SK1500-2

A: 

 Difficult to say as I don’t know which O ring you havefound as a spare.

Below is an exploded diagram of the shower I don’t know ifthis will help or not?

 

 http://www.showerdoc.com/shower-spares/sirrus-by-gummers/GUM-PARENT-34-Sirrus-1500---Thermostatic-Shower 

A: 

This is the standard 1500TS valve there various covers, knobs and levers that go with the valve, however the cartridge remains the same with the exception of the chrome version.

http://www.showerdoc.com/shower-spares/sirrus-by-gummers/GUM-PARENT-34-Sirrus-1500---Thermostatic-Shower

So to answer your question is this the correct cartridge for the Sirrus 1500TS  YES.

 http://www.showerdoc.com/shower-spares/sirrus-by-gummers/GUM-SK1500-2-Sirrus-Thermostatic-Cartridge-(no-Thermostat)-Standard-SK1500-2

 

A: 

Yes it should be straight forward.

http://www.showerdoc.com/shower-spares/sirrus-by-gummers/GUM-PARENT-34-Sirrus-1500---Thermostatic-Shower

 

Are the piston teeth looking forward and is the black bit of the thermostat looking forward.

 

A: Yes the cartridge can be dismantled and if you click on the link below it will take you to an exploded diagram of the 1500 which should be of assistance and also allow you to order a service kit online.

http://www.showerdoc.com/shower-spares/sirrus-by-gummers/GUM-PARENT-34-Sirrus-1500---Thermostatic-Shower

A: If the original piston in your shower was metal then you have the choice of refitting it with your thermostat or buying a new thermostat to fit the new plastic piston.
Also check that you have the thermostat in correctly, it should have the small dia steel pin pointing towards you as you stand in front of the shower.
You may also need to adjust the temp range by removing handle retaining scre ( water will come out the hole, this is normal) inserting small thin flat bladed screwdriver engaging adjusting plunger and turning clock wise to decrease and vice versa, after turning it takes a few seconds for temp to stabilise so allow for this when adjusting.
If you click on the link below it will take you to an exploded diagram and all online ordering if required.

http://www.showerdoc.com/shower-spares/sirrus-by-gummers/GUM-PARENT-34-Sirrus-1500---Thermostatic-Shower

A: Yes this will fit your shower and can be ordered online by clicking on the link below.

http://www.showerdoc.com/shower-spares/sirrus-by-gummers/GUM-SK1500-2-Thermostatic-Cartridge-(No-Thermostat)-Standard