(Source: )

(Source: inforse.dk)

http://sunearthinc.com/

As discussed in DHW #2, three components exist to delivering hot water to a user –1) Treatment & Delivery to Building; 2) Use in Building: Water Heater, Piping, Fixtures & Fittings, Behavior, Water Down the Drain; 3) Waste Water Removal & Treatment.
We are concerned here with the Use in the Building. In DHW#3, we addressed the water heater, here, we address piping.
To Improve the Use in building with respect to the piping we want to deliver hotter water sooner as shown in the diagram below.

Mr Klein and his colleagues offer 5 solutions to delivering hotter water sooner with the least amount of energy and water waste:
1) A central plumbing core, diagramed below would work if plumbing is allowed to direct the space configuration and architecture. Historically, this was how homes were built, providing central space and water heating.

2) A water heater for every hot water fitting. The heater, the energy, flues, extra space and maintenance is more expensive and less convenient than designing effective piping.
3) Many water heaters per home has a similar impact as above, its more expensive and less convenient than designing effective piping.
4) Heat trace on the pipes is expensive to install. Although great on water conservation, heat trace is energy intensive.
5) Circulation loop where 1 cup from every hot water fixture is allowed to be wasted, is the most effective option. Note that all circulation systems can save water, only Structured Plumbing can save energy. See diagram below.

Structured Plumbing as a form of the circulation loop, can minimize the waste of water, energy & time by
1) reducing the volume of water in the pipe (smaller diameter, shorter length)
2) reducing the number of restrictions to flow (decrease “effective length”)
3) increasing the face-velocity (smaller diameter pipe or a demand controlled pump)
4) insulating the pipe (becomes critical for very low flow rates and adverse environmental conditions)

What is the most sustainable thing you can do with your Domestic Hot Water System. 
1st, maintain your storage tank by 1) replacing the plastic drain valve with a brass one so that you can easily drain it with out breaking it. 2) flush out the tank by draining the water in it to remove solids at the bottom of the tank 3) replace the anode about every 3 years.  This can make your tank last 50 years.  You can checkout a fantastic website whose owner is committed to helping us save the hot water heater.  No more water heaters in the dump — or at least a lot less.

2nd, Consider these Myth Busters —
1. Each Water Heater must have 3 separate safety features to prevent a tank to blow up in our homes: thermostat keeps the temperature regulated, ECO, adn the T&P valve or pressure relief valve in case it does get too hot.
2. Legionella.  If you keep you water heater at 122, it is just above the dangerous bacteria’s comfort zone.  At 160, the bacteria will not survive but it is past the 120 scalding zone and you will need to install a mixing valve as part of the system.

3. The Rotten Egg smell comes from the non-toxic sulfate reducing bacteria, Divibrio Sulfurcans. This is caused by elevated sulphur , activated hydrogen from the cathodic reactions in the tank (never remove the anode), or no oxygen (water utilities will oxygenate the water to avoid this problem).
3rd, with a retrofit, be sure to consider the future of DHW.   An excellent current water heater is the A. O. Smith Effex with the low voltage fan and anode for superior gas storage water heater performance (.70 EF). The future of gas water heater is the A. O. Smith Vertex Condensing Storage Water Heater with a 99.1 % Efficiency Factor.  The Condensing unit requires 110 V and a condensate drain. If you are heating with electricity, although strongly discouraged, their future are the electric heat pump which promise at least 2.0 EF.  Finally, the only reason you would want to install a tankless is if, you have limited storage space, you have a need for point-of-use where the unit is literally installed adjacent to the fixture/appliance OR as a booster.

We have a long way to go in understanding the service of hot water to our domestic needs.
According to Gary Klein & Bob Hoover, two experts in hot water that I really respect, three components exist to delivering hot water to a user — 1) Treatment & Delivery to Building; 2) Use in Building: Water Heater, Piping, Fixtures & Fittings, Behavior, Water Down the Drain; 3) Waste Water Removal & Treatment.
Once in the building the simple hot water system energy and water efficiency has as much to do with fixtures and appliances as it does with the actual water heater and the piping delivery method. Bob’s diagram below shows what a simple ‘hot water event” looks like

We turn a faucet on, the valve opens and triggers the water heater. Below, the time for delivery is can be 15 seconds to 3 minutes.  90% of actual use is 30 seconds for hand washing and the cool down is very slow. 

Often, we turn off the hot water valve before we have received the hot water. NREL (National Renewable Energy Lab) measured the ‘hot water events in a master bathroom Lavatory.  They discovered that most Events trigger the hot water, use energy while the end user never gets the hot water.  See below.

A sincere thank you to Gary Klein, Bob Hoover & PG&E for your expertise in DHW.
www.homechi.net

(Source: nrel.gov)

Why is DHW efficiency important?

Water & energy are inextricably bound together from generation to use.  90% of US is thermoelectric power — electricity resulting in burning a fuel (49% coal, 20% NG, 19% nuclear, 2% Petroleum ) to boil potable water that creates steam, generating electricity.  Hydroelectric accounts for 3.8 billion gallons of water evaporated.  Bio-fuels require 8 to 50 water gallons per mile.  Finally, according the the California Energy Commission (CEC) the Water Use Cycle Energy Intensity. In California, Lake Arrowhead uses the most kWh/MG - million gallon compared to any other jurisdiction.

In 2001, the CEC did a study to find out the amount of energy used in relation to water.  They foud that 25% of energy is water-related — Saving Water Saves Energy.

A sincere thank you to Gary Klein, Bob Hoover & PG&E for your expertise in DHW.

www.homechi.net