How far can a flue run in a horizontal direction?

A water heater can be one of the most dangerous appliances in your home because of the carbon monoxide that is created from the result of gas combustion. Unlike a furnace a water heater relies on warm air rising in order to safely vent CO2 outside your home. In order for the vent to work properly it's important that it's installed in accordance with code. 

There are several situations that we come across in which the flue has too far of a horizontal run and can result in downdraft or back draft. Not only is this unsafe for the people living inside the home it can also cause issues with your water heater causing the pilot to extinguish. 

The general rule for a horizontal run of the flu pipe is no more than 75% of the overall rise of the flue. If you measure from the top of the water heater all the way up to the top of the flu at its highest point you should have no more than 75% of that length for your total horizontal run. The total horizontal run may not always be visible from the basement alone at some flus will continue to run horizontal in the attic in order to vent at the desired location. 

Vent offsets 

The total horizontal distance of a vent plus the horizontal vent connector serving draft hood-equipped appliances shall be not greater than 75 percent of the vertical height of the vent. 

Tankless not all they're cracked up to be

As a plumbing contractor who deals with water heaters on a daily basis I get a lot of questions about tankless water heater's. There are a lot of misconceptions associated with tankless water heater's so I wanted to go over a few of the main drawbacks to tankless water heaters. 

The first misconception is that a tankless water heater will give you instant hot water. They are sometimes called instant water heaters because they're heating the water as you use them. You're not going to have hot water instantly when you turn on the faucet. It's actually going to be the opposite effect, it will take longer for the water to get hot at the fixture because the first two seconds of the water running it's got to heat up and so you're you'll actually have cold water that comes through for the first couple seconds. 

The second misconception is that a tankless water heater will save you money. A tankless water heater actually has a higher cost of ownership than a standard traditional atmospheric water heater. While the operating cost can be up to $50 a year less on a tankless, the maintenance cost can be 3 to 4 times that savings. If you fail to keep up with the maintenance on the tankless water heater it will stop working in as little as seven years and at that point you'll have to replace it. 

The third misconception is that they will last longer than a traditional water heater. While they do have longer warranty, warranties don't mean a whole lot when they don't cover labor or parts. The average lifespan for a traditional water heater is about 15 years. Tankless units haven't really been around here in the US long enough to get an accurate reading of average lifespan. 

I also want to point out that there are many applications for tankless water heaters and I actually have one in my own home. I installed a tankless for space reasons and I'm also on propane instead of natural gas. With the higher cost of propane and the ability to perform my own maintenance I will have a payback of under 10 years. 

Don't panic about the new Water Heater Regulations

Recently KCTV 5 new ran a story that covered changes that will affect the way we heat our water. While the article did a good job of explaining the changes and how they would impact the average homeowner, the article did have some misleading information on one important detail.

The news team chose to interview AB May to help gather information for the article. A company that just so happens to be one of the biggest advertisers of all the plumbing companies in Kansas City. At the end of the article they reported that the average life for a water heater was only 7 years. We went back and took inventory on the last 53 water heaters that were replaced over the last 3 months. 

This is a true representation of the average life of a water heater. I can't imagine how many people after seeing this news story decided to replace a perfectly good water heater because of the misinformation provided by the news outlet. It's bad enough that the government is regulating water heaters and causing a significant price increase, the last thing we need is the media to convince homeowners to replace their tanks before they need to.

New Efficiency Requirements for 2015

The Department of Energy has once again increased the efficiency requirements for water heaters. Unfortunately some manufacturers and wholesalers have used this as an opportunity to increase markup on water heaters. While price increases will vary greatly from one wholesaler to another, the manufacturers have increased their pricing across the board.

One of the biggest reasons given for the price increase from the manufacturers was due to the research and facility costs necessary for design modifications. While most water heaters have only faced minor modifications, other tanks require more sophisticated technology and drastic changes in production. The water heaters that will be impacted the most are the commercial water heaters over 55 gallons and specific residential applications that have space restraints.

For water heaters under 55 gallons the new efficiency requirements can be met by adding an additional 2" of insulation, increasing the size of the tank. While the increased insulation only increased cost by roughly $10 per tank, the increase from the wholesaler is closer to $75 per tank. The additional cost is designated to cover the research and production changes necessary for those that have space restrictions. 

Water Heater options for confined spaces

The new efficiency requirements can be met without increasing the size of the tank by adding a flue damper to the top of the water heater. This of coarse means that you will need an electrician to run 110 service to the new water heater to operate the damper. This also means that the water heater will not operate without electricity, not to mention the added expense of hiring an electrician.

This is where the price increase really kicks in. The current pricing that has been provided from the manufacturers will almost double the cost of a traditional water heater as they are priced today. The homeowners that will be the most affected will be those with smaller houses that have space restrictions. 

My personal Opinion

If adding an additional 2" of insulation will save the homeowner money in the long run, many will choose to spend the extra money for higher efficiency. The new regulations would be a good idea if not for the situations where space is limited. 

