热水器问题（续篇）（图）

色盲 · 发表于 2007-10-12 20:59:27

抱歉上次出题的时候对机器的类型没有说明，现补上。因上一帖已经沉没，特另发一帖。

我用过的热水器有两种，一种为直燃式燃气热水器，一种为电热水器。前者没有照片了，这里附一个电热水器的照片，是海尔小海象，左边管子出热水，右边管子进冷水。（冷水管有点漏，房东捆了个塑料绳子= =!)

我用过的这两种热水器都一样，在中途关闭喷头短时间内再打开，刚流出来的水会很烫。另外我注意到，关闭喷头时，最后流出来的也是比较烫的热水。

水阀近观：

本贴由[色盲]最后编辑于：2007-10-14 5:38:52

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据说这世界是彩色的？

salmonfish · 发表于 2007-10-12 22:18:52

阀门的关系

salmonfish · 发表于 2007-10-13 01:27:54

此阀门把手有几个运动自由度？或：

在放水的时候，下列那种情况为真？

1。把手可向前，向左运动。

2。把手可向前，向右运动。

3。把手可向前，向左向右均可运动。

4。均不是。（请说明具体运动方向）

（考试呢？呵呵）

奥数金牌 · 发表于 2007-10-13 05:54:44

看外边能看出什么啊？你得看构造图。你想里边的结构，想冷水到底是怎么加热的，热水器的火是由什么控制的，另外想想冷热水应该是怎么进出的，问题就水落石出了。

还有，冷热混合开关和冷热独立开关，不一样。有的冷水龙头是独立的，（两个龙头两根分管），冷水完全不走热水器。这样的话，那冷水管里永远不会存有热水。

大多数淋浴喷头，不是独立的，（即两根单独分管合并成到一个龙头）那么，这样的话，那个分管的位置和龙头的接法又很重要。这两根分管和热水器的位置是如何的？或者是到底哪根是分管在前？或者说哪根分管离热源近？ anyway，不管在前在后，管里都有可能积攒热水，只不过程度不同。

色盲 · 发表于 2007-10-13 12:09:50

往前掰，开始放水；复位为关水。往左旋转，水温调冷，往右旋转，水温调热。但是，与一般冷热水调节阀不同，一般情况下，只要打开水阀，保持把手居中，即可保证水温基本合适；而一般的水阀是要把把手右偏，保持在中间偏右一点的位置，出来的才是温水。只有到水箱中的热水即将用完时，才需要把把手右偏，获得热水。

另外补充一点，电热水器是一次性把一缸水烧热，洗浴过程中电路断开，不再加热水箱中的水。从这一点和水阀的特点看，貌似热水器水箱中的热水不是在水箱中直接和冷水混和，而是先引出后到一个过渡性的容器中或者在水管中和冷水混和。

热水器的使用说明上有个警告，说开水和关水时手要远离喷头，以免烫伤。有时候关水时最后流出的水也很烫，但不是每次如此。很怪。。。

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据说这世界是彩色的？

Java+ · 发表于 2007-10-13 12:09:53

（1）冷热水的进水管都设计了一个降压阀，目的是使两水混合时压力相当，才能安要求的冷热比例混合成需要的温度，否则，压力大的一方起主导作用。由此，并不一定打开喷头都是先烫后凉。

（2）混合前一般冷水温度大概是20度，热水温度大概是70度，而一般希望的混合温度是大概37度。所以喷头打开前热水温度的影响力更大些，如果把喷头开关把手从正中打开一般是先冷（因为有冷得余水和冷的水管等需要逐步加热）后热到太高（1：1混合成45度），必须重新调节温度才行。

