Weil-McLain EG CH VOLTAGE HIGH — CH / Thermostat1 Input Excessive Voltage
CH VOLTAGE HIGH
CH / Thermostat1 input excessive voltage. Unplug the control P3 connector. Measure the voltage between the control connector's Pins 1 & 3. Is the measured voltage in excess of 24 Vac nominal? If no, inspect the harness for a short. If yes, measure the voltage of the 24 Vac transformer output connector P1 between P1 pins 6 & 7 without unplugging it from the control; if in excess of 24 Vac nominal, replace the transformer; if not, inspect 120 Vac supply power. The table classifies it as voltage.
Applies to
This fault code is displayed by the EG water control (display faults) on EG models (EG-30 through EG-75), as documented in EG Series 7 Boiler Manual, doc 550-100-225/0425 (Table 17 water-control faults; steam uses charts + limit/LWCO) (550-100-225/0425). Codes can differ between controller generations, so always check the manual that matches your unit.
- Weil-McLain EG / EG Steam
- Weil-McLain EG-30
- Weil-McLain EG-35
- Weil-McLain EG-40
- Weil-McLain EG-45
- Weil-McLain EG-50
- Weil-McLain EG-55
- Weil-McLain EG-65
- Weil-McLain EG-75
Controller: EG water control (display faults). Source manual: 550-100-225/0425 (2025-04).
Why a code is not a diagnosis
The code reports the condition the control detected; the underlying cause must be confirmed on site by a licensed technician using the manufacturer's procedure.
Safe things to observe
- Note the exact code, when it appears and what the appliance was doing.
- If the appliance has stopped, call a technician rather than repeatedly restarting it.
- If you smell gas, stop, go outside and call your gas utility's emergency line or 911 before anything else.
Do not
- Do not ignore a code that returns after a reset.
How professional service helps
- A licensed technician diagnoses the cause with the manufacturer's test procedure.
- Combustion and safety devices are verified with an analyser and the manufacturer's procedure after any repair.
Where ROMA provides on-site service
On-site service is currently offered in Greater Vancouver, BC, including Vancouver, Burnaby, Richmond, Surrey, Coquitlam, North Vancouver, West Vancouver, New Westminster, Port Coquitlam, Port Moody, Delta, Langley, Maple Ridge, Abbotsford, Chilliwack, White Rock, Pitt Meadows, Tsawwassen, Anmore, Lions Bay, Belcarra, Bowen Island, Mission. Everything else on this site is reference information you can use anywhere in Canada.
Parts and service
Parts commonly involved
These parts appear in the documented text for this alert. A code reports a condition, not a failed part — a technician confirms the cause by testing before anything is replaced.
Transformer
The transformer is the small component inside the boiler that steps household 120-volt power down to the low voltage the controls use — typically 24…
What a technician checks →
Service for this alert
- Gas Boiler Repair
Licensed gas technicians from ROMA Heating & Cooling diagnose and repair residential and light-commercial gas boilers across…
Every boiler part explained — what it does, how it fails and what a technician checks.
Documented for Weil-McLain EG / EG Steam.
Frequently asked questions
Can I clear this code myself?
Clearing a code without fixing its cause usually just brings it back. Note the code, check the safe items on this page, then call a licensed technician. If your appliance manual describes a user reset for this exact code and it stays away, no call may be needed.
Boiler locked out? Call with the alert text ready.
The brand, model and this alert are passed along when you request service online, so the technician arrives prepared.
On-site service in Greater Vancouver, BC. ROMA lists “Open 7 days” on its site; call to confirm same-day availability.
Sources and verification
- EG Series 7 Boiler Manual, doc 550-100-225/0425 (Table 17 water-control faults; steam uses charts + limit/LWCO) · 550-100-225/0425 · accessed September 7, 2026
Facts checked September 7, 2026. Last updated September 7, 2026. Technical reviewer: not yet assigned.