Temperature and pressure (T&P) relief valves used on residential water heaters are typically designed and manufactured to relieve on pressure at 150 psig and on temperature at 210 degrees F. These relief valves protect the water heater from excess pressures and temperatures by discharging water.
In normal operation of the water heater and T&P valve, no water should be discharged from the valve. A T&P valve that discharges is an indication of an abnormal condition in the system and by discharging, the T&P valve is meeting its designed safety purpose. The causes of discharge can be thermal expansion, excess system pressure, low temperature relief, too high a setting on the water heater, or something in the water heater causing excess temperatures in the heater.
To avoid water damage or scalding due to valve operation, discharge line must be connected to valve outlet and run to a safe place of disposal. Discharge line must be as short as possible and be 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″ (152mm) above floor or a drain where any discharge will be clearly visible. No shut-off valve shall be installed between the relief valve and tank, or in the discharge line.
Vifaa vya joto na shinikizo (T&P) vilivyotumiwa kwenye vifaa vya maji vya maji vya makazi kwa kawaida hutengenezwa na kutengenezwa ili kupunguza shinikizo kwa 150psig na joto kwa 210-degree F. Vifaa hivi vya kuokoa vinalinda heater ya maji kutoka kwa shinikizo la ziada na joto kwa kutolea maji. Katika kazi ya kawaida ya maji ya joto na T & P valve, hakuna maji inapaswa kutolewa kutoka valve. Valve ya T & P ambayo hutolewa ni dalili ya hali isiyo ya kawaida katika mfumo na kwa kutolewa, valve ya T & P inakidhi kusudi lake la usalama. Sababu za kutokwa inaweza kuwa joto upanuzi, ziada ya mfumo shinikizo, chini ya joto misaada, kuweka juu sana juu ya maji ya joto, au kitu katika maji ya joto kusababisha joto ziada katika heater. Ili kuepuka uharibifu wa maji au kuwaka kutokana na kazi ya valve, mstari wa kutolea lazima uunganishwe na mlango wa valve na uende mahali salama pa kuondoa. Mfereji wa kutolea lazima uwe mfupi iwezekanavyo na uwe na ukubwa sawa na muunganisho wa kutolea valve katika urefu wake wote. Mstari wa kutolea lazima uelekee chini kutoka valve na kumaliza angalau 6′′ (152mm) juu ya sakafu au mfereji ambapo kutolewa yoyote itakuwa wazi inayoonekana. Hakuna valve shut-off lazima imewekwa kati ya valve relief na tank, au katika mstari discharge.