# Roof mounted Disco's



## Easy (Oct 18, 2017)

I had an AC unit and condenser that needed to be tied in and I hated to just tex screw the disconnects to the sides of the 2 units. My boss gives me freedom to do the work the way I see fit so I tried something new. 
I used Dura Bloks for feet on my unistrut stands. I'm really not sure if they are intended for that type of installation. I think their actual design is for horizontal runs of conduit on a roof. I hope this installation will pass inspection. 
https://sites.google.com/site/marshmanbrewery/_/rsrc/1582990783575/equipment/1-AC.jpg
https://sites.google.com/site/marshmanbrewery/_/rsrc/1582990804629/equipment/1-AC2.jpg
https://sites.google.com/site/marshmanbrewery/_/rsrc/1582990826068/equipment/1-Condenser.jpg


----------



## ktny (Jan 21, 2020)

I agree with not liking to just zipping the disconnects to the unit. At first i would of said the dura bloks probably are not meant for that type of vertical support however after looking at the brochure with the listing styles of how it can be used they show using strut going vertical and building a rack similar to what you did to support hvac duct with a load support rating of 1000lbs, therefore id come to the conclusion what you did is acceptable, looks really nice and i like the idea much better that zipping the disconnect to the unit itself however that has gotta take at least another hour of labor and alot more of a material cost, if you can get jobs priced out to be doing that id say keep doing what youre doing 

Id post the listing page to it however still have not hit 20 posts, soon my friend soon


----------



## Signal1 (Feb 10, 2016)

That looks very sturdy, and neatly done. 
Love the end caps :thumbsup:


----------



## HackWork (Oct 2, 2009)

I don’t like using tek screws either, I prefer nuts and bolts when I can get in there. 

What you did looks great, and if someone wanted it done that way and is going to appreciate it then it might be worth the huge added cost in labor, logistics, and hardware. .


----------



## flyboy (Jun 13, 2011)

What a waste of money! :vs_laugh:

Not to mention the added risk of possible roof and interior damage due to weather exposure.


----------



## MHElectric (Oct 14, 2011)

You definitely went the extra mile to make that look like quality workmanship. Good job. 

However, can I ask how that will hold up against wind and rain? Would a strong storm not knock that over?


----------



## splatz (May 23, 2015)

MHElectric said:


> You definitely went the extra mile to make that look like quality workmanship. Good job.
> 
> However, can I ask how that will hold up against wind and rain? Would a strong storm not knock that over?


I thought that too at first glance but I looked closer and saw the racks are bolted to the sheet metal with short standoff sections of strut, it's not going anywhere.


----------



## MHElectric (Oct 14, 2011)

splatz said:


> I thought that too at first glance but I looked closer and saw the racks are bolted to the sheet metal with short standoff sections of strut, it's not going anywhere.


 OK, I see that now. Good catch.


----------



## splatz (May 23, 2015)

Easy said:


> https://sites.google.com/site/marshmanbrewery/_/rsrc/1582990783575/equipment/1-AC.jpg


So to get an idea of the cost of this, I'd be guessing about $150 materials cost (strut, fittings, pyramids, and end caps) and a minimum of an hour to build that rack?


----------



## HackWork (Oct 2, 2009)

splatz said:


> I thought that too at first glance but I looked closer and saw the racks are bolted to the sheet metal with short standoff sections of strut, it's not going anywhere.


The first one is bolted to the AHU, but the second one is freestanding. It looks like it’s glued down to the roof.



splatz said:


> So to get an idea of the cost of this, I'd be guessing about $150 materials cost (strut, fittings, pyramids, and end caps) and a minimum of an hour to build that rack?


I would say a minimum of two hours extra, probably more. Designing it takes time, picking out the exact parts, carrying all of it up to the roof with a few extra trips, cutting the strut and filing each piece, putting it together. And then once it’s done you’re at the same point as if you just bolted the disconnect directly to the unit using the same bolts that the rack was bolted to the unit with.


