Watts VTFN Termal Drenaj Valfleri
Watts VTFN Termal Drenaj Valfleri
Watts VTFN Termal Drenaj Valfleri
Series VTFN
Main features
The thermal drain valves have been approved
and factory calibrated in the Watts Industries
Workshops in accordance with the technical
specification of Body R.
THERMAL DRAIN VALVES
VTFN
THERMOFLUX
Positive action thermal drain valve, with manual resetting and optical signal.
2 Protection class : IP40. Set temperature : 95°C. Drain capacity without filling :
VTF 1.1/4" - 176.775 kcal/h equal to 7070 l/h
VTF 1.1/2" - 318.200 kcal/h equal to 12728 l/h.
Dimensioning
A) Partial or zero filling
It should be pointed out that Body R (Dossier R.2.A.) specifies that, in the case of partial or zero filling, the valve
should have a drain capacity not less than :
G= P
25
where :
G = Kv . √∆p
where :
Kv = flow coefficient
∆p = hydrostatic pressure acting on the valve in kg/cm2.
By inserting known numeric values we obtain :
B) Total filling
In the case of total filling from the water main, the flow to be drained at the effective operating pressure should
not be less than:
G= P
80
where :
The flow rate G depends on the hydrostatic pressure ∆p acting on the valve.
VTFN32 VTFN40
∆ (bar) G (l/h) P (kcal/h) ∆ (bar) G (l/h) P (kcal/h)
0,1 3.162 252.982 0,1 5.692 455.368
0,2 4.472 357.770 0,2 8.050 643.988
0,3 5.477 438.178 0,3 9.859 788.720
0,4 6.324 505.964 0,4 11.384 910.736
0,5 7.071 565.680 0,5 12.728 1.018.234
0,6 7.746 619.677 0,6 13.943 1.115.419
0,7 8.366 669.328 0,7 15.060 1.204.790
0,8 8.944 715.541 0,8 16.100 1.287.975
0,9 9.486 758.946 0,9 17.076 1.366.104
1,0 10.000 800.000 1,0 18.000 1.440.000
1,1 10.488 839.047 1,1 18.879 1.510.285
1,2 10.954 876.356 1,2 19.718 1.577.441
1,3 11.401 912.140 1,3 20.523 1.641.853
1,4 11.832 946.572 1,4 21.298 1.703.831
1,5 12.247 979.795 1,5 22.045 1.763.633
1,6 12.649 1.011.928 1,6 22.768 1.821.472
1,7 13.038 1.043.072 1,7 23.469 1.877.530
1,8 13.416 1.073.312 1,8 24.150 1.931.963
1,9 13.784 1.102.724 1,9 24.811 1.984.903
2,0 14.142 1.131.370 2,0 25.456 2.036.468
2,1 14.491 1.159.310 2,1 26.084 2.086.758
2,2 14.832 1.186.591 2,2 26.698 2.135.865
2,3 15.165 1.213.260 2,3 27.298 2.183.868
2,4 15.492 1.239.354 2,4 27.885 2.230.838
2,5 15.811 1.264.911 2,5 28.460 2.276.840
2,6 16.124 1.289.961 2,6 29.024 2.321.930
2,7 16.431 1.314.584 2,7 29.577 2.366.161
2,8 16.733 1.338.656 2,8 30.120 2.409.581
2,9 17.029 1.362.350 2,9 30.653 2.452.232
3,0 17.320 1.385.640 3,0 31.177 2.494.153
Technical features
Valve type VTFN32 VTFN40
Connections 1.1/4” x 1.1/4” 1.1/2” x 1.1/2”
Certificate of ISPEL conformity VST/341/90 VST/342/90
t0 - calibration 95 °C 95 °C
temperature fluid temperature at which the valve
starts to drain continuously
t1 - drain temperature 96 °C 96 °C
max. fluid temperature at which, during the temperature rise
phase, there is maximum opening allowed by the control device,
consequently the nominal flow rate
t2 - closing temperature 92 °C 90 °C
fluid temperature at which, during the temperature lowering phase,
the valve stops draining continuously.
tE - emergency operating temperature 90 °C 92 °C
temperature at which opening of the valve starts in case of damage
to the thermostatic element.
