3 Hydronic piping
System water piping methods
The Outdoor Knight XL is designed to function in a closed loop pressurized system not less than 12 psi (83 kPa). A temperature and pressure gauge is included to monitor system pressure and outlet temperature and should be located on the boiler outlet.
It is important to note that the boiler has a minimal amount of pressure drop which must be figured in when sizing the circulators. Each boiler installation must have an air elimination device, which will remove air from the system. Install the boiler so the gas ignition system components are protected from water (dripping, spraying, etc.) during appliance operation or basic service of circulator replacement, valves, and others.
Observe a minimum of 1/4 inch (6 mm) clearance around all
Low water cutoff device
On a boiler installed above radiation level, some states and local codes require a low water cutoff device at the time of installation.
Chilled water system
If the boiler supplies hot water to heating coils in air handler units, flow control valves or other devices must be installed to prevent gravity circulation of heater water in the coils during the cooling cycle. A chilled water medium must be piped in parallel with the heater.
Freeze protection
Freeze protection for new or existing systems must use glycol that is specially formulated for this purpose. This includes inhibitors, which prevent the glycol from attacking the metallic system components. Make certain to check that the system fluid is correct for the glycol concentration and inhibitor level. The system should be tested at least once a year and as recommended by the producer of the glycol solution. Allowance should be made for the expansion of the glycol solution in the system piping.
WARNING Use only inhibited propylene glycol solutions, which are specifically formulated
for hydronic systems. Ethylene glycol is toxic and can attack gaskets and seals used in hydronic systems.
14 
Outdoor Knight XL Installation & Operation Manual
General piping information
Basic steps are listed below along with illustrations on the following pages (FIG.’s
1.Connect the system return marked “Inlet”.
2.Connect the system supply marked “Outlet”.
3.Install purge and balance valve or shutoff valve and drain on system return to purge air out of each zone.
4.Install a backflow preventer on the cold feed
5.Install a pressure reducing valve on the cold feed
6.Consult the factory for a pump and/or pump cover. If a
7.Install a circulator as shown on the piping diagrams in this section. Make sure the circulator is properly sized for the system and friction loss.
8.Install an expansion tank on the system supply. Consult the tank manufacturer’s instruction for specific information relating to tank installation. Size the expansion tank for the required system volume and capacity.
9.Install an air elimination device on the system supply.
10.Install a drain valve at the lowest point of the system. Note: The boiler cannot be drained completely of water without purging the unit with an air pressure of 15 psi (103 kPa).
11.This appliance is supplied with a relief valve sized in accordance with ASME Boiler and Pressure Vessel Code, Section IV (“Heating Boilers”). Pipe the discharge of the safety relief valve to prevent injury in the event of pressure relief. Pipe the discharge to a drain. Provide piping that is the same size as the safety relief valve outlet. Never block the outlet of the safety relief valve.
WARNING | The relief valve, tee and any other necessary |
| fittings are shipped in the install kit with the |
| boiler and are to be field installed (FIG.’s |
|
12.On any
See the piping illustrations included in this section, FIG.’s
NOTICE | Please note that these illustrations are | |
meant to show system piping concept only, | ||
| ||
| the installer is responsible for all equipment | |
| and detailing required by local codes. |