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Air purging

Roscoe
Roscoe Member Posts: 23
in Radiant Heating
I have an uponor/wirsbo radiant system, approx 2 yrs old. It is fed by a gas-fired Burnham Alpine condensing boiler. A few days ago I added a new loop to the existing manifold. A plumber who gave me advice said that the air eliminator on the system should suffice to bleed the air as long as I ran it. A day later my boiler keeps shutting down with "hard lockout 4 - supply high limit" with possible causes "heating load fast below min" or "bad pump, low primary flow" or "boiler on with no zones on".



I suspect the unit is air bound. I reset the boiler and watched the temp run up very fast (from 100 to 190), then right back down (to 126), then back up again.



I need some advice on whether air is the likely culprit, and the best/easiest way to remove the air. I can provide more info (part #'s, etc) but photos on the system will be difficult.



Thanks in advance for the help

Comments

  • Zman
    Zman Member Posts: 7,611
    Power purge

    You need to power purge your system. The original installer likely installed an isolation valve and a couple of boiler drains for this purpose. This may be tricky without pics.

    Carl
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • Roscoe
    Roscoe Member Posts: 23
    Power purge

    Zman - thank you for the quick reply. I will have to take some pictures and load them tomorrow. A bit more information:

    - the control module is an uponor A303004. The LED for the new zone was red, and I noticed the temp gauge on the feed side was pegged (max is 180 F), with the return side gauge showing 160F. The manifold is an uponor 106604.

    - I turned off the thermostat for the new loop, and the LED stayed red, the actuator stayed engaged, and the circulator continued to run. Perhaps there is a delay, but to be on the safe side, I pulled the wires, and after a minute the actuator, LED! And circulator all turned off. I'm going to wait a day or two to see if the boiler operation returns to normal.

    - I also noticed that the thermostat in question was set at 70, and the current actual temp was only reading 67. Could it be that it will take the room several days to reach temp, and the system was running continuously to bring the temp up? The room has limited floor space (3x6) but has high ceilings and the thermostat is not directly over the floor.

    - my biggest concern (for now) is that the boiler was shutting down and that the temp gauge and the manifold was pegged.
  • Zman
    Zman Member Posts: 7,611
    Delay

    Those thermo zone valves do delay a bit opening and closing.

    It sounds like some of the air moved and is now locking your boiler. Are your air vents open? Most have little caps on top that need to be open. I would not operate your system in an airlocked condition. You could damage your circulators and your boiler.

    Carl
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • Roscoe
    Roscoe Member Posts: 23
    Air caps

    At the end of the Uponor manifold is what I believe to be the air purge. It does not have a cap on it.



    The boiler also provides domestic HW to the house, and has a Tasco 4900 series 3/4" air separator.



    If the air has moved to the boiler, what's the remedy? It's Sunday night, and no HW is really not an option...
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