Water Heaters - 50gal at 120deg providing 15min hot shower - is this normal?
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demount
12-06-04, 08:56 AM
I just installed a 50gal "high-efficiency" Whirlpool natural gas water heater that I purchased from a home center. Retail was $290. The unit being replaced was installed using dielectric unions, so no sweating of pipe was required to install new unit. With the new unit set at 120 degrees, a shower consumes all the hot water in under 15 minutes. This is faster than the leaking unit that was replaced (though the old unit was probably set at a hotter temp). Is this normal? The articles I am reading on the web suggest that the 120 degree setting should be fine, and the unit indicates that it supports a family of 5.
majakdragon
12-06-04, 09:08 AM
demount, Welcome to the DIY Forums.
When you installed the water heater did you notice if there was a tube (probably plastic) sitting in the cold water inlet? Or in the box. You should get more hot water than that from a 50 gallon heater unless you are running hot water only. Or it could be your showerhead.
The energy efficient shower heads are rated at 2-1/2 gallons a minute so a 15 minute, all hot, shower would use 45 gallons of water. That also does not give much time for recovery. If your showerhead is an older one, you could be using more than that figure. I believe your problem is usage and not the heater.
You may have to turn the temp up a bit or reduce shower time. Good luck.
When you installed the water heater did you notice if there was a tube (probably plastic) sitting in the cold water inlet? Or in the box. You should get more hot water than that from a 50 gallon heater unless you are running hot water only. Or it could be your showerhead.
The energy efficient shower heads are rated at 2-1/2 gallons a minute so a 15 minute, all hot, shower would use 45 gallons of water. That also does not give much time for recovery. If your showerhead is an older one, you could be using more than that figure. I believe your problem is usage and not the heater.
You may have to turn the temp up a bit or reduce shower time. Good luck.
594tough
12-06-04, 09:35 AM
At a cost of $290 any mention of high efficiency or other type of comments is probably advertising hype. A better 50 gallon water heater would run closer to $390. Also, 'high efficiency' does not equal 'high demand'.
Anyway, even a modest 50 gallon unit would have a "first hour delivery" rating of about 70 to 80 gallons. So in theory, with a 2.5 gpm shower head, you would get something like 30 minutes of hot water. However, that figure assumes consumption of the 80 gallons over a one hour period, i.e at about 1.3 gpm. So even if your shower head is in fact limiting to 2.5, you have more mixing of incoming cold going on and the outlet temp is going to tend lower. Now, combine that with the time of year. If any of your hot supply lines run through cold attic space or crawl spaces, your water is being cooled considerably before it even gets to the shower. At this time of year, even in temperate San Diego, I find it necessary to adjust my WH up about 2 notches on the dial.
Now, as to specifically why the new heater may be underperforming compared to the old unit, follow Maja...'s recommendation to check and see if the dip-tube is missing or dislodged.
regarding size: 50 gallons is on the edge in supporting a family of five, specs wise. Although you would rarely find anything larger especially installed by the builder. It all depends on how many showers in close succession; any washing machine or dishwasher use around the same time? I might recommend a 'high demand' rated 50 or 60 gallon. Space limitations may preclude that.
Let us know what you find out.
594tough aka jimbo aka jimmy-o
Anyway, even a modest 50 gallon unit would have a "first hour delivery" rating of about 70 to 80 gallons. So in theory, with a 2.5 gpm shower head, you would get something like 30 minutes of hot water. However, that figure assumes consumption of the 80 gallons over a one hour period, i.e at about 1.3 gpm. So even if your shower head is in fact limiting to 2.5, you have more mixing of incoming cold going on and the outlet temp is going to tend lower. Now, combine that with the time of year. If any of your hot supply lines run through cold attic space or crawl spaces, your water is being cooled considerably before it even gets to the shower. At this time of year, even in temperate San Diego, I find it necessary to adjust my WH up about 2 notches on the dial.
Now, as to specifically why the new heater may be underperforming compared to the old unit, follow Maja...'s recommendation to check and see if the dip-tube is missing or dislodged.
regarding size: 50 gallons is on the edge in supporting a family of five, specs wise. Although you would rarely find anything larger especially installed by the builder. It all depends on how many showers in close succession; any washing machine or dishwasher use around the same time? I might recommend a 'high demand' rated 50 or 60 gallon. Space limitations may preclude that.
Let us know what you find out.
594tough aka jimbo aka jimmy-o