6
Maintenance
Hot Water Generator Installation and Operation Manual
Storage tank maintenance
A new tank installation should have a regular inspection
program set up. The first inspection should be within the first
three months of operation. Once the tendency to accumulate
sediment has been established, the inspection program can be
modified to suit the water conditions. Typical inspection
programs flush the tank at six-month intervals and clean the
tank in yearly intervals.
Deliming solvents or acid type flush agents are not
recommended for use in lined storage tanks. These chemical
cleaners are usually designed for use in non-potable systems
such as heating boilers. These chemicals may be aggressive
and cause damage to the tank lining and deteriorate the
magnesium anodes supplied in glass-lined storage tanks.
WARNING
Hot water will be released under pressure.
Avoid contact with the hot discharge water
to prevent the risk of severe scald injury.
Flushing the storage tank
Since the mineral accumulation is occurring in an un-fired
tank it will be in a soft sediment form. This soft sediment can
be removed by a regular flushing of the lower portion of the
tank.
To flush the tank, follow these steps:
1.
Turn off electrical power to the circulating pump and any
other tank accessories.
2.
Close the valve on the hot water outlet on the top of the
storage tank.
3.
Ensure that the drain located on the bottom of the tank
is routed to a floor drain with adequate capacity to allow
the tank to be flushed.
4.
Open the drain valve and allow the incoming cold water
to flush the soft sediment out the bottom of the storage
tank. Use extreme caution, as the water exiting the tank
drain may be very hot. Avoid contact with the hot
discharge water to prevent the risk of severe scald injury.
5.
Observe the color of the water initially discharged from
the tank drain. This water will generally be milky or
slightly discolored by the sediment discharge. Allow the
drain to run until the water runs clear.
6.
Close the drain valve on the tank.
7.
Open the hot water outlet valve on the top of the tank.
8.
Open an adjacent hot water tap to purge any air that may
have entered the storage tank during the draining
process. Close the hot water tap if no air discharge is
observed.
9.
Turn on electric power to the circulating pump and other
electrical components if necessary.
10. Observe tank and piping to ensure all components are
functioning properly.
Cleaning the storage tank
The mineral accumulation in an un-fired tank will be in a soft
sediment form that can be removed by a regular cleaning of
the lower portion of the tank. Many tanks will have a hand
hole or a larger manway to allow access to the interior of the
tank for complete removal of accumulated sediment. An
access opening to remove the manway or hand hole is
provided in the exterior jacket.
The sheetmetal jacket
components are removed with hand tools. The opening will
be in the bottom portion of a vertical tank and on the end of
a horizontal tank (see FIG’s 1 and 2 on page 4 of this manual).
To clean the tank, follow these steps
(reference FIG.’s 7 and 8)
:
1.
Close valves from boiler water or steam supply and
return or condensate pipes.
2.
Turn off electrical power to the circulating pump and
other electrical components if necessary.
3.
Close the valve on the hot water outlet on the top of the
storage tank and the cold water supply to the system.
4.
Ensure that the drain located on the bottom of the tank
is routed to a floor drain with adequate capacity to allow
the tank to be drained.
5.
Open the drain valve and open a vent to allow the air to
enter the tank (manually opening the relief valve will
usually accomplish this). Use extreme caution, as the
water exiting the tank drain may be very hot. Avoid
contact with the hot discharge water to prevent the risk
of severe scald injury.
6.
Allow the tank to drain completely.
7.
Remove the jacket cover over the manway or hand hole.
Remove the bolt(s) securing the tank access opening.
Use a flashlight to observe the sediment collected in the
tank.
8.
Use hand tools to remove all sediment from the interior
of the tank. Use care not to damage the interior lining of
the storage tank.
9.
Use a water hose to flush the remaining sediment from
the interior surfaces of the tank and ensure that all debris
is removed.
Scale or sediment allowed to reach the
potable system can foul valves, pumps, strainers, and
other water fixtures. Ensure that the tank interior is clean
before refilling the vessel.
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