Boiler Reset Control
Overview
A Boiler Reset Control is a devise that automatically controls the boiler water temperature according to a software 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 by providing a better match between boiler output and space heating needs.
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. Industrial applications can be applicable if the application is space heating only, or if there is a process hot water usage that would be unaffected by fluctuating water temperature. (Example: a low temperature process with a mixing valve that reduces the water temperature below the lowest boiler water temperature setting).
A Boiler Reset control can save about 5% of boiler energy costs in residential and small commercial applications. Industrial space heating applications could be even higher, depending on the size of the heat distribution system (ie: system losses are higher from larger systems full of hotter than necessary hot water).
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:
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improve boiler efficiency by not having to heat to as high of a temperature
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improve indoor comfort with less intense heat coming off radiators
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reduce standby looses from pipes and radiators
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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.
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 atwww.invensysibs.com/erie.shtml
tekmar Control Systems Ltd
5100 Silver Star Road
Vernon, B.C., CanadaV1B 3K4
Telephone: 250-545-7749
Go to the Tekmar web site at www.tekmarcontrols.com
Boiler Automation Systems
Source: Text Bob Fegan 10/2003; rev 1/2005; graphic from the Tekmar web site; product image from the Invensys web site;