Installation manual
19
E(D/B)(H/L)Q011~016BB
Unit for air to water heat pump system
4PW67904-1 – 01.2011
Protecting the water circuit against freezing
Frost can cause damage to the hydraulic system. As this unit is
installed outdoors and thus the hydraulic system is exposed to
freezing temperatures, care must be taken to prevent freezing of the
system.
All hydraulic parts are insulated to reduce heat loss. Insulation must
be foreseen on the field piping.
The unit is already equipped with several features to prevent freezing.
■
The software contains special functions using pump and back
up heater to protect the complete system against freezing.
This function will only be active when the unit is off.
■
Only for EDL and EBL units:
As extra safety, a heatertape is winded around the piping to
protect vital parts of the hydraulic system inside the unit.
This heatertape will only be active in case of an abnormal
situation concerning the pump and will only protect internal parts
of the unit. It can not protect field installed parts outside the unit.
Field heater tape must be foreseen by the installer.
However in case of power failure, above mentioned features can not
protect the unit from freezing.
If power failure can happen at times the unit is unattended, Daikin
recommends adding glycol to the water system. Refer to
Caution:
"Use of glycol" on page 19
.
Refer to
"Freeze protection function" on page 35
.
Depending on the expected lowest outdoor temperature, make sure
the water system is filled with a weight concentration of glycol as
mentioned in the table below.
Caution: "Use of glycol"
Also refer to
"Checks before initial start-up" on page 30
.
Minimum outdoor temperature
Glycol
(a)(b)
–5°C
10%
–10°C
15%
–15°C
20%
–20°C
25%
–25°C
30%
WARNING
ETHYLENE GLYCOL IS TOXIC
INFORMATION
(a)
The concentrations mentioned in the table above will not
prevent the medium from freezing, but prevent the
hydraulics from bursting.
(b)
The maximum allowed water volume is then reduced
according to the
figure "Maximum allowed water volume"
on page 18
.
Caution: Use of glycol
■
For installations with a domestic hot water tank, the
use of propylene glycol, including necessary
inhibitors, is only allowed if classified as Category 3
according to EN1717 or equivalent based on the
applicable legislation.
■
In case of over-pressure when using glycol, be sure to
connect the safety valve to a drain pan in order to
recover the glycol.
For this purpose a knock out hole is foreseen in the
backplate of the unit making it possible to connect a
drain pipe to the safety valve.
Connecting a drain pipe is not required if no glycol is
used. The discharged water is then drained via the
bottom of the unit.
NOTICE
For Australia and New Zealand only:
If a hot water tank is connected to this unit and an
antifreeze solution is added to the water circuit, the
antifreeze additive must be non-toxic and coloured with a
dye at a concentration level high enough that any leakage
into the potable water is easily discernible.
Materials approved by Food Standards Australia New
Zealand are acceptable.
NOTICE
Corrosion of the system due to presence of glycol
Uninhibited glycol will turn acidic under the influence of
oxygen. This process is accelerated by presence of copper
and at higher temperatures. The acidic uninhibited glycol
attacks metal surfaces and forms galvanic corrosion cells
that cause severe damage to the system.
It is therefore of extreme importance:
■
that the water treatment is correctly executed by a
qualified water specialist;
■
that a glycol with corrosion inhibitors is selected to
counteract acids formed by the oxidation of glycols;
■
that in case of an installation with a domestic hot
water tank, only the use of propylene glycol, including
necessary inhibitors classified as Category
3
according to EN1717 or equivalent based on the
applicable legislation is allowed. In other installations
the use of ethylene glycol is permitted as well;
■
that no automotive glycol is used because their
corrosion inhibitors have a limited lifetime and contain
silicates which can foul or plug the system;
■
that galvanized piping is not used in glycol systems
since its presence may lead to the precipitation of
certain components in the glycol’s corrosion inhibitor;
that it has to be made sure the glycol is compatible with
the used materials in the system.
INFORMATION
Be aware of the hygroscopic property of glycol: it absorbs
moisture from its environment.
Leaving the cap off the glycol container causes the
concentration of water to increase. The glycol
concentration is then lower than assumed. And in
consequence, freezing can happen after all.
Preventive actions must be taken to ensure minimal
exposure of the glycol to air.
