The Vitosolic controller prioritization of where it directs heat is functioning a little differently than I anticipated. Each "cylinder" (storage tank) is given a priority and has a set "max temp". I thought that the controller would direct heat entirely to the highest priority tank until it reached the "max temp", then it would begin directing heat to the next priority tank.
Instead, it directs heat to whichever tank is 5 degrees below the collector (remembering the that collector is normally rising in temp while the tanks stay relatively static in temps during solar collection period). This actually works just fine, but it means that the higher priority tank may not reach full temp as fast. Still, under this type of control, there is definitely no opportunity wasted to collect and store solar energy.
Saturday, September 27, 2008
Sunday, September 21, 2008
Tubes Installed, System Operating
Installed the vacuum tubes this morning. Today's is cloudy with sun breaks, so the system is cycling the pumps. Later the array should get full sun and both DHW and Heating tanks should be fully heated. The angle of the collector is optimized for a low angle winter sun, the time when the most collection capacity is needed.Saturday, September 20, 2008
System Ready for Vacuum Tube Installation
System flushed with hot water and a little detergent, then drained and charged with Tyfocor HTL to 27psi. This is a special propylene glycol mixture specified by Viessmann. I started with 5 gallons, but had to add approximately 1 gallon of water. Full strength was good for down to -35C, which is -21F. I checked it with an automotive anti-freeze tester (used to check ethylene glycol), and it only showed good for 15 degrees. I will buy another 5 gallons of Tyfocor and repump the system displacing the mixture before the real cold weather comes. I should be able to do it with introducing very little air.
Both circulation pumps that flow glycol to the collector, one for the DHW, and one for radiant heating, were ran and speeds set for the proper flow rates. All sensors were connected to the Vitosolic 200 controller (except for the one that will open zones in case of high temp in the radiant storage tank). The controller functions were checked by using cold and hot water to simulate temperature differentials that started the pumps.
I wanted to make sure that the collector circulation pumps would run so that when I install the vacuum tubes in the collector, the system would transfer heat from the collector and not overheat.
One last point about charging the system with glycol to 27psi. The specification is 37psi. I am guessing that the pressure is necessary to suppress boiling when the collector is running hot. I circulated some glycol through the DHW tank coil and heated up the system. The pressure came up to 30 psi when I got the temp up to 80F. So, I believe the pressure may not only come up to spec, but go higher when the system is in operation.
Both circulation pumps that flow glycol to the collector, one for the DHW, and one for radiant heating, were ran and speeds set for the proper flow rates. All sensors were connected to the Vitosolic 200 controller (except for the one that will open zones in case of high temp in the radiant storage tank). The controller functions were checked by using cold and hot water to simulate temperature differentials that started the pumps.
I wanted to make sure that the collector circulation pumps would run so that when I install the vacuum tubes in the collector, the system would transfer heat from the collector and not overheat.
One last point about charging the system with glycol to 27psi. The specification is 37psi. I am guessing that the pressure is necessary to suppress boiling when the collector is running hot. I circulated some glycol through the DHW tank coil and heated up the system. The pressure came up to 30 psi when I got the temp up to 80F. So, I believe the pressure may not only come up to spec, but go higher when the system is in operation.
Wednesday, September 17, 2008
Collector Support Frame and Header Installed
The support frame was constructed out of Unistrut 1 5/8 and 3/4 electrical conduit supports. The piping is connected, including a vent on the outlet. Other than insulation on the piping, and establishing circulation, the collector is ready for installation of the vacuum tubes.
Saturday, September 6, 2008
Boiler Room Components Addition Nearly Complete
The solar capacity tank (which as my existing DHW tank) is now installed, filled and opened to the boiler system. It is shown on the left in the photo below. The new pump that will carry the heat from the collectors to the existing header that supplies my radiant heat system has also been ran. It is in the photos and is one of the two purple Grundfos pumps that are placed between the tanks.
The other two new pumps, one in the Solar Divicon and the other one below the Divicon, are ready to be test ran once the tubing runs to the roof are done and the Vacuum Tube collector header and support frame for the tubes is installed. The tubes cannot be installed until the system is filled and circulation is established.
If you examine the picture closely, you will see a vertical line with a temp gauge and a flow meter in the line just to the right and above of the left hand tank.
