HVAC System to provide combustion air to the boilers

[chief79]

Hi guys,
i have got 3 makeup air units to provide combustion air to the 3 boilers.
my question is ( IF hvac system stops then boilers shall also stop )thats we want .
for this what controls or system can be required. OR how we can achieve this
thanks in advance

[*TEEKAY*]

Typically this is done by interlocking Boiler(s) with MAU(s). This can be done via series circuit (end-switch on MAU unit damper, current relay on MAU blower, and Boiler Enable relay. Depending on the combustion air requirements for MAU to Boiler ratio, this may work for your system. If there is a conttrol system in place I would use the MAU damper end switch and MAU fan status as inputs to control system so you have more control options.

[hotrodrob]

simplest way would be an air flow switch. if you loose a belt and you don't have air flow sensors tied into the controls you could have some issues with the boiler believing there is make up air. have the air flow switch make/break your boiler control circuit.

[thes]

if your putting in a new make up air system from scratch, field controls makes a nice fan in the can set up, and they offer good tech support!