Government bodies sites:
https://www.gassaferegister.co.uk/https://www.watersafe.org.uk/    http://www.thameswater.co.uk/
http://www.cibse.org/http://www.ciphe.org.uk/https://www.carbontrust.com/home/

Heating manufacturer sites:



http://www.vaillant.co.uk/homeowners/http://www.honeywelluk.com/

Bathroom suppliers:
http://www.burlingtonbathrooms.com/http://westonebathrooms.com/