（3）中途短暂关水再打开，因热水把混合阀附近的水管和冷水都加热了，所以先流出来的一定太热，过一会就正常了。

色盲 · 发表于 2007-10-13 13:39:21

（1）每次短暂关水后打开，出来的水都是先烫后凉。只不过并不是每次关水的时候最后出来的都很烫。

（3）短暂关水后，即使相隔时间很短，先出来的水都很烫。

原贴：

文章来源: Java+ 于 2007-10-13 4:9:53
标题：热水把混合阀附近的水管和冷水都

（1）冷热水的进水管都设计了一个降压阀，目的是使两水混合时压力相当，才能安要求的冷热比例混合成需要的温度，否则，压力大的一方起主导作用。由此，并不一定打开喷头都是先烫后凉。

（2）混合前一般冷水温度大概是20度，热水温度大概是70度，而一般希望的混合温度是大概37度。所以喷头打开前热水温度的影响力更大些，如果把喷头开关把手从正中打开一般是先冷（因为有冷得余水和冷的水管等需要逐步加热）后热到太高（1：1混合成45度），必须重新调节温度才行。

（3）中途短暂关水再打开，因热水把混合阀附近的水管和冷水都加热了，所以先流出来的一定太热，过一会就正常了。

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据说这世界是彩色的？

Java+ · 发表于 2007-10-14 03:04:02

楼主这种情况是水压问题

salmonfish · 发表于 2007-10-14 04:44:00

Thanks for the detailed information and the clear picture.

Now, I believe, the faucet is deliberately designed in this way, and what you observed actually reflects the designer’s wit. Why? The following are the reasoning and the explanation:

1. This is a cold and hot water mixing faucet, that is, cold water, hot water come into the faucet through different pipes, and warm water comes out from a single outlet leading to the shower head.

2. This type of faucet is designed to be installed in a shower chamber, and can be conveniently controlled by the person in the shower chamber. (the manufacture's warning is the evidence)

3. Since a hot water tank connected with this faucet generally should NOT be installed IN the shower chamber, due to the limited space and the wet, steam environment which is unsafe considering the electricity wire, plug attached on the tank.

4. Consequently, hot water from the tank (outside the shower chamber) to arrive in the faucet (in the shower chamber) HAS TO pass through a pipe with certain length.

5. Despite water in the tank is always hot, say 70 C, when the shower has not been used for a while, the water temperature in the hot water pipe at vicinity of the faucet is certainly lower than 70 C, but otherwise still warm, say 35 C.

6. As a designer, how can you design a faucet to avoid, at beginning of a shower, a cold headwater resulted from mixing of cold water and the warm water, 35 C, retained in the hot water pipe.

7. A smart designer should try to make a faucet that at beginning stage of the turning-on process (stage I) can minimize the cold water portion and maximize the warm water portion, and at the full-opening stage (stage II) can readjust (increase) the cold water’s input. Furthermore, at the stage II, user should also be able to adjust the proportion.

8. The faucet used by MM perhaps is this type of smart faucet which has two different hot water/cold water mixing ratios at two different stages of the faucet’s turning on/off process.

9. If it is true, MM should observe:

* At beginning of the every shower, first time when faucet is turned on, warm water flows first (stage I), and with a full turning stage II kicks in (MM also can adjust the water temperature now).

* After a shower, in the process of turning off water, the faucet has to go through the stage I to be completely turned off. Notice at this moment, the hot water pipe filled completely with hot water (70 C, not the 30 C’s water) and the faucet, at stage I, has rather large hot water/cold water ratio, it is natural that the person in shower feels the shutdown water too hot.

* During a shower, the hot water pipe is always full of 70 C’s hot water, so every time when the faucet is turning on or off, it has to pass through the stage I. Consequently, the person in shower will scream.

Read like a scientific essay. Is it publishable, BTW?