Kv - flow coefficient 11.000 20.000
water flow rate in kg/h at drain temperature t1 with differential
pressure ∆p = 1 kg/cm2
KVE - emergency flow coefficient 10.000 18.000
water flow rate in kg/h at drain temperature t1 with differential
pressure ∆p = 1 kg/cm2
P = Drain capacity 176.775 318.200
in kg/h, with partial or zero filling and with ∆p = 0,5 kg/cm2
The above values are taken from the I.S.P.E.S.L. reports enclosed with the certificates of conformity
N° VST/341/90 and VST/342/90 and represent the average of the values obtained during the inspection tests.
THERMAL DRAIN VALVES
Design features
Body and cover Shot-blasted stamped brass
Inlet connection VTF/N32 G 1”1/4 M (ISO 228/1)
Inlet connection VTF/N40 G 1”1/2 M (ISO 228/1) 4
Outlet connection VTF/N32 G 1”1/4 F (ISO 228/1)
Outlet connection VTF/N40 G 1”1/2 F (ISO 228/1)
Thermal sensitive element Wax
Springs Stainless steel
Protective cap Black polycarbonate
Microswitch 220V-50Hz, with manual resetting button
Optical indicator red signalling valve opening
Mounting
Technical specification of Body R ed. 82 (R.3B.1.2) required as follow:
• Thermal drain valve has to be connected to the outlet pipe within 0,5 m from boiler, with the bulb sensing
element into the hot water flow rate (see drawing).
• For correct positioning of the bulb sensing element into the hot water flow rate, respect the measure
showed between end of the threaded and the axis of the pipe (see drawing).
≤ 0,5 m
VTFN40 = 64 mm
VTFN32 = 58 mm
Boiler
Brown
Black NO Contact
Blue NC Contact
Green/Yellow
Maintenance Size A B C D E
No maintenance foreseen for VTFN valves; in case of failure 1.1/4” 222 99 123 35 52
please to dismantle the valve and send to Watts Industries Italia. 1.1/2” 242 114 128 38 60
THERMAL DRAIN VALVES
Safety regulations
The applicable technical specification of Italian Decree DM 1.12.1975 contained in Body R prescribes the
5 use of one or more thermal drain valves in the following cases:
N.B. The minimum permissible inner diameter of the safety piping is equal to 18 mm; under this size, it
is not sufficient to install a thermal drain valve, rather the piping must be replaced as well.
2.2. System with 3-way mixing valve installed on the delivery line
in the case of a single expansion vessel dimensioned for the entire system and in direct connection
with the boiler (Pic. 2)
a) in the case of two or more expansion vessels, of which one is connected directly to the boiler,
if no check valve is provided on the return line (Pic. 3);
N.B. The distance "L" of the thermal drain valve from the boiler should not exceed 0.5 metres.
NOTE
If a check (non return) valve is to be installed in the return piping, make sure that it is correctly positioned.
The three-way valve, installed in the delivery line, can act as a mixer or diverter.
1. In the case of the three-way valve acting as a mixer valve, way 2 (Pic. 5) always remains open;
the sector shifts from way 1 to way 3. The check valve should be inserted in the boiler circuit (Pic. 5)
2. In the case of the three-way valve acting as a diverter valve (Pic. 6) , way 1 always remains open;
the sector shifts from way 2 to way 3. The check valve should be inserted in the user circuit (Pic.6).
1 A 2 1 A 2
B B 3
3 Pic.6
Pic.5
Pic.4
1. Mixer 1. Mixer
2. Check valve 2. Check valve
3. Circulating pump 3. Circulating pump
THERMAL DRAIN VALVES
2
DIFFERENTIAL PRESSURE (bar)
Normal action
1
0,8
0,6
0,5
0,4
0,3
0,2
0,1
1 2 3 4 5 6 8 10 20 30 40 50
2
DIFFERENTIAL PRESSURE (bar)
Positive action
1
0,8
0,6
0,5
0,4
0,3
0,2
0,1
1 2 3 4 5 6 8 10 20 30 40 50
The descriptions and photographs contained in this product specification sheet are supplied by way of information only and are not binding.
Watts Industries reserves the right to carry out any technical and design improvements to its products without prior notice.