Hot water reset

Hot water reset

Hot water reset is an energy-saving automatic control algorithm for hot water boilers that are typically fired with fuel oil or natural gas. A hot water reset control loop measures the outside air temperature; this information is used to estimate demand or heating load as the outdoor temperature varies. The supply hot water temperature is modulated up and down range in an inverse linear ratio to outside air temperature. The typical range for conventional boilers is to vary the supply water temperature from 140 to 180°F as the outside temperature varies from 65 to 0°F.

Implementation

The control system can be made modulate the supply water temperature in two different ways:
#By acting as an operating control on the boiler burners, either modulated on/off, high/low fire, or fully modulating fire, depending on the burner construction. When modulating the actual boiler temperature lower, water temperature needs to have a low limit and be maintained above the flue gas condensation temperature for non-condensing type boilers, typically above 140°F. Condensing type boilers can be made to operate at temperatures below the flue gas condensation limit and raise stated efficiencies from the 85% to 95% range.
#By acting as an operating control on a three-way powered mixing valve or proportional injection pump system that modulates the supply distribution hot water temperature. The mixing valve or mixing pump system recirculates the return water temperature and adds proportionally supply hot water from the boiler for tempering to achieve the desired supply water temperature.


Wikimedia Foundation. 2010.

Игры ⚽ Нужна курсовая?

Look at other dictionaries:

  • Boiler — For the Limp Bizkit song, see Boiler (song). A portable boiler (preserved, Poland) …   Wikipedia

  • Life Sciences — ▪ 2009 Introduction Zoology       In 2008 several zoological studies provided new insights into how species life history traits (such as the timing of reproduction or the length of life of adult individuals) are derived in part as responses to… …   Universalium

  • metamorphic rock — Any of a class of rocks that result from the alteration of preexisting rocks in response to changing geological conditions, including variations in temperature, pressure, and mechanical stress. The preexisting rocks may be igneous, sedimentary,… …   Universalium

  • PID controller — A block diagram of a PID controller A proportional–integral–derivative controller (PID controller) is a generic control loop feedback mechanism (controller) widely used in industrial control systems – a PID is the most commonly used feedback… …   Wikipedia

  • List of Canada's Worst Handyman 2 episodes — This is a list of episodes from Canada s Worst Handyman 2 , the second season of the Canadian television series that seeks to find the worst handyman in the country. Airdates listed are the first air dates on Discovery Channel Canada the date of… …   Wikipedia

  • Trace heating — Electric Trace Heating, also known as Electric Heat Tracing and Electric Surface Heating, is a system used to maintain or raise the temperature of pipes and vessels. Trace heating takes the form of a electrical like heating element run in… …   Wikipedia

  • Spirit rover — (MER A) Artist s concept of Rover on Mars Operator NASA Mission type Rover Launch date …   Wikipedia

  • Condensing boiler — A condensing boiler utilizes the latent heat of water produced from the burning of fuel, in addition to the standard sensible heat, to increase its efficiency. Contents 1 Principles of work 2 Usage 3 Efficiency 4 …   Wikipedia

  • Snowball Earth — The Snowball Earth hypothesis as it was originally proposedcite book author = Kirschvink, J.L. year = 1992 chapter = Late Proterozoic low latitude global glaciation: The snowball Earth title = The Proterozoic Biosphere: A Multidisciplinary Study… …   Wikipedia

  • Decompression (diving) — Divers decompressing in the water at the end of a dive Decompression in the context of diving derives from the reduction in ambient pressure experienced by the diver during the ascent at the end of a dive or hyperbaric exposure and refers to both …   Wikipedia

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”