----------



## 99cents (Aug 20, 2012)

flyboy said:


> What a waste of money! :vs_laugh:


Even if it’s cost plus?


----------



## HackWork (Oct 2, 2009)

Looking back, I have just laid strut on the roof as the plans specced.


----------



## Easy (Oct 18, 2017)

HackWork said:


> I don’t like using tek screws either, I prefer nuts and bolts when I can get in there.
> 
> What you did looks great, and if someone wanted it done that way and is going to appreciate it then it might be worth the huge added cost in labor, logistics, and hardware. .


Well yes your right about the added cost of materials. I cant believe the cost of just spring nuts for unistrut, ridiculously overpriced. My boss has never complained about cost of parts so I'm ok in that respect. I actually did it that way for extra hours on this weeks pay check. Work has been slow mainly because my boss keeps going on vacation and leaves me with nothing to do. I'm lucky to get 30 hours a week and as long as he is happy it seems ok.


----------



## splatz (May 23, 2015)

Easy said:


> Well yes your right about the added cost of materials. I cant believe the cost of just spring nuts for unistrut, ridiculously overpriced.


I just got a pile of strut stuff - everything but the strut itself - from McMaster-Carr. Their prices are usually medium but they saved me a bunch on strut fittings and hardware. Even better, they have a super selection in stock ready to ship. And their web site works very well. Really impressive.


----------



## Easy (Oct 18, 2017)

MHElectric said:


> You definitely went the extra mile to make that look like quality workmanship. Good job.
> 
> However, can I ask how that will hold up against wind and rain? Would a strong storm not knock that over?


If you look closely I ran 6" timber locks into the roofing. The stands are low profile as well so wind won't effect them. I guess the main advantage would be that they are not attached to the equipment so if either the AC of Condenser had to be replaced or worked on it might help facilitate that. I really just needed more hours on this weeks pay check. The labor was about an extra 3 hours including running for parts.


----------



## telsa (May 22, 2015)

Easy said:


> I had an AC unit and condenser that needed to be tied in and I hated to just tex screw the disconnects to the sides of the 2 units. My boss gives me freedom to do the work the way I see fit so I tried something new.
> I used Dura Bloks for feet on my unistrut stands. I'm really not sure if they are intended for that type of installation. I think their actual design is for horizontal runs of conduit on a roof. I hope this installation will pass inspection.
> https://sites.google.com/site/marshmanbrewery/_/rsrc/1582990783575/equipment/1-AC.jpg
> https://sites.google.com/site/marshmanbrewery/_/rsrc/1582990804629/equipment/1-AC2.jpg
> https://sites.google.com/site/marshmanbrewery/_/rsrc/1582990826068/equipment/1-Condenser.jpg


Change your nic to either OCD or Hard. :biggrin:


----------



## HackWork (Oct 2, 2009)

Easy said:


> If you look closely I ran 6" timber locks into the roofing.


The point of using those strut curbs is so that you don’t have to penetrate into the roof :surprise:


----------



## Easy (Oct 18, 2017)

splatz said:


> I just got a pile of strut stuff - everything but the strut itself - from McMaster-Carr. Their prices are usually medium but they saved me a bunch on strut fittings and hardware. Even better, they have a super selection in stock ready to ship. And their web site works very well. Really impressive.


I was in a rush and did not shop around on this job. I picked up the hardware at CED and the 3/8" spring nuts were $1.50 each. I asked for nuts without springs as they work better on slotted unistrut and they brought out some corn nuts ( the ones with rubber washers) $2.50 each. So I spent about 20 minutes ripping the springs out of the box of 100. They don't even stock nuts without the springs. Special order.. pffff Anyways thanks for turning me on to McMaster-Carr. I will certainly check it out.


----------



## HackWork (Oct 2, 2009)

Easy said:


> I was in a rush and did not shop around on this job. I picked up the hardware at CED and the 3/8" spring nuts were $1.50 each. I asked for nuts without springs as they work better on slotted unistrut and they brought out some corn nuts ( the ones with rubber washers) $2.50 each. So I spent about 20 minutes ripping the springs out of the box of 100. They don't even stock nuts without the springs. Special order.. pffff Anyways thanks for turning me on to McMaster-Carr. I will certainly check it out.