These were installed to augment the temp gauge and flow meters in the Divicon, which monitor the flow and temp of the fluid on it's way to the collector from the DHW tank, and the temp of the fluid coming back from the collector. The added flow and temperature metering is to monitor the fluid from the solar capacity tank used for radiant heat going back to the collector, that ties in down stream of the Divicon, and would otherwise not be monitored. Each flow comes from a separate pump. Referring to the schematic would make this a little less confusing. Clicking on it should expand it to a readable size.
.jpg)
This is why I must be able to monitor both flows:
The correct flow rate for a single 30 tube collector is .8 gpm, and will be controlled by using one of the three speeds available on the pumps. The Vitosolic controller will only run one pump at a time, so a flow meter on each pump discharge is necessary to determine what speed setting will give the correct .8 gpm flow on each pump.
2nd reason for monitoring and maintaining equal and correct flows:
In addition to controlling the solar heating system, that neat little Vitosolic controller can also compute and generate a "heat statement" hopefully in the form of how many BTU's you have collected and distributed to your DHW and radiant heat. It does it by measuring temperatures (differential temperatures across the collector to be precise), and calculating the BTU's using a set flow rate programmed in. So, you must have equal and known flow rates for what goes across the collector for the calculated BTU's to be accurate.
Why do you need BTU's? Simple! This is all about saving money. In my case, I have to buy propane which has 91K BTU's per gallon. I am expecting to pay $2.50 to $3.50 a gallon this winter.
I've spent $12,500 on equipment (should get $2000 back with the Federal tax credit), so if propane averages $2.50 per gallon that is 4000 gallons that is required to be saved to pay back on my solar investment. Even with burning almost 2 cords of wood a winter, I still have to buy around 1400 gallons of propane a year. Even if my solar conversion only saves me from buying 1000 gallons a year (I still have to dry my clothes with propane), that is a 4 year payback! I would be thrilled if the payback is any less than 5 years! Time will tell.
The other two new pumps, one in the Solar Divicon and the other one below the Divicon, are ready to be test ran once the tubing runs to the roof are done and the Vacuum Tube collector header and support frame for the tubes is installed. The tubes cannot be installed until the system is filled and circulation is established.
If you examine the picture closely, you will see a vertical line with a temp gauge and a flow meter in the line just to the right and above of the left hand tank.
These were installed to augment the temp gauge and flow meters in the Divicon, which monitor the flow and temp of the fluid on it's way to the collector from the DHW tank, and the temp of the fluid coming back from the collector. The added flow and temperature metering is to monitor the fluid from the solar capacity tank used for radiant heat going back to the collector, that ties in down stream of the Divicon, and would otherwise not be monitored. Each flow comes from a separate pump. Referring to the schematic would make this a little less confusing. Clicking on it should expand it to a readable size.
.jpg)
This is why I must be able to monitor both flows:
The correct flow rate for a single 30 tube collector is .8 gpm, and will be controlled by using one of the three speeds available on the pumps. The Vitosolic controller will only run one pump at a time, so a flow meter on each pump discharge is necessary to determine what speed setting will give the correct .8 gpm flow on each pump.
2nd reason for monitoring and maintaining equal and correct flows:
In addition to controlling the solar heating system, that neat little Vitosolic controller can also compute and generate a "heat statement" hopefully in the form of how many BTU's you have collected and distributed to your DHW and radiant heat. It does it by measuring temperatures (differential temperatures across the collector to be precise), and calculating the BTU's using a set flow rate programmed in. So, you must have equal and known flow rates for what goes across the collector for the calculated BTU's to be accurate.
Why do you need BTU's? Simple! This is all about saving money. In my case, I have to buy propane which has 91K BTU's per gallon. I am expecting to pay $2.50 to $3.50 a gallon this winter.
I've spent $12,500 on equipment (should get $2000 back with the Federal tax credit), so if propane averages $2.50 per gallon that is 4000 gallons that is required to be saved to pay back on my solar investment. Even with burning almost 2 cords of wood a winter, I still have to buy around 1400 gallons of propane a year. Even if my solar conversion only saves me from buying 1000 gallons a year (I still have to dry my clothes with propane), that is a 4 year payback! I would be thrilled if the payback is any less than 5 years! Time will tell.
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