Return flow temperature maintenance with thermal control valve

DN 20 (

3⁄4") / DN 25 (1")

Application range

D

N

2

5

Temperatures

• Heating systems with return flow temperature maintenance

• Solid fuel boilers, wood firing / stove heating systems

The pump sets for the return

flow temperature maintenance are

groups of fittings for pumps that can be isolated. They consist of:

Mounting version 1:

• high-e

fficiency pump

• control valve with opening temperature 45 °C or 60 °C

• 1 thermometer ball valve with red thermometer integrated in the

handle, can be pulled off

• 2 thermometer ball valves with blue thermometer integrated in the

handle, can be pulled off

• connections DN 20: 3⁄4" int. thread

• connections DN 25: 1" int. thread

Mounting version 2 - Additionally required:

• 1 x sealing: DN 20 item no. 2057, DN 25 item no. 2157

• 1 x screw-in fitting: DN 20 item no. 2053, DN 25 item no. 2153

• 1 x pump

fitting DN 20 item no. 2049, DN 25 item no. 2149

Thermal control valve with automatic bypass

1. The thermal valve shuts off the connection to the buffer tank, as long

as the water in the boiler circuit is colder than the opening temperature

of the thermal control valve. The pump circulates the water in the boiler

circuit through the bypass. The small quantity of water in the boiler

circuit can now heat up quickly.

2. When the boiler circuit reaches the opening temperature of the control

valve, the valve reduces the bypass

flow rate and opens the bu

ffer tank

circuit. The cold water from the buffer tank return is mixed with the hot

boiler circuit water in the control valve. This leads to an increase of the

return temperature in the boiler circuit to the desired level and avoids

condensation in the boiler.

3. When the bu

ffer tank return temperature is higher than the opening

temperature, the control valve completely shuts off the bypass.

Thus, the water from the buffer tank

flows directly into the boiler circuit.

Please note:

If the boiler output is controlled by the boiler temperature the boiler

must heat up 20 °C above the opening temperature of the return flow

temperature maintenance. Otherwise, the boiler might reduce the output

even before the thermal control valve is completely open.

Mounting versions 1 and 2:

Separate assembly of the group of fittings in the flow and return.

This version permits an easy isolation of the heat generator without

further shut-off valves. Consider the position of the safety group before

mounting.

01/2024 • Printed in Germany

PAW GmbH & Co. KG • info@paw.eu • www.paw.eu

t = Bypass

t

BY

= Boiler return

t

KR

= return bu

ffer tank

t

PR

= opening temperature

FIX

176