See, this is the logistics part of the job that we have to consider in addition to labor and material.


----------



## Easy (Oct 18, 2017)

HackWork said:


> The point of using those strut curbs is so that you don’t have to penetrate into the roof :surprise:


Yes this is true but I thought it would be best to lock them down some how. I did not want a wobbly set up. I was about to just use treated lumber but that seems lame as wood spits when it's exposed to weather. I also did not want to place unistrut directly on the deck and have it accumulate water in the winter months. I promise to never over due it again. :smile:


----------



## splatz (May 23, 2015)

Easy said:


> I was in a rush and did not shop around on this job. I picked up the hardware at CED and the 3/8" spring nuts were $1.50 each. I asked for nuts without springs as they work better on slotted unistrut and they brought out some corn nuts ( the ones with rubber washers) $2.50 each. So I spent about 20 minutes ripping the springs out of the box of 100. They don't even stock nuts without the springs. Special order.. pffff Anyways thanks for turning me on to McMaster-Carr. I will certainly check it out.


I actually do pretty well on spring nuts locally too but the fittings are insane. They want like $18 for plastic end caps at the one supply house, I don't know how they can say it with a straight face. They are $2.50 at Lowes and $1.50 at McMaster.


----------



## HackWork (Oct 2, 2009)

Easy said:


> Yes this is true but I thought it would be best to lock them down some how. I did not want a wobbly set up. I was about to just use treated lumber but that seems lame as wood spits when it's exposed to weather. I also did not want to place unistrut directly on the deck and have it accumulate water in the winter months. I promise to never over due it again. :smile:


Overdoing it is one thing, but penetrating the roof with screws is going in the opposite direction.


----------



## Easy (Oct 18, 2017)

telsa said:


> Change your nic to either OCD or Hard. :biggrin:


Thanks Telsa .. I totally trust your judgement. I can tell that you are extremely well versed in construction. So your saying that EMT can't penetrate a roof. I really doubt the inspectors will say anything in the small town I live in. There are 4 other AC units on the roof and they are all EMT and flex. At least I used seal tight. The other units have Non-Metal Liquid-tight and plastic fitting. Disco's are all side ways and messed up. The funny part is I bought all the roof jacks for the job some had rubber boots and others were just sheet metal. My boss did not want to use them because he said rubber rots over time and the sheet metal ones won't seal good. The plumber was on the job at that time and said he had some real good ones that never leak. They are made of pure led. So that's what you see in the photos. Led in the work place.. ? not good ?


----------



## Easy (Oct 18, 2017)

HackWork said:


> Overdoing it is one thing, but penetrating the roof with screws is going in the opposite direction.


I guess I can agree but the units are mounted on wood and lagged in. I ran some roof sealant under the feet so it would not leak. Besides the timber looks run through 3" of rubber above that. It will never leak but it is a field modification. And here I was all proud of my work. lol


----------



## Easy (Oct 18, 2017)

Unfortunately this is what I had to work with. The condenser was re-positioned from the actual planned location and my feed came up in the wrong place. I could have ran rigid conduit around to the other side or just build a stand for the disco. See how the door takes up the entire left side of the unit and I really had nothing to mount to on the back side.


----------



## Easy (Oct 18, 2017)

splatz said:


> So to get an idea of the cost of this, I'd be guessing about $150 materials cost (strut, fittings, pyramids, and end caps) and a minimum of an hour to build that rack?


More like $200 material and 3 hours labor. I'm a slow worker.


----------



## MHElectric (Oct 14, 2011)

Easy said:


> Yes this is true but I thought it would be best to lock them down some how. I did not want a wobbly set up. I was about to just use treated lumber but that seems lame as wood spits when it's exposed to weather. I also did not want to place unistrut directly on the deck and have it accumulate water in the winter months. I promise to never over due it again. :smile:


I'm not going to lie, I've also run 3" screws into a roof to support some pipe/flex but that was on a shingled roof and I used a whole bucket of old Henry's roof tar to make sure it wouldn't leak. 

