Ford Focus Mk2: How to replace the thermostat | 1.6 petrol

Since getting this Mark 2 Ford Focus 1.6 petrol, I've noticed that the engine takes a very long time to warm up, particularly in cold weather, and also fluctuates a lot while driving. I suspect that the thermostat is stuck open, meaning that coolant is always flowing through the radiator and causing the car to take longer to get to temperature.
In this video I set out to change the thermostat out for a new replacement.
00:00 - Symptoms
00:49 - Plan of work
01:35 - Remove power steering fluid reservoir
02:06 - Disconnect battery
02:18 - Slacken off alternator bottom bolt
03:21 - Remove alternator top bolt & nut
03:32 - Remove alternator securing stud
04:10 - Remove terminals from alternator
04:34 - Remove alternator
04:59 - Drain coolant
06:12 - Remove coolant pipes
06:22 - Remove thermostat housing bolts
07:07 - Remove thermostat
07:46 - Install new thermostat
08:00 - Refit thermostat housing
08:09 - Refit coolant pipes
08:37 - Refit alternator
09:07 - Refit coolant drain plug
09:15 - Refill coolant
10:14 - Results

[@1066Kitchen]

Great video mine needs changing also they never make them easy do they. Just one question does this car have a tensioner on the pulley belt

[@RobGMyMX5]

Yeah it's a bit of a faff to get to, but not the worst job I've ever done. There is no tensioner on the pulley, the belts are stretchy so held under tension when everything is bolted up