Honeywell Adjustable High Limit Aquastat; Circulating Pump - Viessmann Vitogas 050 ECD Series Installation & Service Manual

Be aware that best overall system performance is achieved
when all components are properly sized. Sizing of the required
circulation pump according to the pipe layout and calculation of
a proper volume expansion tank is vital to obtain the system's
peak performance. See Fig. 4a for multi-zone system using
pumps.
Caution:
The boiler warranty does not cover leaks resulting from
corrosion caused by the use of underfloor plastic tubing
without an oxygen diffusion barrier. Such systems must have
the non-oxygen diffusion barrier tubing separated from the
boiler with a heat exchanger. Viessmann recommends the use
of underfloor plastic tubing with an oxygen diffusion barrier.
Caution:
This boiler is not for use in systems where water is constantly
or frequently replenished. Minerals such as calcium in make-
up water can deposit on heat exchanger causing overheating,
and eventually the boiler will leak. This type of failure is not
covered by warranty. Water must not be drained from system
for use by cleaning personnel.
Do not use this boiler to directly heat swimming pool water.
Use a heat exchanger to separate the boiler water from the
pool water.
Caution:
For underfloor heating applications, an additional immersion or
strap-on aquastat must be installed in the low temperature
underfloor loop (ahead of the mixing valve) to de-energize the
pump and/or boiler to prevent overheating. High water
temperatures can damage concrete slabs.
Adjustable high limit aquastat (see Fig. 4c)
The adjustable high limit aquastat limits the boiler water
temperature during a call for heat from the room thermostat or
other operating control. It is located behind the front access
panel. Honeywell L4008A aquastat or equivalent may be used.
Ensure sensing bulb is fully inserted in well, see Fig. 4c. Set to
a minimum of 140°F. Never permanently bypass high limit
aquastats.

Circulating pump

The pump aquastat is located behind the control panel.
Connect the circulating pump wires to the boiler terminal strip.
Circulating pump supplied by others. Failure to connect
pump aquastat will significantly shorten life expectancy of
boiler heat exchanger. Pump aquastat is factory set at 116°F.
Alternate aquastat is available at 104°F.
Note to Fig. 4a
For multi-zone systems using zone pumps, one pump (usually
the one serving the main living area) should be dedicated to
operate with the pump aquastat located on the boiler (see
wiring diagram). For multi-zone systems a bypass pipe must
be installed. See page 10 for bypass piping details.
Do not wire more than one thermostat end switch from the
zone valves into the boiler thermostat T-T connection. Wiring
more than one thermostat into the boiler thermostat T-T
connection will lead to burner short cycling, which can cause
reduction in life span of the boiler due to probable flue gas
condensation. This type of failure is not covered under the
boiler warranty.
Separate breaker
F
N L
Transformer/Relay
120V
Viessmann
Jumper
Fig. 4b
Using transformer/relay to switch pumps
over 4A current draw.
The following lists typical water flow rates for the Atola-ECD
boiler series:
Flow rate (GPM)
Model for 20°F rise
ECD-65 5.3
ECD-80 6.6
ECD-100 8.3
ECD-115 9.5
ECD-140 11.6
ECD-155 12.8
ECD-180 14.9
ECD-200 16.6
The water pressure drop for ECD-(65, 200) is:
GPM Pressure drop (ft. of water)
10
15
20
Refer to wiring diagrams on pages 19, 20 for wiring a pump
(less than 4A) to the ECD boiler terminal strip. For pumps
greater than 4A use a field supplied switching device to
switch separate 120V power to the pump, see Fig 4b. 120V
(4A) is switched from the boiler terminal strip when the boiler
pump aquastat exceeds its setting.
Caution:
Do not connect pumps with continuous or inrush currents
greater than 4A. For pumps over 4A add a field supplied
switching relay. See Fig. 4b for an example.
Adjustment screw
set to 140°F minimum
Fig. 4c
Honeywell L4008A adjustable high limit aquastat is located
behind access panel
Boiler terminal strip
120V power
input
120V pump
24V 120V output
Thermostat
connections
24V
120V
pump
F
over 4A
Field supplied
F
Flow rate (GPM)
for 30°F rise
3.5
4.4
5.5
6.3
7.7
8.5
9.9
11.0
.33
.60
1.20
140
L
N
G
N
L
T
T