Weil-McLain Ultra 230 Lockout – High Supply Temp

shredmaster

Hi all,
I’m helping a friend troubleshoot a Weil-McLain Ultra 230 boiler that’s locking out due to high supply temperature. Here’s the situation:

• Initially, the P/T check valve was leaking hot water. I found the expansion tank had failed (waterlogged), so I replaced both the tank and the P/T valve.
• After bleeding the zones one by one, I turned on the boiler, but it failed to cycle and locked out with a high supply temp error. The display shows:
  • System Supply: 60°F
  • System Return: 63°F
  • Boiler Out 1: 200°F
  • Boiler Out 2: 193°F
  • Boiler In: 128°F
  • Flue 1: 116°F, Flue 2: 118°F
  • Outdoor: 54°F
• The supply pipe below the primary/secondary connection is very hot, but everything else (zones, system supply/return) is cold.
• Circulators 4 and 6 make noise and seem to be running, but circulator 5 is very quiet, and I suspect it might be bad.

I’ve attached the piping diagram and error screen for reference. I’m not very familiar with primary/secondary piping, so I have some question: If the return circulator (#6) is working, shouldn’t it pull hot water from the P/S connection? Since the connection is cold, is circulator 6 also bad, or is the issue with circulator 5? I’ve also noticed that zone valve 3 is always open, and I can’t figure out why.

I can’t imagine a failed expansion tank leading to this many issues—maybe there’s a simple fix I might be missing?

Any advice would be greatly appreciated! Thanks!

tcassano87

how long has this been an issue? It’s most likely air locked but If it’s been lockout for a while then everything going to be cold cause it hasn’t been running.
it sounds like you have multiple issues, were you able to get the lockout cleared and duplicate the issue in real time?

Also the mixing valve, circulator and piping on that manifold for radiant looks incorrect

HVACNUT

That piping and wiring is atrocious. Not exactly closely spaced Tee's there.

I can't find the PRV, but find a way from it, to the boiler. The boiler is air locked and must be purged. If you need to raise the weight on the Flo valve and purge backwards, so be it. You could also slowly introduce domestic cold from the drain on the bottom of the boiler and find and easy loop to purge through.

Ironman

What’s a “p/t check valve”? I’ve never heard of that.

shredmaster

https://forum.heatinghelp.com/discussion/comment/1850875#Comment_1850875

thanks for your reply! The system was running fine a week ago until the expansion tank failed, causing the P/T valve to leak, which I’ve since replaced. I reset the lockout and started the boiler, but it shuts down within a minute when Boiler Out 1 reaches 200°F, while the system supply/return remain cold (60°F/63°F).

Here’s how I purged the system, step by step:

1. Isolated the radiant heat manifold
   • Shut off the supply and return valves to the radiant heat manifold to isolate that loop.
2. Closed all zone valves and cutoff valves
   • Shut off the cutoff valves on all return lines.
   • Call off zone valves (R1, R2), but zone valve 3 remained open and we don't know where the thermostat is.
3. Purged each zone individually
   • Zone 1 (R1):
     • Manually opened the zone valve for zone 1.
     • Opened the drain for zone 1 to bleed it until water flowed steadily with no air.
     • Shut the drain and zone valve to isolate zone 1, then moved on to the next zone.
   • Zone 2 (R2):
     • Manually opened the zone valve for zone 2.
     • Opened the drain for zone 2 to bleed it until water flowed steadily with no air.
     • Shut the drain and zone valve to isolate zone 2, then moved on to the next zone.
   • Zone 3 (R3):
     • zone valve already open
     • Opened the drain for zone 3 to bleed it until water flowed steadily with no air.
     • Shut the drain and zone valve to isolate zone 3.
4. Turn on the cutoff valves on all return lines.

Do you think these steps were enough to purge the system properly, or did I miss something?

Also, could a circulator have failed? Circulator #5 is very quiet—no sound of water flow. You mentioned issues with the mixing valve, circulator, and radiant manifold piping—any specific fixes I should try? Thanks!

shredmaster

https://forum.heatinghelp.com/discussion/comment/1850898#Comment_1850898

https://www.supplyhouse.com/Weil-Mclain-383-500-275-Pressure-Temperature-Gauge-Check-Valve

these comes with the boiler which was leaking and replaced.

shredmaster

https://forum.heatinghelp.com/discussion/comment/1850877#Comment_1850877

Thanks for your feedback! I agree that the piping and wiring aren’t ideal—the tees aren’t closely spaced. I’ve located the pressure relief valve (PRV)—it’s labeled as #14 in the diagram.
I'll try to figure out the purging methods you suggested. In my response to tcassano87, I outlined my purging steps: isolating the radiant manifold, closing valves, and bleeding each zone. Are these steps correct?

HVACNUT

https://forum.heatinghelp.com/discussion/comment/1850908#Comment_1850908

Pressure Reducing Valve.

tcassano87

If your certain there is no air in the lines and you’ve bled correctly, From what your saying it sounds like the boiler is overheating from the primary circulator/circulators not working. Unless the temperature sensor or board is faulty and it’s giving you a false reading causing it to go into a lockout. Not sure if you said this but what temp is the gauge reading when this lockout occurs?

Have they ever properly down a service on this unit??