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"Heat Flo" - a Honeywell synchron valve copycat for radiant floor system. Anyone heard of this?

I have a 14 year old home built in 2002. It has 3 floors of in-concrete radiant floor heating. I was away for two days and when I arrived home the house was HOT. My upstairs master bedroom zone was set for 64F but the thermostat showed the room was actually 84F. The outside temp today was 57F. To be safe I turned the Heat to "Off" at the thermostat in the Master Bedroom.

After going down to the furnace room and checking the levers on all the valves I can see that only the Master Bedroom zone is "open". All the others are closed. Hopping online I read that you can try tapping or knocking on the valve to see if it will close. I tap firmly 6 times with my knuckles and like magic, I hear the valve close and watch the lever move.

Herein is my first issue: What the heck? Why would knocking on the valve help it get into the closed position? Is this just a temporary fix and if I don't replace something I will need to run down to the furnace room and knock on this valve every day or week?

So, assuming I'm going to need to replace this faulty, sticky valve, I proceed to look for a make/model. There are 7 zones and in the furnace room there are 7 of these "Heat Flo" valves. I refer to them as Honeywell synchron valve copycats because that's what they look like, and they have a Synchron motor inside them.

As you can see from the pictures, the model number / into shows it is:
- Heat Flo
- Model EZV20.224SF
- Input: 24 Vac 5 W
- Date Code: 9105
- Normally closed

Google is usually a trusty friend, but in this case, I'm not finding anything relevant.

So, I'm left with questions:
- can I simply replace the Synchron without draining the system of water?
- if replace the Synchron, what should I replace it with?
- can I do this myself or do I need a professional in?
- how can I diagnose if I need / can replace just the Synchron or if I need to remove this whole valve assembly and weld in a replacement one?

I'm based in Vancouver Canada and likely would source parts from Reliable Parts in Vancouver. Open to suggestions for part sourcing, and if I need a professional to replace this, then I'm also open to suggestions for who to call.



  • richardlau
    richardlau Member Posts: 3
    PS I took pictures of the "Kitchen Supply" instead of the Master Bedroom Supply" simply because they are identical and the Kitchen one is easier to reach.
  • kcopp
    kcopp Member Posts: 4,448
    From the shape of the cover it actually looks like a Erie boiler boss valve. Either way they wire up the same way. The valve it self may attach differently. (Erie had a paddle valve inside vs. the Honeywell Ball)
    This could have been a 1 time issue. I would get another valve an d be ready to swap out heads.
  • Solid_Fuel_Man
    Solid_Fuel_Man Member Posts: 2,646
    My first thoughts exactly, looks like Erie valve to me as well. Maybe they were sold under another name or rebranded for the Canadian market. Most major brond zone valves use the Synchron brand of synchronous motor in the actuator head, just with their own proprietary gearing after the motor'skills own reduction gearing.

    Serving Northern Maine HVAC & Controls. I burn wood, it smells good!
  • PinkTavo
    PinkTavo Member Posts: 64
    edited October 2016
    I typed in the valve model # into a search and found: http://www.heat-flo.com/

    They don't list valves on the site, but maybe someone there can help.

    All of the other sites that came up are Taiwanese, but do show the Model # in their text.
  • GeorgeCristonWidule
    I live in Vancouver and have the same problem!
    Were you able to find any information or where you can get some?
    I don't want to have to replace the whole works with a Honeywell zone valve system
    but 2 out of 3 have failed
    I'm getting desperate...
  • Harvey Ramer
    Harvey Ramer Member Posts: 2,261
    A sticking zone valve can be caused by water quality issues. It may be a good idea to run a hydronic cleaner, Fernox or Rhomar through the system for a couple days and then flush it and add a conditioner.
  • hot_rod
    hot_rod Member Posts: 22,472
    It is not an Erie, but a knockoff. We have several former Erie employees at Caleffi including engineers that developed Erie ZVs they are not aware of a valves licensed to that brand

    At that age you might consider replacing all of them. Typically 20 years at 5000 cycles per year is the design
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • rickyjaswal
    rickyjaswal Member Posts: 2
    I am having the same problem. But can't find this valve anywhere in vancouver. I have tried most of the major part suppliers. Did anyone here find out where to buy it in Vancouver. Thanks
  • Alan (California Radiant) Forbes
    To answer your questions:

    Yes, you can replace just the motor. The Honeywell might work:
    but like others say, it could be the valve itself that's bad.

    I'd replace the entire valve with a Caleffi zone valve:

    And if you don't already have a controller, put a couple of these in to make wiring and troubleshooting easier in the future:
    If you have 7 zones, you will need one 4-zone and one 3-zone controller.

    Can you do the work yourself? Do you know how to solder? Soldering is probably the easiest part. After the system is drained and the new valves installed, purging the lines of air can be tough.
    8.33 lbs./gal. x 60 min./hr. x 20°ΔT = 10,000 BTU's/hour

    Two btu per sq ft for degree difference for a slab
  • rickyjaswal
    rickyjaswal Member Posts: 2
    edited February 2017
    Thanks for the quick reply. I am getting it done from a professional plumber .just finding the right part was really hard.
  • richardlau
    richardlau Member Posts: 3
    @rickyjaswal --- where did you find the part? Was it a Heat Flo or did you replace it with a Honeywell or something like that?
    Who did you use to install it? Thx!
  • danator
    danator Member Posts: 2
    Just replaced 2 out of 4 zone valves with Honeywell by myself. Works well. Thanks for above valuable info.
  • danator
    danator Member Posts: 2
    Special thanks to Alan (California Radiant) Forbes
  • MikeHeating
    MikeHeating Member Posts: 1
    Old thread but I just replaced using this unit and it works perfectly:
    Honeywell 40003916-012 Home Actuator Head/Motor, 24V, for V8043G series, Normally Closed, Zone Valves

  • HomerJSmith
    HomerJSmith Member Posts: 2,511
    edited February 2023
    Why am I commenting on a post from Oct 2016? MikeHeating good to know.
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 8,166

    Edward Young Retired

    After you make that expensive repair and you still have the same problem, What will you check next?