Installing A Domestic Hot Water (Dhw) System - Navien NCB-150E Installation & Operation Manual

When installing the pressure relief valve, follow these guidelines:
Ensure that the valve's discharge capacity is equal to or greater
than the maximum pressure rating of the boiler's space heating
system.
Ensure that the maximum BTU/H rating on the pressure relief
valve is equal to or greater than the maximum input BTU/H
rating of the boiler.
Direct the discharge piping of the pressure relief valve so
that hot water does not splash on operator, or any nearby
equipment.
Attach the discharge line to the pressure relief valve and run the
end of the line to within 6-12 in (150-300 mm) of the floor.
Ensure that the discharge line allows for free and complete
drainage without restriction. Do not install a reducing coupling
or other restrictions on the discharge line.
If the relief valve discharges periodically, this may be due to
thermal expansion caused by expansion tank waterlogging or
undersizing. Do not plug the relief valve.
3.1.3 Space Heating System Piping
When connecting the space heating system, follow these
guidelines:
Tighten the connection valves with care to avoid damage.
After installing the boiler, clean the strainer for space heating
return. Then, test the boiler for proper space heating flow and
inspect for leaks. Instruct the boiler owner that the strainer must
be cleaned periodically to maintain proper space heating water
flow.
The Navien manifold system (optional) allows for easy separation
of the Boiler-Primary loop from the System-Secondary loop(s).
Refer to the following illustration for a typical water piping
example with a Navien manifold system.
Space Heating
Supply
20 Installing the System Piping
Space Heating
Return
3.2 Installing a Domestic Hot Water (DHW)
System
The Navien NCB-E boiler provides domestic hot water continuously
when flow is sensed by the flow sensor. This method is the most
efficient means of heating water by allowing the boiler to operate
at a lower return water temperature by minimizing standby losses,
thus increasing combustion efficiency.
3.2.1 Guidelines for a DHW System
With its multi-purpose design, the Navien NCB-E boiler provides
hot water on demand. This means that the boiler produces DHW
only when the user demands it.
The boiler recognizes a DHW demand when the flow sensor
detects a DHW flow of approximately 0.5 GPM or greater. Once
the flow sensor detects the flow, the boiler immediately goes into
DHW mode regardless of the status of the space heating system.
Read and follow the guidelines listed below to ensure safe and
proper installation of a boiler heating system.
Scald Hazard
Hotter water increases the risk of scald injury. There is a hot water
scald potential if the DHW temperature is set too high. Be sure
to follow the adjustment instructions in the boiler's operation
manual.
About the DHW Quality
Proper maintenance of the boiler is required to ensure that your
DHW meets EPA quality standards. The following table shows the
maximum contaminant levels allowed, based on the EPA National
Secondary Drinking Water Regulations (40 CFR Part 143.3). If you
suspect that your water is contaminated in any way, discontinue
use of the DHW and contact an authorized technician or licensed
professional.
Contaminant
Total Hardness
Aluminum
Chloride
Copper
Iron
Manganese
Maximum Allowable Level
Up to 200 mg/l (12 grains/gallon)
0.05 to 0.2 mg/l
Up to 250 mg/l
Up to 1.0 mg/l
Up to 0.3 mg/l
Up to 0.05 mg/l