John Wood Direct Vent Models No Longer in Production - Manual (Page 12)

CONTROL
If the heater or the controls have been subjected to flood-
ing, shut off the gas at the manual shut-off valve to the
heater and call your gas company.
The heater operates under a fully automatic control.
Once the desired water temperature has been selected,
the gas control will maintain that temperature within close
limits.
DO NOT TAMPER WITH THE GAS CONTROL!
IX) INSTALLATION INSTRUCTIONS FOR
WATER HEATERS APPROVED FOR SPACE
HEATING AND POTABLE WATER HEATING
When using this water heater in the application of a com-
bination space and potable water heating system, be
sure to follow instructions provided with the water heater
and the manual shipped with the air handler.
NOTE the following warnings:
1. The piping and components connected to the water
heater for the space heating applications shall be
suitable for use with potable water. The system should
be installed with new, non-ferrous piping. Do not use
piping, pumps, valves, fittings, solder, gluing and pipe
sealant that are not completely compatible with
potable water.
2. A water heater which will be used to supply potable
water must not be connected to any heating system or
components previously used with a non-potable water
heating appliance. Do not use: piping that has been
treated; broiler seal chromates; or other chemicals.
3. Do not use this heater as a replacement for an exist-
ing boiler installation.
4. Do not introduce toxic chemicals such as those used
for boiler treatment, into the potable water used for
space heating.
5. If the space heating water system requires water with
temperatures in excess of 60°C (140°F), a mixing
valve or other means must be installed in the potable
hot water supply to temper the water and reduce
scald hazard potential.
6. If the heater is installed with a back-flow preventer on
the incoming water line or in a closed system, a
diaphragm-type expansion tank must be installed in
the system to prevent weeping due to expansion (see
Figure 2B).
7. Proper sizing of the water heater for the given space
and potable heating application is essential to ensure
adequate heating capacity. The sizing and installation
of such combination system must be performed by
qualified personnel and be in accordance with public
utility requirements and/or Codes having jurisdiction.
The sizing of the water heater should be based on the
design heat loss of the structure to be heated plus the
potable water requirements.
IT IS IMPORTANT THAT THE WATER HEATER USED
BE OVERSIZED TO ALLOW ADEQUATE HEATING
AND POTABLE WATER HEATING CAPACITY.
- 12 -
HOT
WATER
TO
HOUSE
COLD TO
WATER HEATER
CHECK VALVE CIRC. PUMP
DIRECT
VENT
WATER
HEATER AIR HANDLER
RADIATOR OR RADIANT FLOOR PIPING ARE
VIABLE ALTERNATIVES TO AIR HANDLER.
Figure 5
CAUTION
Hydrogen gas can be produced in a hot water
system served by this heater that has not
been used for a long period of time (generally
two weeks or more). Hydrogen gas is
extremely flammable. To reduce the risk of
injury under these conditions, it is recom-
mended that the hot water faucet be opened
for several minutes at the kitchen sink before
using any electrical appliance. If hydrogen is
present, there will probably be an unusual
sound such as air escaping through the pipe
as the water begins to flow. There should be
no smoking or open flame near the faucet at
the time it is open.