Design a Tankless Hot Water Installation
There are several things that you have to consider with a tankless water heater installation: water hardness, gas flow, exhaust and venting, drains, and the dreaded recirculating pump.
Hard water will kill a tankless water heater. Calcium build-up will destroy the efficiency of the heater and eventually plug the heater. Be sure to test your water for hardness before installing a water tankless water heater. I live in the southwest, and our water is super hard. I needed to install a water softener as part of the installation. I chose to get the Premier 40,000-grain High Capacity Water Softening System from Costco. The price was great, and it appears to have a high quality Watts valve. The water softener has run flawless since November 2013 and our clothes, and bathrooms have never been cleaner. Life before our water softener was full of calcium buildup on everything, and this water softener has been a complete workhorse.
A tankless water heater needs a lot of gas to the heater when it is running. If the heater can’t get the necessary flow of gas, the onboard computer will generate a fault and the heater will not function correctly. If you don’t have a 3/4″ gas line running to the water heater, you are going to need to install that. You need as short of a gas pipe run from the gas meter as you can get with the gas pipe being 3/4″. This is an area that I would encourage you to hire a plumber for. I was blessed that our house had a 3/4″ gas pipe headed directly to the area where the existing water heater was installed. I didn’t need to do any piping from the gas meter to the water heater. Some people suggest that you need to test that you have enough pressure from the gas meter and to install a larger meter from your gas company. I didn’t do any special testing and the gas meter is the original gas meter that was installed with the house in 1991.
Exhaust and Venting
Venting a tankless water heater is just as important as making sure it gets enough gas. You can’t just use the existing vent that you have for your tank water heater. An example of incorrect venting is the following installation that is completely wrong: One of the vents on the water heater installation above is used for the fresh-air intake. There are so many problems with this water heater installation it is amazing that it even worked in the first place.
What is a Recirculation Pump for a Tankless System?
Sometimes called a circulator pump, it is a pump that periodically circulates water back to the water heater to be reheated. There’s a clue that this is not a cost-free technique. This prevents water in the pipe from cooling off, so it is hot when you turn on the tap or shower.
A recirculation system includes:
1). A water heater and pump combined or separate. This can be a tankless water heater with an integrated recirculation pump or a water heater and an external pump. The Rheem RTGH is one of example of a unit with a built-in recirculation pump. Other models, like the Rinnai RL water heaters, can be programmed to start an external pump during peak water usage times.
2). A recirculation method – 2 options. The first option is a dedicated return line for circulation. That means your home would have three pipes instead of two – cold, hot and recirculation. This is a viable option if it is installed when the plumbing is originally installed or if you have a one-story home and pipes in the basement or crawlspace are easily accessed. If your home doesn’t have a recirculation line, then a bridge valve will be installed at the furthest fixture that allows the cold water line to be used as the means of cycling water back to the water heater.
3). A way to control when the circulation pump runs. The two common options are a timer that periodically turns on the recirculation and an aquastat or thermostat that turns on the pump to keep water in the line at the desired temperature.
HOW TO CHOOSE A WATER HEATER
Heating water is the second largest single user of energy in the home. While we all enjoy a soothing hot shower, rising energy costs—along with their adverse environmental impact—make it a good time to take a closer look at the various options now available.
Storage Tank: The most common hot water system used in homes. Water is kept constantly heated in the storage tank by electricity, natural gas, oil, or propane. Hot water is drawn out of the top of the tank when a faucet is turned on and cold water flows in the bottom to replace it.
Tankless: Also known as on demand water heaters. Water is heated by electricity or gas when the water flows through it without the need for a tank.
Solar: Water is circulated from the tank through a solar collector where it is heated by the sun. If the water in the tank is not hot enough, a conventional water heater is used to bring it up to the desired temperature
Factors in Choosing a Water Heater
So which type of water heater is right for your home? There are several factors to consider including the price of the system and installation, the cost and availability of energy sources, the energy factor (EF) rating of the water heater, and whether the system meets new water heater regulations.
A tankless water heater saves you money!
In contrast to a conventional storage (or “tank”) water heater – which heats the water with a relatively small burner, the tankless water heater applies more energy (over 5 times more -32~40,000 BTU for a tank unit and 150~500,000BTU for a tankless) per second to the water so that it can be heated instantly . This higher energy output requires a higher volume gas supply than the tank water heater, and a larger exhaust vent also. Even though the rate of gas usage is significantly higher when the unit is running, it runs for a fraction of the time of a conventional water heater and gains it efficiency in that way.
A tankless water heater saves you space! A tankless water heater is also significantly smaller than a tank water heater – only about the size of a bed pillow, giving you the space back that a tank water heater would otherwise occupy, the tankless water heater can even be installed flush mounted within a wall, taking up virtually no space at all!
A tankless water heater saves on repair and replacement costs! You can also expect a tankless water heater to last many times longer than a tank water heater, up to 25 years! Compare that to the 2-12 year life expectancy of a tank water heater.
How to get hot water faster from a tankless water heater:
You are heating the water quickly but wasting more water down the drain and waiting longer for hot water.
We love tankless water heaters because they are more energy efficient, you will never run out of hot water (when properly sized) and they take up less space.
But in order to get hot water faster without wasting water down the drain you need a circulation system. One that returns the cold water in the hot water line to the water heater and one that has a high speed pump to move the water faster than just water pressure alone can.
And it needs to be a system that does not operate continuously (continuous operation voids the water heater’s warranty) and that does not keep your water lines hot unless there is a demand for hot water (wastes energy and promotes pinhole leaks).