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Water Systems
The Challenge
First, we are on a septic system. That means it's not all that wise to run lots of cold water down the drain to get hot water flowing from the faucet. That led us to consider a recirculating hot water system.
Second, our choices of energy were solar, geothermal, wind, coal, wood, electricity (on the grid), and propane (to name the common ones -- we discounted exotic choices such as nuclear because the permit process is too burdensome.) Other petroleum options (diesel, heating fuel, etc.) are less attractive due to availability in the area, cleanliness of burning, and so on.
Even though we're not tree-hugging greenies, we briefly considered solar, but decided that in snow country, it's a bit of a hassle, and since we are trying to maximize the trees on our tiny 1/4 acre lot (for shade, not for hugging,) siting of the panels would be a challenge. Furthermore, we think solar panels don't make a very attractive roof. Wind is unreliable, even at an airport. Coal is a hassle to get, and there wasn't a good place to put the boiler. Ditto for wood. Besides, one of these days they'll outlaw burning wood (and probably coal.)
One of our neighbors who is building a house seriously considered geothermal heating for his heated garage floor and driveway, but decided that the cost of going down far enough was not worth it. He is opting for a boiler to run hot water under the concrete, and I imagine it will be propane-fired.
The realistic choices came down to propane and electricity. We opted for propane for hot water heaters as well as the heating furnaces. Propane will also supply the backup generator, and since we can use the single source for all those needs, we went with propane. Note that in our area, the local electricity provider still charges only eight cents per kilowatt-hour, so electricity is very competitive with the rising propane prices. But at this point, we're going with propane.
Hot Water Heating
To
introduce a little fuel efficiency we researched and ultimately decided
to install on-demand, tankless hot water heaters. There won't be any
hot water tanks that are inefficiently heating water all the time. The
on-demand heaters detect when water starts flowing, and then fire their
burners to heat water instantly. After careful consideration, we selected
the Takagi TK-2, primarily based on the availability of trained service
personnel in the Redding area.
We have two of these heaters on two separate circuits. One heater supplies the master bath and the kitchen. The second unit supplies the guest bath, the first floor bath, the wet bar, the laundry and the hangar sink. With two circuits working, there will be plenty of hot water to supply simultaneous showers plus the laundry and kitchen. There is also redundancy in case one of the units fails. And, of course, the hot water supply is available until the propane tank runs empty -- no more running out of hot water halfway through a shower!
These
units are configured with remote control boxes in the laundry room.
These remote units can set the output water temperature for the heaters,
and the remote controls display error codes in case of faults in the
heaters. Thus, the controls let us turn down the temperature for volume
use, such as filling a tub, or turn up the temperature for the dishwasher.
For example, to fill the jacuzzi tub in the master bath with 105-degree water, the temperature control on the water heater can be set to 105 (or, say, 108 to account for heat loss on the way from the heater to the tub.) Thus cold water doesn't have to be mixed in with overly hot water to bring the temperature down. Propane is not wasted heating the water to 120 or 140, as is typical with a hot water tank, only to add cold water back in at the filler faucet or shower to bring the temperature back down to something below scalding hot.
Recirculating System
The hot water system is a closed loop. That is, the water is pumped from the hot water heaters to the farthest point of each of the two circuits, and then a return line brings the water back to the heater inlet side where it mixes with input cold water from the street. Recirculating the hot water has multiple benefits:
-
since hot water is circulated through the hot water
lines, there is very little cold water to run down the drain when
a hot water faucet is opened. Essentially, the water in the riser
or branch circuit off of the main loop needs to be drained of cold
water to get to the hot water. This puts much less water down the
drain and into the septic system, and it wastes less water (a green
kind of thing to do!)
- less propane is used to heat the water that is recirculated since it has already been heated. The function of the tankless heater is to bring input water up to the programmed temperature. If the input water is already warm, it takes less energy to heat it to the preset level.
But wait!, you say. Don't recirulating pumps waste energy keeping the water going round and round? Well, not if the pump only runs when there is demand! The pump systems we've selected have a manual trigger. At each sink, there is a small momentary pushbutton. Depressing the button turns on the recirculating pump for that circuit, so no cold water has to be wasted to trigger the pump and heater. Then, when hot water faucet is opened, hot water will be at the faucet (or at least at the branch/riser.) The flow of the faucet keeps the heater burning.
