If you intend on direct connecting  combustion air from the outside to a boiler or water heater, you must consider freeze protection.  Copper Fin boilers hold a very low volume of water and in cold climates, the heat exchanger can be exposed to conditions which can cause freezing. When a heat exchanger freezes, it cracks the tubes or headers and can cause a great deal of damage to both the boiler/water heater and the facility by flooding the room.

Simply applying a damper to the air inlet does not solve the problem as each unit has a unique firing sequence which the damper must be coordinated with.  For instance, if the unit is purging, stuck in purge, locked out on flame failure, off on low water, off on low flow, or other safety features, how will you operate this damper?  You can't simply close it when the gas valve is not engaged, because you risk straining the fan if it is not shut down for safety reasons, pre-purge, or post-purge conditions.  Only the manufacturer fully understands it's firing and operating sequence!

Through years of research RBI has developed and implemented a freeze protection package (optional) that is directly linked to the units sequence.  The freeze protection package is pre-wired and directly interlocked with the boilers operating sequence through a series of relays and controllers. RBI's system is pre-wired directly in the control panel (when ordered with optional freeze protection).  A termination point is installed on the boiler. The damper is shipped loose, but with a fairly long 'pigtail' to plug into the termination.  This system makes it very easy for the contractor to install, and no separate control panels and wiring are necessary. 

Be sure when you apply a copper fin boiler with sealed combustion air, you specify and demand a pre-engineered, pre-wired freeze protection package accepted only directly from the boiler or water heater manufacturer. 

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