Safety devices for use in hot water systems

1982 ◽  
Keyword(s):  
Water Systems ◽  
Hot Water ◽  
Safety Devices

Paper 4: Controls for Low-Pressure Hot-Water Heating

1967 ◽  
Vol 182 (5) ◽  
pp. 122-128
Author(s):  
F. Porges
Keyword(s):  
High Temperature ◽  
Water Temperature ◽  
Heat Balance ◽  
Low Pressure ◽  
Water Systems ◽  
Hot Water ◽  
Safety Devices ◽  
Advantages And Disadvantages ◽  
Use Of Time ◽  
Protection Devices

The paper describes modulating control for low-pressure hot-water systems. Compensators and mixing valves are described, and their advantages and disadvantages discussed. The use of time switches is described and typical programmes given. Frost-protection devices for overriding time switches are reviewed, and a strong plea is made for greater simplicity. Difficulties which can arise from faulty positioning of thermostats are discussed. Thermostats detecting lower temperatures than they are intended to can cause safety devices to shut the plant down unnecessarily, and examples are given of such occurrences. Heat retained in the boiler refractories can cause the water temperature to go on rising after the burner has shut off. A heat balance is drawn up and suggestions made for preventing this phenomenon from operating high-temperature safety devices. The difficulties of sequence control of two or more boilers in parallel are discussed. It is difficult to find a method of detecting part load which does not make the boilers hunt; this problem is discussed and a solution for one particular case is offered.

A Design Method for Thermosyphon Solar Domestic Hot Water Systems

1987 ◽  
Vol 109 (2) ◽  
pp. 150-155 ◽  
Author(s):  
M. P. Malkin ◽  
S. A. Klein ◽  
J. A. Duffie ◽  
A. B. Copsey
Keyword(s):  
Flow Rate ◽  
Design Method ◽  
Water Systems ◽  
Hot Water ◽  
Average Flow Rate ◽  
Domestic Hot Water ◽  
Average Flow ◽  
Solar Fraction ◽  
Wide Range ◽  
Flow Circuit

A modification to the f-Chart method has been developed to predict monthly and annual performance of thermosyphon solar domestic hot water systems. Stratification in the storage tank is accounted for through use of a modified collector loss coefficient. The varying flow rate throughout the day and year in a thermosyphon system is accounted for through use of a fixed monthly “equivalent average” flow rate. The “equivalent average” flow rate is that which balances the thermosyphon buoyancy driving force with the frictional losses in the flow circuit on a monthly average basis. Comparison between the annual solar fraction predited by the modified design method and TRNSYS simulations for a wide range of thermosyphon systems shows an RMS error of 2.6 percent.

Long term durability of crosslinked polyethylene tubing used in chlorinated hot water systems

1999 ◽  
Vol 28 (6) ◽  
pp. 309-313 ◽  
Author(s):  
T.S. Gill ◽  
R.J. Knapp ◽  
S.W. Bradley ◽  
W.L. Bradley
Keyword(s):  
Water Systems ◽  
Hot Water ◽  
Polyethylene Tubing
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