Glacially slow hot water

March 19, 2010 3:50 PM

Master bathroom shower takes FOREVER to get hot water. The hot water heater is outside, less than fifteen feet from the actual shower. Other faucets in the house are much farther away (up to 30-40 feet away) never fail to get us hot water in less than 15-30sec. What gives? How do I fix it?

It takes almost four minutes to get hot water in our shower, even with the hot on full blast. I usually wake up in the morning and turn on the shower first. Then brush my teeth, pee, and usually weigh myself. Sometimes I have time to scoop the cat litter. By then, the water is usually warming up. I am really hoping this isn't an expensive fix. I'm just trying to figure out WHY it takes so long to get to the shower, when the heater is so close by? Is there a cheap (ish) fix? I feel like I'm wasting water, but not sure what to do about it.
We've been in this house for a year now.

posted by Spyder's Game to home & garden (13 answers total)

Just because it is physically close doesn't mean that the plumbing goes to that shower first. Can you follow the outlet line from the heater and see where it goes?
posted by nestor_makhno at 4:14 PM on March 19, 2010 [3 favorites]

If you can reach the pipe from the heater, you'll be able to feel when it gets hot. Perhaps there's some weirdness in the piping such that the route to your master shower has to go via other rooms instead of direct. Feeling the warmth in various pipes might identify the route.
posted by anadem at 4:17 PM on March 19, 2010

Before the water can be warm at the shower, it has to warm up the pipe. If there's a long stretch of pipe which is, for instance, running through an unheated wall, then it will take longer.
posted by Chocolate Pickle at 4:22 PM on March 19, 2010

Do you have a very low-flow shower head? In particular a low-flow aerated head would have lower take longer to get the cold water out of the pipe and would need to get hotter to feel hot to you (because of the fine spray). That's the only thing I could imagine other than the above-mentioned screwy-pipe-routing.
posted by madmethods at 4:38 PM on March 19, 2010

We have a similar problem. My husband swears that turning on the hot water tap at the sink and waiting for the water to run hot there *before turning on the shower* is the key to getting the shower up to temperature quickly.
posted by MonkeyToes at 4:49 PM on March 19, 2010

The problem is in your water heater. The observation about the other faucets may be misleading if you use those faucets more often than your shower.

Worth reading: previously.

As suggested there, you may need a new diptube.
posted by beagle at 4:57 PM on March 19, 2010

"... Then brush my teeth, pee, and usually weigh myself. ..."

You could have a mis-calibrated, broken or mis-installed anti-scald mixer valve. In newer constant temperature type valves, pressure variations in the cold water line can actually delay delivery of hot or warm water substantially. That's because when the cold water pressure drops, the hot water is nearly cut off completely, and warmed water in the line cools off, waiting for the anti-scald valve to open up a little for it to flow and warm the pipes, eventually letting through whatever amount of hot water is going to be mixed for your maximum allowed shower temperature. The newer valves have to have a wider range of control of hot water to avoid the seasonal temperature adjustments needed by the old anti-scald valves, as cold water line temperature went up or down by a seasonal 20 to 40 degrees Fahrenheit. But though they don't require adjustment to maintain constant temperature, they don't expect additional demand and pressure losses on the water supply lines they are controlling, either.

Scoop the cat litter and weigh yourself, but don't flush the toilet after peeing, or run cold water in the sink as you brush your teeth, if you expect this type of anti-scald protection to work quickly in your shower.
posted by paulsc at 4:59 PM on March 19, 2010

I was going to suggest the anti-scald valve, too, but paulsc has far more info on it than I could provide.

Is this a recent change in your shower? Or has it done this since you moved in? And how old is the house?
posted by Alt F4 at 5:24 PM on March 19, 2010

Wait a second. The hot water heater is outside? So is it a tankless model? If so, and especially if you have a low-flow head on the shower, it's possible that there isn't enough volume of water flowing through the tankless heater for it to register that it needs to turn on.

If what I just wrote out is correct, you have two options I can think of:
1. Get a regular, non-low-flow showerhead.
2. You can do what MonkeyToes suggests, and turn on the hot water in the sink before you turn on the shower's hot water. It might feel wasteful, but it's probably wasting less than your current four-minute routine.
posted by Alt F4 at 5:29 PM on March 19, 2010 [1 favorite]

Galvanized pipe?
posted by pianomover at 6:42 PM on March 19, 2010

Just because it is outside doesn't mean it is tankless. This is a common setup in older homes in the southwest. Tha antiscald valve is another good idea.
posted by nestor_makhno at 11:14 PM on March 19, 2010

Hey, all! So, no, the water heater is not tankless. It is a 40 gallon tank, I think, and yes, we are in the southwest. California, to be exact. So...I guess I have to call a plumber? The heater is outside, and it would be difficult (if not impossible) to reach and follow the line down under the house.

We bought the house a year ago, showerhead was the current one, no idea if it's low flow or not, there isn't a heck of a strong water flow coming out of it. I can have a plumber check into the anti-scald valve. Also, my first thought was also that the pipes took the hot water to the far parts of the house first, and then it came back to the master bath.

House was built in 1938 and has since been added onto twice.

Pianomover - Galvanized pipe? Care to elaborate?
posted by Spyder's Game at 9:18 PM on March 20, 2010

Galvanized pipes will corrode over time, as indicated by the following corrosion symptoms:

* high levels of zinc or iron in tap water
* a “metallic“ taste of the water
* poor water flow due to blockage from mineral buildup
* discolored water (brown, red or yellow water)

Given the age of your house, you may have galvanize pipe.
posted by malp at 8:31 AM on March 21, 2010