Why do I shiver upstairs?

December 29, 2007 1:11 PM

Why does my upstairs shower run out of hot water long before the one downstairs? I only have one water heater...

For the past 4-5 months, the upstairs shower cools down to lukewarm after just a few minutes. It used to stay piping hot for as long as I might want to use it, just like the downstairs one still does. My water heater is only two years old and hasn't been adjusted since it was (professionally) installed.

Can anyone explain this phenomenon? Is it something I can fix myself?

posted by tomwheeler to home & garden (17 comments total)

Perhaps you're losing heat through inadequately insulated pipes. It takes longer for the water to reach the second floor than it does to reach the first floor, hence more heat loss, and faster depletion of hot water.
posted by BeaverTerror at 1:17 PM on December 29, 2007

It's possible that the shower heads have different rates of flow. The lower-flow head would allow you to have hot water for a longer time.
posted by wryly at 1:22 PM on December 29, 2007

To make you feel better, I have this problem too. My showers are limited to about 10 minutes.

I've never used the basement shower in the 8 years I've lived in my house, so I don't know if its better. In fact, I seldom (never) go into the basement bathroom. There are probably small animals living in there by now...
posted by BeaverTerror at 1:29 PM on December 29, 2007

I agree with BeaverTerror. It is likely that the ratio of hot to cold water in the upstairs tap is higher, due to the fact that the hot water straight from the tap is cooler due to distance and heat loss. Easy enough to find out. Run just hot upstairs and measure the temp with a thermometer and then compare to the same on the ground floor. If the temp is the same, then something else is amiss.
posted by qwip at 1:30 PM on December 29, 2007

If your pipes are not fully insulated properly you would notice this in the winter time, as the exterior cold was getting into the pipes, having them retain less heat in line, and also the incoming water into your hot water tank is colder (i believe, i could be making this up) as the outside temperature is lower. So instead of your water heater having to keep a tank of water at 120 degrees with additional water being added to the tank being 60-70 degrees, it is now being added at 30-40 degrees.

You may want to look into a tankless water heater as an alternative / supplement to the tank in the basement. My parents house is a 3 story victorian, and even with a modern water heater, it takes 7 minutes for the water to get warm on the 3rd floor, and then you get about 15-20 minutes of hot water. Not to mention the amount of water we waste waiting for it to heat up. So they are now looking into a tankless system for the bathrooms (we use hotwater heat also).

A tankless system would sit inline to your shower / bathroom hot water line, and only turn on / heat the water as it was being used. It may not be as theoretically efficient as your central tank system, but it limits the heat lose in transit by only heating the water at the last yard before you actually use it.
posted by mrzarquon at 2:24 PM on December 29, 2007

So you have a shower temperature control, or do you set the ratio of hot and cold manually? If the former, it's possible that the temperature control isn't working properly and is mixing in too much cold with the hot.
posted by zippy at 2:25 PM on December 29, 2007

Could you give us some more information?

What kind of hot water heater do you have?

Are you in a detached home or an apartment?

Do both showers have the same types of valves? What sort of valves are they? (i.e. separate hot/cold faucets or single knob mixer type)

How old is your home? What sort of insulation do you have?
posted by davey_darling at 2:30 PM on December 29, 2007

What kind of mixing valve have you got, both upstairs and downstairs? If you're getting good hot water up there for a while and then it goes lukewarm, but downstairs it stays hot, assuming this is consistent, I think there is something wrong with your mixing valve. See third Q/A way down the bottom of this page. As described, the mixing valve could be set incorrectly.
posted by beagle at 2:31 PM on December 29, 2007

If you happen to have a tankless water heater already as mrzarquon mentions, these require a -minimum- flow to trip the heating valve. This happened to me: new installation, shower worked fine; but after a couple years' lime accumulation decreased the flow through the shower head the valve would come on, go off, come on, go off....
posted by jet_silver at 2:43 PM on December 29, 2007

Whatever the cause, getting a low-flow, but high-pressure showerhead will allow you to take a longer shower without feeling like you are depriving yourself.
posted by The Deej at 2:52 PM on December 29, 2007

Checking the mixing valve in your shower is easy. When the shower gets cold, turn on the adjacent sink faucet. If it runs hot, then the problem is the shower valve. If it runs cold, then you have simply run out of hot water.

