Which size would you go with?

[Gusherb94]

Trying to decide between a Bradford White 50 gallon 65,000 BTU model, or the 75 gallon model. Existing is a 25 yr old Ruud 50 gallon 60,000 BTU WH. Hard to size a new one based on that because the thermostat is worn out and it's definitely not putting out like it used to.
The factors are: 3 people, there is 2 simultaneous showers fairly regularly, almost never 3 simultaneous showers. There is a traditional top load washing machine, rarely turned on at the same time as a shower but often is right before or after a shower. Dishwasher can be turned on at the same time as a shower as well.

The big catch point for me is whether to include the 100 gallon whirlpool tub as it's hardly ever used but is every once in awhile. It seems like it would be silly to have a massive tank just for the once or twice a year that tub is used, but it would still be nice to be able to fill it completely. That is pretty much the difference between a 50 gallon tank or a 75 to me. Not sure how others would look at this.

The other factor is size, if I go with a 50 it'll be a bit smaller and lighter then the 75 gallon tank.

 

[Reach4]

One thing that could be done is to keep the heater on maybe 130 most of the time, and kick it up to 160 when you anticipate more need for the hot tub. Current code says that you need to have a mixer valve do the mixing of hot and cold for most of your loads. Exceptions that I know of are dishwasher and clothes washer. Most people would have a single mixer for the whole house rather than one for the bathrooms and one for the kitchen because it is cheaper and simpler.

Sounds to me as if 50 gallon might be close to making it figuring 50F degree water coming into the cold water and giving you a 105F bath. So 50/50 50F cold and 160 degree hot gets 105F bath. But that does not account for overcoming the cool pipes and the tub. As you draw the bath, some more heating is going on, but on the other hand, the heater is not going to give all hot as mixing goes on. I think you might want the 75 gallon WH to be more sure. But wait. You will have at least one body in the tub. Figure about one gallon less water needed for each 7 pounds of body that will be under water at the same time. It is a waste to fill the tub to the overflow only to lose 10 or so gallons of bathwater to the overflow when you go in. So maybe the 50 gallon will will be plenty.

Not a pro. My reasoning may be off.

 

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[Gusherb94]

It looks like it's going to be a 75 gallon tank. The quotes I got for the high recovery 50 and 75 were within 100 dollars of each other. May as well go with the one that for surely can handle the whirlpool tub.

Funny thing is, I called three places, two quoted Bradford, and one quoted State, two of them quoted within $50 of each other for a Bradford and a State, and the third Bradford quote was over $250 more then the first two, which ironically matches what I can get a 75 gallon Rheem at the Cheapot for.

 

[hj]

You have to know whether they are quoting "old stock" heaters which are MUCH cheaper, and smaller, than the "approved" current models.

 

[Gusherb94]

You have to know whether they are quoting "old stock" heaters which are MUCH cheaper, and smaller, than the "approved" current models.

Hmm. I just assumed that they're all selling the new ones now. Is $1000 about the going price of the new, compliant 75 gallon atmospheric tanks?

 

[Dj2]

Sounds right.

 

[Gusherb94]

Sounds right.

Yep, I guess the State and one of the Bradfords quoted are old stock then. Went back and looked at the prices I wrote down and all the standard 50 gallon tanks are within 50 bucks of each other. The 75 gallon tanks must sell slowly.

 

[Dj2]

Most average homes use 40 gal and 50 gal WHs.

With 3 people in your house, I really don't see the need for a 75 gal WH. But it's up to you.

I have rentals with families of 3 and 40 gal tanks, and nobody reports any hot water shortages.

Some new heaters are rated high recovery - consider a 50 gal high efficiency.

 

[Jadnashua]

A big soaker tub with a high volume valve can deplete a big tank quickly, regardless of high recovery. It can become an issue if anyone else is trying to use water at the same time. Now, running one at 140-degrees or maybe higher with a tempering valve can make it 'look' like a larger tank with the exception that higher temperatures will also mean bigger standby losses.

 

[Jadnashua]

A big soaker tub with a high volume valve can deplete a big tank quickly, regardless of high recovery. It can become an issue if anyone else is trying to use water at the same time. Now, running one at 140-degrees or maybe higher with a tempering valve can make it 'look' like a larger tank with the exception that higher temperatures will also mean bigger standby losses.

 

[Gusherb94]

It may be a worn out dip tube, or the worn out and inaccurate thermostat, but the current 50 gallon tank can barely cut it in the winter. And during that time I remove the plastic dial so I can turn the thermostat beyond the stop in the dial and (beyond 160) which gives me about 140 degree water.
Two showers will run it out fairly easily, or a washload and a shower. The saving grace all these years has been that it's fast recovery, so water is hot enough to use again after about 15 minutes.

Most of my neighbors seem to have 40 or 50 gallon tanks and none of them seem to complain. The only one I know of with a 75 gallon tank is the one next door and they have a whirlpool tub also. Our 50 gallon has always seemed a bit taxed for as long as I can remember (the past 15 years at least)