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4.2 Installing a Domestic Hot Water
(DHW) System
The cold water supply pipe installation must comply with the
Water Supply (Water Fittings) Regulations and Scottish Water
Byelaws.
The NCB700 is fitted with a stainless steel plate heat exchanger
for producing domestic hot water. The boiler does not have a
hot water store and in case of a demand for hot water the boiler
will heat the domestic water flowing through the plate heat
exchanger up to 65°C (adjustable) instantaneous.
In regions with a water hardness value higher than 200 ppm
(2.67 mmol/l), calcium deposits should be removed from the
plate heat exchanger on a regular basis. If problems occur
when using sanitary water with a chlorine content higher than
150 mg/l, no recourse can be made to the terms of the warranty.
In order to prevent calcification Navien recommends applying a
water softener.
The hardness of the water is variable in the United Kingdom
and other countries. The water company can provide exact
information about this. The domestic water installation can
be connected to the boiler by means of 15 mm compression
fittings. If the cold water supply pipe is fitted with water meter,
check valves or loose jumper stop cock, then a DHW expansion
vessel must be fitted.
CAUTION
The installation must be made by sufficiently qualified
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technicians, authorised to do so.
For correct installation, all the requirements and
●
recommendations described in the Regulation for
Heating Installations in Buildings (RITE) must be
complied with, together with all other national and/or
local regulations applicable at the time of installation.
Refer to the following illustration for a typical DHW piping
example for the boiler.
Bottom View
DHW Outlet
Water Inlet
Adapter
Adapter
Condensate
Outlet
26
Installing the System Piping
When installing the DHW system, follow these guidelines:
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About the DHW Quality
Proper maintenance of the boiler is required when water quality
does not meet European standards. Damage caused by poor
water quality is not covered under warranty. The following table
shows the maximum contaminant levels allowed, based on the
European drinking water guideline: 98/83/EG dated 3 November
1998. If you suspect that your water is contaminated in any
way, discontinue use of the DHW and contact an authorised
technician or licensed professional.
DHW Quality
Navien is not responsible for performance issues of the domestic
system by scaling or accumulation of dirt; suitable steps shall be
taken by the installer and user to avoid water quality related issues.
Connection of the drinking water installation should be done
according to the Water Supply (Water Fittings) Regulations and
Scottish Water Byelaws.
Condensate
Drain Hose
Condensate Pipe
Cold Water Supply
Hot Water Supply
If the cold water supply pipe is fitted with water
Note
meter, check valves or loose jumper stop cock, then a
DHW expansion vessel must be fitted.
Use only pipes, fittings, valves, and other components (such as
solder), that are approved for use in potable water systems.
Tighten the connection valves with care to avoid damage.
Keep the hot water piping system as short as possible, to
deliver hot water to the fixtures more quickly.
After installing the boiler, clean the cold water inlet filter. Then,
test the boiler for proper DHW supply and inspect for leaks.
If the cold water supply pipe is fitted with water meter, check
valves or loose jumper stop cock, then a DHW expansion
vessel must be fitted.
Parameter
Water type
pH
Conductivity (at 20°C in μS/cm)
Chloride (ppm)
Iron (ppm)
Hardness (°dH / ppm)
Number of bacterial colonies at
22°C (number/ml). pr EN ISO 6222
Value
Potable water
7.0-9.5
Max. 2500
Max. 150
Max. 0.2
1-12 °dH / 17-224 ppm
Max. 100
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