家用热水循环系统是一种家用水预热和循环的环保系统。该系统可配合燃气热水器、容积式、即热式、太阳能、空气能等多种热水器使用，有回水管和无回水管都可以安装。
什么样的家庭适合用循环水？ 如果家庭用热水管道较长（热水器距离热水龙头较长），每次使用热水的时候，需要等待好长一段时间，并且要出掉好长一段时间冷水，白白的浪费。 此家庭可以考虑装一个热水循环系统。 还有什么地方适合用循环水？ 统一供水的宾馆以及24小时营业场所，为了让顾客随时用热水，可以设置循环水温度控制，一直保持水管的温度，使水管不再有冷水。24小时满足热水需求。一些水循环供暖家庭，以及一些需求温度恒定的水或者由循环供暖场所。例如药材种植**动物的养殖场所。
安装回水系统时须提前安装一套止回阀，回水系统工作时抽动管道内的冷水（热水管道内的冷水这时会由止回阀流向冷水管道，冷水管道内的水又流向热水器，这样形成一个内循环）从而通过热水器来进行加热。机器工作时间可根据热水管道长度来设定。
回水管路
回水管道，是从热水管的远段再接回一条水管到热水器的下方，回来的这条水管是我们常说的回水管。
优点
有回水管的话，我们会把止回阀安装在回水管和冷水管的连接处，回水系统工作时，冷水管道内的供水主要是通过回水管来提供了，这样的话机器工作时间如果稍长一点的话，也不用还害怕，热水管道内的水跑到冷水管道内了，因为到冷水管道内的热水到了机器回水器那里，机器感温探头感应到有热水的时候机器即停止工作，这样家里洗手盆那里用冷水的时候也不会出来热水了。
缺点
我们安装时会把止回阀安装在距离热水器远端洗手盆下方的热水管和冷水管的连接处，这样的话如果机器稍微工作时间长一点的话会造成，我们在使用远端洗手盆冷水的时候，也会放出一点热水，因为机器工作的时候时间稍长一点，机器循环过来的热水会通过止回阀流向冷水管。这样我们在安装止回阀洗手盆时用冷水会出一点热水了，这点弊端通过对机器的时间设定也可以减少或者避免放冷水时出热水的时间，要通过几次调试后一般都可以解决。
适用范围
可适用于各类燃气热水器、电热水器、太阳能热水器、空气能热水器、壁挂炉、地暖等热水循环。
舒适性
预热循环 技术的应用实现了热水的即开即用，使家庭用热水的舒适性得到很大提高，可多点恒温供水，洗浴智能优先、多楼层供水、快速方便。
节水性
预热循环技术同时还避免了传统热水器中管路冷水的无端浪费，节省大量的生活用水。
节能性
循环系统对加热系统间的实时监控，避免了洗浴时浪费水、气、电等资源，同时采用快速预热技术可以根据进水温度使热水器自动选择不同的活力加热，节能效果非常显著。
机械板
功能：
1.提前预热、无需等待。2.当家庭水压不足时，可辅助增压。
3. 随时可视出水温度，直观反映温度变化情况。
4.采用超静音屏蔽式水泵，工作声音小，不影响正常家居生活。
5.根据循环管路的长短可设置1-5分钟。
优点：
机械版程序少，操作简单，使用之前按一下，有复位开关，冬天用的着，夏天不用。
适用场所：
两个冲凉房，适宜大众客户
电脑板
功能：
1.提前预热、无需等待。
2.当家庭水压不足时，可辅助增压。
3. 随时可视出水温度，直观反映温度变化情况。
4.采用超静音屏蔽式水泵，工作声音小，不影响正常家居生活。
5.根据循环管路的长短可设置不同。
6.当温度低于设定温度，循环系统自动启动热水器循环加热。
优点：
无需人工操作，即可随时全自动保持热水的保温供应。
适用场所：
24小时营业场所
遥控板
功能：
1.提前预热、无需等待。
2.当家庭水压不足时，可辅助增压。
. 随时可视出水温度，直观反映温度变化情况。
4.根据循环管路的长短可设置不同。
5.采用超静音屏蔽式水泵，工作声音小，不影响正常家居生活。
6.当温度低于设定温度，循环系统自动启动热水器循环加热。
7.实现100-1000米距离内无线穿墙遥控，并可根据需要增设遥控器。
优点：
室外机安装位置远，开关不方便，有回水管的在任何地方开水都相当于开关，有遥控器在室内可以遥控了。早晨起来想冲凉，不用动，在床头遥控一下，在起来到浴室去冲凉可以啦。打开直接出热水。
适用场所：
室外机安装位置远的场所
水控版
功能：
1.提前预热、无需等待。
2.当家庭水压不足时，可辅助增压。
3. 随时可视出水温度，直观反映温度变化情况。
4.根据循环管路的长短可设置不同。5.采用超静音屏蔽式水泵，工作声音小，不影响正常家居生活。
6.当温度低于设定温度，循环系统自动启动热水器循环加热。
7.内置水流开关设计，当水管中有水流动时时循环系统自动启动，并可设置9个工作时间段。
优点：
开一下热水龙头然后关掉即可循环。
适用场所：
室内室外场所都可试用
1.机械板的经济实惠，因为机械板的组件少，故障率肯定低。
2.建议壁挂炉用户使用水流控制的，因为可以设定时间段控制，也是说在一定的时间内可以达到随时使用随时有热水。
3.一般别墅或者发廊等洗浴中心可以选择全自动方式，所谓的全自动是把热水器温度设定到42度，把循环水系统设定到38度，然后有一个温控感应的探头链接到回水管末端，这样一旦温度低于38度会自动启动，启动N次，很是浪费，建议一般家庭不要使用这种功能。
注意事项
1.一般家庭用电请使用220V AC电源，使用其他电源会对机器造成损坏，甚至危及人身安全。
2.在移动、拆卸机器或长期不使用的情况下，请拔掉电源插头，以免触电或对机器损坏。
to mind, as I do, how we used to walk home together, she and I;
and I wonder stupidly about that, all the dreary dismal day.
