Water Heaters - new 80gal water heater running out of hot water too soon

had a 40gal hot water heater. before the last family member (3 of us) could finish their shower they were out of hot water, so we purchased an 80gal whirlpool from lowe's. well same problem..last person is getting partially cold shower. can anyone tell me how much water an 80gal should produce? btw we never run the washing machine on hot water, nor do we use the dishwasher while taking our showers. thanks for any help!!!

An 80 gallon tank would give you about 56 gallons of water at above 100º . If your shower heads are 2.5 GPM you would have about 22 minutes of water. Notice that this does mean that you start with hot water at the set temperature, but it will gradually cool as more cold is mixed in. In theory you should get 70% of the capacity of the tank at an acceptable temp (100º+).

You need to be ready to pound on the door when the first person has used their 7 minute allotment!

If you set the water heater temperature higher then mix in more cold water you will effictvely increase the overall amount of hot water available, although theres a scald hazard if you set it too high. you could add a temperature control valve to prevent this

You dont say electric or gas. Ill go for electeric and the bottom element is not kicking on right. Or did turn power on and you blowed the element before it was full of water. Cold water in on the dip tube side???
Lots of ifs post back in the same post.


ED ;)