Venting My Troyer Horizontal Gourds With PVC Elbows

[Steve Kroenke]

Venting My Troyer Horizontal Gourds With PVC Elbows

I have been using Troyer Horizontal gourds for several years with excellent results. The long and narrow shape of the Troyer Horizontal gourd with its restricted tunnel like entrance area provides a relatively safe and deep cavity for the martins. The martins are deep inside and the restricted entrance area greatly reduces access by owls and hawks to the nesting chamber.

Though I like the Troyer Horizontal gourds a lot, their long narrow shape with limited vertical depth may increase potential heat and humidity problems during the hot summer months if the gourds are not vented. Heat and humidity may be able to build up more easily in such cavities with entrances cut lower down in a chamber where air tends to stay confined in the nesting area rather than rising up toward an entrance located farther up from the nest.

In natural woodpecker cavities, the entrance is cut high up from the bottom of the nest cavity and hot air can rise up and channel out. Woodpeckers have been excavating cavities for thousands of years and many birds, including purple martins have been nesting in them. Woodpeckers may have evolved such an excavation behavior in part to facilitate the expulsion of hot air from their nest cavities.

The Troyer Horizontal gourd has two indentions with canopies in the upper back so that vent holes can be drilled. I have been drilling either a ¼ or 3/8 inch vent hole in a downward pointing angle under the canopies to provide ventilation for heat and humidity. This approach has worked in adequately ventilating my Troyer Horizontal gourds under most situations. The canopy and downward pointing vent hole keep most rainwater out.

For the 2011 martin season, I have recently vented most of my Super Gourds and all my Excluder Gourds with ¾ inch 90 degree PVC elbows in the upper necks. Each gourd has a downward pointing elbow in the neck area so that hot/humid air may be able to rise and flow out. Some of my Super Gourds have a round canopy venting system installed where I have drilled four 3/8 inch vents in the upper neck and then inserted a plastic canopy over the holes to keep rainwater out.

I like the PVC elbow approach so I have incorporated it in most of my Troyer Horizontal gourds for the 2011 martin season. Using a 1 and ¼ inch hole saw, I have drilled out the upper canopies on the gourd backs and installed two ¾ inch 90 degree PVC elbows. The hole is just a tad smaller than the outside diameter of the PVC elbows so I ream out the hole with a knife. Then I insert the elbow and caulk around the perimeter to hold the elbow in place and seal it. The ¾ inch vent holes will provide for much more possible airflow than the ¼ or 3/8 inch vents I have been using. Also the downward pointing PVC elbows will eliminate all chances of any rainwater entering the vent holes. Though using downward pointing drilled vents under canopies eliminated most rainwater, there was still always a chance for some to enter during driving rain storms.

You could also use PVC elbows that have a threaded end. In this way you could screw the elbow in the hole cut in the gourd and caulk may not be needed for holding/sealing. The threaded elbows are probably more expensive so if you had many gourds then this approach may be more costly. I elected to use the non-threaded PVC elbows and this has worked well for me.

If you haven’t ventilated your plastic or natural gourds, then this is good time to do it before the martin season begins.

Here are some photos of Troyer Horizontal gourds with PVC 90 degree elbows installed as vents.

Steve

This photo shows one of my Troyer Horizontal gourds with the back canopies drilled out. I use a 1 and ¼ hole saw to cut the holes and this hole initially is slightly smaller than the outside diameter of a ¾ inch PVC elbow which is about 1 and 5/16 inch. I use a knife to slightly enlarge the hole so that the PVC elbow fits snuggly inside.



This photo shows one of my Troyer Horizontal gourds with the two PVC elbows inserted inside the holes and caulk applied around the perimeter to hold and seal the elbows. I probably overdo the caulk application and don’t smooth it real nicely!



