[retiredguy123]

Originally Posted by bob47

If there was no backflow preventer in the water supply line, your water pressure would always remain at supply pressure. With a backflow preventer, as cold water expands when it is heated, it increases the pressure on the water heater and pipes in your house.

Correct. Assume that you take several showers and use all of the hot water in the water heater, and then shut everything off in the house and leave for several hours. The water heater will come on and heat up the cold water in the tank causing thermal expansion and a significant increase in the water pressure throughout the house. But, if you have an expansion tank, the water can expand into the expansion tank and prevent the pressure increase. It only requires a small amount of thermal expansion of the water to create a significant pressure increase.

[Paula]

Originally Posted by Bay Kid

My hot water heater is a 2004 located in the garage. It looks great and heats the water well. It doesn't have an expansion tank. Should I be looking to replace this now?

If it ain't broke, don't fix (or replace) it!

[Topspinmo]

Originally Posted by Arctic Fox

Mine is 27 years old. I guess they made them properly back then.

Other posters have changed their still-working ones at 5 years, 10 years, 12 years etc. etc. so how do you decide when to replace a perfectly-working one? Seems like guesswork to me.

Do whatever you feel comfortable with.

Depends what you feel comfortable with? Another factor how much metals in water, on city water water heater last longer. In country on well water if makes to 10 years you’re on borrowed time. On city water some were around 15 years or so, over 20 very lucky IMO.


IMO for two options? Wait for leak (and it will leak eventually, hopefully you’re home) or inspect it every day looking for drips or sprays. When mine failed in Oklahoma on well pump (8 years cause I brought cheap one) it sprayed cause the bladder tank kept falling below 40 PSI. Course it happen in night on other side of house and that room got flooded and water run down into air handler ducts being it was down flow system. Quit mess.

[Bay Kid]

It still looks great but it does make popping, cracking noise when it is heating the water.