Gas or Electric Tankless Heater For Large Families
6:40 on a school day. Two kids in two showers, dishwasher on, and whoever’s third gets cold water. I hear that one in Newark all the time. Usually it’s parents who went tankless because somebody said the hot water never runs out. For large families the fuel matters some. Sizing matters more, and that’s where most of these jobs go wrong.
Gas Puts Out More Hot Water
If a family’s running two showers and a sink at once, I’m usually quoting a Navien or a Rinnai. Those top out around 199,000 BTU. In a Delaware winter that’s about five gallons a minute. A Stiebel Eltron Tempra 36, which is about as big as home electric gets, does maybe three and a half. One shower and change.
For large families that difference is most of the decision.
What nobody budgets for is the gas line. The old 40,000 BTU tank ran fine on half-inch. Tankless wants three-quarter from the meter, plus new PVC venting out a wall or the roof. It’s a full day, usually. Two if the run’s long.
What January Does to a Tankless Heater
This was a family of six off Route 896. They’d bought an electric unit online and had somebody put it in that fall. It worked fine until the second week of December, when the second shower every morning started coming out lukewarm. They thought it was defective.
It wasn’t. Winter water coming into a Newark house is somewhere in the mid-40s to low 50s, and the heater has to get it to 120. Call it a 70-degree rise. Every tankless loses flow working that hard. Electric loses more because it’s already close to its limit.
We pulled it, ran a bigger gas line, and hung a Navien where the electric one had been. That took most of a day. I don’t think we’ve heard from them since, which is how you want it.
Where Electric Makes Sense
No gas at the street? Then it’s probably electric.
We did one a while back for a family of five. No gas service, and a 200-amp panel with room left in it. Mom worked nights, so showers were spread out all day and laundry was a Sunday thing. We put in a Tempra 36 in about half a day. No complaints.
A lot of large families aren’t set up like that, though.
Usually the panel’s the problem. The Tempra pulls 150 amps on three 50-amp breakers, and plenty of the older ranches and split-levels around here are still on 100 or 150. So that’s a panel upgrade first. We do electrical too, so somebody looks at the panel on the first visit.
How Big a Unit You Actually Need
Size it for your worst 10 minutes, not a normal day.
That’s two gallons a minute per shower, roughly, and another gallon or so for the dishwasher or kitchen tap. People forget the washer. For large families with three bathrooms that can go past seven gallons a minute, and no one unit’s doing that in January. We’d put in two. Navien and Rinnai both sell cascade kits for it.
Newark water leaves scale, too, and tankless heat exchangers clog faster than tanks. Flush it once a year. It’s about an hour with a little pump and some white vinegar, and you can do it yourself if there are isolation valves on it. If there aren’t, get them put on during the install.
Get It Sized First
A too-small unit doesn’t break. It just leaves somebody cold every morning till you give up and replace it, and then you’ve paid for two installs. Our tankless water heater installation starts with a load calc and a look at your gas line and panel. Fixed right the first time, so large families aren’t planning showers around a heater.
FAQ
gas or electric for a family of 6?
Gas, most of the time. You get more hot water per minute, and that’s what counts when showers overlap. Electric works for some large families, mostly ones who spread things out and have the panel for it.
can I just hook tankless up to my old gas line
Probably not as-is. Older lines are usually half-inch, sized for a tank, and whole-house tankless needs way more gas. We check pipe size and how far it runs from the meter before we quote you anything.
do you need a permit in Newark to swap a water heater
Yep. The City of Newark requires one, and gas work in Delaware has to be done by a licensed plumber. We pull the permit and deal with the inspector.
how long do these last with a big family running them nonstop
Usually 15 to 20 years, even for large families, as long as it gets flushed every year. Skip that and it won’t make it. The heat exchanger’s usually what goes first.
which one’s cheaper to run
Depends on your rates more than the heater, honestly. Newark has its own electric utility, so dig out a recent electric bill and your gas bill and we’ll run the numbers on what your house actually uses.
