Hydraulic Connection; General Information - Viessmann VITODENS 111-W Technical Manual

Design information
Condensate lifting system (accessories)
A
A Condensate inlet
B Condensate lifting system
C Condensate drain

6.6 Hydraulic connection

General information

System design
Viessmann condensing boilers can generally be installed in any fully
pumped hot water heating system (sealed unvented system).
The boiler must be correctly sized and selected.
The circulation pump is an integral part of the appliance.
Minimum system pressure 1.0 bar (0.1 MPa).
The boiler water temperature is limited to 82 °C.
To minimise distribution losses, we recommend sizing the heat distri-
bution system to a max. flow temperature of 70 °C.
To meet the requirements of the Energy Saving Ordinance [EnEV -
Germany], use a clock thermostat (accessory) for constant tempera-
ture mode and weather-compensated mode. The control unit does
not have an integral time switch.
Chemical anti-corrosion agents
In correctly installed and operated sealed unvented heating systems
corrosion is generally avoided.
Never use chemical anti-corrosion additives.
Some manufacturers of plastic pipes recommend the use of chemi-
6
cal additives. In such cases, only use anti-corrosion additives offered
by the heating trade that have been approved for boilers with DHW
heating via single-walled heat exchangers (instantaneous water
heater or DHW cylinder).
For this, observe the VDI guideline 2035 [or local regulations].
Heating circuits
The integral boiler control unit can be used to control a directly con-
nected heating circuit without mixer. The mixer extension kit availa-
ble as an accessory can be used to control a heating circuit without
mixer and a heating circuit with mixer, each with a separate heating
circuit pump.
Plastic pipework for radiators
We also recommend the use of a temperature limiter to restrict the
maximum temperature for plastic pipework in heating circuits with
radiators.
Attic heating centre
The installation of a low water indicator, compulsory according to the
DVGW [Germany], is not required when installing boilers in an attic
heating centre.
The boilers are protected against water shortage in accordance with
EN 12828.
VIESMANN
56
(cont.)
C
B
Safety valve
A safety valve in accordance with TRD 721 is integrated in the
Vitodens (opening pressure 3 bar (0.3 MPa)).
Route the discharge pipe in accordance with EN 12828 into a drain
outlet (drain outlet kit available as an accessory). The drain outlet
incorporates a siphon as a stench trap.
Low water indicator
According to EN 12828, a low water indicator can be omitted for boil-
ers up to 300 kW, as long as heating can be reliably prevented when
there is a water shortage.
Viessmann condensing boilers are equipped with a low water indica-
tor (boil-dry protection). Tests have verified that the burner will be
automatically switched off in the event of water shortage due to a
leak in the heating system and simultaneous burner operation,
before the boiler or the flue system reaches unacceptably high tem-
peratures.
Water quality/frost protection
Unsuitable fill and top-up water increases the level of deposits and
corrosion and may lead to the boiler damage.
Observe VDI 2035 regarding quality and amount of heating water,
including fill and top-up water.
■ Flush the heating system thoroughly before filling.
■ Only fill with water of potable quality.
■ Fill and top-up water with a water hardness in excess of the follow-
ing values must be softened, e.g. with the small softening system
for heating water (see the Viessmann Vitoset pricelist):
Total permissible hardness of the fill and top-up water
Total heating Specific system volume
output
kW < 20 l/kW
≤ 50
≤ 3.0 mol/m 3
(16.8 °dH)
> 50 to ≤ 200
≤ 2.0 mol/m 3
(11.2 °dH)
≥ 20 l/kW to ≥ 50 l/kW
< 50 l/kW
≤ 2.0 mol/m 3 < 0.02 mol/m 3
(11.2 °dH) (0.11 °dH)
≤ 1.5 mol/m 3 < 0.02 mol/m 3
(8.4 °dH) (0.11 °dH)
VITODENS