This photo shows my lowered 24 gourd Super System with a combination of Troyer Horizontals gourds with cling plates and with tunnels/porches, Excluder Gourds and Super Gourds. All the Troyer Gourds have the two PVC elbows installed in the upper backs where the canopy vents are located. All the Super Gourds have my round canopy vertical venting system with four vent holes cut in the upper neck and a plastic lid inserted over the neck to provide cover from rainfall. All the Excluder Gourds have a single PVC elbow installed in the back of the upper neck.



This photo shows one of my lowered 24 gourd Premium Systems with Troyer Horizontal gourds with tunnels/porches and PVC elbows installed in the upper gourd backs.



This photo show the upper back of a Troyer Horizontal gourd with vent holes cut under the canopies. I have used this approach in the past with good success. I will still have some of these gourds for the 2011 but will probably change them all to PVC elbow vents in the future.

[Scott D.- La]

Steve,
Good Job, That should help keep them cooler and easy to plug till the weather warms which, looks like may be a long winter from the temps were getting already. Your on a roll this year getting everything done early.

[Steve Kroenke]

Hey Scott,

I have made good progress getting ready for the 2011 martin season relative to venting my gourds and preparing pre-nests. I am still working on my Troyer Horizontals and venting these gourds with PVC elbows is not difficult. I ordered 400 PVC elbows online and will be using all of them!

Regarding pre-nests...I found a lot of pine needles on a nearby dirt road that are just perfect relative to softness. They make excellent pre-nests and can be easily arranged inside my gourds.

I am sure you are getting ready for the upcoming martin season, too.

Steve

[John Miller]

Steve

Looks great. I think venting is important and wish all the gourd makers would give more attention to this..some do. It's probably more important just for air exchange and preventing a build up of moisture than heat buildup... a wet rotting nest sure can't be good.

That said..I'm trying to simplify more and will be just trying to drill some holes on some Excluder gourds this year rather than the PVC elbows, although I've used lots of those. I will drill upward slanting holes opposite the hanging holes.. Then...a big heat wave will hit here in July when I have a few nests left to fledge, and I'll panic and will add some lids with big PVC elbows in gourds with late nesters! whew. can't wait.

John

John

[Steve Kroenke]

Hey John,

I agree with you regarding moisture/humidity build-up inside unvented plastic gourds. I had some problems with this before I vented my Troyer Horizontals with the vent holes under the back canopies. Just adding those two vent holes did wonders in mitigating heat/humidity issues in my Troyer Horizontals. I remember checking some of my nests in unvented gourds and they were wet and nasty and the inside of the gourd felt like a sauna.

The heat/humidity problem is probably more common and intense in the Deep South and mid-west. I have talked with some martin landlords who live in the northeast and upper mid-west and they indicated they had not experienced heat/humidity problems with unvented plastic gourds. But even folks in northern areas can still experience days of hot humid weather in July. It is probably best to have some kind of venting system in place.

Your simplified system of drilling vent holes under the hanging holes would probably work fine in most situations. This would allow an escape route for hot humid air.

Good luck with your venting!

Steve

[trank]

Steve

I agree with your comment about northern landlords having some type of venting system in place.
Last summer I experienced some problems like you described but only with the THG's. As the nestlings grew inside the gourds they generated more heat and with the warm days and cool nights condensation developed and the heat/humidity could not escape fast enough. The gourds turned into saunas making for an unhealthy and dangerous environment so I drilled vent holes in the back canopies like you described .
At the end of the season I vented all my THG's. I used elbows 3/4" 90deg. that have removable caps so during our cold spring weather here in WI. I can put them on to help retain some heat inside the gourd.

Tom

[Steve Kroenke]

Hey Tom,

Thank you for sharing your experiences with heat/humidity up north.

I can remember seeing "dirty looking" martin nestlings inside the gourds with their feathers matted together. I am sure it was miserable inside the nests under those conditions.

So far the venting has eliminated those problems for martins in my colony.

You mentioned that the PVC elbows can be capped during the cooler times and that is an advantage with this approach. We don't have as much of a problem with that down here in the Deep South but farther north is a different situation.

