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Design Tips from Jeremy Mills: Solar Hot Water Heating Expert!

We had the opportunity to have a great conversation with Jeremy Mills over at Alternate Energy Technologies, LLC all about the ins and outs of installing solar hot water heaters.

Who is Jeremy Mills?

About six years ago, Jeremy decided renewable energy was the place to be and he got into the industry by offering free labor on alternative energy installations. He quickly learned a lot about how to size, install and troubleshoot solar thermal technologies.

Once Jeremy was a bit more experienced, he went to work for AET, doing factory direct installations and ultimately he became the foreman on their crew. He spent some time working in the AET factory learning about the manufacturing process of the solar hot water collectors and then ultimately left AET for a while to gain further experience.

After doing installations for other companies and for his own business throughout the south and on Grand Cayman Island, he is now back at AET managing the AE solar design and installation division providing technical support and services to AET dealers everywhere.

Jeremy credits his time as an installer for truly cementing his solar hot water expertise and allowing him the time and hands on experience to really know what to expect when it comes to BTU production, sizing pipe runs, manifolds and the like.

Tips from the Expert:

1. A lot of people try to cut corners by using non-copper pipe in their systems. They'll use PVC pipe to save money but Jeremy says copper is the way to go, especially in the solar loop. Cutting corners on the piping you use will only lead to more maintenance in the future - so if you want less maintenance hassle, stick with copper!

2. If you're installing a drainback solar hot water heating system, you never want to mount your panels horizontally.

3. Always maintain slope on your lines; both in supply and return.

4. Only use closed cell insulation like Rubiflex or Armaflex for pipe insulation. Likewise, make sure that any external pipe work is protected from UV because otherwise it will break down.

5. When running the sensor wire only use shielded stranded wire.

6. Make sure the shield is grounded at the controller only.

7. When attaching the sensor to the return pipe at the top of the solar hot water collector, make sure you clean the sensor and the pipe and use a thermal compound* to prevent oxidation and false readings after installation.

8. Keep any sensor wires far away from high voltage electrical wires.

9. If you have a system that uses propylene glycol, the glycol should be tested once per year for breakdown and acidity.

10. In a drainback hot water heating system, always be sure to mount your pump below the drainback reservoir.

11. Make sure your system can be drained and filled from the lowest point in the loop.

12. Always use flashings when making roof penetrations - on pipe AND collector mount feet

*Thermal compound is the same stuff used to attach a processor fan to a computer processor - you can get it at Radio Shack or from AET

Key Things to Avoid or Consider

1. Some people forget that all sensor connections should be "no-ox'd" and should be completely water tight. No-Ox or No-Lox prevents oxidation of the wires which is why you'll get and maintain a good signal.

2. From time to time, people will mistake the supply and return lines and get them backwards - so keep an eye out for that!

3. Be careful not to oversize a pressurized closed loop glycol system or a direct system. If there is too much in the collector and in your water storage system and you don't use the hot water, the system can overheat which will break down the glycol in the system and ultimately lead to overall system failure.

4. People will usually go with the cheapest option which means no drainback in their closed loop solar hot water heating system. Generally, drainback is advisable although sometimes it doesn't fit because of slope limitations or logistics. Consider whether or not to implement a drainback carefully since spending a little more money up front on your system can save you quite a lot in the long run.

5. You have to be careful in choosing your pump size. Sometimes with two story or more buildings, you need to incorporate additional pumps or you may have to just size up. Carefully choose your pump depending on the size of building, the number of collectors and the size of system.

6. Once you have your system installed, use sizing and flow rates to tune the system for optimum performance.

7. Consider a blue and white flow meter for your drainback solar hot water heating system. A blue and white flow meter is never a bad idea for easy tuning!

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