How to avoid clunking of Tunze pumps

[Matthias]

This is a question from Larry (came over email - please ask for support in this forum - makes our support easier - thank you):

HI Matthias..

I hooked up the ptc this evening... came on as expected running high speed ..since the temp delta is 3 + degrees

heres the problem....

i have tunzes running on the profilux... voltage set at 3v-8v power range min 1 % max 60%

runs perfect without the ptc hooked up...

when i hook up the ptc to a l port.... now when the tunzes go to minimum they stop spinning and then start up clunking...

when i unhook the ptc from an l port ..the tunzes are fine and dont stop spinning...

i tried increasing the min a few% but same thing happens..

it appears there is some sort of interference from the ptc on the l ports.....

is this possible? any thoughts? solutions?

Answer:
If there are other devices on the L-ports (like PTC or dimmable lamps) the output voltage of the L-ports may drop down some mV. In some cases this is enough to fall below the threshold where the Tunze pump will run (is usually 3V).
Simple solution: Increase the lower output voltage of the L-port where the Tunze-pump is connected, e.g. to 3.5V

[Micha578]

The steps to set up the output voltage for the 1-10V signal may stop the problem, but if someone wants to set up the pumps to start and stop to make a reeflike current, they will clunk again.

As i told in this thread, the clunking noise of the Tunze Pumps is a fault of the pump itself. If you contact the Tunze Support you will get a new drive for it.

[AQUA-IT]

I have copy this in the english part!