We're replacing our tank with a more efficient one and we can't go tankless given the cold input temperatures in Canada and the amount of output we need (for a triplex with 7 people).
So I've been researching tanks. Both Rheem and Bradford White seem to offer the most efficient, high quality tanks. I've determined from my calculations that we could get away with something in the 100-120FHR range to serve the peak shower time in the morning for the household.
One thing I'm completely confused by though is the Bradford White high performance energy saver 25gallon tank. Every tank we've seen is around 50-75 gallons with an FHR ranging from 80-120. This 25 gallon tank says it has an FHR of 155 gallons (200 gallons FHR for the 50 gallon tank). I'm wondering first how is this possible, and second, why this listing would say it's intended for a 1 person household.
What one person would ever use 155 gallons of hot water in an hour? I'm positive that our house, with 3 showers and low flow heads at 10 minutes a shower with 90 degree rise would use about 105 gallons of hot water. What am I missing with this particular tank? It seems too good to be true that a 25gallon tank could serve us and its even more confusing to say that 155gallon FHR is only good for one person.
I've realized what's wrong with my assumptions that 150FHR would serve our house. If I assume we need 105 gallons for a a worst case scenario of 3 simultaneous 10 minute showers, repeated twice (ie 6 showers over 20 minutes) then that's 105 gallons in 20 minutes, not an hour. So I need to take the recover of the tank for an hour, divide by 3 and add it to the capacity. So its recovery is 82gal/hr which means in the first 20 minutes we'd only get 45 gallons (approx) of water.