This Weil McLain boiler troubleshooting guide explores common problems and steps you can take to identify and possibly solve them.
Keep in mind the risks associated with boilers – severe burns, gas explosion and the risk of shock. Proceed cautiously with the diagnostic steps you take. If you believe there’s a risk of injury, leave the job to a pro. With that caveat out of the way, let’s explore troubleshooting a Weil McLain boiler.
Here are common boiler problems for this or any brand. In the next section are Weil McLain boiler troubleshooting tips the pros use to determine verify what is wrong.
A burned-out thermocouple is the top cause of a Weil McLain boiler not responding to the thermostat’s call for heat.
Insufficient water pressure will prevent the boiler from creating enough hot water to adequately heat your home. Adding make-up water will solve it, but the goal is to determine the cause of low pressure in the system. An early clue of low water pressure, besides insufficient heat, is the boiler making popping and/or rattling noises.
There’s something amiss if your Weil McLain boiler is turning on, running a short cycle and shutting off. The clues are hearing it cycle on and off, or you might first notice your home’s temperature being more than a few degrees higher or lower than the thermostat set point.
When zone valves fail, they either won’t open to allow heat into a zone or they get stuck open and too much hot water enters the zone.
It’s wise to have a CO detector near your boiler and low to the ground since CO is heavier than the normal mix of air in your house.
Depending on the specific problem you’re experiencing, one or more of these tools will prove helpful for Weil McLain boiler troubleshooting.
This section reviews common problems and Weil McLain boiler troubleshooting tips to determine their cause.
If the electrical circuit for the boiler is on and the power switch on or near the boiler is on, crank the heat way up. If the boiler doesn’t start, it’s time to check the thermocouple:
Low water pressure is a common cause:
When a boiler cycles on frequently, and your home is too cold or too warm, try these troubleshooting tips:
This is one of the easiest Weil McLain boiler troubleshooting issues to diagnose. Make sure the thermostat setting for each zone is where it should be, and if one zone is still too hot or cold, an electronic zone valve needs to be replaced.
The most common cause of leaking carbon monoxide is the plugging of the boiler heat exchanger fins with dirt and debris. If your CO alarm goes off, the safe approach is to open your home’s doors and a few windows to ventilate the area, evacuate the house, and call a boiler technician from outside. Here’s what the technician will do to check the heat exchanger:
Boilers present many significant dangers. Turn off power to the unit before opening the cover. This will eliminate the risk of shock. If you smell gas or oil fumes at any time, there’s a risk of explosion. Don’t ignite anything, and evacuate your household immediately. Call your utility company or emergency services from outside your home.
Finally, remember that carbon monoxide is deadly, so it’s important to have a detector near the boiler. If it sounds an alarm, turn off the boiler until you can inspect and repair it.
Weil McLain boilers are a reliable source of comfortable heat that should give you 15+ years of dependable service. If these troubleshooting tips don’t solve the problem or if you don't find your issue here, call a qualified Weil McLain technician. If these tips have been useful, perhaps sharing this post on social media will help others identify their boiler issues and avoid dangerous problems too.