User manual cointra te 80 water heater - Water Heaters

if its was that simple you would have had a answer . I n fact if its that simple why ask . But I will look in to it .

I am not familiar with the model. Is this a 10 gallon water heater? the volume of water can not change. The temperature can usually be adjusted and even placed in vacation mode. Also the pilot light might be out, this would be the only thing I could think of that would stop all hot water. You mentioned output. If you are referring to flow this would be a restriction in you pipes possibly. If you have old galvanized pipes this would explain the reduction in flow. Also if this is a tankless water heater a reduction in flow would explain in not working at all. If the flow of water is not adequate enough a tankless heater will now turn on. If it is a Tankless water heater then there is a filter located on the cold side. To check this turn off the cold water, relieve the pressure by piping the TPRV Valve "Temperature, Pressure Relief Valve. Then take the cover off the filter. clean all that nasty gunk off the filter, reinstall it and you are back in business. The heater should be as good as new.

leaks in line get loca repairman repair guy there soon

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

http://waterheatertimer.org/Leaking-water-heater.html
http://waterheatertimer.org/pdf/AO-Smith-heat-pump-service-manual-321547.pdf

Gene

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

Usually, this means that the water tank is leaking. It is not worthwhile to fix the leakage unless you have welding equipment. Just buy a new one.

Either the pilot is not lit, or the thermostat/gas valve is not working.

In my experience thermocouple either work or they do not.when a water heater runs for a length of time before the interupter cuts the pilot or on some modules safety cut out sensor also known as over heat thermostat cuts the gas supply the problem can normally be found in the flue restricting the disposal of waste products of the combustion or the lach of air flow through the appliance

You probably need commercial 150gallon gas water heater.
Or three 80 gallon tanks, depending on number of people.

80 gallon residential gas heater is rated for low-demand 6-8 person household.
80 gallon residential electric is rated for low-demand 5 person household

80 gallon is not correct for 14-28 people in 7 apartments
http://waterheatertimer.org/Whatsize2.html
http://waterheatertimer.org/Two-water-heaters.html

Call local plumber, or local code department.

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