Technical data

a) Note:
- To reliably prevent boiler corrosion caused by condensation of flue gases, the boiler return flow temperature must
not under any circumstances be below 150°F/65°C. A boiler circuit pump with a boiler mixer should be provided according
to the diagram for this purpose. The boiler circuit should be designed such that the temperature difference between
the forward flow and the return flow is equal to or less than ∆t 15°C / 27°F.
- For integrating heat consumers, see Spec Sheet 4000.
- The expansion tank has to be connected to the boiler above the boiler forward flow and without any shut-offs.
b) Safety-relevant equipment included in the scope of performance provided by the installing
heating engineer
M 20 Boiler pump
Y 20 Boiler mixing valve
SV Safety valve, pressure set to max. 3.0 bar, homologated component as per DIN 3440
Nominal width of the valve, of the connection line and of the exhaust pipe as per DIN 4751 Part 2
TS131 Thermal run-off safety valve R ¾”, homologated component; special-purpose design for opening
temperature 212°F/ 100°C, (safety heat exchanger built into boiler). With the Pyrot-400 and Pyrot-540, two safety
heat exchangers in parallel are required but only one thermal run-off safety valve.
KW. Cold water inlet, min. 36 psig/ 2.5 bar, max. 51 psig/ 3.5 bar
WMS... Water level control device, homologated component; required in Germany starting from systems over 350
KW, Installation recommendation: WMS with magnetic transmission of the float movement to a switch unit
EL Air separator (recommendation: absorption-type degasser)
ExH... Expansion tank closed, with design certification; for heating system (Recommendation: connect on cool return flow,
connected to the boiler via the forward flow without any blockage units)
ExS… Expansion tank closed; with design certification; for safety heat exchanger, max. 4.0 liters, 145 psig/ 10 bar
DAZ Pressure indication device (pressure gauge)
TAZ Temperature indication device (thermometer)
c) Design recommendation
Model
KRT
Boiler circuit
(VL, RL,BP)
Thermal
run-off
safety valve
TS-131
(Quantity)
Water
through-put
required at
2.5 bar
/36 psig
l/h GPM
Storage tank
(accumulator)
Volume³)
L USG
Supply
line ZL
Drain pipe
AL²)
Safety relief
valve
Watts or
Conbraco
30Lb or 60Lb
Safety
line
SL²)
150 NW 50 1 915 4 1500 396 R¾" R 1" ¾" ¾" NW 40
220 NW 50 1 1230 5.4 2200 581 R¾" R 1" ¾" ¾" NW 40
300 NW 65 1 1500 6.6 2500 660 R¾" R 1" 1" 1" NW 50
400 NW 80 1 1880 8.3 3200 845 R¾" R 1" 1" 1" NW 50
540 NW 60 1 2266 10 4300 1136 R¾" R 1" 1¼" 1¼" NW 65
1) Threaded connection for supply line
2) Length of the exhaust pipe up to 4.0 m 13ft (for longer lines, see DIN 4751 Part 2)
3) On request, we will be glad to provide a project-based offer on the storage tanks(s).
d) Equipment recommendation from Viessmann delivery program
- Note: The equipment below will only be supplied via the installing heating engineer
North America
voltage Grundfos voltage Grundfos
and part and part
Boiler model
KRT-
pump freq.
phase number
Vi. Part
Number
phase number
Vi. Part
number
150 UPS 32-80 F 60 Hz 3 x 208-230 V 96402710 9560240 1 x 230 V 96402709 9560239
220 UPS 40-80/4 F 60 Hz 3 x 208-230 V 96404950 9544478 1 x 230 V 96404949 9560255
300 UPS 50-80/4 F 60 Hz 3 x 208-230 V 96404960 9560274 1 x 230 V 96404959 9560273
400 UPS 50-80/4 F 60 Hz 3 x 208-230 V 96404960 9560274 1 x 230 V 96404959 9560273
540 UPS 50-80/4 F 60 Hz 3 x 208-230 V 96404960 9560274 1 x 230 V 96404959 9560273
1) For ∆t 15K, 27°F as per illustration
Any additional resistors (heat meters, slide valve) require redesigning of the boiler pump!
Spec Sheet
Pyrot Rotation Heating System
Installation, closed system
vIESmAnn
6960-2