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Raypak MVB 5042004 User Manual

Page 13

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Relief Valve Piping

Temperature & Pressure Gauge

The temperature and pressure gauge is shipped loose

for field installation and must be installed within 12

inches of the boiler outlet (if possible) in an easily

readable location. Installation must comply with ASME

Section IV as well as all applicable national, state and

local codes.

Hydrostatic Test

Unlike many types of heaters, this heater does not re-

quire hydrostatic testing prior to being placed in

operation. The heat exchanger has already been fac-

tory-tested and is rated for 160 psi operating pressure.

However, Raypak does recommend hydrostatic test-

ing of 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 anti-freeze. Raypak recommends conducting

the hydrostatic 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.

To perform hydrostatic test:

1. Connect fill water supply. With bleed valve open,

fill heater with water. When water flows from bleed

valve, shut off water. Close bleed valve. Carefully

fill the rest of the system, making sure to eliminate

any entrapped air by using high-point vents. Close

13

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.

Cold Water Operation

This heater is equipped with a proprietary condensate

evaporation system which will evaporate any conden-

sate that may begin to accumulate inside the primary

heat exchanger with water temperatures as low as

120°F (49°C).

Heaters operated with an inlet temperature of less

than 120°F (49°C) MUST have a manual bypass (see

Fig. 16) or an approved low-temperature operation

system (Figs. 9 and 10) to prevent problems with con-

densation.

This

piping

is

similar

to

a

primary/secondary boiler installation, with a bypass

acting as the secondary boiler piping. Raypak strong-

ly recommends that thermometer(s) be placed into the

heater piping next to the in/out header to facilitate tem-

perature adjustment. Inlet water temperatures below

120°F (49°C) can excessively cool the products of

combustion, resulting in collection of condensate in the

heat exchanger area beyond the capacity of the con-

densate evaporation system.

Failure to reach or exceed 120°F (49°C) within 7 min-

utes may damage or cause failure of the heat

exchanger, combustion chamber, or other parts within

the combustion chamber. It can cause operational

problems, bad combustion, sooting, flue gas leakage

and reduced service life of the appliance and the vent

system. A bypass allows part of the heater discharge

water to be mixed with the cooler water returning to the

heater inlet to increase the heater inlet temperature

above 120°F (49°C). This precautionary measure

should prevent the products of combustion from con-

densing beyond the ability of the condensate

management system employed in this heater in most

installations. Warranty claims will be denied for

damage or failures caused by condensation.

Cold water operation issues are applicable to both

cold water start and cold water run applications. Cold

water operation for 7 minutes or less on initial daily

start-up is acceptable. Where cold water starts will last

WARNING: Pressure relief valve discharge piping

must be piped near the floor and close to a drain to

eliminate the potential of severe burns. Do not pipe

to any area where freezing could occur. Refer to

local codes.

CAUTION: Damage due to internal condensation

may occur if the heater inlet water temperature does

not exceed 120°F (49°C) within 7 minutes of start-

up.

CAUTION: This heater requires forced water

circulation when the burner is operating. See Table F

and Table G for minimum and maximum flow rates

and water pump selection. The pump must be

interlocked with the heater to prevent heater

operation without water circulation.

NOTE: Minimum pipe size for in/out connections is

2 in. NPT for 504 and 754 models and 2-

1

2

in NPT for

1104–2004 models. Verify proper flow rates and ∆T

as instructed in this manual.