Good luck with your martins in 2011.

Steve

[bbillyc]

I've had the heat and sauna like issues with mine even far north here in Canada. I discovered that it really affected the health of the fledglings who had droopy tails and couldn't fly very well, whereas the vented wooden boxes the fledglings were healthy and were pro aviators right out of the door. This year all of my horizontal gourds will be vented but I was thinking that the vents should be a little higher to remove the heat right from the top of the gourds and remove that stratified layer of dead moist air.

[Steve Kroenke]

Hey bbillyc,

It appears that folks "up north" can experience heat and humidity just like we do "down south". We probably have more hot humid times, but all it takes is just a few days to create problems for martin nestlings.

You definitely could install any vents higher up on the Troyer Horizontals as long as this does not create rainwater inflow. Since I had already cut vent holes in the canopies in the upper backs, I just drilled out those and installed the PVC elbows there. So far, venting under the canopies has worked well for my gourds and probably manages to help evacuate a lot of any built up heat and humidity. Having the vent holes even higher up near the top area may facilitate the removal of rising hot air and humidity.

Thanks for sharing your observations and good luck with your venting in 2011.

Steve

[John Miller]

Steve

I want to offer a disclaimer on something I said...worked over the weekend on Excluder gourds. Said I planned to try and simplify and drill two small (3/8" to 1/2") upward slanting holes in the neck opposite the hanging holes, rather than using the PVC elbow vents.

I found that in the Excluder...the wall is very thick on the side (seams there), and my holes have enough thickness in the bottom of the upper slant that it satisfies me that water won't get in. Unfortunately in my holes front and back, the gourd wall is less thick and I think the thinner hole might let water in...so back to the beloved PVC elbows for those. (Most of my gourds, the hanging rod runs side to side and precludes a vent hole there..but I am using the simple side vent holes for a few gourds that the rods run front to back.)

Your technique of making a lid cover out of an access cap would work well on vent holes drilled in the neck of a vertical gourd to keep water out...but I'm always looking to keep things simple and quick...especially as we have so many gourds!

John

[Kelly Applegate~MN]

Steve, excellent information and I couldn't agree more with the need to vent the Troyers. Up here in the north we have a similiar problem with them building up moisture. The problem for me starts at around 21 days of age. The gourd with young are heated up in the hot july weather, then then the cool evening air creates a temp difference creating condensation on the inside of the gourd, which runs down the side of the gourd and into the nest material. On top of that, add the moisture in all the respiration from the young and adults, the humidity of the air in general, and it is a wet mess! It gets especially bad near fledging when the adults can no longer keep up with fecal sacs and the entire nest of fledglings is caked with fecal matter and unable to fledge properly. I'm going to add vents to all of them for 2011. Probably 2 in the back, and 1 in the neck somewhere. I'm also going to slice off the round lip on the inside of the neck, I think it's more of an obstacle than anything.

[Tim Mangan-Kansas]

I agree with all that has been said about the importance of venting. For those using threaded PVC vents, following is a picture of the tool I use to cut the hole in the plastic gourd, along with the threaded PVC vent. I have also used this tool to cut holes in my aluminum housing. It is 3/4" hole saw. Once the hole is cut, I don't have to do any filing as the threaded PVC vent will screw right in without any problems.

Tim

[RC Moser]

I glued screening in mine so wasps or yellow jackets wouldn't be able to enter the elbows. you can verily see the screen up in the elbow.

[Carlton]

Do you think that the T.V.G's with the four small holes drilled out up top would vent better than the T.H.G. and the back vent holes? I am trying some T.V.G. in 2011 along with my standard T.H.G.

[Steve Kroenke]

Hey John,

When I used horizontal natural gourds, I started cutting vent holes almost on the gourd tops. To keep rainwater out, I attached aluminum canopies via caulk over the holes. This worked fine. I cut a few vent holes on the upper back curvature of some of my Super Gourds and covered them with gabled aluminum canopies. This worked. It was easy to cut out small pieces of aluminum, bend them in a "gabled canopy", and then glue them over the vent holes with caulk. You could possibly do this with your Excluder Gourds rather than go the PVC elbow approach. Just another idea for you to consider.

