BOILER - (2 Zone) - OVER HEATING

[Chacamasur]

Hey guys,

- Laars Boiler
- Temp that is set for the High is 165F
- 2 Zones (Lower Floor and Upper Floor)

Trouble Shooting

I turning on the Lower Thermostat, Boiler engaged (started cycle), Reached 165F and shut off - Cycle Complete and 100% what should happen.

I turned on only the UPPER Thermostat, Boiler engaged --> got to 165F and continued Passed this temperature, then it got to 210F and I turned off the Boiler.

What's going on, has anyone experienced this before? is in a VALVE Replacement or something Bigger?

Cheers,

 

[Dana]

Hey guys,

- Laars Boiler
- Temp that is set for the High is 165F
- 2 Zones (Lower Floor and Upper Floor)

Trouble Shooting

I turning on the Lower Thermostat, Boiler engaged (started cycle), Reached 165F and shut off - Cycle Complete and 100% what should happen.

I turned on only the UPPER Thermostat, Boiler engaged --> got to 165F and continued Passed this temperature, then it got to 210F and I turned off the Boiler.

What's going on, has anyone experienced this before? is in a VALVE Replacement or something Bigger?

Cheers,

When a boiler overheats it's usually related to the controls on the boiler, not the zone controls. Since Laars has sold literally dozens of boiler models of multiple types over the past 70 years, details like model numbers would be useful for figuring this out. More information about the zone controls, circulation pump(s), and zone radiation could be useful too, but the burner should turn off when it hits the programmed or aquastat high limit even if the thermostat is still calling for heat. Low flow or low radiation on a zone can cause the temperature to rise more quickly than high flow, large radiation zones, cast iron boilers take longer to heat up than finned water tube boilers, but it still shouldn't overshoot the high-limit setting. It could be something simple like re-seating an aquastat's sensor, but it could be lots of things, many of which could be model-dependent.

As presented this is akin to, "My Ford car was fine when I went down one road, but ran rough when I went down another so I turned it off." Not enough information to really go on.