Frost stat. IP65 Where from

[bernardgreen]

Due to onset of cold weather I have decided to fit automatic heating control to our sewer pump in place the present manual system.

But cannot find a suitable IP 65 frost stat to fit in the pump chamber.

Operating at 1°C

Preferably change over contact

Load is 120 watt resistive at 240 volt

 

[RF Lighting]

Would RS part number: 440-7972 be any use?

 

[bernardgreen]

Thanks RF

One idea was to use that type of room stat in a metal box.

Using metal to avoid the thermal insulation of the plastic box and subsequent slow turn off response.

Since response time is not critical ( within the hour will do ) I may try the plastic box for ease of fitting. Working in there is not the nicest of places on a freezing cold day.

The ideal type was a finned tube about 3 inches long and 2 inch diameter with a four core flying lead. ( Com NC NO and earth ) with set point adjustments under two screwed in blanking plugs. These appear to have been dis-continued.

 

[Pensdown]

http://www.electrocontrols.co.uk/datasheets/A01.pdf

Part no EC-3W any good?

 

[Taylortwocities]

How about http://www.bnthermic.co.uk/product.php?id=17

I got this by the radical method of using Google and searched for
"Frost thermostat IP65"

It took 0.00000001 of a second to come up with a shed load of suggestions.

Google is great, you should try it...

 

[bernardgreen]

Thanks guys. may now have the near ideal ( and better then previous ) solution. I am now looking at monitoring pipe temperatures instead of the air temperature in the pump chamber.
.

 

[Taylortwocities]

Maybe something like this then?
http://www.sontay.com/Datasheets/ST/ST-FRxx.pdf

 

[bernardgreen]

From the Sontay data sheet

The body of the device must be located at a point where it
will not be subjected to temperatures lower than the setpoint.

In cold weather the air temperature can drop below the temperature of the pipe work and remain lower until the pipe work eventually cools down. This has "confused" other capillary frost stats in similar applications.

The pipe work takes some considerable time to cool down to freezing when the air is below freezing. As a result sensing the air temperature without heating the air means the heating comes on much earlier than it needs to. That is not a problem regards electrical costs but there is a slight risk of the liquid being heated above the maximum working temperature of the pump if direct on pipe trace heating is used.