I would highly suggest never doing that on a flat rubber roof. Its a big deal for some roofers to come out and patch that stuff. 

But don't lose any sleep over it - you live, you learn. I can't even begin to count the amount of stuff I've screwed up.


----------



## HackWork (Oct 2, 2009)

Easy said:


> I guess I can agree but the units are mounted on wood and lagged in. I ran some roof sealant under the feet so it would not leak. Besides the timber looks run through 3" of rubber above that. It will never leak but it is a field modification. And here I was all proud of my work. lol


Those unistrut curbs are made out of recycled rubber pressed together. Moisture can get through them. With all the flexing from that rack moving around and the roof underneath it, a small crack in the sealant can easily lead to a leak.

I’m not trying to give you a hard time, I just suggest not doing it like that anymore.


----------



## Easy (Oct 18, 2017)

HackWork said:


> Those unistrut curbs are made out of recycled rubber pressed together. Moisture can get through them. With all the flexing from that rack moving around and the roof underneath it, a small crack in the sealant can easily lead to a leak.
> 
> I’m not trying to give you a hard time, I just suggest not doing it like that anymore.


Maybe I should drive the lags in deeper and apply some black liquid rubber over the holes above the lags. That way the inspector won't see them. It's good to learn from mistakes and I value your suggestion of not doing it again. It is an old building with rolled tar roof. My boss is going to have the roof coated with some new product the roofer sold him on. Not the elastimaeric product but something similar. Hopefully nothing will leak. I will point it out to the roofer and see what he thinks.


----------



## telsa (May 22, 2015)

Easy said:


> Thanks Telsa .. I totally trust your judgement. I can tell that you are extremely well versed in construction.* So your saying that EMT can't penetrate a roof.* I really doubt the inspectors will say anything in the small town I live in. There are 4 other AC units on the roof and they are all EMT and flex. At least I used seal tight. The other units have Non-Metal Liquid-tight and plastic fitting. Disco's are all side ways and messed up. The funny part is I bought all the roof jacks for the job some had rubber boots and others were just sheet metal. My boss did not want to use them because he said rubber rots over time and the sheet metal ones won't seal good. The plumber was on the job at that time and said he had some real good ones that never leak. They are made of pure led. So that's what you see in the photos. Led in the work place.. ? not good ?


Where did THAT come from ? :surprise:


----------



## Easy (Oct 18, 2017)

telsa said:


> Where did THAT come from ? :surprise:


"Change your nic to either OCD or Hard." 
I thought you were talking about my conduit run. You said Hard and I thought you meant Rigid. Not sure what nic means.


----------



## Easy (Oct 18, 2017)

ha ha it finally sunk in. duuu my name ... hmmm yes I do kind of over do it.. I talk way too much and get a hurry at times. Thanks for the insight.


----------



## 99cents (Aug 20, 2012)

No way I’m penetrating that roof without authorization from the landlord. Every commercial job I do requires their roofing contractor to be involved even if he’s a goof who cuts through conduit with a Sawzall (that was a nice surcharge). If you’re concerned, fasten a couple of pieces of strut to the unit with OCD reminiscent of Chicken Steve.


----------



## JoeSparky (Mar 25, 2010)

The work looks top notch:thumbsup: That being said, I prefer profit over looks. Especially somewhere like a roof where only your colleagues will see it. You, the tin knockers and the roofers are the only ones who would normally see this. 
I would have tek screwed the disco right over the KO and slapped a chase nipple through the back. If you don't like teks, then 2 nuts and bolts and the chase will work just as well. Short amount of flex out of the LB to the bottom of the disco. Bam! 2 hours faster and $60ish cheaper per unit


----------



## telsa (May 22, 2015)

Notions:

1) I hate LBs -- so my style is to transition with a Sealtite 45. ( Sealtite 90s can be a $#@%^ to work with.)

