How to mount the PHE sensor in the pipe housing?

I need to fit a new PHE sensor to a Pulsacoil III.  The existing sensor simply 'rests' in the housing - so a 4-5mm dia sensor is a very loose fit in a ~15mm housing, and is probably not doing a good job of measuring water temperature.  It seems that there should be some form of retaining piece, and/or some thermal connection to the pipe (silicone grease possibly?).  Could anyone tell me what the sensor-pipe joint should look like?
Many thanks,
Peter

Peter wrote:I need to fit a new PHE sensor to a Pulsacoil III.  The existing sensor simply 'rests' in the housing - so a 4-5mm dia sensor is a very loose fit in a ~15mm housing, and is probably not doing a good job of measuring water temperature.  It seems that there should be some form of retaining piece, and/or some thermal connection to the pipe (silicone grease possibly?).  Could anyone tell me what the sensor-pipe joint should look like?
Many thanks,
Peter

Hi Peter
Yes the sensors on the Mark 3 Pulsacoil are dry pocket sensors. To get the best reading from those sensors, use "Non - Silicone Heat Transfer Compound" (RS stock No 503-347). This is also used as cooling compound on the PC between the cooler and the CPU ( if you are familiar with this kind of stuff). You can ask at a local PC dealer for this compound ( in the High street, probably not at pc world or so). Or have a go on the online store at RS.
hope this helps
Mario at Mario's Boiler Service

It's still in the online shop at RS for £ 5.01 ( probably plus VAT) Stock No 503-357 / Catalogue page 2374. This last for about 100 sensors plus I have used my tube for about 10 to 12 month for business. Also useful for many other things if you are in for self build PC's and other electronic things and DIY.
hope this helps
Mario at Mario's Boiler Service

Mario,
many thanks for the prompt reply.
Peter

Hi Peter,

You can also find these heat sink compound in Wolseley stores - Plumb Centre, Part Centre.

Also before changing Parts it maybe worth checking out the self check Pulsacoil mini guide which you can request via this link: Pulsacoil 3 (III)

Check that out, I would strongly recommend that because I went to a job last week where a company had replaced both sensors, PCB and the Pump, All in needed was a simple top up and the main unit to be left on.

Hope this helps