Bosch AQUASTAR 125B LPL operati, Installation And Operating Instructions Manual

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13
WATER IS TOO HOT
1. Gas flow is higher than necessary.
Move gas control slide to the left.
2. Temperature (aquastat) control is set too high
If unit is plumbed in a recirculating loop system the aquastat
temperature relay for the primary circulator pump is possibly
set too high.
WATER IS NOT HOT ENOUGH
1. Water flow rate is too high.
Decrease the flow rate.
2. Gas flow is not optimal
Move gas control slide to the right.
3. Temperature (aquastat) control is set too low
If unit is plumbed in a recirculating loop system the aquastat
temperature relay for the primary circulator pump is possibly
set too low.
4. Btu input is too low due to insufficient gas pressure
It is extremely important for a tankless instantaneous
water heater to have the right size gas line to obtain
the correct gas pressure
See specifications on page 2. Unlike storage tank water
heaters, the burners of a tankless water heater must be
very powerful to heat water instantaneously since they do
this only at the time hot water is actually being used. It is
therefore imperative that the gas pressure requirement be
met exactly. Insufficient gas pressure will directly affect
the water temperature at the time of usage. See pages 2
for correct gas pressure settings.
5. Btu input is too low due to insufficient gas supply
Make sure your main gas line is fully opened. If using LP
gas, be sure that the size of the propane tank is adequate
to supply the required gas pressure.
6. Cold water is mixing with the hot water between
the AquaStar and the outlet
Compare water temperature at outlet of the AquaStar (hold
the AquaStar’s outlet pipe with your hand) and at the tap. If
these two are very different, check for mixing valve or
plumbing crossover (see “MAIN BURNERS WILL NOT
IGNITE...” paragraph #5).
7. Parts in water flow valve are corroded so that the
gas passage is not fully opening
Contact your service person or Controlled Energy.
6. Crossover in household plumbing
The AquaStar burner activates when there is sufficient water
pressure drop in the AquaStar water valve assembly — ie.
when a hot water faucet is opened. If there is a crossover in
the plumbing, the necessary pressure drop in the AquaStar
will be insufficient, or totally eliminated. A plumbing
crossover can be caused by a bad washer at a single lever
faucet or incorrect plumbing or a mixing valve in the line,
etc. which permits hot and cold water to mix in the
plumbing. The crossover will create a back pressure in the
system preventing the pressure drop in the Aquastar (i.e.
cold water is entering the water heater from both sides and
the burners will not come on).
To confirm there is no crossover in the plumbing, shut off
the cold water supply to the AquaStar. Open your hot water
taps.
There should not be any water flowing. If there is water
flowing, there is a crossover in the plumbing. This is a
plumbing problem, not an Aquastar problem. Please contact
your plumber.
7. Water valve parts may be dirty or components
damaged.
First check that the venturi is free from dirt particles.
Water valve and component parts must be totally free of
dirt. In hard water areas, mineral deposits can eventually
(3 to 5 years in hard water areas) corrode the water valve
parts to a point where they will need replacing. Any sign of
moisture or corrosion at the joint of the water valve and the
gas valve is a sign that the water valve assembly
components need to be replaced immediately.
Note: Water valve for model 125BL is part # 8707002478
for both LP and NG models. (Contact service person to
clean water valve or replace if corrosion is present).
PILOT LIGHT GOES OUT DURING OR AFTER USE
1. Gas pressure too low
Very low gas pressure may be caused by low delivered
gas pressure, a jammed gas regulator or undersized gas
lines. If the gas lines are undersized, there may still be the
specified static gas line pressure. However when the water
valve opens,and gas enters the burners, the pressure could
drop sharply, causing the pilot flame to go out. Have a gas
technician confirm the gas pressure both static and at
maximum Btu output. Specifications for your heater are on
page 2.
2. Pilot may be dirty or weak
See Page 9 for instructions on pilot maintenance.
3. Burners are not shutting down immediately when
hot water is turned off or when a circulator pump
has stopped operating
Note: If burners don’t shut down immediately when the hot
water is turned off, the heater will overheat and the ECO
will shut-off the gas. Rebuild the water valve assembly using
the repair kit from CEC (part#8 703 406 214).
4. Temperature controls are set too high
If unit is plumbed in a recirculating loop system insure that
the aquastat or relay for the primary circulator pump is set
for no hotter than 140°F. This is necessary to prevent pilot
outage due to overheating. The temperature slide control
on the 125BL may also need to be lowered to prevent
overheating.