( RT Connector + Sealtite 45 coupling => Sealtite )

2) IF, and only if, I can find a 'dead' panel on the RTU, I'll shamelessly mount to it every time. By 'dead' I mean a location that does not interfere with any routine HVAC service calls.

2a) That may, or may not, entail coming out of the lower backside of the disconnect into the interior of the RTU via a bushed chase nipple.

3) It's so common for a RTU to be so far away from a GFCI receptacle that it's common for my work-up to include one, just to satisfy Code.

3a) In which case, I prefer to mount a Bell box immediately ahead of the disconnect for said receptacle -- with the RTU feeders passing through the Bell box. ( It's that deep.) This is done so I only need one raceway and I don't need any kick-back from the AHJ.

&&&

nic = forum nickname :smile:

OCD = Obsessive Compulsive Disorder = perfectionism :devil3:


----------



## telsa (May 22, 2015)

BTW, you'll have to ask for Sealtite 45s. 

Normal practice is for your supply house to proffer 90s.

Many a j-man has never seen a Sealtite 45, BTW.


----------



## telsa (May 22, 2015)

splatz said:


> I actually do pretty well on spring nuts locally too but the fittings are insane.* They want like $18 for plastic end caps* at the one supply house, I don't know how they can say it with a straight face. They are $2.50 at Lowes and $1.50 at McMaster.


Classic digital entry error -- missed the decimal point. :crying:


----------



## VELOCI3 (Aug 15, 2019)

Looks good. Those little RTUs should have a factory option for equipment mounting. BTW where’s the nearest GFI?


Sent from my iPhone using Tapatalk


----------



## Wirenuting (Sep 12, 2010)

Easy said:


> Unfortunately this is what I had to work with. The condenser was re-positioned from the actual planned location and my feed came up in the wrong place. I could have ran rigid conduit around to the other side or just build a stand for the disco. See how the door takes up the entire left side of the unit and I really had nothing to mount to on the back side.


When I've had penetrations like that, I'll slip a vent cap over the stub up and pour some roofing patch into it. Even if the roof had been sealed nicely your pipe will begin to leak over the next 10 years. The cap and tar will keep the water from tracing down the run. 
When ever possible I'll use strut on the condensers and mount the disconnect on it.. I don't block access to the units, but I don't worry about them replacing the condenser 10 years from now.. By then you'll be replacing the disconnect anyway. 
They should have placed that unit better to accommodate you. Line sets can be routed easier. 

Looks nice how you did it.


----------



## 460 Delta (May 9, 2018)

Uni-Strut is erector set building for grown men (and women). If the boss doesn’t care about extra hours spent and materials, I say go for it.


----------



## Easy (Oct 18, 2017)

I have a receptacle mounted on the other side or the AC so as to be code compliant there is another recep. about 40 feet away at another AC unit so I had no choice but to add one. I agree that form follows function and the install was not a beauty contest but rater my attempt to do a good job. 

1. If I was to mount the disco directly to the AC unit and nipple in then the 2 bolt holes above that would not be raintight and water could come into the controls through those holes.

2. Another reason I did the 2 racks was for the fact that both units had feeds that were too far out from the units and would have been a trip hazard.

3. I am very concerned about water penetrating the roof but that being said this installation is at the apex of the roof and water will not accumulate there and most likely never make it through the 3" of rubber that slopes at 45 degrees and make it through the sealant I applied.

4. I believe in this case that water will more likely penetrate the 4 lags that hold down the satellite dish or the coax cables that are just ran directly through the roof coming from the satellite dish. See Photo ....

5. As for the condenser there is no logical place to really mount a disco.

6. If either piece of equipment ever needed to be replaced the disco's could stay in place without any rework.

7. I'll never run a screw into a roof again.. Too much liability and I agree with that.

https://sites.google.com/site/directlightingco/_/rsrc/1583028930628/hardware/1-AC2.jpg


----------



## VELOCI3 (Aug 15, 2019)

Easy said:


> I have a receptacle mounted on the other side or the AC so as to be code compliant there is another recep. about 40 feet away at another AC unit so I had no choice but to add one. I agree that form follows function and the install was not a beauty contest but rater my attempt to do a good job.
> 
> 1. If I was to mount the disco directly to the AC unit and nipple in then the 2 bolt holes above that would not be raintight and water could come into the controls through those holes.
> 
> ...




