Most replacement water heaters get picked by reading the sticker on the old one. Forty gallons went in, so forty gallons goes back, and nobody asks whether forty was ever right. Sometimes it was. Plenty of times the house has changed since that tank went in, and the family has been running out of hot water halfway through the second shower and blaming the heater for something that was really a sizing problem. When the old tank finally gives out, it is the one moment you get to fix that, so it is worth thinking it through.
Matching the old tank is a guess
The heater that is failing now was sized for whoever lived in the house when it went in, or by whoever was in a hurry that day. Since then the kids may have become teenagers who take long showers, a parent may have moved in, somebody may have added a bathroom or put in a big soaking tub. Or it can go the other way, the kids moved out and the house is running a tank twice the size it needs, heating water nobody uses around the clock.
A straight swap also carries forward whatever mistakes came with the old install. We see undersized tanks in houses where somebody squeezed one into a closet that could not fit the right size, and oversized ones that were simply what the supply house had in stock. None of that has to repeat. Before we bring anything out to your house, we would rather ask a few questions about who lives there and how they use hot water, because the answer decides the heater, not the sticker on the old one.
Count the people, then find the busy hour
The number of people in the house is the starting point, but the number that really matters is peak demand, the stretch of the day when the most hot water gets pulled at once. In most houses that is the morning. Two or three showers stacked back to back, the dishwasher running from the night before, maybe a load of laundry because somebody needs a uniform. Some families peak at night instead, with baths and dishes landing together after dinner.
A tank heater is rated by how much hot water it can deliver in that first busy hour as well as by how much it holds, which depends on the size of the burner or elements as much as the tank. Two heaters with the same gallon number can perform differently when everybody gets up at once. So we ask how many showers happen back to back, whether there is a big tub, and what runs at the same time. Then we size for that busy stretch, which is the only time the heater actually gets tested.
It helps to think about what is coming, too. If a baby is on the way, a grandparent is about to move in, or you are planning that bathroom remodel for next spring, tell us. A water heater stays in the house a good while, and sizing it for the family you will have makes more sense than sizing it for the family you had the day the old one quit.
What our water leaves in the bottom of a tank
The supply around here is heavy with minerals, and a tank heater collects them. Every time water is heated, some of those minerals drop out and settle on the bottom of the tank, right on top of where the burner is trying to send its heat. Over time that layer gets thick enough that the heater works harder and longer to do the same job, and you start hearing it, a rumbling or popping when it fires up.
That sediment layer is a big part of why tanks in this valley wear out the way they do. It insulates the bottom, overheats the steel, and takes up room that should hold hot water. Flushing the tank once a year drains that sediment out before it builds up, and it does more good here than it would in a place with softer water. If you are putting in a new heater anyway, it is a good time to start that habit. Our water heater repair page covers what to do when an existing tank starts making noise.
Venting, gas and the things that changed since last time
Swapping a water heater is not just unhooking one tank and hooking up another, especially on a gas unit. The vent has to be the right size and run for the new heater so combustion gases actually leave the house. The gas line feeding it has to supply enough gas for the new burner, and a heater sized up from the old one may need more than the existing line delivers.
California also expects water heaters to be strapped so they cannot tip over in an earthquake, and many installs call for an expansion tank and a properly piped relief valve discharge. Requirements like these may have changed since your last heater went in, so an old install that seemed fine can come up short when the new one goes in. We check all of it as part of the job rather than leaving it for you to find out later. Our water heater installation page walks through the connections in more detail, and none of it is the place to cut corners.
Outdoor enclosure or garage, and the old tank goes with us
A lot of homes here have the water heater outside in a steel enclosure against the stucco, and plenty of others have it in the garage. Both work fine. Outdoor installs need a sound enclosure, a vent that clears properly, and supply lines that are protected from the weather. Garage installs need the right clearances, the heater raised where the code calls for it, and room to service it later. If you have been wanting the heater somewhere else, the replacement is the time to talk about it, though moving one adds gas, water and vent work.
When the new heater is in and running, the old one leaves on our truck. You do not have to figure out how to get a heavy, rusty tank to the curb or find out where it is allowed to go. We go through the whole process on our water heater installation page for Redlands homes, from sizing through haul-away.
What people ask when the old tank quits
Should I just go one size bigger to be safe?
Not automatically. A bigger tank keeps more water hot all day whether you use it or not, and on gas it may need a larger supply line or different venting. If your family is regularly running out during the morning rush, bigger can be right. If not, a properly sized heater with a good first-hour rating usually serves better.
Does sizing change between gas and electric?
How we size it stays the same: who lives in the house and how much hot water the busy hour pulls. What changes is how fast the tank reheats. A gas tank usually recovers faster than an electric one of the same size, so an electric heater may need a little more storage to keep up with the same family.
Do I need a permit to replace a water heater?
In most places, yes, a water heater replacement is permitted work, because the venting, gas connection and strapping all matter for safety. It is part of why we look at the whole install instead of just setting a new tank in the old spot. If anything about your current setup needs to change to meet the rules, we explain it before we start.
If the old heater is leaking, rumbling or just not keeping up, call (909) 888-8736 and tell us who lives in the house and where the tank sits, or put it in a message. We will size the new one to fit the people using it.