well most Pressure Relief Valves (PRV's) leak because of bad seals from junk in your water that eats the rubber seal but sometimes it can be to much pressure or the water heater is too hot. I would check to make sure your pressure or temp is not the cause before I would replace the PRV. Almost all potable water heater PRV's are set to release pressure at 150 PSI. If its leaking because of the bad seal then you have to replace it because most are non replaceable parts.
A T&P valves is unique in that is can relieve either pressure (150 PSI) or temperature (210 F) a "Relief valve is used for liquids and a safety valve is used for vapor such as air or steam.
A PRV is a pressure reducing valve and normally found on either the supply to a Hydronics boiler or incoming domestic water and if one is failing you would also get telltale signs such as water hammering (hydraulic shock)
If the T&P valve seeps this could caused by water expanding when heated called "pressure temperature relationship "
Many times if the incoming pressure is excessive and then the water is heated one would need to install an expansion tank compatible with domestic water supply
Leaks can be caused by all kinds of things:
The water enters in a cold state & is a certain physical volume. Once heated the water expands slightly within its container (the heater) & therefore applies pressure within the heater or more to the point against the wall of the heater.
It happens when the pressure inside the tank exceeds the design pressure limit to which the valve is designed.
To cure this problem, turn the heat level down at each element or on the gas control.
My guess is that the hot water heater is installed downstream from a pressure reducer to limit the maximum water pressure that the water heater is exposed to.
Water expands when it is heated, this expansion increases the pressure. The bladder tank absorbs the extra pressure, protecting the hot water heater.
More than likely it is restiction in your water heater.
Generally this is caused by pressure being built up from the water getting hot in the hot water heater. By code you should have a hot water heater expansion tank on the cold water inlet of the water heater to absorb the added pressure. If this is your problem, the excessive pressure could possibly burst your water heater. The faucet stem or cartridge or washer may be loose or moving and blocking flow.
Only if installed incorrectly
Yes install a bronze booster pump designed for hot water
Not directly.
You are running the water heater out of hot water faster than it can heat the incoming cold water.
The Thermostat and Temp and Press Valve is faulty and needs to be replaced. or the PRV (pressure reducing valve) is dirty and must be replaced
It is a water heater, not a hot water heater. There would be little point in using a hot water heater. I assume that is your point.
You may have a restriction in your hot water heater exit pipes. There may be corrosion. How old is the house and how old is the hot water heater? What type of pipe is there going out of the hot water heater? You need to know this to fix the problem yourself without hiring a plumber.
if an element is constantly expanding and contracting (if you keep switching the hot water heater off and on again) all the time it causes cracks and over time the water leaks into the element causing it to short which means you have to replace it.