Viessmann Temp Sensor w/ Caleffi SEP4 Hydraulic Separator??

HydronicRookie

Can the Viessmann LLH sensor easily fit inside the Caleffi SEP4 hydraulic separator sensor well?



Has anyone had any problems with them working in tandem?

hot_rod

looks like

a 6mm diameter sensor? about 1/4" bolt size? There are a few different well sizes out there, most US size thermistors are larger 1/2" diameter. The Euro stuff and solar sensors tend to be 6mm.



How close does the sensor match that well?



For sure, use some heat transfer paste, or silicone acoustic grease in the well.



It's easier to find small tubes or bottles of the acoustic paste sometimes.

gennady

Sensor.

Install sensor on the outlet of separator to the heating system. Strap on. Even with viessmann LLH it is recommended. All you need is to control temperature of the water to the system.

hot_rod

sensor location

we show both locations with the separator, in the latest Idronics 15. If you install it on the pipe, be sure to insulate it. I would still use some heat transfer paste.



With both the boiler and system circs running, depending on flow rates, you will get some temperature blending in the separator. I prefer sensors in a well, but the sensor on the pipe downstream would read the "blended" temperature.



Another tip if you ever need to install a sensor on a bolt or pipe is to get a screw lug from an automotive or electrical supply. The early solar tanks had a stud welded onto them for sensor mounting.

HydronicRookie

Easy enough

Thanks for this. It definitely alleviates concern about a peg and hole mismatch.

HydronicRookie

Thermal Grease

Great pro tip regarding the thermal grease, will definitely get some and use it in either scenario but also insulate the strapped sensor if I don't end up using the well. Thanks!

gennady

blended temperature

Isn't it what we want? Outdoor reset sets system inlet temperature, and this is system outlet pipe on separator. Even on Viessmann's LLH we install strap on sensor , not in the well.