Raypak 133 Installation & Operating Instructions Manual

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Raypak 133 Installation & Operating Instructions Manual Manual pdf 25 page image

25Controls—GeneralRelief ValveA new combination temperature and pressure (T&P)relief valve, complying with the Standard for ReliefValves and Automatic Gas Shut-Off Devices for HotWater Supply Systems, ANSI Z21.22, must beinstalled in the opening provided on top of the storagetank at the time of installation. No valve is to be placedbetween the relief valve and the storage tank.The pressure rating of the relief valve must not exceedthe 160 maximum working pressure indicated on thewater heater rating plate. The BTUH rating of the reliefvalve must not be less than the BTUH input of theheater.Connect the outlet of the relief valve to a suitable opendrain. The discharge line must pitch downward fromthe valve to allow complete draining (by gravity) of therelief valve and discharge line. The discharge lineshould be no smaller than the outlet of the valve. Theend of the discharge line should not be threaded orconcealed, and should be protected from freezing. Novalve of any type, restriction or reducer coupling,should be installed in the discharge line. Local codesshall govern installation of the relief valve.Pump Time DelayThere are two versions of the Pump Time Delay. Thefirst is an electronic device that allows the operator toset a variable time (3 to 10 minutes) for the pump torun after the heater shuts off. See Fig. 21 (A). The timeis factory-set at 7 minutes and it can be re-adjusted inthe field.The second version is a fully enclosed solid state TimeDelay Relay (TDR) with a white jumper that selectsone of two time delays. See Fig. 21 (B). If the jumperis on pins 6 and 7 (default) the delay time is 5 minutes.If the jumper is not on pins 6 and 7, the time delay is10 minutes.In a conventional system, when the tankstat is satis-fied, the main gas valve closes, but the pumpcontinues operating. With either time delay relay theheater pump is programmed to continue running for anoptimum period of time in order to absorb the residualheat from the combustion chamber and use it in thesystem. The pump then shuts off until the next call forheat is received from the tankstat.Electronic IgnitionThe intermittent ignition device conserves energy byautomatically extinguishing the pilot when desiredtemperature is reached. When additional heat is need-ed, the pilot re-ignites electrically, eliminating the fuelcosts of maintaining a constant pilot. To ensure safeoperation, the gas valve cannot open until the pilotrelights and is confirmed.Operating ControlsOn models 0514-1826, models with mechanical mod-ulating controls have one or more Robertshaw Unitrol7000 Series hydraulic snap on thermostatic combina-tion gas valves. These valves have the pressureregulator and 24-volt operator built-in. The hydraulicactuator will throttle the heater input to adjust the firingrate and meet the required load. This, in effect, pre-vents costly fuel consumption, as compared to anNOTE: Pump will come on when power is firstapplied to heater.Fig. 21: Economaster Time Delay Relays (TDR)612(A)(B)Table J: Electronic Ignition