How do I get hotter water sooner?

January 13, 2007 2:59 PM

Cure for the takes-too-long-for-our-water-to-heat-up blues?

We have a 40+ year old house in the usually temperate SF Bay Area. It takes about five minutes for the water in the shower, bath, or any of the sinks to begin to get warm, and then a few minutes more to actually get hot. What can I do about this? I hate wasting water waiting for things to heat up, but I hate cold showers even more.

The house is a split level, with almost all of the house above the garage. Our 10-15 year old gas hot water heater is located in the garage -- probably a 30' run of pipe from water heater to our shower. The water pipes are copper, uninsulated, and accessible. Water pressure is fine. Will the simple foam pipe sleeves that are sold at Home Depot make a noticeable difference? Would a better/different water heater make a difference? Once the warm water arrives, there's plenty of it. Thanks!

posted by mosk to home & garden (18 answers total)

You might consider installing a hot water recirculation pump.
posted by whatisish at 3:06 PM on January 13, 2007

Pipe insulation is a good idea anyway, but probably won't make a difference, because it won't keep water hot during the (presumably) many hours between showers.

You could consider an instantaneous water heater (electric model is described, but they make them in gas also). This would need to be installed somewhere near your shower, like in a closet. Even an electric one might turn out to be more efficient than your old water heater.

It is odd that it takes 5 minutes for the hot water to get through 30 feet. I noticed this at my brother's house in California also -- maybe there's some California plumbing peculiarity.

If you go with a recirculating pump, you definitely want to insulate the pipes to cut down on heat loss, but you'll see your gas bill go up, significantly, anyway. If you take showers at pretty regular times, you could put a timer on the pump so it starts up before you usually shower, and shuts down after.
posted by beagle at 3:24 PM on January 13, 2007

keep in mind that to do this, you will need to run a return line from the furthest hot water user back, through a pump, and back to the hot water heater

http://www.lainginc.com/howhot.htm
posted by defcom1 at 3:27 PM on January 13, 2007

Actually there are methods of adding a recirculating pump to an existing plumbing system using the cold water line. How well this works depends on the geometry of your plumbing. Also there is some minimal mixing of the hot and cold water supplies. Some people do not like to cook with water that comes from the hot water heater. The system will also increase your gas or electric hot water bill.

The instantaneous water heater might work but you need some space to install it and it may require plumbing and electrical remodeling.

Five minutes is a long time -- or does it just seem like it when you are waiting. I suspect that in the Bay area there may not be any insulation in your walls so you need to heat up not just the water but all 30 feet of copper pipe.

As beagle said, pipe insulation can't hurt and is cheap, but it won't do much over a couple of hours of time. You will probably only have access to some of the length.
posted by JackFlash at 3:56 PM on January 13, 2007

Try something: stand by the water heater (after no one has used any hot water for a few hours). Have someone turn on the shower all the way to hot. Put your hand on the outlet pipe of the tank. I'll bet it takes a while to get hot, which means you are actually getting cold water out of the tank for a while before it gets hot. Otherwise, the 30 feet of pipe just can't take that long to get hot water to where you're using it. You may notice that the burner switches on, as well. If this is the case, I think there is cold water stratifying in your tank at the outlet (hot and cold water stratify naturally in the absence of water flows and heat input -- like when you dive into a lake and hit the cold layers down below), and it all needs to run out before you get any hot water. This would be the case especially if the outlet pipe is not right at the top of the heater. A new (better) heater would fix this. But ask a plumber for an opinion, too.
posted by beagle at 4:11 PM on January 13, 2007

I'm sure the thing is that the cold pipe cools the first warm water that comes through. I have the same kind of situation in my house with the pipes going several metres through a crawl space. Just want to let you know that it's useless to buy electrical heat tape for your problem. I got it so the pipes never freeze in winter, but I was a little surprised it doesn't also make the hot water arrive sooner.
posted by Listener at 4:16 PM on January 13, 2007

In the meantime while you're figuring it out, you could leave a couple pitchers or buckets in your shower to fill while the water is heating, later using the water for plants or doing dishes.
posted by salvia at 4:28 PM on January 13, 2007

You may need a new diptube.
posted by lee at 4:29 PM on January 13, 2007

Beagle's last post reminded me of the recent litigation about hot water heater dip tube failures. The dip tube is a long tube at the inlet to your heater that makes sure that the cold water going into the tank enters at the bottom. When the dip tube breaks, the incoming cold water mixes with the hot water at the top of the tank so that you don't get really hot water.

