Normal Operation - Girard Products GSWH-1 Service Manual

NORMAL OPERATION

A tankless water heater, also referred to as an "on demand" water heater, rapidly heats water as
it flows around and through the heat exchanger. The output water temperature depends on the
temperature of the input water and the flow established at the faucet by the user; the faster the
flow, the cooler the water; the slower the flow, the hotter the water.
The gas control valve of the GSWH-1 and the GSWHAF-1 features a dual BTU solenoid that can
operate in 'High' mode (34,000 BTUs) or 'Low' mode (27,000 BTUs) depending on the input
temperature of the cold water. Colder water (65°F or less) causes the burner to operate in
'High'. Warmer water (70°F or more) causes the burner to operate in 'Low'. NOTE: When the
input water temperature is between 65°-70°F the unit may operate in 'High' or 'Low' depending
upon precise thermostat settings. A thermostat setting may vary +/- 5°F.
Prior to normal operation the user must ensure that all air has been purged from the water lines,
the Water Heater Power Switch is in the 'ON' position and the REMOTE Mode Switch (see below)
is set in the desired position (AUTO or LO). The 12VDC power is normally left ON while the RV is
in use with no use of LP gas. In many cases the switch may be set to 'On' the entire camping
season. This will not harm the unit in any way.
To start the water heater the user should fully open the hot water faucet, wait for hot water to
flow and decrease the flow (which results in hotter water) to obtain the temperature desired.
Note: although the Girard tankless water heater is instantaneous, the water in the system (pipes)
must be purged before the user will feel hot water at the faucet. Thus, the further the water
heater is located from the faucet/shower the longer it will take for the user to feel hot water. The
ideal location for any water heater is in the center of the coach.
During normal operation the hot water faucet behaves somewhat like a typical mixing valve: it
(faucet) increases the water temperature when turned clockwise (reducing the water flow) and
decreases the water temperature when turned counterclockwise (opening and increasing the
water flow).
The user may mix the hot water with cold water, but normally this is not recommended: The
increased total flow (Hot plus Cold) will reduce the inlet pressure; which in turn, reduces the flow
of water through the heat exchanger of the water heater: this will cause the hot water output
temperature to increase defeating the effect of the cold water. In some cases adding cold water
may result in limiting. (See last paragraph, this section)
When the Mode switch is set to AUTO, a thermostat will cause the burner to switch automatically
from High to Low when the inlet water temperature goes above 70 ºF and from Low to High
when it goes below 65 ºF. Note: A thermostat setting may vary +/- 5°F.
If the output temperature exceeds 123 ºF an Emergency Cut-Off (ECO) thermostat will shut
down the unit to prevent scalding; this operation is both normal and desirable and is commonly
referred to as "limiting".
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