Here is a link to an old posting of mine dealing with the aluminum canopy subject; there are photos:

http://purplemartin.org/forum/viewtopic.php?t=9003

Steve

Kelly,

Thanks for sharing your observations relative to venting Troyer Horizontal gourds for martin colonies way up north! Yes, you could use three vent holes and I had thought about doing something similar. I was going to leave the regular vent holes in the upper back canopies and then add a PVC elbow somewhere higher up. But I elected to go with two PVC elbows since these are ¾ inch diameter vents and two of them would provide for considerable airflow.

The outer lip in the older Troyer Horizontals with tunnels/porches can create problems for martins becoming entrapped in srehs. When martins are fighting inside the cavities, sometimes a martin can become wedged in the sreh with a tunnel that has a double entry configuration. It is probably better to have a “clean” tunnel without any inner lip. With the inner lip, martins sometimes try to turn around inside this foyer area when fighting and can become trapped, particularly when srehs are used.

If you go with three vents in your Troyer Horizontals, maybe you could post a photo on the Forum. Thanks.

Steve

Hey Tim,

I like the idea of using threaded PVC elbows. It would be a lot less “messy” without using caulk! I had so many of them to do that I went with the regular elbows (probably less expensive) and caulk. What size PVC elbows do you use with the ¾ inch hole saw? I use a 1 and ¼ inch hole saw for my ¾ inch PVC elbows. Thanks.

Steve

Hey RC,

Thanks for that tip about inserting some screen into the PVC elbow to keep wasps out. We always have some wasps showing an interest in our housing but the large number of martins in our colonies tends to keep the wasps away. I will often see a wasp flying through my colony, but she seems to be intimidated by all the martins when they are around and she rarely tries to enter any cavity. But if a wasp visits when the martins aren’t around, she will definitely check out the cavities. What I have generally observed is that if martins move into a cavity first, then wasps tend to stay away. If a wasp manages to establish territory inside a cavity and start constructing a nest, then the wasp may keep the martins out.

Steve

Hey Carlton,

In 2010, I used 12 Troyer Verticals with the vent holes cut in the upper neck canopies and the martins did fine in them; I didn’t notice any significant issue with heat or humidity. I will be using 40 Troyer Verticals in 2011 and all have the upper neck canopy vent holes. All my Troyer Horizontals were vented in the upper back canopies and the martins did fine in them too.

I don’t know if there is a significant difference relative to heat/humidity removal between the venting in the upper neck of the Troyer Verticals and venting in the upper back of the Troyer Horizontals. The vertical shape may facilitate the evacuation of heat/humidity as it rises up and out the upper neck vent holes (chimney effect). Also any wind that blows through the entrance hole may help to push the warmer air up and out the upper vent holes in the gourd neck. Hot air rises and vents higher up may be more efficient in removing this air.

The Troyer Horizontal’s shape is longer and shallower than the Troyer Vertical so heat and humidity may spread out throughout the cavity. The entrance hole would allow wind to flow through the gourd and facilitate the expulsion of heat/humidity out the upper back vent holes.

So drilling vent holes in the canopies for both Troyer Verticals and Horizontals probably works well under most situations. You could even add a PVC elbow to the upper back of a Troyer Vertical and have two venting systems in place.

Steve

[Tim Mangan-Kansas]

Steve:

I use a 1/2" threaded PVC elbow with my 3/4" holesaw. It is schedule 40 PVC made by LASCO and I purchase them from Lowes. Although the elbow fits tightly, I do take the extra step of caulking around the PVC. Don't recall the price nor the difference in cost between the threaded and non-threaded.

