Formula To Calculate The Expansion Vessel Pre-Pressure - Daikin Altherma 3 WS EWSAH06UD 9W Series Installer's Reference Manual

8.1.2 Formula to calculate the expansion vessel pre-pressure

EWSAH/X06UD
Daikin Altherma 3 WS
4P675765-1 – 2022.04
▪ Domestic hot water tank kit – Pressure balancing. To prevent large pressure
differences at the taps and damage to the shower valve due to high‑pressure
cold water (5 bar), provide a dedicated 3.5‑bar feed to both cold water and hot
water taps. To do this, also connect the cold water supply for the cold water taps
to the pressure reducing valve of the domestic hot water tank kit.
f
e
a Cold water supply into house at 5 bar
b To 5 bar taps
c Pressure reducing valve (set to 3.5 bar) (part of the domestic hot water tank kit)
d Indoor unit
e Dedicated 3.5 bar feed – to/from DHW tank
f Dedicated 3.5 bar feed – cold water
g Cold water taps
h Hot water taps
i Shower
▪ Domestic hot water tank – Pressure relief valve. A pressure relief valve (part of
the inlet control group) with an opening pressure of 8 bar prevents excessive
water pressure in the water circuit.
▪ Domestic hot water tank – Pressure and temperature relief valve. The pressure
and temperature relief valve prevents excessive water pressure (≥10 bar) and
excessive water temperature (>95°C) in the domestic hot water tank.
▪ Thermostatic mixing valves. In accordance with the applicable legislation, it may
be necessary to install thermostatic mixing valves.
▪ Hygienic measures. The installation must be in compliance with the applicable
legislation and may require additional hygienic installation measures.
▪ Recirculation pump. In accordance with the applicable legislation, it may be
required to connect a recirculation pump in between the hot water end point
and the recirculation connection of the domestic hot water tank.
a b
a Recirculation connection
b Hot water connection
c Shower
d Recirculation pump
The pre-pressure (Pg) of the vessel depends on the installation height difference
(H):
Pg=0.3+(H/10) (bar)
a
b
g g
f
c
e
h h
d
e
c
d
8 Piping installation
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Installer reference guide
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