November 23, 2002
Mason by Day, Geek by Night
Panoramic view from atop the bluff. (Click on photo for larger image.)
With pocket protector and slide rule (Slide rule?...What's that?) in hand, I went to work this week writing a computer program and installing an A/D (Analog to Digital) converter to remotely monitor the temperatures at the house.
The A to D converter has a total of eight analog inputs, which allows me to monitor eight different sensors inside and outside of the house. So far I have decided to use the first four to monitor outside temperature, inside temperature, solar in and solar out temperatures.
The A to D converter is hardwired to a PC via an RS-232 (serial) interface. Using a home grown Visual Basic program, the PC constantly reads the A to D converter and on the hour, saves the data to disk.
To further secure my permanent membership in the geekdom hall of fame, I use a macro program to automate a dial-out to the Internet at 58 minutes after each hour, transferring the data to the Day Creek web site. This means that you can share in my geekiness by viewing the house stats almost live. This is all quite experimental at this point, so don't go calling me up in the middle of the night if it ain't workin'. With that disclaimer said, here's the temporary link for you to see for yourself: http://www.daycreek.com/dc/html/gettemperatures.asp
Having new tools to monitor the solar heating system, I discovered a problem with the solar heating system Thursday evening. I looked at the inbound side of the floor manifold and discovered the temperature was 79 degrees while the outbound side read 63 degrees. This was occurring 3 hours after the sun had set. Both these numbers should be within a degree or two of each other. What was happening? The heat from the sand bed was moving out of the floor and into the solar panels through a process known as thermosyphoning.
Thermosyphoning is a process similar to hot air rising in a chimney, except with fluids instead of a gas. If this process is left to continue, the heat stored in the sand bed would eventually be replaced by outdoor temperatures. The collectors also make effective radiators in reverse!
But...that shouldn't be happening because there is a check valve in the system that was installed to prevent such a thing from occurring. In other words, the check valve prevents the fluid flow from reversing.
I temporarily stopped this from occurring by turning a ball valve to the closed positioncutting off the flow. I sent an email off to Steve Krug asking him if check valves can stick open. Sure enough they can, and with advice from Steve and my friend Tom, I went outside with a hammer and banged on the check valve. This did the trick, but I hate the idea of a "bang-on" fix. Will it happen again? I hope not!
Steve stated that they can "stick" open by means of debris getting stuck in the valve. As soon as he mentioned that, I envisioned my nemesis coming back to haunt mea dead carcass of a lady bug! They were crawling all over the place when the collectors were installed and I flushed a bunch of them out of the system during the installation process. Is there one left floating around? I hope not!
So, if you check out the temperature web page some evening and the inbound temperature is higher than the outbound temperature (by more than a couple of degrees), you'll know it's happening again. (Unfortunately I won't be up at the house to bang on the valve this week, so hopefully this won't be the case.)
If it keeps happening, I might have to do some modifications to the system to add a secondary check valve or replace the existing one. I certainly don't want to have to drain and refill the system.
Tuesday morning I put on my astronomical beanie and watched the Leonid meteors from the house in Minnesota. I thought about going crazy again like last year and driving to some remote part of the world, but thought better of it and instead stayed put at the house. The moon was full, which was certainly going to wash the sky out, if by some strange chance it was clear in Minnesota.
The odds were against me for clear skies, but by a stroke of luck it stayed clear most of the night and there never were more than a few clouds. I started viewing at 2:30 in the morning and watched until sunrise. It was a beautiful night with the clear skies and quiet surroundings. Occasionally I would hear the sounds of coyotes or animals foraging in the woods but other than that it was quiet...well...until about 4:00 a.m. That was when my coat pocket started ringing. It was Jo calling me to make sure I didn't oversleep. The skies had just cleared in northern Illinois and she was seeing them from the bedroom window too. So we gave each other a play by play of the event -- how romantic!
It was quite a sight to behold even with a full moon in the sky. I was amazed at how many bright meteors there were. One can only imagine how intense the shower/storm would have been with no moon to spoil the show. At the peak, I could see anywhere from 10 to 15 meteors per minute! The peak only lasted for a matter of minutes though and sharply fell off from such high numbers.
I did get a few good photographs with and without meteors. The moon made the landscape look like mid day in the summer, but with fog obscuring some of the bluffs, made the photographs quite eerie. All and all it was worth getting up for and I was very fortunate to have clear skies.
Also during this week, I started construction on the first inside cordwood wall. This wall will be the wall behind the bathroom shower stall so it will never be seen. With weather conditions stable in the house, this will be a good test wall to test different cordwood mixes. Cliff Shockey used a very simple mix of masonry cement and sand for his interior walls and experience no cracking. I tried his mix with the first four courses of wood and after only a day and a half, discovered quite a few cracks.
It was then that I decided to do some testing. I called the local cement company in town and asked if they had any cement retarder on hand. They did and for a few bucks I got a large jar of the stuff. The retarder is quite concentrated so I've started out cautiously and I will report my findings here on Day Creek over the next month. I will be trying different amounts, but from what Rob Roy and others have reported, it slows up the setting time long enough to prevent cracks. We shall see...stay tuned.
I'll be here in Illinois this week with Jo getting ready for Thanksgiving, so the next journal will be in a couple of weeks. Have a great Thanksgiving!
A foggy moonset.