We take 7-10 min showers typically and have very cold water in mid-winter--below 40 F. We can run all three showers simultaneously and run washing machine or dishwasher without problems. Of course we have a front loading washer, an energy star dishwasher, and 1.5-1.6 gpm showerheads. We've not ever run out of hot water except for the whirlpool tub, even when 3 more adults were staying with our family of four. This was true even at 125 F set point in mid-winter for 50 gallon tank with company staying.
Originally Posted by jadnashua
However, I note the dual showerheads listed by the original poster for the master bath. And I assume all of their showerheads will be in the 2.2-2.5 gpm range. Then add in the slow recovery rate of electric vs. what we have for gas. So it seems best to go for some overkill in the infrastructure, even if a 2nd tank is never installed.
If the last tank in the series failed they would notice immediately. If the first tank failed and they dont use very much water,they might not would realize it.
Originally Posted by Runs with bison
In a parallel install with gas they would notice right away because the tanks draw equally and when one tank goes out the water temp drops alot because its mixing cold water from one tank.
If the parallel install was electric and one of the top elements when out they would notice a drop in initial temp right away....if one of the bottom elements quit working they wouldn't know unless they made a substantial draw.
In the home we rented before we bought this house the WH was electric, believe it was a 50 gallon. My wife had a habit of taking 15+ minute showers with the 7+ gpm waterhog showerhead (which gave a poor spray...I've had better showers from 1.5 gpm showerheads.) There was no warm water left by the time I got to the shower.
Originally Posted by Hackney plumbing
The kids were still little enough that they would play in the shower for 20+ minutes if we didn't drag them out. Fortunately, their shower had a regular 2.5 gpm showerhead so this wasn't a problem until the 2nd one tried to do the same thing.
I know what you mean. My wife can drain a 50 gal by herself with just a shower and we have average 65 degree cold water and I have my thermostat set at 135 degrees.
Originally Posted by Runs with bison
I made a mistake on the post you quoted me on......I said a 70 gal tank wouldn't be big enough for one of the girls showers but I meant to say a 70 gal wouldn't be big enought under those conditions for all three girls to shower.
High-flow showers and heating hot water with electricity SCREAMS for drainwater heat recovery on the showers, independently of how many HW haeters or total volume. Even at 7 cents kwh there's a good economic argument in high-volume shower uses. (IIRC In Seattle PSE's residential retail rates are running more like 12 cents/kwh, delivered.) At typical one-showerhead flows it would roughly double the effective showering time, even for an electric tank (and turns a typical small-burner 40 gallon gas fired tank into about an hour-long shower at Seattle's incoming water temps.)
Sizing the tank volume for the anticipated tub fills is most critical, but you'll need to go higher than that if you anticipate other large draws simultaneously tub fills. Drainwater heat recovery may do wonders for shower performance, but does SQUAT for tub fills.
From an efficiency point of view the distance from the tank to the load counts. In an average CA house something like 17% of the total water heating energy is thrown away as "abandoned" hot water in the distribution plumbing. Locating the tank nearest the most-often used taps (which aren't necessarily the highest volume use taps) makes a difference. Insulating all distribution and near-tank plumbing (even the cold side) with 5/8" wall closed cell foam pipe insulation does too.