On a system heated by gravity flow from a back boiler what sort of temperature would you expect the hot water to reach. The hot water storage in question is an Elson tank with no thermostat other than what is on the boiler. We measured the HW temp today and it was only 53 degrees. I'm enquiring on behalf of a young lady. At present she is only able to get about five inches of water in the bath before it runs cold. It is a council property but they just seem to be fobbing her off. They told her she had a 55 gallon storage capacity but we've worked out it is only 35. any advice greatly received.