I just came across an interesting item describing the three most common types of coolant for solar hot water systems and some of their properties. The article seems to be written by the manufacturer so there may be a bit of bias, but it does highlight the issues inherent in coolant selection. It is short and easy to read.
Have you ever heard of the concept of an “Earthship“? I was introduced to the concept by my brother-in-law about 14 years ago and was blown away. What is an Earthship then? In a nutshell, an Earthship is an Eco-friendly home, made predominantly from recycled materials, designed to be as close to “off-grid” as possible.
The concept of Earthships arose in the halcyon flower-power days of the 1970s in various states in the southern USA. The concept seems to have developed by Michael Reynolds, an architect from New Mexico. As you can see in the linked Wikipedia article, his idea was not without problems, but it was, none-the-less revolutionary. Michael has a website where he educates about, demonstrates and promotes the Earthship technology. The site has designs for a number of systems that an Earthship needs if it is to meet code (see figure 2, below). Continue reading What the heck is an Earthship? … maybe an idea whose time has come!
Regardless of what anyone tells you, if you live in North America your pool should not be losing more than about an eighth of an inch of water (3 mm) each day in the summer. If it is losing more that that…don’t ignore it and don’t let people tell you that the larger amount of water loss is to be expected. An inch of pool water is a huge amount and the western world is just beginning to understand that water is our most precious resource. Don’t waste it like I did!
My family has had an in-ground swimming pool since the kids were little. Generally, we have only had to fill up the pool in the early spring and we are more-or-less good for the rest of the season. There is a bit of evaporation, but it is usually replaced by rainfall. This year, unfortunately, was “off the charts” as far as water consumption goes and that is an environmental disaster. Continue reading Pool leaks are an environmental disaster!
I spent 6 months living in Kathmandu back in the 90s. It was commonplace for the power to go off each evening for 2 or more hours and to cope with the outages everyone had battery backups and gas-powered generators.
But over here in Canada we have never needed battery backups or generators to keep things running. The electrical system is far more reliable here than it was in Nepal in the 90s. That being said, we do still get the occasional power outages but for the most part they are little more than an inconvenience. The same cannot be said for solar thermal systems when the power goes out. Continue reading Solar Thermal – What to do when the power goes out!
The City of Ottawa has a nice new web page that acknowledges the existence of solar energy, and in particular solar domestic hot water (SDHW). The site, which can be found on ottawa.ca gives information about two different types of SDHW systems: a CSA approved factory packaged system and not factory packaged system. Both types of installation need a building permit.
Both installation types must be installed by a qualified installer (CanSIA certified) but non-factory packaged installations must be certified compliant with CSA F379.1-09 (the reference standard for SDHW) and with the Ontario Building Code by a professional engineer licensed in the Province of Ontario.
This doesn’t sound like a lot of help, but when I had my solar system installed, there were no guidelines or standards available and we had to slog through a morass of bureaucracy to get our installation approved, so that guidance is very welcome.
This information should make the process of installing SDHW more transparent and it should really reduce some of the risks to the homeowners and installers. Good job Ottawa!
- Solar Thermal Program (miahillery.wordpress.com)
As I mentioned in earlier blog entries, my system has a number of failsafe features to maintain system heat and pressure within tolerable boundaries. In the summer, the system dumps excess heat into the swimming pool, and in the winter it dumps the excess heat into a radiant water heater in the basement.
This spring I got to see what would happen if I didn’t have these alternate heat sinks and I found out how robust the failsafe systems are in my installation.
Here’s what happened. To change my secondary (failsafe) heat sink from the basement radiant water heater to the swimming pool for the swimming season I need to open or close 3 manual valves. This spring, due to a brain malfunction, I only switched two of the three valves which meant that I had shut off the alternate heat sinks entirely. When I then manually switched the compter controlled valve (that determines whether to send water to the primary or the secondary heat sink) to use the “secondary” heat sink to dump heat, I had inadvertently gotten rid of all the system’s sinks. Effectively, I was just taking hot water from the solar collectors and circulating it back to the collectors without dumping any heat.
The first thing I noticed was that the pressure in the system built up (quickly) to 80 psi, from its normal 40 psi. This immediately got my attention and I looked at the collector temperature and found that it was 120 C – yes, that is degrees celsius, which means that the system was now boiling. I looked at the valve settings and realized my mistake and adjusted the valve settings appropriately, but by that time, it was too late … the failsafe features of the system had kicked in. My system had begun dumping antifreeze into a five gallon drum to reduce the pressure in the system. By the time I had realized this, the system was almost empty and the pressure had dropped to about 60 psi (by this time almost all vapour).
When I called my installer, he explained to me what had happened and suggested hooking the cold water from the city up to the antifreeze loop and filling the loop with fresh cold water. This had the effect of reducing the temperature and pressure immediately and everything and everyone calmed down immediately.
So what did I learn. Well…first and most important, even if you understand your solar system, you should not take it for granted. Keep checklists that help you with seasonal conversions and follow them. Second…the failsafe systems work. Even if I had not noticed the problem, the system would have emptied and the worst that would have happened is that my pump would have burned out. Finally, I learned how important it is to have your installer (or other expert’s) number close at hand…in my case the installer’s cell phone number was dymo-taped onto my controller and I was able to get hold of him – even though he was up at the cottage.
Does this make me less happy with my solar hot water system? On the contrary, I now know that even if I screw up, the family will still be safe, and I will be able to fix up the problems without spending a lot of money.
Solar system components
When you start to think about a solar system, you have to remember that the industry is relatively new in Canada. It has been used in Europe for decades, but its penetration on this side of the Atlantic has been marginal until recently. That means that you have to be conscious that some of the product on the market may not have been certified for use in Canada. The components that were installed in our house and that I will be speaking about below were all CSA approved and the “non-packaged” installation proposal that prepared was certified as compliant with the Ontario Building Code by a professional engineer.
It is a sad fact, but if you don’t get any sun, you don’t get any solar heat. But even the grayest areas of the country get a significant amount of sun. Thermomax, a is a Canadian company that uses European technology to provide solar hot water products. Its web site has done a great job of crunching the numbers to see how much water can be heated by a solar unit given the amount of sun available by region in Canada. Its regional comparison page can be found here. They also have a great set of interactive, audio enhanced graphics that explain how solar thermal energy systems work in various configurations. They can be found here.
I will be using their charts to get a better handle on how much money I have saved in the 4 years since I installed my system and will report back to you in a future blog entry.
In my earlier post I discussed how we decided to select solar hot water in our new house, but before we made the decision we had to understand something about the technology so that we could evaluate the options available to us. In this post, I will be describing the components involved in solar thermal systems in very general terms and I will wrap it up with a discussion of the “gotcha” points we ran into when implementing our solution.
When we bought our new house about 4 years ago, we wanted to be able to take some control over the utility costs so that when energy prices rise, we would have a bit of protection. There are lots of technologies out there that are environmentally friendly, but not all of them are suited to use in a sub-division and many have a low rate of return on investment. Further complicating matters is the fact that many of the municipal inspectors have no idea what they are looking at when presented with some of the new technologies. So which one to choose… Continue reading Solar Hot Water – Not easy, but worth it!