As he suggested, put your hand on the hot water pipe just above the heater. It should get hot almost instantly as soon as someone turns on a hot water faucet. If not, then you may have a broken dip tube and need a new heater. Unfortunately the date for settlements from the defective heaters has expired.
posted by JackFlash at 4:30 PM on January 13, 2007

Thanks -- great suggestions to research. FWIW, the five minutes may be subjective, but if it's an exaggeration, it's not by much. I grew up in a house of a similar vintage a few miles from our current home, and it never took this long to get hot water. As beagle suggested, it's a California house from the early 60's, so the walls are uninsulated (in fact, we only got the attic insulated this year). However, most of the plumbing runs beneath the floor joists. Since the house is a split level and built against a gentle hill, I have good access to the pipes via the utility space off the garage.

I like the idea of a recirculation pump but don't want to increase our utility bill significantly. However, we aren't home during the day, so the thought of using an intelligent timer to control such a pump is intriguing. I think if it were only our shower a separate instantaneous electric or gas heater would also be an option, but it would be nice to solve this for the whole house.

Finally, I am very intrigued by the idea that the water in the heater itself may be stratified, and this is why it takes so long for us to get hot water, despite the relatively short distance from heater to faucet. I'll have to test that out when my wife gets home.

So thanks for the great suggestions, I'll follow up more after I have a chance to look at the water heater itself.
posted by mosk at 4:31 PM on January 13, 2007

I agree with Lee. That would be my first guess.
posted by JayRwv at 4:40 PM on January 13, 2007

I totally agree with beagle... 30 feet, 5 minutes, no way.

The first thing to do is see if the hot water heater is making hot water at all. Go grab the outlet pipe and see. it will be noticeably warm at all times, close to the tank.

ALso, do you have this problem with your washing machine or dishwasher? Is there any place in the home where it works right?

This is a clear malfunction of SOMETHING. The place to start is the water heater, and from there, the distribution pipes. Do NOT assume that it was ever installed correctly or plumbed correctly, either. I have fixed many plumbing problems in brand new houses over the years.
posted by FauxScot at 6:04 PM on January 13, 2007

I had this happen to me in a couple of apartments. What was happening was the the hot water heater would switch off to conserve energy, and the water in the tank would cool overnight.

My solution was to run the hot water for a brief period of time, and then turn it off. It took the same amount of time for the water to get hot, but I wasn't wasting the water in the meantime.
posted by yeolcoatl at 6:42 PM on January 13, 2007

some trivia... 100' of 1/2" copper pipe holds 1.02 gallons,
100' of 3/4" copper pipe holds 2.29 gallons
and a low flow shower head expels 2.5 gallons per minute.
posted by digital-dragonfly at 7:28 PM on January 13, 2007

Any chance there is a pressure tank somewhere in the line after the water heater? There shouldn't be, but if you had seen the Goldbergesque plumbing in my 50 year old house, you wouldn't think it a stupid question.
posted by bh at 7:51 PM on January 13, 2007

It's possible you might also have a malfunctioning or improperly set tempering valve. Such things are often installed after the initial plumbing work is done, in homes where the water heater size might not be sufficient for the demands of suddenly water loving teenagers. They work by mixing cold and hot water, to limit the maximum temperature of the hot water, and increase the draw time of the hot water tank, so that at least warm water is available longer. They are not unlike anti-scald valves included with many mixer valves, but because they are centralized on the water heater outlet line, work for the whole house, and are effective at reducing the cost of hot water for the household, and extending the overall time that at least warm water will be available from a smaller tank.
posted by paulsc at 9:10 PM on January 13, 2007

Seconding looking for, and checking, a tempering valve. Five minutes is too much time to heat up a thirty foot run of copper pipe.
posted by flabdablet at 11:25 PM on January 13, 2007

No one has said you need a new furnace. Maybe you do. My electric water heater went a couple weeks ago and I now have hot water like never before. Like a hot tub. I bet one of the two elements was burned out all that time, or both were malfunctioning. Your boiler is gas, but still, perhaps it too needs replacing. I wish I had guessed this before, as replacing it before it leaked would have been much neater. So I'm passing on this suggestion.
posted by Listener at 3:20 PM on May 13, 2007