|
Flushing toilet and the shower
This is something that's been bugging for a long time.
Lots of times on TV, there's a person in the shower, someone comes and flushes the toilet and the person in the shower starts screaming and freaking out. Why does the person in the shower react that way? Is this some special reaction that was invented for TV purposes or something? I decided to take a hot shower and have a relative flush the toilet and the only thing that happened was the water pressure dropped slightly, no big deal. Nothing else happened. So why do all these people on TV freak out? I probably wouldn't normally post such a silly question but that new commercial I keep seeing about flushing the toilet while someone's in the shower is starting to irritate me. I just don't get it. |
If the temperature of your shower water doesn't change when someone
flushes the toilet in your bathroom, your shower has a pressure-balanced valve. This means that when you set the water temperature, what you're setting is the proportion of hot water to cold. When someone flushes the toilet, part of the cold water pressure is diverted to refilling the toilet, so the amount of cold water going into the shower drops, but the valve automatically makes a corresponding drop in the amount of hot water so the temperature of the water coming out of the shower head remains the same. In contrast, with old-style shower fixtures, when someone flushes the toilet, the amount of cold water going into the shower drops but the amount of hot water doesn't, hence the scalding. Most new construction nowadays uses pressure-balanced valves. It's even required by code in some places, for safety reasons, i.e., to prevent the scalding that's made fun of in the commercials. A step up from pressure-balanced valves is temperature valves. You tell them what temperature you want the water and they adjust the proportion of hot to cold automatically to reach that temperature. |
|
We do not have pressure valves on our shower and yet we don't have the
problem. Further this shouldn't be an issue. Hot water only flows out of the tank when cold water is flowing in. If you flush the toilet, overall water pressure should be reduced. If your house water input is strong enough when you flush the toilet, you should have a surplus of water to continue the cold stream to the shower AND the toilet. However, if your water pressure is too low, when you flush the toilet it will divide the water in half, and you'll end up with hot water and not enough cold to counter it. The solution is to increase the feed pipes going to your bathroom. Alternately (and I like this solution).. I turn the heat on my hot water heater down to the point where I only need to use hot water (not cold water) during a shower. Not only does this eliminate the ability to scald the person, but you also use less gas/electric to heat the water, as it is not scalding temperature. If you need to add water to cool it down.. it is too hot! wrote: This is something that's been bugging for a long time. Lots of times on TV, there's a person in the shower, someone comes and flushes the toilet and the person in the shower starts screaming and freaking out. Why does the person in the shower react that way? Is this some special reaction that was invented for TV purposes or something? I decided to take a hot shower and have a relative flush the toilet and the only thing that happened was the water pressure dropped slightly, no big deal. Nothing else happened. So why do all these people on TV freak out? I probably wouldn't normally post such a silly question but that new commercial I keep seeing about flushing the toilet while someone's in the shower is starting to irritate me. I just don't get it. |
You're right that if there is sufficient water pressure and
the cold-water feed pipe to the bathroom is large enough, flushing the toilet won't cause the temperature in the shower to change noticeably. Another thing that would prevent the problem, in the absence of pressure valves, is a separate feed pipe to the shower which some houses have. However, that's not a really useful answer for someone who *does* have the problem of the shower temperature changing when someone uses the cold water. Putting in a larger feed pipe to the bathroom is an expensive operation. Increasing the water pressure, if the pressure is low in the whole house, is even more expensive. Installing a pressure valve in the shower is a much less expensive way to solve the problem. As for keeping the hot water heater temperature low enough that you can shower with only hot water, you're right that that saves money and reduces the risk of scalding, but this has several disadvantages: * It makes your dishwasher (if you have one) work much harder and/or not get your dishes as clean. * Your clothes washer (if you have one) may not get your clothes as clean (if your washer does automatic temperature control, this will probably only be true on the "hot" setting). * Your hot water will get used up more quickly if there are periods of the day when you're using a lot of hot water. |
The two answers sound right to me.