本贴由[salmonfish]最后编辑于：2007-10-13 20:46:26

本贴由[salmonfish]最后编辑于：2007-10-13 20:49:32

本贴由[salmonfish]最后编辑于：2007-10-13 21:50:5

本贴由[salmonfish]最后编辑于：2007-10-14 10:0:4

色盲 · 发表于 2007-10-14 13:27:23

Thanks for your thoughts and reply. I agree with your point that this faucet is deliberately designed to mix together hot and cold water to obtain warm water of suitable temperature. However, you didn’t give the underlying mechanism controlling the water temperature. Moreover, what I observed does not agree with your analysis. Actually, at the beginning of a shower, what comes out first from the faucet is warm water of a temperature barely higher than human body temperature, and then cold water, and then warm water of a comfortable temperature suitable for shower. All through the process of the shower, you don't need to turn the faucet handle to adjust the temperature at all, unless the tank is running out of hot water, in which case you have to turn the faucet to the right to raise the water temperature. However, in this case you have to hurry up... as you won't get much warm water even if you turn the faucet to the very right... You know, you are running out of hot water.

www.ddhw.com

While taking a shower, if you turn off the faucet for some while, say, some seconds, and then turn it on again, you will get scalding water first, then cold water, and then warm water good for your shower. Again, you don't need to adjust the position of the handle to obtain and maintain suitable temperature. I tried again and again, and this never fails. Interestingly, you will get really hot water as soon as you turn it on again even if you have kept it off for only one or two seconds. www.ddhw.com

www.ddhw.com

I guess the faucet automatically controls the temperature by balancing the pressure of the hot/cold water. At first, the hot water can not mix in unless cold water gives way and forms a vacuum, therefore what first comes out is lukewarm water (the part of water originally stayed in the vicinity of the hot water tank) and cold water from the cold water pipe, and then warm water as a result of balanced mixture of hot and cold water. Then when you turn off the faucet, the warm water flows out. Because at this point no cold water is allowed to get in, while on the other hand no valve exists to stop hot water from flowing into the shower pipe, the shower head is filled with very hot water. If you wait long enough, the water might cool down and you won’t scream when you re-open the faucet; however, generally you can’t wait that long, therefore you will get scalding water…

The above is just a guess, which is subject to further tests and open to discussion.

www.ddhw.com

You answer is a good description of your reasoning process; however, it is not a complete essay. A scientific essay features a thorough review of past research and relevant theories, a keen analysis of the current developments and identification of possible gaps in the field, statements of your research question and your method, design of your experiment or case study and analysis of your data if applicable, then your discussion of the results so far, and then your conclusion. It also needs to begin with a good introduction connecting your research to a broader theoretical context and possibly your statement about why the research is important. If you are interested, you could pick a good question which has not been tackled and make an investigation in related theories, analyse them, and see how further you can advance. If you can propose anything novel or completely solve the problem, you can get it published. I think you are good at mathematics. So, why not? www.ddhw.com

本贴由[色盲]最后编辑于：2007-10-14 12:33:5

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据说这世界是彩色的？

salmonfish · 发表于 2007-10-14 18:05:48

Once I get back home, I'll draw a picture of such type faucet.

Sorry, out on the road now.

..............

.................

色盲 · 发表于 2007-10-14 20:09:21

Nice trip~~~

See you~~

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据说这世界是彩色的？

salmonfish · 发表于 2007-10-15 19:20:12

色盲 · 发表于 2007-10-16 08:57:58

So quick!!!!

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据说这世界是彩色的？

salmonfish · 发表于 2007-10-16 18:35:27

本贴由[salmonfish]最后编辑于：2007-10-16 14:32:14

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热水器问题（续篇）（图）

阀门的关系

请再多一点细节。

回复：热水器问题（续篇）（图）

3 [:-K]

热水把混合阀附近的水管和冷水都[:-M][:-M][:-M]

回复：热水把混合阀附近的水管和冷水都[:-M][:-M][:-M]

回复：回复：热水把混合阀附近的水管和冷水都[:-M][:-M][:-M]

a scientific essay about the faucet [:-K][:-K]

回复：a scientific essay about the faucet [:-K][:-K]

picture

Looking forward to it [:)]

示意图（图）

[:O][:O]

piece of cake.