Welcome! Here are the website rules, as well as some tips for using this forum.
Need to contact us? Visit https://heatinghelp.com/contact-us/.
Click here to Find a Contractor in your area.

How to set up a post purge cycle on a new Burnham Boiler

Have a recently installed ESC Burnham boiler with a Burnham ODR, two Taco 007 zone pumps and a Taco 504 relay board.

The pump is designed to be powered by the yellow and white wires in the terminal box.  But when two pumps are used and controlled by the 504, the yellow and white wires remain capped, and the circulators are controlled by the 504.  So the ODR doesn't have a chance to communicate with the zone pumps.

What would it take to set up a post purge cycle for each pump, controlled by the yellow and white wires within the terminal box?   Taco makes a post purge card for the 504, but that would utilize the zone designated for the hot water circulator. 

I know one school of thought is that it's not worthwhile, but with 20+ years of life left to go in this system I'd like to maximize it's functions. 



  • Tim McElwain
    Tim McElwain Member Posts: 4,556
    Here is your answer from

    Burnham Rep:

    As you stated the post purge function is only active with a PC600 when the priority zone is satisfied and when using a reset control of theirs. I only know of one way to do this when you have more than one zone pump and that would be to use a 120v time delay on each pump that activated in reverse from one that you might see on an air handler. The constant source of power would go to the relay and the power coming out would go to the respective pump. The Taco panel pump output would activate the relay on a heat demand but the post purge timer would only activate after the output to the relay was interrupted by the tstat being satisfied. My advice was not to experiment as it can get expensive and an unknown is whether the components needed are even made.

    Did you already ask this question of another rep?
  • 04090
    04090 Member Posts: 142

    Thanks, Tim.

    Will look into adding a time delay relay to each circulator rather than expecting existing controls to do it and yes, post purge was brought up by Mike K. in another thread as an alternative to salvaging a HW+ from the old system. 

    Burnham's literature claims that "All settings on the IQ Outdoor Reset Option Card can be customized for ideal performance in any heating system" so I was hoping making the post purge feature from the ODR work was just a matter of  finding the right way to connect things.
This discussion has been closed.