Hydronic Heating

Hydrostatic Test

Unlike many other types of heaters, Raypak heaters do not require hydrostatic testing prior to being placed in operation. The heat exchanger has already been factory-tested and is rated for 160 PSI maximum oper- ating pressure. However, Raypak does recommend hydrostatically testing the piping connections to the heater and the rest of the system prior to operation. This is particularly true for hydronic systems using expensive glycol-based antifreeze. Raypak recom- mends conducting the hydrostati c test before connecting gas piping or electrical supply.

Leaks must be repaired at once to prevent damage to the heater. NEVER use petroleum-based stop-leak compounds.

1.Connect fill water supply. Fill heater with water (be sure bleed valve is open). When water flows from bleed valve, shut off water. Close bleed valve. Carefully fill the rest of the system, being sure to eliminate any entrapped air by using high point vents. Close feed valve. Test at standard operating pressure for at least 24 hours.

2.Make sure constant gauge pressure has been maintained throughout test.

3.Check for leaks. Repair if found.

Low Temperature System

Heater requires minimum inlet temperature of 105°F. Consult the following sections for piping details.

Temperature & Pressure Gauge

The temperature and pressure gauge is shipped loose for field installation.

Pump Selection

In order to ensure proper performance of your boiler system, you must install a properly sized pump. Raypak recommends using a 20°F ∆T as design ∆T. (∆T is the temperature difference between the inlet and outlet water when the heater is firing at full rate). If a ∆T other than 20°F is necessary, see Table E for flow rate requirements.

Pressure Drop in Feet of Head Feedwater Regulator

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


Model	Input	Output	10°F ∆T		20°F ∆T		30°F ∆T		Min. Flow			Max. Flow
No.	MBTUH	MBTUH	gpm	∆P (ft)	gpm	∆P (ft)	gpm	∆P (ft)	gpm	∆P (ft)	∆T	gpm	∆P (ft)	∆T
HD101	100	85	17	1.3					13	0.7	14	44	8.8	4
HD151	150	128	26	3.0	13	0.7			13	0.7	20	44	8.8	6

HD201	199	169	34	5.3	17	1.3			13	3.4	27	44	8.9	8

HD251	250	213	44	9.2	21	2.1	14	1.0	13	0.7	34	44	9.2	10
HD301	299	254			25	3.1	17	1.4	13	0.8	40	44	9.4	12

HD401	399	335			34	5.6	22	2.5	17	1.4	40	44	9.8	15

*Flow switch will not activate at less than 12 gpm.

NOTE: Basis for minimum flow — 13 gpm or 40°F ∆T maximum flow — gpm, except for header.

Table E: Heater Rates of Flow and Pressure Drops

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.

Hydrostatic Test

Low Temperature System