Furnace Condensate & New D.O.E. Rules


Recently, I have had questions about the “acidity” of the condensate from 90+% efficient furnaces.  These questions have come from architects, engineers, city inspectors and sales people. 

As you may or may not be aware, as of May 1,2013 — less than 8 months from now, the new D.O.E. standards go into effect for FURNACE efficiency.  This will mostly impact the northern tier of states.  Basically, after May 1, 2013, 80% furnaces cannot be installed in the states in blue. (the rest of the D.O.E. requirement for A/C, Heat pumps, and packaged units go into effect January 1, 2015 as of now and subject to change).

Only 90+% efficient furnaces can be installed.  Because of this, there will probably be even more questions about the acidity of the condensate from 90+ furnaces. As more people are exposed to the required 90+% efficient furnaces, that question is sure to arise.

The question I have had is: How acidic is the furnace condensate and will it damage the drainage pipes or sewer system?

The answer is:  the typical condensing gas furnace will produce condensate the has a pH ranging from 3.5 (the same as orange juice) to 6.5, but is usually in the 5.0 area.

The rating scale for pH is from 0 to 14, with 7.0 pH being the neutral center line, neither acidic nor alkaline.  Numbers below 7 indicate an acidic condition and numbers greater than 7 indicate an alkaline condition. [now we are becoming chemists :>)].

Since 90% efficient furnaces have been around since the mid 1980’s, testing has indicated and history has confirmed that there are no long-term effects from discharging condensate from high-efficiency gas furnaces into either municipal or on-site sewer systems. One of the reasons is that most residential waste water discharge is slightly alkaline. By adding slightly acidic furnace condensate, the resulting waste water will tend to approach a neutral condition. Actually, the furnace condensate helps because most public sewage systems will add acid as part of their process to correct the pH to a neutral condition.  Because of this, most local regulations that had required neutralizers to be used in the past have now dropped those requirements. You will still need to check with your local authorities for code requirements in your area.  We also state this in the installation manuals that come with our units:

Now, for those areas that will require that neutralizers be used on 90+% efficient furnace, we  do have available. through our Source 1, a neutralizer kit part # S1-1NK0301 and refills for those kits for maintenance of the neutralizer part # S1-02630228000.

As the new requirements go into effect, keep this in mind in case you have an inspector or architect who asks you about furnace condensate.

(pH information in this post was from an “M” letter written back in 1997 by an engineer named Dennis Aughenbaugh – furnace production manager for York at that time).

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About yorkcentraltechtalk

I have been in the HVAC industry most of my life. I worked 25 years for contractors on anything from residential to large commercial boilers and power burners. For the past 23+ years I had been employed by York International UPG Division ( a division of Johnson Controls) as a Technical support/Service Manager but I am now retired. One of my goals has always been to "educate" dealers and contractors. The reason for starting this blog was to share some knowledge, thoughts, ideas, etc with anyone who takes the time to read it. The contents of this blog are my own opinions, thoughts, experiences and should not be construed as those of Johnson Controls York UPG in any way. I hope you find this a help. I always welcome comments and suggestions for postings and will do my best to address any thoughts, questions, or topics you may want to hear about. Thanks for taking the time to read my postings! Mike Bishop
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7 Responses to Furnace Condensate & New D.O.E. Rules

  1. Whit Perry says:

    Great information Mike. Do you have anything on how to check your venting with a magnahelic on 90+ furnaces, what it should be, etc.? Thanks and have a great weekend!

  2. smithrobin says:

    Well the information is very informative and help full for the use of furnace and get the benefits effectively.
    Heating and Cooling Toronto

  3. rich poirier says:

    what are the risks of sharing an opening with a copper gas line and the condensate drain pipe from a high eff furnace. If there is a condensate leak up stream [ ie combustion vent assembly, traps, fittings etc. ] will the condensate put the copper gas line at risk. I have made this argument and have been told not to worry about it. I think this could be an issue , what do you think?

    • copper pipe is used for water pipes

      • rich poirier says:

        this is a lp system where 5/8 soft roll copper is used as a gas supply line, the question I am try to convey is how at risk is the copper gas line if the condensate drain on the furnace if condensate leaks on the gas line. I have a tec who is sharing the same hole through the floor condensate and gas lines.

      • I am not a metalurgist, but, since the “acidity” of the condensate is about the same as orange juice, it should not effect the copper. Maybe over a very long period of time it might.
        If this is a concern, I would consult a metalurgist or chemist to see if there could be an effect on the line.

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