Hot water at faucet


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Old 03-06-23, 05:43 AM
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Hot water at faucet

I have an issue with hot water at the faucet.

Some of my faucets get hot water within 10-15 seconds, whereas some bathrooms in my house take close to 90 seconds. Yes, the bathrooms that are closest to the hot water heaters (I have two in the basement) obviously get the hot water faster. However, the master bathroom, which is not close to the heaters also gets hot water within 10-15 seconds.

So the question is why is it that the master bathroom gets hot water nearly instantly whereas a bathroom in the adjacent bedroom takes 90 seconds.

This bothers me because I feel is such a waste of water. Thank you.
 
  #2  
Old 03-06-23, 07:23 AM
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How old is your house? Do you know if you have PEX piping from a manifold to each location? There may be a recirculation loop to the master bath to ensure that hot water response there is quick. If the adjacent bath takes that much longer it is not part of the recirculation loop.
 
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Old 03-06-23, 08:41 AM
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It may be that the fixtures that take a long time are served by 3/4" pipes instead of 1/2" pipes. A 3/4" pipe has about 2 1/4 times the cross section as a 1/2" pipe, so you have to move 2 1/4 times more water through it before the hot water arrives.

3/4" pipes are often used to feed areas with multiple fixtures where the total need for water may exceed what can be reasonably carried by a 1/2" pipe.
 
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Old 03-06-23, 08:56 AM
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Could be that the hot line for upstairs is also feeding the kitchen sink and a dishwasher so the hot is being used often.
 
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Old 03-06-23, 11:00 AM
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The house is 13 years old. Pipes look like PVC. I appreciate all the responses.

Do you guys think there is an easy fix to this? I'm expecting responses which include "it depends"
 
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Old 03-06-23, 11:15 AM
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I had the same problem in a 3rd floor bathroom so I recently installed one of these recirculating systems. The diverter valve is mounted under the sink a few feet away from the shower.

It has reduced the wait time for hot water in the shower from about 60 seconds to 15 seconds. I, too, am hoping that the reduction in wasted water will offset any minor electrical cost. The pump has a timer so the system can be set to run only when hot water is likely to be needed.

Unfortunately that bathroom is on a branch nearest to the hot water heater, so the recirculation does not benefit the other bathroom and fixtures. However, I could install a second diverter valve that would solve that problem. That bathroom tub/shower is mostly unused so I did not bother to do it.
 
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Old 03-06-23, 11:35 AM
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As you say, for the most part any potential fix depends on the root cause.

The only (relatively) easy fix that is pretty much guaranteed to work regardless of the underlying cause would be to install an undersink recirculating pump. They work by pumping water out of the hot water line and into the cold water line until the water is hot. Then the pump stops. They can be set to work all the time, or during certain hours, or when a pushbutton is pressed, or even activated by a motion sensor when someone walks into the room. Since the water doesn't go down the drain, it is not as wasteful as just running the water until it's hot. If you have it set to run all the time, it does waste energy because you will be heating more water than you would otherwise.

There are some downsides: You need a receptacle under the sink. Sometimes, you have to let the cold water run when you want cold water from brushing your teeth or whatever. Because the pump pumps warm water into the cold water line, when you first run the cold water it may be warmer than normal. Installation is simple if you use the built-in timer or let it cycle all the time. If you want a pushbutton or motion sensor, that has to be installed and wired in.

One quick thing you can try is to measure the hot water flow rate in the problem bath and compare it the flow rate in the "good" bath. Just time how long it takes to fill up a container using only hot water in both rooms and compare the times. It may be that the problem bath has lower flow rate faucet. Or you might have a shutoff valve that is partially closed for some reason. If the flow rate in the problem bath is significantly lower that the other bath, that would explain the difference in times.
 
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Old 03-06-23, 11:48 AM
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You need a receptacle under the sink.
The pump can be mounted under the sink but it does not have to be. Mine is mounted at the hot water heater.
 
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Old 03-06-23, 01:15 PM
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The pump can be mounted under the sink but it does not have to be. Mine is mounted at the hot water heater.
True, but then you need a separate water return line from the area; not needed if you mount the pump under the sink.
 
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Old 03-06-23, 02:16 PM
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Donít need a separate return line. The diverter valve sends the return water back through the cold water pipe. When the diverter valve senses 98 degree water it stops the flow back to the hot water heater. It also is a check valve so cold water does not feed into the hot water faucet.
 
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Old 03-06-23, 06:47 PM
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Learn something new every day; I hadn't seen that system before. Thx!
 
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Old 03-07-23, 08:26 AM
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Thank you everyone. Really appreciate the replies.
 
 

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