Going into the back of the disco instead of the bottom would help with dripping water inside and running to the LB. Plus any water that would ride the conductors right to the ST conn


Sent from my iPhone using Tapatalk


----------



## 99cents (Aug 20, 2012)

telsa said:


> Notions:
> 
> 1) I hate LBs -- so my style is to transition with a Sealtite 45. ( Sealtite 90s can be a $#@%^ to work with.)
> 
> ...


A Canadian would just run Teck up and in.


----------



## Wirenuting (Sep 12, 2010)

Easy said:


> I have a receptacle mounted on the other side or the AC so as to be code compliant there is another recep. about 40 feet away at another AC unit so I had no choice but to add one. I agree that form follows function and the install was not a beauty contest but rater my attempt to do a good job.
> 
> 1. If I was to mount the disco directly to the AC unit and nipple in then the 2 bolt holes above that would not be raintight and water could come into the controls through those holes.
> 
> ...


I just noticed were you are. 
We've all heard that song, "It never rains in Southern California.. 
I deal with lots of snow some years. Pipes and other rooftop items melt the surrounding snow first.


----------



## MHElectric (Oct 14, 2011)

telsa said:


> 3a) In which case, I prefer to mount a Bell box immediately ahead of the disconnect for said receptacle -- with the RTU feeders passing through the Bell box. ( It's that deep.) This is done so I only need one raceway and I don't need any kick-back from the AHJ.


Can you explain this a little further? Why would you need to set the bell box before the disconnect? And what issue would the AHJ be able to have against you if you came out of the bottom of the disco with a GFI bell box instead?


----------



## Easy (Oct 18, 2017)

Wirenuting said:


> I just noticed were you are.
> We've all heard that song, "It never rains in Southern California..
> I deal with lots of snow some years. Pipes and other rooftop items melt the surrounding snow first.


We prey for rain in So Cal. and pay premiums for water. It's very hard to keep a green lawn in the summer. I can definitely see issues with water intrusion on roofs that get snow especially around conduit fittings and enclosures or even dummies like me that run screws into roofs.


----------



## wcord (Jan 23, 2011)

Looks really good. Easy to put in place

I came up with a different way, but requires a bit of welding.
The assembly is a piece of 1/4 plate with 4" 'C' channel welded to it. Then I weld whatever Unistrut is required for the installation. My roof receptacle is on one side, with the disconnects on the other
I use a 24x24 patio block , bolt the assembly to the block with 3/8 rod.
I use a piece of underground rated Styrofoam to protect the roof from the rough concrete and the bolts.

One pic shows a completed install for a single condenser, the other wasn't finished when the pic was taken.

Only down side is getting the damn block up on the roof:surprise:


----------



## splatz (May 23, 2015)

wcord said:


> I came up with a different way,


These look like a good solid setup, very nice. I like the idea of using foam board as a mat, cheaper and easier to get up there than rubber matting. 

On the first picture, what's that around the cables where they penetrate the roof?


----------



## wcord (Jan 23, 2011)

splatz said:


> These look like a good solid setup, very nice. I like the idea of using foam board as a mat, cheaper and easier to get up there than rubber matting.
> 
> On the first picture, what's that around the cables where they penetrate the roof?


The roofer supplied the penetration. I've never seen one like that before. usually its been the neoprene cone.


----------



## splatz (May 23, 2015)

wcord said:


> The roofer supplied the penetration. I've never seen one like that before. usually its been the neoprene cone.


It looks like a jello mold of polyurethane foam ...


----------



## CoolWill (Jan 5, 2019)

The lesson here is: Never post pics of your work on ET.


----------