There used to be another reason - some 2 or 3 decades ago, in Britain anyway, there were shower units that heated the cold intake as it passed through/across some kind of electric element situated behind the main panel: I had one myself installed to replace the bathtub. You pulled a cord with a red ball on it and the one with a black ball to switch off. There must have been a control to adjust hot and cold flow, but I don't remember it. Anyway, if someone ran a cold tap in any other room, the resulting drop in pressure would cause the heating device to automatically switch off as a safety feature, so you were standing suddenly under a spray of freezing cold water ..... great fun. -- Ian Ft Worth, TX |
* Your hot water will get used up more quickly if there are periods of the day when you're using a lot of hot water. While I agree with most of your points on hot water.. will it really? I mean since it's not heating it nearly as hot could it actually get it "hot" quicker as there isn't as much overhead? |
Matt writes:
* Your hot water will get used up more quickly if there are periods of the day when you're using a lot of hot water. While I agree with most of your points on hot water.. will it really? I mean since it's not heating it nearly as hot could it actually get it "hot" quicker as there isn't as much overhead? Some tank water heaters have pretty good recovery time, but I can assure you from personal experience than a couple people taking showers plus the dishwasher and maybe the clothes-washer running around the same time can easily exhaust a 40-gallon tank, and that's when the water's set to 120 degrees, which is the most common recommendation for safety and energy efficiency. A shower uses about 2 gallons per minute. If your hot water is set to 120 degrees and you shower at 100 degrees, probably about 2/3 of the water you're using is hot water, so you're using 1.66 gallons of hot water per minute. That's 100 gallons of hot water per hour, which is higher than the recovery rate of the best tank water heaters. Add in baths, which use a more water than showers, and appliances, and you can easily use up your hot water. If your heater is set lower, it'll get used up faster. We've got a 40-gallon tank. I'm hoping that it wears out and we have to replace it before two of my four kids get old enough to decide they need to shower every morning like I do :-). |
|
Ian wrote:
Been reading these last posts with a certain rueful amusement - Well, this is texas in the summer, I guess. -- Ian So bottom line to this is; you're not sure where you live or what season it might be. |
G Henslee wrote:
Ian wrote: Been reading these last posts with a certain rueful amusement - Well, this is texas in the summer, I guess. -- Ian So bottom line to this is; you're not sure where you live or what season it might be. ROFLOL |
|
|
Jonathan Kamens wrote:
Matt writes: * Your hot water will get used up more quickly if there are periods of the day when you're using a lot of hot water. (snip) We've got a 40-gallon tank. I'm hoping that it wears out and we have to replace it before two of my four kids get old enough to decide they need to shower every morning like I do :-). Very true. :) The teens in my house used to shower till the water temperture drops regardless of what temperture I set for the tank. Now I have a 12 minutes rule, I'll bang on the bathroom door and if they ignore the warning then I'll head to the basement and shut the tank inlet valve. ;) Cold water showering are not subject to the 12 minutes rule. FC |
wrote:
(Ian) writes: wrote: Well, this is texas in the summer, I guess. So bottom line to this is; you're not sure where you live or what season it might be. This makes no kind of sense to me, I'm afraid. Has this poor soul been at the cooking sherry again,or sniffing glue or something? He was making a feeble joke based on your inclusion of the phrase "I guess" at the end of the sentence quoted above. Well, I did briefly consider this possibility, but dismissed it on the grounds that no one would willingly embarrass himself in this way. Have they started installing PCs with internet access in Homes for the Hopelessly Backward, d'you suppose? -- Ian |
"While I agree with most of your points on hot water.. will it really?
I mean since it's not heating it nearly as hot could it actually get it "hot" quicker as there isn't as much overhead? " The issue isn't how fast it gets hot. The issue is how much heat there is there to begin with. If you have the water heater set at 140, then you have 40 gallons of 140 degree water, which has significantly more heat than say 110 degree water. When taking a shower, you will have use more of the 110 degree water, so the already heated supply in the water heater will be gone faster. And as for how fast it heats, the water heater only can heat water at a certain rate while the unit is on, no matter what the temp is set to. |
On Tue, 12 Jul 2005 16:56:18 -0400, someone wrote:
While I agree with most of your points on hot water.. will it really? I mean since it's not heating it nearly as hot could it actually get it "hot" quicker as there isn't as much overhead? Yes it will. The whole point of a storage tank is that it uses a relatively small burner or heating element where the rate of recharge is much less than the peak rate of use. The tank stores the btus needed. Your tank has less btus stored. It cannot heat the incoming cold water even to the (only slightly lower temp you use) at the usual rate of use. If it could you would have the equivalent of a "tankless" heater and not need the tank at all. Maybe you don't use much hot water at a time. If you have only a few people in the household and a large tank, that is more possible. Reply to NG only - this e.mail address goes to a kill file. |
Flushing toilet and the shower
|
| All times are GMT +1. The time now is 06:55 PM. |
Powered by vBulletin® Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.
Copyright ©2004 - 2014 DIYbanter