LAARS Technical Bulletin 24-23: Installing Mini-Therm® JX Boiler Without a Low Loss Header

Applicable Products:

Mini-Therm JX Product Line, sizes 50-100 Problem Statement: Mini-Therm JX

Models 125, 150, and 200 are built standard with a low loss header, but models 50, 75, and 100 are available with or without the low loss header. If you are installing a Mini-Therm JX boiler without the low loss header, in a Zone Valve system, you could potentially “dead head” the boiler pump if there is no bypass installed. This can lead to pre-mature failure of the boiler pump and also “kettling” within the heat exchanger due to a sudden loss of flow. If this bypass is not installed, it can also lead to condensation forming on the heat exchanger which can lead to combustion issues and a shorter life expectancy of the unit.

CORRECTIVE ACTION:

To ensure that this does not happen, it is important that a bypass be installed between the supply and return piping before any of the zones. The valve in this bypass will need to be adjusted so that the return water temperature does not fall below 120 degrees while the unit is operating at full fire. Adding this bypass will ensure that the unit does not condense. Also, when the unit loses its call for heat, and the pump goes into its “post run” time, the pump will continue to move water through the boiler and the bypass loop, preventing the pump from “dead heading”. See example below:

Preferred action:

Add the Laars Low Loss Header, kit number CA019600:

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