Carrier 50BV020-064 Make Piping Connections, a50-8253, DHS Pressure Limit Location, a50-7268tf

a50-8253

Fig. 18 — DHS Pressure Limit Location

a50-7268tf

Fig. 19 — DHS Limit Switch (P/N 190060)

Step 4 — Make Piping Connections

CONDENSER WATER PIPING (Water-Cooled Only) — Always follow national and local codes when installing water piping to ensure a safe and proper installation. Connections to the unit should incorporate vibration eliminators to reduce noise and vibration to the building, and shutoff valves to facili- tate servicing.

Prior to connecting the unit(s) to the condenser water system, the system should be flushed to remove foreign material that could cause condenser fouling. Install a screen strainer with a minimum of 20 mesh ahead of the condenser inlet to prevent condenser fouling and internal condenser tube damage from foreign material.

Supply and return water piping must be at least as large as the unit connections, and larger for long runs. Refer to the System Design Manual, Part 3, and standard piping practice, when sizing, planning, and routing water piping. See dimen- sion drawings (Fig. 2-14) for water connection sizes and locations.

Units are furnished standard with a copper heat exchanger. A cupronickel heat exchanger is also available as a

factory-installed option. Copper is adequate for closed loop systems where good quality water is available. In conditions where scale formation or water treatment is questionable, the optional cupronickel heat exchanger should be used. Where the water is especially corrosive or could lead to excessive fouling, intermediate plate frame heat exchangers are recommended.

CAUTION

Galvanized pipe or fittings are not recommended with 50BV units due to the possibility of galvanic corrosion caused by dissimilar metals. When selecting piping materials, use only approved piping materials that meet applicable codes and that will handle the temperatures and pressures that may be experienced in the application. Piping systems will sweat if low temperature fluid is used in the system. For these applications, supply and return water piping should be insulated to protect from condensa- tion damage. The minimum recommended entering water temperature to the unit is 50 F.

The unit is capable of operating with entering water temper- atures as low as 50 F, without the need for head pressure control. If the entering water temperature is expected to be lower, or more stable unit operation is desired, a field-supplied water-regulating valve may be used.

This unit has multiple independent refrigerant circuits with separate condensers. The individual condensers are manifolded together on the waterside to provide easy, single-point water connections. In order to achieve proper head pressure control when a water-regulating valve is used, a temperature-actuated valve is recommended. This allows any of the independent refrigerant circuits to operate while still modulating condenser water flow in response to loop water temperature.

A glycol solution should be used if ambient temperatures are expected to fall below freezing or if the loop water temper- ature is below 50 F while operating in the reverse cycle heating mode (heat pump units only). Refer to Table 4, which lists freezing points of glycol at different concentrations. A minimum concentration of 20% is recommended. Water pressure drop will increase and unit performance will decrease with increasing glycol concentrations.

Units with factory-installed waterside economizers have cooling water passing through the economizer and condenser in series while operating in the economizer mode. During normal operation, water bypasses the economizer coil.

Table 4 — Glycol Freezing Points

% GLYCOL	FREEZE POINT (° F)
	Ethylene Glycol	Proplylene Glycol
20	18	19
30	7	9
40	–7	–5
50	–28	–27

All manual flow valves used in the system should be of the ball valve design. Globe or gate valves must not be used due to high pressure drops and poor throttling characteristics.

Do not exceed recommended condenser fluid flow rates shown in Tables 5A and 5B. Serious damage or erosion of the heat exchanger tubes could occur. Piping systems should not exceed 10 fps fluid velocities to ensure quietness and tube wall integrity. Refer to Tables 5A and 5B for condenser water pres- sure drop versus flow rate. Flow rates outside of the published range should not be used.

Ball valves should be installed in the supply and return lines for unit isolation and water flow balancing.

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