14-03 Heat traps

Question: 14-03Code Section: 12Date: 4 January 2014OBC 2006 Reference:

Question Submitted:

Section Hot Water Piping Insulation

(1) Hot water pipes that are vertically connected to a hot water storage tank shall have heat traps on both inlet and outlet piping as close as practical to the tank, except where the tank,
(a) has an integral heat trap, or
(b) serves a recirculating system.
(2) The first 2.5 m of hot water outlet piping of a hot water storage tank serving a non-recirculating system shall be insulated to provide a thermal resistance of not less than RSI 0.62.
(3) The inlet pipe of a hot water storage tank between the heat trap and the tank serving a non-recirculating system shall be insulated to provide a thermal resistance of not less than RSI 0.62.

My question is two parts: #1. Is this requirement for residential, commercial, ICI ? #2. If this heat trap is required what are inspectors looking for in minimum sizing?


#1. The code section referenced in the question applies to the energy efficiency of a building or part of a building of residential occupancy within the scope of Part 9 and is intended for occupancy on a continuing basis during the winter months.
OBC defines residential occupancy as: An occupancy in which sleeping accommodation is provided to residents who are not harboured for the purpose of receiving special care or treatment and are not voluntary detained.

#2. The 2012 OBC does not specifically regulate a minimum size of a heat trap installed to satisfy the noted code regulation. Many hot water tanks have integral heat traps installed from the factory. This can usually be identified by a sticker on the tank or in the manufacturer’s literature. For hot water tanks that do not incorporate factory installed heat traps, they must be installed on the inlet and outlet connections. Heat traps are very simple to install often consisting of an assembly of rigid piping and fittings to form a physical trap or be flexible piping (ie. Pex) formed in a loop. They are an effective way to prevent cooling of hot water in water heaters by natural convection (hot water rises and is then displaced by cold water beneath it). The heat trap stops this process, thus keeping the hot water inside the insulated storage tank. The Code Technical Committee recommends a minimum 6” trap or diameter loop of piping to effectively achieve this. The authority having jurisdiction should be consulted and manufacturers recommendations should also be considered.