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View Full Version : What is the purpose of a collector box on a building downspout?


Dingbang
09-13-2017, 11:56 AM
It's a box installed in the downspout on the outside of a building. I Googled enough to find out that the thing is called a collector box, drain box, leader head, or collector head. What is its purpose?

The third image down on this page illustrates what I'm talking about: http://www.nosansignature.com/blog/exterior-selections/copper-gutters

I understand that they can be ornamental, as in that pic, but they also come in entirely plain designs. The one that got me wondering is on the side of a drab, three-story office building and is simply a flat box on the downspout, a few feet from the rooftop. It appears to be functional and not at all cosmetic. Why is it needed, rather than just having the water flow straight through the vertical run of the downspout?

Bill Door
09-13-2017, 12:02 PM
Maybe as a vacuum breaker?

CalMeacham
09-13-2017, 12:07 PM
It's a box installed in the downspout on the outside of a building. I Googled enough to find out that the thing is called a collector box, drain box, leader head, or collector head. What is its purpose?

The third image down on this page illustrates what I'm talking about: http://www.nosansignature.com/blog/exterior-selections/copper-gutters

I understand that they can be ornamental, as in that pic, but they also come in entirely plain designs. The one that got me wondering is on the side of a drab, three-story office building and is simply a flat box on the downspout, a few feet from the rooftop. It appears to be functional and not at all cosmetic. Why is it needed, rather than just having the water flow straight through the vertical run of the downspout?

Beats me. I don't think I've ever seen one before. Certainly they're not necessary to the proper functioning of a downspout, since every other downspout I've seen worked fine without one.

You don't need it to break vacuum -- rainwater never comes close to filling the cross-section of a downspout.

I vote for "Ornamental"

Channing Idaho Banks
09-13-2017, 12:11 PM
It adds to the noise the gutters make when they're only dripping.

HeweyLogan
09-13-2017, 12:17 PM
From e-gutters -

"Our Conductor Heads enhance both traditional and contemporary architecture.
They are traditional installed under the soffit to let air into the line which then prevents
excess noise (gurgling) and helps stop vacuum lock. Conductor Heads are also used
under a valley area to drain rainwater to the next level or ground drain."

http://www.egutter.com/RAIN-GUTTER-COMMERCIAL-GUTTERS-GUTTER-SUPPLY-GUTTER-GUARDS/Leader-Heads-Conductor-Heads-Collection-Box-Copper-Aluminum-Galvanized-Steel

Makes sense.

Peter Morris
09-13-2017, 12:21 PM
Youtube explains it. (https://www.youtube.com/watch?v=DVm83SukRyQ&t=0m38s)

Dingbang
09-13-2017, 12:58 PM
Thanks!

Evan Drake
09-13-2017, 02:07 PM
They may also catch debris, or act as a choke-point for twigs etc.; here's a nice one (http://www.britainexpress.com/images/attractions/editor/Farnborough-Hall-6294.jpg) from Farnborough Hall (http://www.britainexpress.com/attractions.htm?attraction=3622) in Warwickshire, probably 17th century.


In mediaeval times we made do with jutting out spouts, like this gargoyle (https://i.pinimg.com/736x/33/ee/36/33ee3615e354f86999c0d70f54dffc98--rosslyn-chapel-knights-templar.jpg) at famed Roslyn Chapel.

aceplace57
09-13-2017, 05:46 PM
I see a lot of rain collector barrels. They water the plants and yard with it.

It's an old school idea. My grandparents had a big wooden cistern on stilts beside the house. Raising it up, 12 ft. gave them good water pressure.

Bijou Drains
09-13-2017, 07:06 PM
until recently in Colorado it was illegal to keep the rain that fell on your roof by catching it in a container. That's because the rain "belonged" to people downstream. That's what happens when you live in an area like the Western US where water is a big deal because there is not a lot of it to go around.

Isilder
09-14-2017, 12:05 AM
The reason your sewerage pipes have a vent is that the air pressure doesn't blow through the S/ P bends and make a foul smell inside, and to prevent the S and P vents emptying into the sewerage due to atmospheric pressure pushing into the pipes....

But the rain water pipes don't have S and P bends, and so there is no such issue with air pressure interfering with P and S bends .


The only sensible thing a collector box does is provide a place to install a filter, to collect twigs and leaves. Some of the collector boxes seem to have overflow facility, so that if it is clogged with twigs etc, it does't flood the roof. But if the top of the collector box is open, then it is automatically an overflow facility.



If its in the middle of a pipe, it doesn't seem to be much use as a filter, or overflow device, since only stuff that can fit all the way through can get to that point. But it might be useful as a junction box.

MrDibble
09-14-2017, 05:20 AM
It's also known as a leader head (https://en.wikipedia.org/wiki/Leader_head).

HeweyLogan
09-14-2017, 08:46 AM
The only sensible thing a collector box does is provide a place to install a filter, to collect twigs and leaves. Some of the collector boxes seem to have overflow facility, so that if it is clogged with twigs etc, it does't flood the roof. But if the top of the collector box is open, then it is automatically an overflow facility.

This makes no sense. Why would you want a filter half-way down the entire run? It makes more sense if it were a filter to have it at the top, where it catches whatever detritus before it gets into the system, like with screens and the like they really use.

Further, doesn't it make more sense if it were to overflow to have it happen at the top where if it goes over it's going over the gutter, the eave, etc? With the collector box acting that way you have the overflow going over up next to the sheeting/siding etc and right down to the foundation. That's a worse result than having it over-top the gutter. rflow were to happen, to downspout happen at the top, where if it happens it just goes over the gutter, away on not down the side of the building itself.

In other words, what are you basing the idea on it functioning as a filter/spill over device?

But it might be useful as a junction box.

Which the website I referred to (a crappily written one I admit, but one that offered a quick and concise explanation) said the same thing as well.