Indesit water not getting hot fitted new thermostat and cheaked heater ok

Was the heater working ok before you fitted the new thermostat?
If no, you probably have a blocked heater matrix. That means you have to either try flushing the coolant system to remove the blockage .. or.. replace the heater matrix, which isn't an easy task.

If the heater was working ok before you changed the thermostat then it's likely you still have air in the system.

Set the heater controls to hot, remove the radiator cap/coolant bottle cap and start the engine. Let it tickover and warm up. Hopefully any trapped air will be purged from the cooling system.

Are you sure that the thermostat is okay? Thermostats have a small valve in that allows air to pass through. If your thermostat is mounted like a clock ..i.e .. the face looking out - the air valve must be at the top.

Replace thermostats
http://waterheatertimer.org/How-to-replace-thermostat-on-electric-water-heater.html
If problem continues, replace elements
http://waterheatertimer.org/How-to-replace-water-heater-element.html

Gene

If you need further help, I’m available over the phone at https://www.6ya.com/expert/gene_9f0ef4df2f9897e7

1) Reliance 606 Electric water heater, AO Smith subsidiary.
Good brand.
Copy following links:
http://waterheatertimer.org/How-to-test-water-heater-element.html
http://waterheatertimer.org/How-to-replace-thermostat-on-electric-water-heater.html
http://waterheatertimer.org/How-to-troubleshoot-electric-problems-with-water-heater.html

2) First: Test elements using cheap multimeter from hardware store.
Next: If elements test OK, then replace both thermostats.

3) If that doesn't solve problem, then add comment Jan 2013 and report what you find.

If you need further help, I’m available over the phone at https://www.6ya.com/expert/gene_9f0ef4df2f9897e7

check your recirc pump , it was siezed on mine , take it off the motor and it will be all wobbly ,

Sounds like you have a bad thermostat. You can change the thermostat, but if the heater is more than 8 or 10 years old you might be better off to replace the entire heater. Thermostat replacement is easy:
1 turn off the gas 2 drain the heater 3 unscrew pilot, main burner, and thermocouple lines from bottom of thermostat. 4 unhook gas line from thermostat. 5 unscrew thermostat from heater tank. Use pipe sealer when you install new thermostat, and gas line fittings. burner and thermocouple lines seal on a taper seat and do not need sealer. after reassembly check for leaks with soapy water, not a match, light the pilot and turn up the temp. The heater may sweat quite a bit while it is heating up the first time, this is due to the cold water on the inside and the fire on the outside. some water may drip in the bottom of the heater and you might think you have a leak, but let it heat up completly, if the water is still dripping after the tank is hot then you need to find the leak.

Check the elements, if you have access to a meter to check them. If they are getting power to elements and you have no hot water.
The elements are not working correctly. I had some elements check out ok till the thermostat's turned on and the elements didn't heat.
Sounds like the elements are bad.

I am assuming that everything was fine and then all of the sudden available hot water usage time dropped.

On a dual heating element hot water heater it can be

1. Internal tank loaded with sediment (drain and purge from lower garden hose fitting)

2. Thermostat or element problem with ONE of the 2 heaters. (Trouble shoot element thermostat)

3. Check Circuit breaker for partial trip of the breaker.

I have a similar problem with an Indesit oven. There are two thermostats one controlling the oven temperature which i think you have replaced and another over-temperature stat to prevent the oven getting to hot should the temp stat fail to control the temperature. The over- temperature stat could be operating to quickly and this cuts power to the the digital display, oven light, temp light and circulating fan. I am going to replace this over-temp stat

I no longer need help. Took the item back. Didn't come close to fitting around the hot water tank.
Thank you

It's possible you have a bad vaccum line to the actuator door in the heater assembly
or possibly a stuck thermostat