1. Use glycol only if needed for freeze protection fluid.
2. Propylene glycol is the recommended freeze protection
fluid.
3. Make sure to flush the boiler system before adding glycol.
4. Determine the freeze protection fluid quantity using
system water content, following the fluid manufacturer's
instructions. Boiler water content is listed on page 7.
Remember to include expansion tank water content.
5. Local codes may require a backflow preventer or actual
disconnect from city water supply.
6. When using freeze protection fluid with automatic fill, it is
suggested to install a water meter to monitor water makeup.
Freeze protection fluid may leak before the water begins to
leak, causing the concentration to drop, which reduces the
freeze protection level.
7. The freeze protection set points may be lowered when freeze
protection fluid is used (see the Knight XL Service Manual).
8. Consult the glycol manufacturer for details on the suggested
mix of glycol and water for the desired freeze protection
level and the de-rate effect it will have on the boiler output.
Test / replace freeze protection fluid
1. For systems using freeze protection fluids, follow the fluid
manufacturer's instructions.
2. Freeze protection fluid must be replaced periodically due to
degradation of inhibitors over time.
3. It is recommended to test the glycol concentration annually
and adjust within the desired set points.
11
Start-up
Installation & Operation Manual
Oxygen prevention
Dissolved oxygen can have a negative effect on the boiler
system. Oxygen can cause iron oxide to generate iron deposits.
Oxygen may also increase the rate of corrosion on non-stainless
steel parts of the system. A low pH level combined with oxygen
further enhances its corrosive effects. After boiler installation,
check for air leaks in the following areas:
• Suction gasket
• Pump
• Air valve
• O-ring gaskets
Precautions include installing a water meter to evaluate the
fresh water volume entering the system (should be no more
than 5% system volume). Additional volumes of fresh water
could indicate that a leak is present.
Fill and test water system
1. Fill system only after ensuring the water meets the
requirements of this manual.
2. Close automatic and manual air vents and boiler drain
valve.
3. Fill to correct system pressure. Correct pressure will vary
with each application.
a. The minimum cold water fill pressure for a system is
12 psi.
b. Pressure will rise when the boiler is turned ON and
system water temperature increases.
4. At initial fill and during boiler startup and testing, check
the system thoroughly for any leaks. Repair all leaks before
proceeding further.
Purge air from water system
1. Purge air from system:
a. Connect a hose to the purge valve (see purge/drain
valve in the piping diagrams in this manual). Route the
hose to an area where water can drain and be seen.
b. Close the boiler or system isolation valve between the
purge valve and fill connection to the system.
c. Close zone isolation valves.
d. Open the quick-fill valve on the cold water makeup
line.
e. Open purge valve.
f. Open the isolation valves one zone at a time. Allow
water to run through the zone, pushing out the air.
Run until no noticeable air flow is present. Close
the zone isolation valves and proceed with the next
zone. Follow this procedure until all zones are purged.
g. Close the quick-fill water valve and purge valve and
remove the hose. Open all isolation valves. Watch that
system pressure rises to correct cold-fill pressure.
h. After the system has operated for a while, eliminate
any residual air by using the manual air vents located
throughout the system.
i. If purge valves are not installed in the system, open the
manual air vents in the system one at a time, beginning
with the lowest floor. Close the vent when water
squirts out. Repeat with remaining vents.
2. Open the automatic air vent (diaphragm-type or bladder
type expansion tank systems only) one turn.
3. Open other vents:
a. Starting on the lowest floor, open air vents one at a
time until water squirts out.
b. Repeat with remaining vents.
4. Refill to correct pressure.
CAUTION
Eliminate all system leaks. Continual
fresh makeup water will reduce boiler
life. Minerals can build up in the heat
exchanger, reducing heat transfer,
overheating the heat exchanger, and
causing heat exchanger failure.
58
