HTP 850 LPHL - Manual (Page 15)

15
LP- 205 REV. 3.28.14
B. RELIEF VALVE
Connect discharge piping to a safe disposal location following the guidelines on the following page.
To avoid water damage or scalding due to relief valve operation:

Discharge line must be connected to relief valve outlet and run to a safe place of disposal.

Terminate the discharge line in a manner that will prevent possibility of severe burns or property damage should the relief
valve discharge.

Discharge line must be as short as possible and the same size as the valve discharge connection throughout its entire length.
 Discharge line must pitch downward from the valve and terminate at least 6” above the floor drain, making discharge clearly
visible.

Discharge line shall terminate plain, not threaded, with a material serviceable for temperatures of 375 o F or greater.

Do not pipe discharge to any location where freezing could occur.

No shutoff valve may be installed between the relief valve and boiler or in the discharge line. Do not plug or place any
obstruction in the discharge line.

Test the operation of the relief valve after filling and pressurizing the system by lifting the lever. Make sure the valve
discharges freely. If the valve fails to operate correctly, replace it with a new relief valve.
 Test relief valve at least once annually to ensure the waterway is clear. If valve does not operate, turn the boiler “off” and call
a plumber immediately.

Take care whenever operating relief valve to avoid scalding injury or property damage.

For boilers installed with only a pressure relief valve, the separate storage vessel must have a temperature and pressure relief
valve installed. This relief valve shall comply with Relief Valves for Hot Water Supply Systems, ANSI Z21.22 CSA4.4
FAILURE TO COMPLY WITH THE ABOVE GUIDELINES COULD RESULT IN FAILURE OF RELIEF VALVE OPERATION,
RESULTING IN POSSIBILITY OF SUBSTANTIAL PROPERTY DAMAGE, SEVERE PERSONAL INJURY, OR DEATH.
C. BACKFLOW PREVENTER
Use a backflow preventer specifically designed for hydronic boiler installations. This valve should be installed on the cold water fill
supply line per local codes (see Boiler Piping Details, Part 4, Section G).
All piping methods shown in this manual use primary/secondary connection to the boiler loop. This is to avoid the possibility of
inadequate flow through the boiler. For other piping methods, consult your local HTP representative, or refer to Boiler Piping Details in
this manual, Part 4, Section G.
D. SYSTEM WATER PIPING METHODS
EXPANSION TANK AND MAKE-UP WATER
1. Ensure that the expansion tank is sized to correctly handle boiler and system water volume and temperature.
BOILER WATER VOLUME
300 2.9 Gallons
500 4.2 Gallons
850 5.8 Gallons
Table 2
Undersized expansion tanks cause system water to be lost from the relief valve, causing make-up water to be added. Eventual boiler
failure can result due to excessive make-up water addition. SUCH FAILURE IS NOT COVERED BY WARRANTY.
2. The expansion tank must be located as shown in Part 4, Boiler Piping Details, or following recognized design methods. See
expansion tank manufacturer’s instructions for details. Always install an expansion tank designed for potable water systems.