I have a 50 gal. gas water heater which run out of hot water when my daughters uses the whirlpool tub in the morning leaving me without hot water in the shower unless I have to wait for 20 minutes. I initally plan to change it to a 80 gal. gas water heater but this question pop-up: Would it be cheaper for me to buy a 30 or 40 gal electric water heater and connect it to my 50 gal water heater using the electric water heater sort of just a storage tank? Is it cheaper utilitywise on my monthly heating bill compared to getting a 80 gal. water heater? Please help!!!!!

 

Repacing an servicable 50-gallon HWH with a 80-gallon unit is impractible for this reason---your "disposing" of 50 gallons of capacity. Better to keep the 50-gallon unit and add the 80-gallon unit to the system if you'r giving serious consideration to purchasing the 80-gallon unit.

As to the gas/electric operating expence, it depends on the rates charged by the Utility Co.Is electric "competitive" with gas? Local plumbing contractors are probably knowledgeable on this issue or the guys at the local pumbing-supply house.

 

gas water heaters are usually quite a bit more expensive than elec ones, and there's a little more involved to install one.

I think I would just install a 30 or 40 gal elect upstream from your existing gas heater, and put it on a clock switch (timer). Have the heater run for a couple hours, starting when your dauhter usually fires up the whirlpool tub. being fed warm water, your gas heater should then be able to keep up with the demand.
set the elect heater thermostats at a low setting (warm). This combined with the timer should keep your costs fairly low.

 

Norm is right on the money. I had the same situation when I built an addition with a master bathroom with a 75 gallon Jacuzzi tub. With my 40 gallon water heater, I couldn't even get the tub full with hot water before it would run out. I thought about cranking up the thermostats in the heater, but with a couple of little one's running around the house that wasn't a good idea. I then looked into an instantaneous booster heater for the tub - but to get the size required would have I would have needed a 90 amp circuit! I then though about changing to a larger tank, but I had just put in the 40 gallon tank and couldn't return it. Besides, I only had room under my house for a low-boy tank. I then turned my attention to a second 40 gallon tank. I first considered plumbing the two tanks in "parallel", but for reasons I don't exactly remember that would not have been practical from a plumbing point of view.

What I finally did was connect the two tanks in series, with the new tank upstream from the existing tank. I changed the elements from 4500 watt to 3500 watt so I could reduce my circuit size down to 20 amps. Since we don't use the jacuzzi tub but a couple times a month (if that), we only turn the "auxilliary" water heater on about an hour before we are going to use the tub (or if we have overnight guests). 95% of the time, the second water heater is merely a (cold) water storage tank, but is there to provide the necessary hot water when we need it.

In your case, I don't mean to preach, but does your daughter really need to use 75 gallons of hot water for her bath EVERY DAY? If so, then Norm's suggestion of putting a time clock on the auxilliary heater may be the way to go.

 

I have two 40-gallon tanks in series. In the winter, I keep both of them turned on. In the summer when we don't need as much hot water, I shut off the heat to the first one.

 

Thank you for all you suggestions. It seems it was really a good idea to put a series between the two water heater but added to that the timer would be helpful too. I appreciate your help