June 18, 2007

TTY /dev/ttyAM0

READ_TIME 1000

LOG_TYPE 1

LOG_FORMAT "%b %d %H:%M:%S Sensor %s C: %.2C F: %.2F"

CNT_FORMAT "%b %d %H:%M:%S Sensor %s #%n %C"

HUM_FORMAT "%b %d %H:%M:%S Sensor %s C: %.2C F: %.2F H: %h%%"

SENSORS 16

ROM 0 0x28 0x84 0xEC 0xC0 0x00 0x00 0x00 0xEA 5 Outside (roof)

ROM 1 0x28 0xA4 0xCD 0xC0 0x00 0x00 0x00 0x69 6 MBR Floor (Thermacrete)

ROM 2 0x28 0xEC 0x95 0xC0 0x00 0x00 0x00 0x16 7 MBR Subfloor (plywood)

ROM 3 0x28 0x3C 0xC5 0xC0 0x00 0x00 0x00 0x47 8 Big room (NE corner)

ROM 4 0x28 0x72 0xD6 0xC0 0x00 0x00 0x00 0x13 9 Munchkin Return (

ROM 5 0x28 0x2A 0x8D 0xF5 0x00 0x00 0x00 0xB0 10 Panel Outlet (roof)

ROM 6 0x28 0x76 0xC7 0xC0 0x00 0x00 0x00 0x7E 11 MBR Wall

ROM 7 0x28 0x9E 0xC0 0xC0 0x00 0x00 0x00 0xA7 12 Munchkin Supply

ROM 8 0x28 0xA1 0x88 0xF5 0x00 0x00 0x00 0x70 13 Heat exchanger inlet

ROM 9 0x28 0x99 0x87 0xC0 0x00 0x00 0x00 0x9A 14 MBR Earth (concrete)

ROM 10 0x28 0xD3 0xB2 0xF5 0x00 0x00 0x00 0xBF 15 Domestic Hot Water

ROM 11 0x28 0xB3 0x9B 0xC0 0x00 0x00 0x00 0xBE 16 Hall ceiling

ROM 12 0x28 0x0B 0x9A 0xF5 0x00 0x00 0x00 0x1C 17 Solar tank

ROM 13 0x28 0xEB 0xE0 0xC0 0x00 0x00 0x00 0x2C 18 MBR mid insulation

ROM 14 0x28 0x67 0x83 0xF5 0x00 0x00 0x00 0x2D 19 Heat exchanger outlet

ROM 15 0x28 0x0F 0x9B 0xF5 0x00 0x00 0x00 0x0D 20 Water tank flame

Cat-5 between closet and hot water tank room on south side:

Green/Green-white Temperature Sensor Network (DS1820)

Orange/Orange-white 12VDC Relay for recirculation pump, connects to Orange/Brown from relay box on wall of hot water tank room

Brown/Brown-white 12VDC relay for solar panel pump, connects to Red/Black from relay box on wall of hot water tank room

These two pumps are controlled by the ARM system. The recirc pump comes on when the gas-fired hot water tank outlet falls below 100F and the solar tank is above 105F. The recirc pump turns off when the gas-fired hot water tank outlet goes above 110F.

The solar panel pump turns on when the panel temperature is above 95F and turns off when it falls below 90F. When we put the sensor in the panel rather than on the side of the panel, these figures will change to 150F and 100F.

The pool solar heating system has four temperature sensors. These sensors are supplied with 5VDC and generate an analog voltage proportional to the temperature, about 100 mv per degree C, as I recall. They generate about 3VDC at room temperature. These sensors are read by the 8 channel A/D converter in the ARM TS-7200. They connect to the ARM via Cat-5 cables. There are two Cat-5 wires that run from the pool equipment in the back yard to the ARM. There is one four-wire cable (not Cat-5) that connects from the sensor on the roof and the ARM.

The one control the ARM system has is the diverter valve. It has two positions and is controlled by 24 VAC that is sent by the ARM system via a relay on the Tri-M PC/104 card. When the leftmost panel reaches 150F, the ARM system switches the diverter valve so that water coming from the pool pump is sent to the panels. When the panel drops below 100F, the ARM system switches the diverter valve so that the water goes straight back to the pool, without going through the panels. The ARM sends the 24VAC signals to the diverter valve via a heavier gauge wire normally used for sprinkler system valves. It uses three wires, a common, a signal for switching the water one way, and another for switching the other. A switch on the diverter valve reverses the sense of these signals and can be used to temporarily open or close the diverter valve. But it must be left in the position that corresponds to the sense of these signals that the ARM software uses. There is always 24VAC on one or the other of the diverter valve controller. Limit switches in the diverter valve stop the motor in the diverter valve once it has reached the commanded position, but the controlling voltage stays present. During the winter, I switch off the 24VAC relay that is mounted next to the ARM system to save power (the 24VAC transformer stays warm when powered even unloaded, not very efficient).