Tim

[trank]

Here's a picture of a vented THG with removable caps which might be helpful for northern landlords. I believe there is also a threaded version that could also be used to screw the caps on.

Tom

[Indiana_Tom]

I have 12 new THG's to put up next year. I have been looking at a lot of the pictures to get some ideas on how to vent them the best and how to keep water out.

One issue I see is the rod fitting through the top of the gourd to hold it on the rack. It would seem to me that any rain moving along the rod toward the gourd would be directed right to the manufactured holes in the gourd, some of which would go inside.

Remedy ---- Cut some short lengths (1/4 inch) of plastic tubing, in my case 3/8s inch diameter. Slide them on the rod with one on each side of the gourd. This would cause any rain drops running down the mounting rod to drip off when it gets to the piece of tubing instead of continuing to the hole in the gourd.
Next ---- Cut a 4 inch length of 2 inch diameter PVC pipe. Cut the short piece of PVC pipe length wise in half. About a half inch from each end, drill two small holes. Center the PVC canopy over the gourd where the mounting rod attaches the gourd. Using a short length of wire or a small cable tie to go through one of the holes, down under the mounting rod and back up through the other hole. Twist it tightly on the top. Do the same with the two holes on the other end of the canopy. This would keep water from entering the mounting holes in the top of the gourd.

Then I thought, if I do it this way, why not drill a couple of 3/8s inch vent holes in the very top of the gourd under this PVC canopy. It would be protected from the weather and in the uppermost part of the gourd. That is the best place for venting.

The only problem I can foresee is not having an easy way to close the vent holes during an early season cold snap.

I will have to learn how to add photos. Mainly how to reduce size.

Any thought would be welcome. I am still experimenting.

[Scott D.- La]

Indiana Tom,
You are correct, rain will run down the rods and into the gourd. I put 2 rubber washers at the end to stop it.

The pic that Trank (Tom) provided is a excellent chance to get this information to the manufacturer. I will say it slow.

The hanging hole is the Problem and the Solution. Delete the hanging hole and mold a neck atleast 3 to 4 inches tall, by 2 inches wide. This will leave you with a Vent Chimney. Then you mold a cap to fit over that chimney. You will make your hole through the cap, and the chimney however, you don't want the cap to sit flush on the top of the chimney. You want to leave a gap of atleast 3/8 of a inch so it will VENT properly. This will leave you with a waterproof and vented horizontal gourd. If you make this change, you could also mold into your cooling cap, a lock tab, so that your pin will keep the gourd from moving side to side and braces will not be needed anymore to keep them from moving. Mold wing entrapment guards into the tunnels, I have the pattern. It would take alittle money to change the mold however, it will be money well spent in the end. I would be willing to make an example with one of my Troyer's.
Edit/After more thought, a one peice dome would give Much more venting area. The locking tabs would also be molded in the dome. Instead of a single gap, this would give you up to 20 vent holes under the lip of the dome and allow unrestricted air flow and be completely waterproof.

[Dave Duit]

I hope this idea will help anyone who is venting THGs with PVC elbows.
I first drill out two holes on each THG about 2/3 the way up to fit schedule 40 threaded 1" PVC elbows. Screw on a 1" RIGID brand steel Conduit Locknut halfway to the end of the threads. Next, insert the elbows into the holes. Through the access port, screw on a 1" RIGID brand insulating bushing onto the threaded elbow inside the goard and apply a bead of lexel caulk against the bushing. The bushing will only screw on so tight, because the backside of the bushing will touch the butt end of the threaded elbows. Push the elbows toward the back of the goard wall so it squishes the lexel between the bushing and interior goard wall. Then, go back to your locknut and apply a bead of lexel caulk where the elbows come out of the goard. Snuggly screw down the locknut against the back of the goard. You have now completed two sturdy elbow vents for your THG.
I believe this is a small improvement idea; because over time the elbows will eventually become less stable due to end of year handling. It is just a way to strengthen the weakest point of the elbows when using only lexel caulk.