TO: Builders and Plumbing/Gas Contractors:
The rapid corrosion of boiler heat exchangers caused by the high oxygen permeability rates of polybutylene tubing and other materials used in hydronic heating systems has resulted in the replacement of boilers as early as three (3) years after installation as well as potentially unsafe appliance operation.

However, polybutylene tubing is now manufactured with an oxygen-barrier coating which reduces the oxygen permeability to 0. 1 grams per cubic meter per day or less.

In accordance with Article 6.2.1.1. of the Vancouver Building By-law, the City of Vancouver recognizes the Residential Hot Water Heating Association of BC (RHWHA) guidelines as good engineering practice. Therefore, the use of "non-barrier" polybutylene tubing (or any tubing with oxygen permeability rates exceeding 0. 1 grams per cubic meter per day) in hydronic radiant panel systems shall be limited to:

• systems where the radiant panel system(s) is isolated from the boiler system by the use of a stainless steel or copper heat exchanger, or
• Systems using entirely non-ferrous components.

ALSO, please be advised that in accordance with RHWHA guidelines, radiant only systems shall operate as two temperature systems utilizing a mixing valve unless the manufacturer's published data (which is acceptable to the authority having jurisdiction) allows the boiler and venting system to function safely otherwise. The boiler must not operate at such a low temperature as to cause the flue gasses to condense in the chimney and/or boiler.

 EFFECTIVE IMMEDIATELY, should you install a hydronic radiant panel system with piping not meeting the above requirements (with respect to permeability) your District Building Inspector will advise the Building Permit holder and record this information on record drawings during the slab inspection and inform the District Plumbing Inspector to check on final to ensure that the system is in accordance with Items 1 and 2 above prior to granting final acceptance or Occupancy Permit clearance.

MBK/IMcM:lc
NOT98-01