The old thermostat that came with the Pacet fan kit was a capillary type with a probe that you stuff up the top hose. I've never been much of a fan of these as there is a risk of leakage where the capillary connection enters the hose. So I forked out for a nice aluminium billet housing with a modern sealed thermostatic switch unit from ebay. It was only about a fiver more than a replacement pacet capilary one so well worth the extra.
The instructions stated it was to be fitted on the hot side of the radiator, ie the top hose. I must admidt I thought about fitting it to teh bottom hose because, a there is more space, b it would be measuring whatever the radiator was coping or not and c I wasn't convinced that it wouldn't cause problems due to a lack of flexability in the top hose as the standard hose is a bellows type to allow flex.
Anyway after a few Club Triumph Forum discussions and finding out at my local TSSC meeting that a couple of guys have them fitted to the top hose I went ahead and fitted it there. If I had fitted it to the bottom hose I would have had to experiment to find a suitable switch as the temperature would have been lower so it saves a lot of hassle.
The kit stated that it must be fitted with a relay to switch the fan, the old capillary kit didn't need a relay so I had to do a bit of wiring and fit a relay. Anyway all done now and having tested it it works fine. Temperature sender fitted is a 90/82 degree one which comes on at about 7/8's of the way top the red on the temperature gauge and switches off just above 1/2 way.
New arrangement, billet aluminium adaptor in the top hose and relay fitted.
Old Knackered capillary unit previously fitted.