Bard GVDM-26 User Manual

INSTALLATION INSTRUCTIONS

GVDM-26

DOMESTIC HOT WATER DESUPERHEATER

PUMP MODULE KIT

© Copyright 2009

Bard Manufacturing Company, Inc.
Bryan, Ohio 43506

Since 1914...Moving ahead just as planned.

Manual No.: 2100-517
Supersedes: NEW
File: Volume I, Tab 9
Date: 02-06-09

Manual 2100-517
Page 1 of 11

CONTENTS

General ................................................................. 3

Description ............................................................ 3

Location ................................................................. 3

Electrical Connection............................................. 3

Soldering Tubing ................................................... 3

Installation Procedure – General ........................... 3

Operation of the Heat Recovery Unit .................... 4

Start Up and Check Out ........................................ 4

Maintenance .......................................................... 4

Control Board Sequence of Operation ................ 10

WIRING DIAGRAM

............................................................ 5

FIGURES

Figure 1 Mounting Directly onto Unit ................. 6

Figure 2 Air Purge Port ...................................... 7

Figure 3 Remote Mounting & Piping .................. 8

Figure 4 Single Tank System .............................9

Figure 5 Thermistor .........................................10

Figure 6 Replacement Parts ............................ 11

Manual 2100-517
Page 2 of 11

COPYRIGHT FEBRUARY 2009

BARD MANUFACTURING COMPANY, INC.

BRYAN, OHIO USA 43506

GENERAL

The pump module kit should only be installed by trained
technicians. These instructions serve as a guide to the
technician installing the pump module kit. They are not
intended as a step-by-step procedure with which the
mechanically inclined owner can install the unit.

DESCRIPTION

The system is designed to heat domestic water using heat
recovered from a water source unit’s hot discharge gas.

LOCATION

There are two options for the mounting location of the
GVDM-26 Domestic Hot Water Desuperheater Module.
First, there are pre-punched mounting holes for it on the
side of the geothermal heat pump beneath the filter rack.
Factory supplied in the kit are interconnect tubes that
connect the pump module to the water source unit (See
Figure 1).

The second is to locate the GVDM-26 on a wall adjacent
to the geothermal unit or storage tank/water heater. (See
Figures 3 and 4.)

Because of potential damage from freezing or
condensation, the unit must be located in a conditioned
space, therefore the GVDM-26 must be installed indoors.

Locate the storage tank as close to the geothermal heat
pump and pump module as the installation permits.
Keep in mind that water lines should be a maximum of
25 feet long measured one way. Also, the vertical lift
should not exceed 20 feet. This is to keep pressure and
heat losses to a minimum.

ELECTRICAL CONNECTION

The GVDM-26 is equipped with a standard 115V 3-prong
plug. The unit is rated at .9 amps and can normally be
plugged into any convenient electrical outlet.

NOTE: Make sure outlet is grounded, and that the

circuit will handle the added load. If any
concerns in this regard you should run a
separate grounded circuit to the main panel.

INSTALLATION PROCEDURE – GENERAL

Before beginning the installation, turn off all power
supplies to the water heater and unit, and shut off the
main water supply line.

TWO TANK – In order to realize the maximum energy
savings from the heat recovery system, it is
recommended that a second water storage tank be
installed in addition to the main hot water heater. Fossil
fuel fired water heaters must be a two-tank installation.

Tanks specifically intended for hot water storage are
available from water heater manufacturers (solar hot
water storage tanks). A well insulated electric water
heater without the electric heating elements will also
make a suitable storage tank.

The size of storage tank should be as large as space and
economy permit but in no event should it be less than
one-half of the daily water requirements for the
occupants. As a guide in estimating the daily family
water requirements, The Department of Energy
recommends a figure of 16.07 gallons of hot water per
day per individual. For example, a family of four would
require 64.3 gallons per day (4 x 16.07).

ONE TANK – The single hot water tank may be a new
hot water heater (sized to 100% of daily water
requirements) or the existing water heater in the case of a
retrofit installation. The existing water heater should be
drained and flushed to remove all loose sediment. This
sediment could damage the circulating pump. The
bottom heating element should be disconnected.

NOTE: Make sure water heater thermostats are set

below 125° on One Tank Unit.

WATER PIPING – All water piping must adhere to all
state and local codes. Refer to piping diagrams for
recommended one and two tank installations. Piping
connections are 1/2 inch nominal copper plumbing.

A cleanable “Y” type strainer should also be included to
collect any sediment.

SOLDERING TUBING

NOTE: The “inlet” and “outlet” thermistors should be

removed from the tubes prior to soldering/
brazing operation so they are not damaged.
They are clipped onto the “DSH COIL INLET”
and from “DSH OUTLET” tubes of the GVDM­26 Module. Once soldering operations are
complete, and the tubes have cooled, reattach
the sensors and wrap with provided insulation.

WARNING

Never alter or plug factory installed pressure
relief valve on water heater or auxiliary tank.

Manual 2100-517
Page 3 of 11

OPERATION OF THE HEAT RECOVERY UNIT

START UP AND CHECK OUT

The pump module is a very simple device containing
basic controls and a circulating pump. Heat is
transferred from the hot refrigerant (discharge gas) to the
cool water.

The operation of the Desuperheater Pump Module is
controlled first by the operation of the Geothermal Heat
Pump and secondly by internal controls within the Pump
Module. A low voltage signal from Thermostat “Y” is
connected to the internal control board of the GVDM-26
and acts as the primary on/off switch for the circulating
pump.

Also connected to this board is a temperature overlimit
device which shuts down the GVDM-26 once inlet water
has exceeded 125° so the water cannot create a scald
condition.

There are also two (2) thermistor sensors connected to
the control board. These thermistors are measuring and
controlling to ensure there is a positive heat differential
across the water being circulated. When operating in
Part Load Condition, there are certain conditions
(Ground Loop Temperatures versus Hot Water
Temperatures) that potential exists where heat could
transfer from the hot water into the refrigeration system
instead of the refrigeration system into the hot water.
Through the control board logic, these thermistors
ensure there is at least 2° positive differential between
entering/leaving water temperatures and will shut down
the pump accordingly.

Be sure all shut off valves are open and all power
supplies are on. Open a hot water faucet to permit any
air to bleed from the plumbing.

NOTE: The inherent design of this pump for maximum

efficiency means this pump is not self-priming.
It is imperative to check that the air has been
adequately bled from the system. There is a
bleed-port built into the pump module that can
be utilized after the system water has been fully
restored. See Figure 2 for this bleed port
location.

Turn ON the air conditioning system and verify the
circulating pump will operate. Feel the “Water to Unit”
and “Water from Water Heater” tubes for noticeable
difference in temperature. Turn OFF the system and
verify that the circulating pump stops.

NOTE: When checking the refrigerant operating

pressures of the ground source heat pump. The
GVDM-26 must be turned off. With the
GVDM-26 operating a wide variance in
pressures can result, giving the service
technician the indication there is a charge
problem when the unit is operating correctly.

MAINTENANCE

CLEANING THE HEAT EXCHANGER – If scaling of
the coil is strongly suspected, the coil can be cleaned
with a solution of phosphoric acid (food grade acid).
Follow the manufacturer’s directions for the proper
mixing and use of cleaning agent.

Manual 2100-517
Page 4 of 11