Could be air could be gas lack of. I'll assume you have a full tank and the water flows air free from hot taps. If still having problems then enter the following in your search engine box
carver cascade 2 operation manual
The top one is, or on my list is,
www.thomson-caravans.co.uk/advice/maintenance/.../carver-user.pdf click on it and you will get the operation manual. Check the main gas pipe to each appliance you may find each one Teed off has it's on stop valve so each appliance can be isolated if it developes a leak so allowing other appliances to continue to be used.
Hope this helps. Also if dealer bought and it is faulty check the warranty.
One last thing Truma aquired Carver heater etc
contact them if still faulty.
Contact Details:
Email technicalATtrumauk.com
salesATtrumauk.com
Don't forget to change AT to normal email address symbol. This forum won't accept the normal email symbol.
Website www.trumauk.com
Telephone 01283 586050
Fax 01283 586051
Address Truma UK Ltd
Park Lane
Dove Valley Park
South Derbyshire
DE65 5BG
Bob
February 2012