, it should work fine as long as the monoflo loop hasn't been "hacked up" into more than one zone.
  • cyrus_pinkney cyrus_pinkney @ 8:17 PM
    Contact this user

    should've just asked you directly

    @R Maninno strikes again!

    I should've just asked you directly, but thanks for the answer. The original loop is still in tact, but it appears that they tee off for 2 baseboards in the basement, but the entire house is on one zone.

    Should I be using the Grundfos UPS15-58 for both pumps in my setup?
  • R Mannino R Mannino @ 8:23 PM
    Contact this user

    The 3 speeds

    give you some adjust ability to tweak the system. A true monoflo system has a very low head loss. I learn from the guys here too ya know. I have seen a hacked up monoflo system or two that needed a higher head circ to over come the issues.
    This post was edited by an admin on October 16, 2013 8:24 PM.
  • cyrus_pinkney cyrus_pinkney @ 8:28 PM
    Contact this user


    alright, I'll use those pumps for both, then.
  • Rich Rich @ 10:51 PM
    Contact this user

    For reference

    The hydraulic resistance of a 3/4" B & G Monoflo tee is equivalent to 70 Ft of pipe , a 1" is 23.5ft and an 1 1/4 is 25 ft. .  Stay outta trouble .
    You didn't get what you didn't pay for and it will never be what you thought it would
  • cyrus_pinkney cyrus_pinkney @ 10:17 AM
    Contact this user

    how is the tee measured?


    thanks for the input. This might be a ridiculous question, but the tees I have on my system all come off a 1" loop and feed up to the radiators with 1/2". Does the fact that the tee feeds into 1/2" matter?
  • Rich Rich @ 4:47 PM
    Contact this user

    Be most

    concerned with the Big loop , water has no choice but to flow through the emitters . Are there 2 MF tees per emitter (cringe) ? If so you are gonna need a hell of a pump .  The tee is measured through the run of the fitting .  They are not low loss systems as previously mentioned .
    You didn't get what you didn't pay for and it will never be what you thought it would
    This post was edited by an admin on October 17, 2013 4:56 PM.
  • cyrus_pinkney cyrus_pinkney @ 9:25 AM
    Contact this user

    single mono-flo tee

    I guess we can both breath easy Rich, there is a single mono-flo tee for each radiator. The funny thing is, I believe the system was installed backwards, or at least the tees are. I have only owned the home through a half a winter, so I don't know how well it's performed. After dismantling the boiler I realized that the pump (which I have been under the impression is almost always on the return) is a Dayton 5GD80. If the pump is indeed on the return, then the tees are with the pump, meaning the arrows on the mono-flo tees point AWAY from the pump. Is it possible that all of these tees could be installed incorrectly? Or is it possible that the pump is on the feed? It's a big ol' oil-fired American Standard, if that makes any difference.

    My question now, going forward, should I pipe it correctly and have my feed going in the direction of flow with the tees towards the return on the boiler? I fear that after 50+ years of the water running in one direction, if I reverse it, I may screw something else up.
    This post was edited by an admin on October 18, 2013 9:26 AM.
Post a Reply to this Thread