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Boiler no heat, cold zone or relief valve on heat-up.

A licensed boiler technician should do this work, and nobody else should touch a tank while the system is hot.

Customers put it like this

  • The boiler is locked out
  • One zone stays cold
  • The baseboard gurgles
  • Water came out of the boiler relief valve
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Stop first if

  • You smell gasLeave the building now. From outside, call emergency services or the gas utility.
  • Flue gas at a drain or dry trap, or a CO alarm soundsVentilate and leave the building. From outside, call emergency services or the gas utility.
  • Water is on wiring or controlsKeep clear of it. A qualified person kills power at the disconnect while standing somewhere dry. Otherwise call a licensed electrician.
  • The boiler may have run dryKeep clear. Shut it off only if it can be done without risk. Call a licensed boiler technician.
01

Ask on the call

6

Homeowner? These are the questions a good technician will ask you. Having the answers ready makes the first visit count.

  1. Is it hot water or steam?
  2. Is it the whole system or one zone?
  3. Is there a code or lockout light?
  4. Does the relief valve discharge on heat-up?
  5. Do you hear gurgling or crackling near the pump?
  6. How often is water added, and is there a fill meter?
02

Bring

6
  • Pressure gauge
  • Surface thermometer
  • Air gauge for the expansion tank
  • Electrical meter
  • Digital manometer
  • Flashlight
03

Check on site

6
  1. Name the piping layout. Note where the tank, separator, vent and pump sit.
  2. Record pressure and supply and return temperature, cold and through heat-up.
  3. See if relief discharge lines up with heat-up. Note tank type and air charge.
  4. Listen at the pump inlet.
  5. Read the fill meter over a known period. Check the relief valve and tank before hunting pipe.
  6. A licensed boiler tech works on board supply, flow switch, limits and lockout codes.
04

Keep on the record

5
  • Pressure and temperature log
  • Fill meter readings
  • Expansion tank charge
  • Any code
  • Piping photo

General guidance for a qualified person, not a finding about any home. The person on site decides.