Roof Leaks caused by HVAC roof mounted systems. Air Conditioners on roofs that leak can cause hundreds of dollars in repairs. The problem is finding the responsible party. I can’t tell you how many times, year in and year out, how I have been blamed for a leaky roof I installed, only to find out that someone installed a AC on the roof poorly years after I did the roof. When it leaks, who do you call, the roofer! The photo to the left shows how a HVAC contractor from the Sacramento area has bent , broken and stuffed his roof mount HVAC stand poorly into this roof. There is no way this roof would not leak, and it did, and who did the home owner call? Yep, you got it , me. The shingles and underlayment needed to be repaired and during this job a broken rafter was discovered and replaced.  As you can see to the right the unit’s stand on the bottom left is extended more than the right side to make up the sag in the roof. The HVAC contractor cut a rafter and it loaded too much weight on what is called the cripple rafter which had no purlin support.

{ A cripple is a rafter that runs from a hip to a valley} This HVAC contractor that did this horrible job is a large company that does a lot of advertisement, but will never get a referral from me because of this type of work. There were many issues with this installation and don’t get me wrong because for the most part HVAC contractors are great. This installation was very poor and did not get inspected by the Building Department. I have seen many maintenance issues on a Air  Conditioners that also caused leaks. I hate having to tell the customer they need to call the HVAC Contractor that work on the roof recently to come back out and fix this problem. Did you know I have seen small 1/2 holes stabbed into the elbow so the HVAC contractor can temp/test the return air, then leave that little hole. I could go on and on but I think the point is made. This area of the roof is most important to get right and hiring the best to do the two jobs is critical. I have for years developed great working relationships with HVAC Contractors.

As a roofing contractor it is good to have a few you can trust and use because things can really go well if the two know each other and work good together. The reason why is this, when the roof and HVAC are being done at the same time, both contractor that have worked together  both understand each others job responsibilities. Of course having both jobs done by the same contractor would have the best results. There are not to many contractors that cross over trades, so having the two contractors having past experience together is a good scenario. It normally goes like this. The old HVAC removed. The roof is removed. Exposing the roof can be useful to the HVAC contractor setting the new curb or stand. Having the heavy AC unit off the roof the roofer can install the roofing easier and making a clean good looking job. The HVAC contractor then lifts the new AC and sets it on the stand and seals the unit to the plenum. Best of both worlds, if both are done at the same time.

If not I advise an inspection of the both contractors to make sure this area of the roof perform well for years.See the Downloads tab for specifications, submittals and FanDrafter filesYork, PA  -  January 03, 2012.  American Cooling Technology (ACT) has recently ramped up to full production on its new high performance CR-4 roof mount condenser unit. ac unit sliding doorThe CR- 4 further expands ACT’s existing North American product line that includes a full range of split system air conditioning units including roof mounted units for school and shuttle buses.military air conditioning units for sale Based on market feedback from customers who participated in field trials, we’ve made the CR-4 unit smaller and lighter than competing high capacity roof mount condensers.     split unit ac heat

At less than 10 inches tall, the low height of the CR-4 unit increases roof clearance and provides a cleaner, sleeker look to the air conditioning installation.  The low profile and tapered leading edge of the unit eliminates the need to install a branch guard typically required on a standard rooftop condenser. The CR-4 is available in both 12 Volt and 24 Volt and can be supplied as a dual loop unit to be connected to two automotive style compressors or as a single loop to connect to a single high capacity  transit compressor. This flexibility makes the CR-4 a good fit for both conventional- and hybrid-drive buses. By relocating the air conditioningcondenser from the typical position under the bus floor to the roof of the bus, the capacity and operating efficiency of the air conditioning system improves because the system uses cleaner air from the top of the bus through the unit’s heat exchanger. All ACT Split Systems use non-ozone-depleting HFC-134a refrigerant and the CR-4 delivers a high cooling capacity (165,000 Btu/hr. IMACA).

It also is easier to install than its predecessors. The design specifications of the CR-4 unit include a one-piece “drop in” construction to dramatically simplify and reduce the time it takes to complete the installation. In addition, the unit’s modular construction allows for improved access to internal components, making it easier to service. This translates to less downtime, which is critical for bus fleets operating on tight budgets. ACT’s CR-4 rooftop condenser can be matched with other ACT components to provide a complete HVAC system that meets various vehicle sizes, duty cycles and geographic locations.Roof Mount Air Conditioner Units Northern Air Systems roof mount air conditioner units are designed and built with the highest reliability. Rugged construction provides dependable cooling in the most demanding environments Designed for 24 hour operation in high load demands, from -30 to 125 Fahrenheit Available in painted stainless steel construction with marine coatings