More likely it is just uninsulated pipes.

If your pipes are uninsulated, in the winter not only are your hot water pipes colder but your cold water pipes are colder. This means you have to need a higher percentage of hot water when you mix it for your shower, depleting your hot water tank more quickly. The longer run of pipes makes the effect more noticeable upstairs and when the weather is especially cold.

Your easiest solution as wryly and deej suggested above is to change your upstairs and maybe downstairs showerheads to low-flow models. Check with your water department and they may even supply these for free as a conservation measure. Or you can do it yourself for around $20 as shown here.

Another thing you can do is to install pipe insulation on any exposed water pipes in your basement or crawl space. This stuff is very cheap, only a dollar for a six foot section. It is a foam tube with a slit all the way down its length for installation. You just cut it to length with a kitchen knife and place it over the pipe.

Your third step might be to see if you can get blown-in insulation for the walls where the plumbing runs.

A last step and most expensive would be to have a plumber install a tankless heater in the upstairs bath.
posted by JackFlash at 3:10 PM on December 29, 2007

Do you have separate controls for hot and cold water, or a single lever? If you have a single lever, the mechanism to protect you from being scalded might be making your showers cold (I have fixed this by opening up the fixture and making adjustments per documentation I found on the Moen website). But since this is a new problem, is it possible that the hot water temperature was changed 5 months ago, and that exacerbated one of the other scenarios?
posted by reeddavid at 3:31 PM on December 29, 2007

This may not even help you at all, but the (almost) same thing happened to us. We have a one-level home with two bathrooms. The bathrooms are pretty much right next to one another in the layout. After the house and water heater were about 3 years old, the bathroom that was a little further back ran out of hot water after 1-2 minutes of use while the "closer" bathroom could use hot water for 20-25 minutes or more with no loss in heat. We had someone come and check it out and it turned out that the burners (terminology may not be precise) for the "back" bathroom had gone out and had to be replaced. This apparently happens a lot in areas of the country that have excess lime in the soil and water. The lime builds up and harms the inner workings of water heaters. Plus, they just don't make things like they used to. My mom and dad have had the same water heater for 30 years... Anyway, hope you're able to get it fixed! Best of luck.
posted by susiepie at 4:52 PM on December 29, 2007

My house is detached and about 55 years old. There are separate knobs for the hot and cold water in both showers. I have a gas water heater which is about two years old. I can't say much about the insulation, except that it's the same as it ever was (i.e. before this problem started).

This issue started in late summer, but it does not appear seasonal since it's happened in hot, warm and cold weather this year. It happens in both the morning and nighttime. Susiepie's answer seems like the closest match so far.
posted by tomwheeler at 9:40 PM on December 29, 2007

I meant to add that the water heater is of the cylindrical tank variety. The amount of time that the upstairs shower cools off seems to have little or no relation to how much hot water was recently used; for example, by other people showering, the washing machine or dishwasher.

The faucet in the sink in the upstairs bathroom seems to also go lukewarm when the shower does. I say "seems to" because I have not tested it enough times to be confident it is always true.
posted by tomwheeler at 9:48 PM on December 29, 2007

What are the chances that you could get a make/model number, or even a pic of your hot water heater?

I've never seen or heard of a large tank style hot water heaters that would have separate zones as susiepie's answer seems to suggest.
posted by davey_darling at 11:37 PM on December 29, 2007

I thought of one other possibility. Hot water heaters send water out via a dip tube that sticks down, away from the cold water inlet, into the interior tank region where presumably the water has mixed to a stable temperature. This dip tube can brake, leading to the outbound water sometimes going cold even when the tank itself is filled with hot water.

Pure speculation from this point, but let's say this tube is broken. it's possible that when you draw water from one faucet, it creates more turbulence than the other faucet, which leads to mixing and steady hot water from one faucet, but limited to nonexistent hot water from the other.

If all else fails, ask your plumber to check the dip tube on your tank.
posted by zippy at 9:35 PM on January 1, 2008