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zone valves and overtemp

lowercanada Member Posts: 13
Neighbor texts me, "I got home last night and the house was at 82 degrees".
System is two zone, base-ray, typical Honeywell zone valves, Weil Eco 2 boiler, new old style round Honeywell T-stats.....
I pop over this morning (I missed the text last night). He thinks he has it figured out, thinks one of the zone valves was "stuck". Left the system off overnight.
We set one zone to call for heat, turn on disconnect, system fires up, heats up, flow through selected zone valve piping....but continues firing past target temp shown on boiler display.
Anyone have an idea what might be going on with this system?

No time for extensive troubleshooting as he and I have places to be, but.....but I do see a small parts box, inside is an outdoor reset sensor.....so I guess it was never installed.

Oddly enough, I was recently at another friends house, she just had a new Rinnai wall hung installed, also two zone. It seems to have a mind of its own. Installers retained existing 1st floor T-stat (Honeywell programmable) and added new 2nd floor programmable to replace old round type.
(And I'm just curious here, when did plumbing companies start supplying T-stats, valves, etc. with their trade name on them? I find it annoying, myself)
Her system seems to be inconsistent as far as responding to the old 1st floor T-stat....I've set the upstairs one to off, called for heat at the first floor, and sometimes the boiler responds, other times it doesn't (possibly when the upstairs on is set to heat, but satisfied).
The Rinnai manual says that in ECO mode the system shuts down at intervals....could it be in shut-down when I've seen no response to a call for heat?
(And another "rant".....don't any installers leave the manuals in a nice ziplock bag near the boiler anymore...it's PITA tracking down the installation and user manuals on the web, but thank Dog, so far the OEMs haven't decided that those are secret yet)

I have a few general questions re zone valves in a small 2-zone setup. I think they are typically wired in "parallel"....i.e. either one can call for heat?
Do you always need a multi-zone valve relay, or is that functionality part of the typical wall-hung boiler control board?
Other than the "hand on hot pipe test", what's the best way to tell if a zone valve is opening? Does the manual over-ride lever move when it's working (seems not...and I see some tinkerers have added LED indicator lights....)



  • Alan (California Radiant) Forbes
    You may have a few things going on there, but you will have to watch what happens as the zone heats up to find out the cause.

    Thermostat calls for heat, opens the zone valve and turns on the boiler. The boiler should heat to what it's limit control or curve is set to and then stop. If it doesn't, perhaps an aquastat problem, perhaps something else.

    To continue, once the thermostat is satisfied, the zone valve should close and the boiler turns off. If not, then something is going on with either the thermostat or zone valve.

    Honeywell V8043 zone valves have a sliding lever for manual operation, but it is not an indicator, i.e. will stay in one position open or closed. You have to manually move it to see if the valve is open or closed.

    Use your meter to test for proper signaling.
    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
  • lowercanada
    lowercanada Member Posts: 13
    Reading the Honeywell spec., I think I saw a note that manual open position disables the end switch, and is meant to be used when flushing or filling or de-aerating?
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 8,167
    edited March 2022

    Reading the Honeywell spec., I think I saw a note that manual open position disables the end switch, and is meant to be used when flushing or filling or de-aerating?

    Basically correct. The manual lever does not disable the end switch. It actually opens the valve but stops short of activating the end switch. On that Valve, you can push the lever with a little gusto and make the end switch activate, but the valve will promptly return to the point where the lever locks and keeps the valve open but the end switch will be deactivated.

    With the cover off the valve actuator, and at the proper angle, you can see if the valve is open or closed. You can also see if the end switch is engaged. But you need to be looking at the valve operation to know what position the gears and cams are in to determine the open/closed & on/off position. Honeywell does not label anything inside the actuator in order to make it easy to understand. I still get confused. or is that just old age setting in

    Edward Young Retired

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

  • Zman
    Zman Member Posts: 7,607
    edited March 2022
    I really like the often overlooked "hand on pipe" method. Sometimes the ball inside the valve breaks down and water leaks by. To diagnose that, you either drain down and disassemble the valve or feel the pipe.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
    EdTheHeaterManrick in AlaskaSTEVEusaPA
  • hot_rod
    hot_rod Member Posts: 22,479
    what size circulators? sometimes high head circs can bleed across closed zone valves. Especially when someone removes one of the springs on HW zone valves :o
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream