Energy Efficient Hot Water Boiler Plant Design Part 4: What To Do With Boiler Condensate

By Chad Edmondson

A properly applied condensing boiler generates a lot of condensate – 5 gallons for every 1,000,000 BTUH input.  In a large commercial or institutional building this can easily add up to several hundred gallons per week.  But where does all that condensate go? 

You can’t put it down the drain.  First of all, it may be too hot.  Most commercial building codes do not allow water any hotter than 140°F into the sewer system.  It is also too acidic (3-5 pH).  Boiler condensate has been known to eat through concrete floors so simply directing it to a floor drain is not an option.  Besides, there are certain environmental and health risks associated with putting boiler condensate into the sewer system, not to mention strict building codes.   So between the boiler and the drain you need a neutralization kit.

What is a condensate neutralization kit?

Condensate neutralization kits are available through boiler vendors and typically consist of a plastic container filled with some sort of neutralization media.  It maybe limestone, marble, alkaline chips or other material containing calcium carbonate. The neutralization media increases the pH of the condensate so that the acid levels are lowered to a point that is suitable for drain disposal. 

The neutralization system should be added in the drainpipe between the boiler and the building drain.  It should be piped with either PVC, plastic or cast iron piping.  The condensate will flow into the neutralization tank by gravity, so it needs to be installed below the outlet on the boiler or water heater.  If this is not possible, a pump may need to be installed.

If you are designing a condensing boiler system, a properly designed neutralization kit must be included in the specification, as you are the one responsible for making sure that disposal of boiler condensate is handled according to state and local codes.  This can be a prefabricated kit from a vendor or one that you design yourself from assembled materials and components.  The option is yours – just don’t forget include a neutralization kit into the plans!