Domestic Hot Water Piping, Piping-Heating Boilers

Piping—Heating Boilers

All high points should be vented. Purge valves and a bypass valve should be installed. A boiler installed above radiation level must be provided with a low water cut-off device. The boiler, when used in connec- tion with a refrigeration system, must be installed so the chilled medium is piped in parallel with the boiler with appropriate valves to prevent the chilled medium from entering the boiler.

The boiler piping system of a hot water heating boiler connected to heating coils located in air handling units where they may be exposed to circulating refrigerated air, must be equipped with flow control valves or other automatic means to prevent gravity circulation of the boiler water during the cooling cycle. It is highly recom- mended that the piping be insulated.

Three-Way Valves

Valves designed to blend water temperatures or reduce water circulation through the boiler should not be used. Raypak boilers are high recovery low mass boilers not subject to thermal shock. Raypak offers a full line of electric sequencers that produce direct reset of boiler water temperature. Refer to the Controls Section in our Complete Catalog.

Domestic Hot Water Piping

When designing the water piping system for domestic water applications, water hardness should be consid- ered. Table F indicates the suggested flow rates for soft, medium and hard water. Hardness is specified as grains per gallon.

Air-Separation/Expansion Tank

All boilers should be equipped with a properly sized expansion tank and air separator fitting as shown in the piping diagrams (Fig. 10–12).


Model	Input	Output	Soft (0–4 grains per gallon)					Medium (5–15 grains per gallon)					Hard* (16–25** grains per gallon)
No.	MBTUH	MBTUH
No.	MBTUH	MBTUH	∆T	gpm	∆P	MTS	SHL	∆T	gpm	∆P	MTS	SHL	∆T	gpm	∆P	MTS	SHL
HD101	100	85	9	20	1.8	1-1/2	3.8	7	26	3.0	1-1/2	6.3	4	45	9.2	1-1/2	18.0
HD151	150	128	13	20	1.8	1-1/2	3.8	10	26	3.1	1-1/2	6.3	6	45	9.2	1-1/2	18.1
HD201	199	169	17	20	1.9	1-1/2	3.9	13	26	3.2	1-1/2	6.4	8	45	9.4	1-1/2	18.2
HD251	250	213	21	20	1.9	1-1/2	3.9	16	26	3.2	1-1/2	6.5	9	45	9.6	1-1/2	18.5
HD301	299	254	25	20	1.9	1-1/2	3.9	20	26	3.2	1-1/2	6.5	11	45	9.8	1-1/2	18.7
HD401	399	339	34	20	2.0	1-1/2	4.0	26	26	3.3	1-1/2	6.6	15	45	10.3	1-1/2	19.1

∆T = Temperature rise, °F.

∆P = Pressure drop through heat exchanger, ft.

SHL = System head loss, ft. (System head loss is based on the heater and tank placed no more than 5 feet apart and 50 feet equivalent length of tubing and fittings.)

gpm = Gallons per minute, flow rate. MTS = Minimum tubing size.

*Must utilize optional cupro-nickel tubes.

**With Hard Water (16-25 grains per gallon), the operating control must be set no higher than 130°F for scale free operation. For operating tem- peratures above 130°F, a water softener must be utilized.

Table F: Domestic Water Heater Flow Rate Requirements

HD101, HD401 specifications

Raypak is renowned for its commitment to high-quality heating solutions, with the HD101 and HD401 models standing out in their product range. These units are designed specifically for commercial applications, providing reliable and efficient hydronic heating systems. The HD series embodies innovation while addressing the unique demands of larger spaces.

One of the main features of the HD101 and HD401 is their stainless steel construction, which ensures increased durability and resistance to corrosion. This design choice enhances the longevity of the units, making them ideal for various installations in commercial or industrial settings.

Both models are equipped with a high-efficiency heat exchanger that maximizes heat transfer while minimizing energy consumption. This feature is particularly significant in today’s environmentally conscious market, as it contributes to lower operating costs and reduced carbon footprints. The heat exchangers are engineered for easy maintenance, offering simplicity when service is required.

In terms of technology, the HD101 and HD401 include advanced digital controls that allow for precise temperature regulation. This user-friendly interface enables operators to easily manage and monitor heating parameters, facilitating optimal performance and energy management.

The models also feature modulating burners that adjust their output according to the heating demand. This capacity for modulation results in smoother operation and an overall increase in efficiency, as the burners can maintain consistent temperatures without excessive energy use.

Another noteworthy characteristic is their compatibility with various control systems, including BMS (Building Management Systems). This adaptability allows for seamless integration into existing infrastructure, providing users with greater versatility and control over their heating environments.

Both the HD101 and HD401 come with advanced safety features, including flame rollback protection and pressure monitoring, ensuring safe operation even in demanding conditions. Additionally, their compact design allows for easy installation in limited spaces while still providing powerful heating capabilities.

Ultimately, the Raypak HD101 and HD401 are exceptional choices for those in need of high-efficiency commercial heating solutions. With their robust construction, advanced technology, and user-friendly features, these models promise to deliver reliable performance and energy savings for years to come. Whether for a large facility or a specific industrial application, they stand ready to meet the heating challenges of today’s commercial landscape.