The top manifold for the panels has a vacuum breaker, so when the pump turns off, of when the diverter valve shuts off water going to the panels, the water in the panels will drain back down to ground level. It is important that water not stay in the panels. On a cold night, the panels could freeze and burst. On a sunny day, sill water in the panels will boil and could damage the PVC pipes. There is a passive drain on the pipes that take water up to the panels that allows some amount of water back into the pool even when the system is operating normally. The passive drain T’s off from the 2” PVC at ground level, on the side of the house near the water faucet and the sprinkler box. It goes through a check valve and joins a pipe used for filling the pool from the house cold water supply.

The pool pump is on a timer and it is important for this timer to run the pump during the times that the solar panels are warm. Currently there is no way for the ARM system to control the pool pump. However, I do plan to install a pool pump that is controlled by RS-485 commands and the ARM system does have the ability to talk RS-485.

The heating system consists of a Munchkin boiler that Kevin Smith of Lipp Hydronics installed in 2004. Kevin’s system has three zones that are controlled by conventional Shaw thermostats. In 2005 I added five more zones, for the central bathroom, Annie’s study, Lillian’s bedroom, the old living room, and the big room. In 2006 I added the master bedroom. Kevin’s three zones and the MBR are copper tubing in Thermacrete. The rest of the zones are Onyx tubing stapled up under the wood floors. The copper/thermacrete floors have a lot more thermal inertia and thermal conductivity. So they hold the heat longer and then transfer the heat from the circulating hot water to the floor surface more quickly. They also cause the circulating hot water to chill more quickly, naturally.

Flow of hot water to all nine zones is via a Taco pump and a Munchkin boiler. Flow of water to each zone is regulated by a Honeywell 24VAC zone valve on the return side of each zone circuit. The MBR zone has five loops and each loop has a ball valve on the supply and a gate valve on the return. The big room zone has four loops. The old living room has two or three loops (I can’t remember now!). The rest of the zones that I did have just one loop each. I have never adjusted the gate valves on any zone, they are all full-open.

The zone valves have four wires. Applying 24VAC to two of the wires causes a small motor to run that opens the valve. The other two wires come from a limit switch that closes when the valve is fully open, which takes about 15 seconds. When the 24VAC is removed from the valve, it closes immediately via a spring. The valves also have a lever on the side of the valve that allows the valve to be held open regardless of whether it is powered or not.

The wires from the six newer zone valves (i.e., the ones for the part of the house that I did) go into a Taco box in the back closet. This Taco box sends its “request for heating” to the four zone Taco box in the Munchkin closet. This four zone box is one that Kevin installed and it takes in the three zone thermostats and three zone valves that Kevin installed. Its fourth input comes from the six zone box that I installed. In this way, the two Taco boxes are cascaded to form a nine zone system. The two boxes are connected via the Orange/Orange-white pair in a Cat-5 that goes between the two closets, under the floor.

The thermostat inputs for the six-zone box come from six small relays on the Tri-M PC/104 card plugged into the ARM box. The ARM box thus mimics six thermostats. It decides when to activate each zone based on the temperatures it reads from just three thermostats, one in the ceiling of the central hall, one in the wall of the MBR, and one in the big room’s far corner. A Bash script runs every five minutes, reads the temperatures, records them, and calls a C program “solar” that controls the zone relays. The Tri-M board’s relays connect to the Taco box via two Cat-5 lines. I intend to rewrite the “run_solar” Bash script and the “solar” C program in Perl to make it easier to read and maintain.

To do:

1. Control the new pool pump via RS-485

2. Control the recirculation pump and the solar panel pump via the ARM system

3. Find a way to control the solar panel pump from the ARM system (all eight relays on the Tri-M board are in use – buy another Tri-M board?)

4. Fix up the wires, use terminal blocks, better mount the ARM system.

5. Put the ARM system on 12VDC and battery-back-up the 12VDC system