The problems with the DHH “Letter of Intent – Solar Water Heating System Design Requirements” are known by the LA Solar Pro’s and most other installers by now.  LSES will post the problems here for its members and friends so that they may be aware of what we are challenging.  This has been the topic of many meetings and has been summarized below:

The August 4, 2010 release of a “Letter of Intent – Solar Water Heating System Design Requirements” by the Louisiana Department of Health and Hospitals (DHH) has caused great concern and problems for solar hot water installations in Louisiana.  It was distributed to numerous city and parish permit office officials for their interpretation and subsequent enforcement.   Numerous groups including the Louisiana Solar Energy Society and the Alliance for Affordable Energy have already come out against the requirements.  If a refresher is needed on solar hot water basics and terminology it can be found here: http://homepower.com/basics/hotwater/

The 10 page DHH letter covers some basic, common sense requirements mixed in with many absurd declarations.  Some of these are:

1.       The outlaw of “direct circulation and open loop systems” – This method of solar water heating is ideal for our climate, is the lowest cost and therefore the quickest payback, and has been the recommended system of choice for over 10 years by the Louisiana Department of Natural Resources.  With our state paying for 50% of the purchases it would make sense to keep a low cost solar water heating option available.

2.       The requirement of “double-walled heat exchangers to protect the potable water from contamination by the heat transfer fluid” – “Heat transfer fluid” in most solar water heater systems is water.  In some cases where “drainback” cannot be accomplished a mixture of food-grade glycol and water is used.  The use of non-toxic fluid is actually a requirement in the letter.  For the freeze protection level required in Louisiana the typical mix is 25% food-grade glycol with 75% water.  DOWFROST, the most common used heat transfer fluid is USDA and FDA approved for this purpose and is non-toxic.  Specific labeling on the tank indicates the non-toxic fluid requirements should replacement be needed in the future.  Why would a double-walled, less efficient heat exchanger be required when only non-toxic fluids can be used?  In addition, how could a failure of a heat exchanger with UNPRESSURIZED NON-TOXIC fluid contaminate a pressurized water system?  Has it ever anywhere in the world?

3.       The requirement of a “reduced pressure principle type backflow preventer assembly” to be “installed immediately downstream of the water meter” – This has caused the greatest amount of heartburn out of all of the requirements listed in the letter.  The backflow preventers, also known to plumbers as “RPZ’s” are an additional cost to insure backflow protection in the unlikely event of a pressurized heat exchanger failure filled with toxic fluid contaminating the public water supply.  To add to the absurdity, the requirement is that they be placed above ground at the street fully exposing them to damage, theft, tampering and freezing.  Most homeowners, when presented with the requirement of an RPZ sticking up in their yard at the street will decide against solar hot water for that reason.  An alternate to putting these RPZ’s at the street and locating them at the heat exchanger would make a little more sense than street mounted but is not allowed.  RPZ’s can only be installed by a licensed plumber that holds a Water Supply Protection Specialist (WSPS) endorsement which further increases the cost.  Then the letter places the burden of maintenance and annual inspection on the homeowner for life on the installed RPZ.

In addition, to adhere to current plumbing code, if the line between the meter and the home is galvanized the line will have to be replaced as it cannot be spliced. This adversely affects the economic  feasibility of solar hot water installations.

Many solar hot water systems installed in Louisiana are non-pressurized, drainback type meaning they can never cause any backflow pressure on a water system, much less one that is operating under normal pressure.  The letter does not address or exclude these systems nor does it exclude systems where the solar fluid is plain water.

It appears there are good intentions in protecting the public water supply but this letter seems to miss the mark.  When this letter and its requirements have been discussed with parish permit officials, licensed plumbers and licensed solar installers all agree that this is not necessary, costly and detrimental to the installation of solar thermal water heating systems in Louisiana.

First, here is the link to the Letter of Intent: http://www.dhh.state.la.us/offices/publications/pubs-204/Letter%20of%20Intent%20-%20Solar%20Water%20Heaters.pdf

*** UPDATE 11/4/11*** –    The DHH has issued a “Revised Letter of Intent” which strikes “PROBLEM #3″ listed above.  This is a start to retracting the entire letter and will save on some of the state mandated installation costs for the Louisiana homeowner.  It does not retract issues #1 and #2 above.  Reread these and also the following:

http://homepower.com/article/?file=HP102_pg124_Letters_2

Jeff Shaw
Director – LSES