Mounting Solar Thermal Collector Arrays

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Actually mounting the solar collectors comes after you've completed the long process of planning and marking out their locations on the roof. Follow these guidelines to install your collectors:

  • Start with the first collector at either end if you are mounting a multi-collector array, then work towards the middle. The entire area should be marked out beforehand.
  • Remember that all solar thermal collectors must be mounted with a slight pitch towards the supply end, so that you can drain them for maintenance. An inch for every 8 feet of run is sufficient. This is critical in drainback systems, so you should exaggerate the pitch by doubling the normal figure (an inch for every 4 feet of roof run).
  • If you're new to solar thermal installations, mount the collectors one at a time. If you have plenty of experience, you may prefer to install all the mounting brackets before lifting any of the collectors to the roof.
  • Install the bottom mounting brackets for the first collector.
  • If the collector will be mounted flush at the roof angle, install the top mounting brackets. If not, install the riser legs as required.
  • Either move to the next collector mounting location or install the first collector, as desired.
  • Once all mountings and collectors are installed, move on to connections and plumbing.

 

Joining collectors together

There are two ways to join multiple collectors together into a single array: brass unions or copper couplers. The former is generally a better option. Brass unions are soldered onto the collectors while they are still on the ground or are sometimes even fitted at the manufacturer's factory. The best choices use an O-ring or gasket. There's less soldering to do on the roof and they are more forgiving for minor adjustments – you can snug them up as you are mounting the collectors and only tighten them once everything is in place. They're also friendlier if you ever need to replace an absorber plate.

Copper couplers are tougher to use. You'll need to clean and flux the collector nipples before you slide the couplers together and you may find that each subsequent connection becomes finicky if the collectors are already mounted – the couplers aren't very flexible and rarely line up precisely. The alternative is to connect them before fixing the collector arrays on their brackets, but then the mounting hardware might not line up properly. If you decide to use copper couplers, mount all the collectors and push them tight together before soldering.

While we're talking about the collector nipples, it's important to note that they are quite fragile and bend easily. It's extremely rare for them to line up precisely (although they will be close!), so you'll need to be careful when adjusting thing – again, brass unions are more forgiving than copper couplers, which require the nipple to be perfectly round. There is a tool to help you reform bent nipples, which you can get from a plumbing supply store.

  • If you're using brass unions, you can tap them with a rubber mallet to get them to