Residential Water Heating

Issue

Circulating hot water systems distribute hot water to faucets on a “closed loop” system that circulates water to deliver it on demand. Heating water accounts for up to 25% percent of energy use in a typical home. High efficiency water heaters use 10% to 50% less energy than standard models. When combined with complementary products like insulation blankets and timers, advanced systems can save significantly on utility costs. Energy savings from high efficiency water heaters depend on several factors such as heater location, family size, use behavior, heating fuel used, climate zone, and the size and placement of water pipes.

Overview

Consumers face many considerations when selecting a new water heater for their home or business. There are several types of high efficiency water heaters each with different advantages and payback periods – including:

  • Efficient storage tank heaters
  • Demand (tankless) heaters
  • Heat pumps
  • Tankless coil and indirect heaters
  • Solar heaters with electric back-up

After making their purchases, owners can achieve further energy savings in fairly simple and inexpensive ways. Options include installing thermal blankets, insulating hot water pipes, and installing a timer that turns the heater off at night when occupants do not use hot water and/or during utilities’ peak demand times during the day.

Requirements

In the 2015 IECC, requirements for service hot water systems, including circulation systems, are found in section R403.5.

Typical Problems

Standard issues concerns that arise include:

  • Not notifying building tenants of a manual pump switch
  • Not informing clients of energy saving features of a manual switch

Previous Codes

The 2009 IECC emphasizes that a manual control must be “readily accessible”. The language in the 2003 IECC, however, is slightly vaguer, stating in Section 504.4 than circulating hot water system pumps or heat trace must be “arranged to be conveniently turned off” either automatically or manually.

Resources

Special Topic: Pipe Insulation

Pipes carry heated or cooled liquids from boilers or heaters to faucets and other fixtures connected to mechanical HVAC and circulating hot water systems. The energy code requires pipes carrying heated or cooled fluids to be insulated to reduce heat loss from the liquid contained within them and the pipes themselves. This is especially important for pipes carrying hot water, as heating and transferring liquid through un-insulated piping wastes significant amounts of energy. The 2009 IECC covers pipe insulation in Sections 403.3 and 403.4; the 2012 IECC covers it in Section 403.3; the 2015 IECC covers it in Section 403.4. These requirements are mandatory for all climate zones.

Older versions of the IECC (2003 and back) were complicated, requiring calculations for a variety of different systems, pipe sizes and locations. The 2006 IECC simplified pipe insulation requirements by removing these calculations and mandating R-2 insulation for Sections 403.3 and 403.4. The 2009 IECC is identical to the 2006 version for pipe insulation requirements save for one modification: the insulation value in Section 403.3 changed from R-2 to R-3.

Building code officials must be aware of the requirements covered in the IECC and need to ensure that:

  • Correct insulation is included and inspected
  • Labeling on pipe insulation is clear and identifiable
  • Plans and specs are reviewed and requirements are met

Standard issues/concerns that arise include:

  • Hard to find supply of required insulation
  • Insulation not included in original bid
See also:

Image credit: BECP Resource Center