Hot water re-circ line & vertical head loss
大家好，
我正试图为我们的RE-CIRC线条施加泵。我们有一个1楼的房子，在房子的一端拥有一个无水加热器。我们的2间浴室位于房子的另一端。
The hot water runs from our 6 gallon reserve tank horizontally for a few feet and then down probably 10’ into the slab, and then across the house in the slab for about 55’ to our master bathroom shower. Then the return line begins around the shower and goes up about 10’ back into the attic and then runs back the 55’ through the attic, back into the tank. I have already done all the head loss calculations for the piping, with a target flow rate of about 1GPM and the head loss from friction is around 3.41 feet, and that’s probably high because I was running a worst case example.
我的问题是，我发现的所有头部损失计算器都没有关于系统中的垂直头部损失这是我需要考虑到泵的计算吗？我发现一篇文章说垂直提升的一些东西并不重要，因为返回线以重力带回来。但是，这假设热水器位于车库或地下室水平上推水然后回到返回线路 - 这不是我们的系统设计。我应该在从主淋浴到返回阁楼的10'推到阁楼 - 如果还有一个10'掉落进入板块的地方，那么
Any clarification regarding vertical head loss and residential re-circ pump sizing would be much appreciated.
谢谢
GBA Detail Library
由气候和房屋部件组织的一千个建筑细节的集合
答复
乔，
When sizing a recirc pump, you have to calculate the head (or head loss). To do this, you have to know the total length of the pipe, its diameter, the number of fittings, and whether or not there are any check valves. The vertical distance from the top of the loop to the bottom of the loop is irrelevant.
有关更多信息，请参阅：
http://www.instructorworkshop.org/App_Content/instructorsworkshop/files/PRESENTATIONS/2010Presentations/09_GRUNDFOSHOTWATERRECIRCULATIONPHCC.pdf
http://www.clevelandaspe.org/orlando%20symposium%202013/high-rise%20design%20-%20hot%20water%20recirculations%20and%20general%20pumping%20practics.pdf.
http://shop.solardirect.com/pdf/water-heaters/solar-hot-water/active-solar/pumps/grundfos-guide.pdf.
http://www.pexuniverse.com/content/how-size-circulator-pump
http://www.taco-hvac.com/uploads/filelibrary/100-41.pdf.
我同意马丁。
马丁，
谢谢。这正是我所做的 - 我实际上使用了Taco-HVAC计算器。
It sounds like I need a new plumber. He sized the pump way too high because he said the water has to push against 10' of head pressure to make it up the shower wall into the attic where the return line starts.
纯粹的学术 - 你能解释'为什么'垂直距离是无关紧要的吗？与重力或系统加压有关的事情？我在发布的链接中找到了一些信息 - Grundfos演示文稿，即我昨天其实发现 - 但它仍然不清楚，因为我们的再循环循环与大多数例子不同，我发现地下室中的热水器等。
Always appreciated...
乔
乔，
如果您从深井泵送水，并且水柱的顶部暴露在大气中，则必须抬起水。水是密集的，所以需要很多能量。你把水从那里带到了这里。如果你必须在绳子的末端用桶子拉起它，你的手臂会累。
相反的情况是水的水库，在山顶的大气中开放。如果您粘在储存器中的管道并运行管道下坡，并将水电发电机放在山顶，可以发电 - 因为流水有能量可以提取。而不是施加能量（当你需要抽水时，你可以抽水），你可以得到一些“免费”的能量。
When water circulates in a closed loop, the water flowing downhill balances the water being pushed uphill. You don't have to add energy to the system to pull any water to the top of the hill, because it doesn't stay there. You just need a little bit of energy -- the energy required to overcome the friction of the pipe and fittings.
Another way to describe this: because it's a completely closed system, the water flowing down creates suction at the top that helps lift the water flowing up.
If you were pumping water up for a decorative fountain, letting it flow down in the open over some rocks, there would be no opportunity to create suction at the top, so then the pump would need to do the full work of pumping it up to that height.
And the recirculator pump sizing issue all beside the potential efficiency problems/losses of having a tankless water heater in the attic instead of inside conditioned space, and located at the opposite end of the house from the bathrooms...
Maybe there's a valid reason for putting it there, but it's hardly optimal.
Thank you all for the explanations... Most appreciated.
达娜，
我们刚刚一年前搬进了这个家。热水器挂钩总是在房子的这个结束时 - 厨房和洗衣机。即使我们将它移到房子的另一端 - 以大费用，我们仍然需要一个Recirc线/泵将热水带到房子中间的水槽和厨房。我们安装了小型6加仑储备罐以运行Recirc线。
此外，阁楼最有可能在不久的将来转换，因此最终被调节。
这笔钱绝对将在调节阁楼而不是移动热水器！
在一个理想的世界中，HW加热器将位于厨房和浴室之间的一半，但如果一切最终在条件空间最终会有零ROI。
达娜，
是的 - 我至少在阁楼的中间辩论，但炉子在我们施加的区域，另一个自由空间是主要的阁楼转换空间。
In a perfect world, I would have like to gut the entire house and redo everything exactly how I wanted. And the funny thing is - we love the house and the layout, and for the most part things were done right. But I'm noticing all the time that I like things done right and the contractors I've been dealing with just like things done.
Thankfully for everything else there's Green Building Advisor ;)
If only you had a network of contractors who are as informed as you all are, and could send them our way.