12/06/2012 20
GI202
Desuperheater, Domestic Hot Water
General
TTHERM GEO series units may be equipped with a double wall desuperheater and an integrated circulating
pump (can be a price deduct) that can provide Supplemental Domestic hot Water (SDW). This is done by
stripping heat from the superheated gas leaving the compressor.
Fuses
– the desuperheater pump is fed from the pump’s 10-amp fuses. The fuses are located on the pump relay
board in the line voltage control box. At the pump relay board top, moving the blk/red wire from the P tab to
the SWH tab (or vice versa) provides a “switch”.
General Plumbing and Installation Suggestions
1.
Insulated ½” copper piping should be used from the hot water tank to the desuperheater connections on
the left side of the unit. The copper tubing should be straight to maintain good water velocity and
prevent air pockets from forming at the pump inlet.
WARNING
NEVER USE PEX TUBING WHEN CONNECTING A DESUPERHEATER TO THE DOMESTIC
WATER SYSTEM. NORMAL CYCLING OF THE DESUPERHEATER PUMP CAN CAUSE THE
DISCHARGE WATER TEMPERATURE TO EXCEED THE RATED TEMPERATURE OF THE
PEX CAUSING THE PEX TO FAIL. THIS HAS CAUSED FLOODING IN BASEMENTS.
DESUPERHEATER MUST BE PLUMBED IN COPPER.
2.
Shut off valves should also be used to service the desuperheater pump without draining the entire hot
water tank. Note: Always be sure these valves are open when pump is running.
3.
Pump problems develop by running the pump dry or with air in the system. All air must be purged from
the desuperheater plumbing before the pump is engaged.
4.
To purge the air from the desuperheater lines close the ball valve between the desuperheater return,
boiler drain, and the bottom port of the water heater. Open the boiler drain allowing water to flow
through the complete desuperheater circuit purging out the air. When all the air is purged, close the
boiler drain and open the ball valve to the bottom of the water heater.
5.
Never operate the system without the high temperature switch (normally factory installed) as tank
temperatures could become dangerously high.
6.
Poor water quality may reduce the effectiveness of the desuperheater pump or not allow the pump to
circulate.
7.
Desuperheater maintenance includes periodically opening the drain on the hot water tank to remove any
deposits. Hard water may cause scale buildup in the desuperheater coil reducing its effectiveness.
8.
The temperature difference between the water entering and leaving the desuperheater will depend on the
desuperheater entering water temperature. The desuperheater will make less hot water in cooling.
9.
For the maximum efficiency from the provided desuperheater module, TTHERM GEO suggests a
water
heater preheat tank
as shown in Figure 7. The Figure 7A single tank plumbing and application is
shown for information only.
There are a number of ways the desuperheater/pump can be plumbed into the building/household water heater
tank.
However
, many common methods used
are not
very effective because they simply circulate already
heated water from the water heater tank through the desuperheater. The heat pump desuperheater cannot
effectively produce hot water energy if the temperature of the water entering the desuperheater is close to or
beyond the compressor gas capability to transfer energy into this circulated water – typically 110° F to 130° F.
In TTHERM GEO heat pumps the desuperheater is automatically disabled when it is unable to add
additional hot water energy to the water heater or preheat tank. TTHERM GEO units have the
option of the desuperheater operating whenever the compressor runs or it can be disabled in cooling
only by removing jumper J14 on the GEO Logic controller board.
Содержание TVA series
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