longer than 7 minutes or where cold water operation is continuous, provisions must be made to mix higher temperature outlet water with the colder inlet water and thereby raise the inlet temperature to at least 120°F (49°C) within the 7-minute time limit.

Cold Water Starts

Cold water starts, where the inlet water temperature remains below 120°F (49°C) for more than 7 minutes, must have cold water start protection. Known pro- tection methods consist of mixing heated outlet water with the inlet water using a bypass to raise the inlet to 120°F (49°C) or higher. Once the system is heated up and has return water temperatures of 120°F (49°C) or higher, the mixing of outlet water with inlet water is no longer needed and the bypass can be shut off. If the bypass is not shut off as the system heats up, the out- let temperature may continue to climb and trip the high limit, thereby shutting down the heater. Thus an auto- matic valve system, such as a three-way proportional valve to control the bypass, should be used.

*

*Maximum 4 times the pipe diameter or 12”, whichever is less.

Fig. 9: Cold Water Start

Cold Water Run

Cold water run differs from cold water start in that the system water entering the heater remains below 120°F (49°C) continuously. Typically, this is the case in swimming pool heating and water source heat pump applications as well as some others. If the system

water is kept in a narrow temperature range of no more than 10°F (5°C), a permanent manual bypass can be employed and manually adjusted to achieve an inlet temperature of 120°F (49°C) or higher as adjust- ed at the minimum temperature in this narrow temperature range (i.e. Range 75°F to 85°F, adjust bypass with temperature at 75°F (24°C)) so that when temperature is 85°F (29°C), minimum inlet tempera- ture would be 130°F (54°C). An injector pump arrangement may also be utilized to keep the heater loop at or above 120°F (49°C). An injector pump approach has the added value of being able to adjust to changes in the system water coming back to the heater take-off.

*

*Maximum 4 times the pipe diameter or 12”, whichever is less.

Hydronic Heating

Pump Selection

In order to ensure proper performance of your heater system, you must install a correctly-sized pump. Ray- pak requires designing for a ∆T within the range of 10°F to 40°F (5°C to 20°C). See Table F for accept- able flow rates for each model (∆T is the temperature difference between the inlet and outlet water when the heater is firing at full rate).

Feedwater Regulator

Raypak recommends that a feedwater regulator be in- stalled and set at 12 psi minimum pressure at the highest point of the system. Install a check valve or back flow device upstream of the regulator, with a manual shut-off valve as required by local codes.

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Raypak 503-2003 manual Hydronic Heating, Pump Selection, Feedwater Regulator, Cold Water Starts, Cold Water Run
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503-2003 specifications

The Raypak 503-2003 is a notable entry in the world of water heating solutions, renowned for its efficiency and reliability in both residential and commercial settings. This model is designed to provide exceptional performance while maintaining ease of use and minimization of environmental impact.

One of the standout features of the Raypak 503-2003 is its advanced heating technology. The unit utilizes a durable, copper heat exchanger which ensures quick and efficient heating of water. This heat exchanger is known for its ability to transfer heat effectively, leading to reduced energy consumption and lower utility bills. The design also allows for a seamless operation, ensuring that the system heats water swiftly without sacrificing performance.

In addition to its efficient heating capabilities, the Raypak 503-2003 is equipped with innovative controls. The digital control panel allows users to easily set and adjust the desired water temperature. This feature provides a level of convenience that simplifies operation while enhancing user experience. Furthermore, the smart technology employed in the unit ensures that it operates within optimal parameters, avoiding unnecessary energy expenditure.

Durability is another hallmark of the Raypak 503-2003. Built with heavy-duty components, this water heating solution is designed to withstand the rigors of continuous use. The rugged construction ensures longevity, making it a cost-effective investment for homeowners and businesses alike. Moreover, the unit is designed to be resistant to corrosion and wear, further extending its lifespan and reliability.

The energy efficiency of the Raypak 503-2003 is a crucial characteristic that sets it apart from competitors. Rated with a high efficiency score, this model contributes to lower emissions and is environmentally friendly. It adheres to various energy standards, making it a suitable choice for those looking to reduce their carbon footprint while enjoying reliable water heating.

Noise reduction is another important feature of the Raypak 503-2003. Designed with quiet operation in mind, the unit operates with minimal noise pollution, allowing for a pleasant environment in both residential and commercial spaces.

In summary, the Raypak 503-2003 combines advanced heating technology, user-friendly controls, durability, and energy efficiency into a robust water heating system. This makes it an excellent choice for those in need of dependable and sustainable heating solutions. Whether for daily home use or for larger commercial applications, the Raypak 503-2003 stands out as a leader in its class.
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