Solar hot water system mantenance

        Installed in August of 2005 my SDHW system has been a learning experience. After storing 2 salvaged flat plate collectors from a 1970's system and reading up on several system designs in Home Power magazine I made the leap. After building a tube within a tube heat exchanger that was featured in Home Power I was ready to go. Second, I say second because it took me two times to learn that the domestic side water loop would require a bronze circulating pump to survive the high lime content in my non  softened water supply. Then everything ran like clockwork and provided over 50% of my hot water needs (100% during the summer months)for the next 10 years.
       Year after year all was well until around November of 2015 and I noticed that the system was not pumping. Thinking that the problem was with the anti freeze filled solar loop I did not want to mess with this until warmer spring weather. So I waited until last week. Then I noticed that there was a small black burn mark on the circuit board where a relay for the differential temperature controller was. After replacing the relay still no go. Now I had the problem zeroed in as a locked pump that allowed high current to fry the relay. The plan was to replace the hot side loop antifreeze side and pump.

After draining the system I was ready to replace the pump and refill however the pump was just fine.

So I want ahead and refilled the system and bled off any trapped air. So far so good.

Now would have been a good time. I was a bit fuzzy on remembering the system details and how all the pieces, pumps, check valves, loops, air vents expansion tanks, etc, etc. fit and work together. But, I plunged ahead. Shutting off the water supply and removed the domestic loop pump. Locked solid just as I suspected. Even the bronze pump could only last 10 years.

Here is where things got ugly. The picture shows the correct stack up with the compression plate behind the pump cartridge flange. For some odd reason on the first try I put it on the other side. A total failure to seal the water and when I turned on the main, in the basement, water shot out all over before I got upstairs! And back down!! I had a lot of time while cleaning up the spillage to THINK!

After replacing the pump cartridge with a new bronze one I also installed a flow indicator in the domestic side. There is just something about seeing the flow in the system that gives me piece of mind.

And in a few short minutes of operation the pressure was up and the solar loop was hot. That heat was being transferred by the heat exchanger to the domestic water. There would be a solar shower tonight!

Mortise and tenon table base

A few months ago a former student brought in some old barn timbers for a table base he was making and wanted to know if I could join them together for him. Sounded interesting, I said OK. How hard could it be?

We unloaded the pieces, two Oak 8x8x36 beam supports and one 10x10x48 Oak beam piece. I began to think about it. A drawing and model would be needed.

At first glance it looks like a no brainer. Cut the pieces and then put them together with a hand full of Kreg pocket screws. Right? Well not quiet. This was going to be a nice half lap joint with the vertical piece joined to it with a tenon through both bottom pieces. A bit of a head scratcher for sure. Upon closer examination you can see the two 10" long mortis slots cut into the beam supports. Think about that for a second.

Taking into consideration that the tenons would be two inches wide and what I wanted for strength I cut the housing depth for the half lap joint.

With the half lap cut now it was time to work on the cutting the mortis into it to receive the tenon on the vertical piece. That tenon would not be as simple as a nice 4x4 because of the 10" mortse already in the pieces.

OK then, hear you have it. The base pieces half lapped together with the mortise cut into it. Can you visualize what the tenon it going to look like?

But first I needed to rig up a "helper" to assist me in lifting the 80 pound vertical piece. I knew that I would be handling this piece a lot to get it cut and fit. This little worm screw winch left over from the bridge project would do the trick nicely.

After leveling up the bottom so that the vertical piece sat plumb it was time to start drilling out some wood so the tenons could be cut and squared up.

And there your have it! I counter bored a 1/2" lag bolt through the bottom tightened it up. 

Easy as pie.