There had been some talk on occasions of my going to
boarding-school. Mr. and Miss Murdstone had originated it, and
my mother had of course agreed with them. Nothing, however,
was concluded on the subject yet. In the meantime, I learnt
lessons at home. Shall I ever forget those lessons! They were
presided over nominally by my mother, but really by Mr.
Murdstone and his sister, who were always present, and found
them a favourable occasion for giving my mother lessons in that
miscalled firmness, which was the bane of both our lives. I believe
I was kept at home for that purpose. I had been apt enough to
learn, and willing enough, when my mother and I had lived alone
together. I can faintly remember learning the alphabet at her
knee. To this day, when I look upon the fat black letters in the
primer, the puzzling novelty of their shapes, and the easy good-
nature of O and Q and S, seem to present themselves again before
me as they used to do. But they recall no feeling of disgust or
reluctance. On the contrary, I seem to have walked along a path of
flowers as far as the crocodile-book, and to have been cheered by
the gentleness of my mother’s voice and manner all the way. But
these solemn lessons which succeeded those, I remember as the
death-blow of my peace, and a grievous daily drudgery and
misery. They were very long, very numerous, very hard—perfectly
unintelligible, some of them, to me—and I was generally as much
bewildered by them as I believe my poor mother was herself.
Let me remember how it used to be, and bring one morning
back again.
Charles Dickens ElecBook Classics
f
David Copperfield
I come into the second-best parlour after breakfast, with my
books, and an exercise-book, and a slate. My mother is ready for
me at her writing-desk, but not half so ready as Mr. Murdstone in
his easy-chair by the window (though he pretends to be reading a
book), or as Miss Murdstone, sitting near my mother stringing
steel beads. The very sight of these two has such an influence over
me, that I begin to feel the words I have been at infinite pains to
get into my head, all sliding away, and going I don’t know where. I
wonder where they do go, by the by?
I hand the first book to my mother. Perhaps it is a grammar,
perhaps a history, or geography. I take a last drowning look at the
page as I give it into her **nd start off aloud at a racing pace
while I have got it fresh. I trip over a word. Mr. Murdstone looks
up. I trip over another word. Miss Murdstone looks up. I redden,
tumble over half-a-dozen words, and stop. I think my mother
would show me the book if she dared, but she does not dare, and
she says softly:
‘Oh, Davy, Davy!’
‘Now, Clara,’ says Mr. Murdstone, ‘be firm with the boy. Don’t
say, “Oh, Davy, Davy!” That’s childish. He knows his lesson, or he
does not know it.’
‘He does not know it,’ Miss Murdstone interposes awfully.
‘I am really afraid he does not,’ says my mother.
‘Then, you see, Clara,’ returns Miss Murdstone, ‘you should just
give him the book back, and make him know it.’
‘Yes, certainly,’ says my mother; ‘that is what I intend to do, my
dear Jane. Now, Davy, try once more, and don’t be stupid.’
I obey the first clause of the injunction by trying once more, but
am not so successful with the second, for I am very stupid. I
Charles Dickens ElecBook Classics
f
David Copperfield
tumble down before I get to the old place, at a point where I was
all right before, and stop to think. But I can’t think about the
lesson. I think of the number of yards of net in Miss Murdstone’s
cap, or of the price of Mr. Murdstone’s dressing-gown, or any such
ridiculous problem that I have no business with, and don’t want to
have anything at all to do with. Mr. Murdstone makes a movement
of impatience which I have been expecting for a long time. Miss
Murdstone does the same. My m