Thus, to "prime" the system, the button is pushed momentarily to turn on the pump. Since the pump keeps water flowing through the heater, the heater keeps firing to heat the water going by. When the hot water goes all the way around the circuit, the pump shuts off and the hot water system is primed with hot water. Because the flow has stopped, the heater turns off. This whole cycle should take a few seconds.
Then, when the faucet is opened for usage, the flow starts again and the heater kicks in to keep supplying hot water. The pump does not restart since the water on the inlet side of the pump is still hot. No wasted energy! Cool, huh?
The recirculating system combined with the ability to set heater temperature
for big jobs means we will minimize wasted energy and water just to
get hot water of a certain temperature to a given faucet. We feel so
green -- this makes up for not going solar. 
The pump system we chose is the A.C.T Metlund Hot Water D'MAND system. It supports both retrofit and new construction applications. The owner of the company, Larry Acker, was extremely helpful. He supported our plumbing contractor directly and answered all the installation and application questions. We borrowed a picture from his web site above. We don't have the remote thermosensor. Also, we didn't install the wireless buttons for activiating the pump -- we hardwired buttons at each hot water faucet. In the end, we think we will be happy with this system.
One additional item we added to each hot water circuit is an expansion tank. The expansion tank accepts the increase in volume as water is heated and absorbs the shock of the system starting and stopping.
Pipe
Most of the supply and recirculating lines are PEX. PEX is "cross-linked polyethylene", or in other words, plastic tubing. It is easier to install than copper or galvanized since it is flexible tubing. Far fewer connections have to be installed. Fittings are pressed on the the tubing. Years ago, plastic pipe was frowned upon due to its softening in the hot water lines. But these days, PEX is in common usage, and we opted for it.
Interestingly enough, our plumber, Richard Bacciarini, told us that it is required by the building department in Lake Tahoe. It turns out that PEX is resistant to bursting when water freezes in it since it will expand slightly. Furthermore, all of our PEX tubing is wrapped in insulation jackets, both hot and cold. I asked Richard to color code the tubing -- blue paint for cold and orange for hot. The hot recirculating line is not painted.
The downside to PEX, according to Richard, is that the tubing wandering through the walls and joists doesn't look as neat and orderly as straight runs of copper with clean elbows for turns. On the other hand, fewer turns means less noise, so the PEX should be quieter and provide much less resistance to flow.
The PEX tubing is terminated at most locations with copper or galvanized stubs coming out of the wall. These metal pipes will provide the rigidity necessary to support valves and fixtures.
The drain pipe is ABS plastic except where there might be a noise problem, and then it's galvanized. The propane lines are steel.
Water Filtration
One day, Kelli and Richard were discussing the quality of the water. Kelli took a water sample in a gallon jug and let it stand on the counter for several days. At the end of the period, there was a layer of sand on the bottom. Not good. We had several breaks in the water line in the street this summer, and obviously, the lines weren't flushed well. We are on the farthest street from the "water filtration" plant in town, and we get whatever crud flows downhill.
That started the investigation of the water quality. Kelli got a pool testing kit and checked the pH. The test came out relatively neutral. However, when we had a filter dealer come to the site, he tested the pH and the water was *very* acidic -- way too much chlorine. The dealer said he wouldn't drink the water, and the plumber said the water would eat the copper tubing in the water heaters.
Trinity Center has a primitive water system. It was installed years ago, and is aging. Swift Creek water is diverted through a sand pit filter, and then chlorine is injected. Whether this system provides a consistent level of chlorination is questionable. Furthermore, when the relatively frequent breaks in the main lines under the streets are repaired, the system is typically not fully flushed.
Hence, we have decided to install a three-stage water filtration system in our house. It will first treat the water for proper pH, then filter the water for sediment, and finally irradiate the water with UV for sterilization. It is an automatic system that monitors water quality and corrects pH as needed. Some of our neighbors just drink bottled water, but with this system, we're also protecting all the plumbing.