Boiler Reset Control

Overview

A Boiler Reset Control has been a standard energy management recommendation for commercial boilers for several years. Now some manufacturers are making economical units available for residential boilers.

A Boiler Reset Control is a devise that automatically controls the boiler water temperature according to a program based on outdoor temperature. The water can be run a little cooler during fall and spring, and a little hotter during the coldest parts of the winter. This improves boiler efficiency and indoor comfort.

A Boiler Reset control can save about 5% of boiler energy costs in a residential application.

Operation

Boiler distribution systems are designed for the coldest outdoor temperature conditions. Fortunately, the boiler seldom operates in design conditions. Turning down the boiler water temperature can:

improve boiler efficiency by not having to heat to as high of a temperature
improve indoor comfort with less intense heat coming off radiators
reduce standby looses from pipes and radiators
reduce losses to unheated spaces if boiler pipes pass through them

The advantages of doing this with an automated control are:

consistent settings to help your boiler perform well
handles sudden temperature changes
it gets done (noticeable savings only result when action is taken over a long period of time)

A boiler reset control has two temperature sensors – one outside the house and one in the boiler water. As the outdoor temperature goes up and down, the control adjusts the water temperature setting to the lowest setting that is meeting the house heating demand. There are also limits in the controls to keep a boiler from operating outside of its safe performance range.

Savings estimates vary from 5 to 30%, but in a standard residential application (boiler shut-off during the mostly non-heating-season), the savings are likely to be closer to 5%.

Boiler Reset Controllers should only be installed by qualified technicians. Equipment cost is $200 to $500 plus installation. Typical payback for a medium to large house is about 5 years; longer for smaller houses.

Manufacturers

Invensys Building Systems, Inc.
1354 Clifford Avenue
P. O. Box 2940
Loves Park, Illinois 61132-2940
Telephone: 815-637-3000

Go to the Invensys web site at www.invensysibs.com

tekmar Control Systems Ltd
5100 Silver Star Road
Vernon, B.C., Canada V1B 3K4
Telephone: 250-545-7749

Go to the Tekmar web site at www.tekmarcontrols.com

Source: Text Bob Fegan 12/2008; graphic from the Tekmar web site; product image from the Invensys web site;