Various Anode rods used for water heaters

Most residential and commercial water heaters have Anode Rods that are also referred to as sacrificial rods. The anode rod is designed to help prolong the life of the water heater by attracting sediment to the rod instead of the outside of the tank. The most common types of anode rods used are made from either steel, aluminum, zinc, and magnesium.

Most residential water heaters will use an aluminum anode rod for their standard tanks. An aluminum anode rod is of the least expensive options and will last longer than most other anode rods. The AO Smith GCV-50-300 residential water heater has an aluminum anode rod with a steel core to protect against corrosion. The GCV has a 6 year warranty and is one of the most common water heaters installed by plumbing professionals. The same water heater is available in a 10 year warranty, the only difference in the tank is the anode rod used magnesium instead of aluminum. This is a bit surprising due to the fact the magnesium actually breaks down faster than aluminum. Without an anode rod the tank will rust out sooner.

If aluminum was consumed you would experience arthritis like symptoms and could upset your stomach.

A magnesium anode rod is slightly more expensive than other materials but can actually offer health benefits if consumed in drinking water. The downside to magnesium anode rods is that they dissolve much faster than other materials and may need to be replaced after 6 years.

Zinc anode rods are often mixed with aluminum or steel and are not as common today as in the past. The zinc can react with different metals to promote growth of bacteria. Many people that report a sour smell from their hot water have a zinc anode rod to blame. The anode rod can be replaced which should resolve the problem.

Water Softeners impact on an Anode Rod

A traditional salt water softener can break down an anode rod much faster than the normal rate. It is recommended that homes with a water softener replace the anode rod every 3 years to help protect the tank from corrosion.

 Health Risks of Aluminum Anode Rods

The actual risk of using an aluminum anode rod is debatable. Wikipedia stats that under normal circumstances Aluminum is not water soluble and is well tolerated by both plants and animals. You should also consider that most of the time you will not drink from the hot water supply lines unless you have a circulating pump and a bad faucet cartridge that allows hot water to mix in with the cold.

The problem with Tankless water heaters

Over the last 5 years there has been a growing curiosity regarding tankless water heaters. Most people seem to like the idea of only heating water as you need it rather than constantly having 50 gallons of hot water on standby. Not only does it seem to make more sense but it also takes up a lot less space. You also don't have to worry as much about the possibility of a tankless water heater leaking all over your floor. When it really comes down do it there are 3 main factors that make owning a tankless water heater a tough sell.

Performance

One of the biggest misconceptions about tankless water heaters is that you will have an endless supply of hot water. While it is true that you will never actually run out of hot water, you may experience a significant drop in the flow rate at which the water is delivered. 

Most tankless water heaters have a rating that is measured in Gallons Per Minute (GPM). What you may not realize is that the GPM of each unit is going to vary with the temperature of the incoming water as well as the desired temperature for delivery. Here in Kansas City, our water lines are buried 36" below the surface to prevent them from freezing in the winter time. This also keeps the incoming water cold during summer months. The average water temperature is going to be about 65 degrees, while the average desired delivery temperature is about 125 degrees. The tankless unit needs to be able to increase the water temperature by 60 degrees to meet the family needs. This is known as temperature rise. Problem is that most of the ratings for tankless water heaters assume only a 40 degree rise. As the temperature rise requirement increases, GPM will decrease. 

Reliability

Most people take for granite just how reliable a traditional atmospheric gas water heater really is. For many people they will never have an issue with their water heater. When a traditional unit has a problem they also have the luxury of calling almost any plumber in town and can feel confidant that they will be able to make the repair. In most cases it's the thermocouple or gas valve, it cost a few hundred dollars and you're back up and running that day.

Tankless water heater are far more technical than a standard unit. There are more moving parts, more electronics, and they can be more difficult to troubleshoot. In most cases a tankless water heater repair will require a special technician that will often be part of a large company. You may also have to wait several days on shipping since these parts can be expensive and unique to the model.

Cost of Ownership 

One of the biggest incentives for homeowners to consider switching to tankless has been the energy savings that can result from a lower utility bill. The average tankless unit has a yearly operating cost of around $194 per year while the average atmospheric unit has a yearly cost of $282. The initial cost of a gas water heater is anywhere from $800-$900 going with a quality tank installed by KC Water Heater. The average tankless installation will be anywhere from $2600-$3200 depending on the model selected and the installation requirements. This would suggest that a tankless unit would have a 20 year payback, assuming the unit doesn't ever need repairs.  

The thing that most people forget regarding costs is the maintenance required for a tankless unit. If you don't perform a yearly flush on a tankless unit the performance will drop significantly and eventually will stop working all together. The cost to perform the yearly flush is about $150-$200 per year.

Adding a second water heater

Checking the flue size

If you are considering adding a second water heater you will need to be sure your flue is large enough to support additional BTUs. Here is an example of a home in which the homeowner wanted to add a second water heater to help fill up a large tub. The water heater flue was a 5" Type B double wall pipe serving two appliances with a total distance of 30'.

The first step in determining if a flue is large enough to support an additional water heater is to add up the BTUs for the existing water heater and furnace. This home had a furnace that was sized at 150,000 BTU and a water heater that was 40,000 BTU for a total of 190,000 BTU.

The maximum BTUs allowed for this situation was 193,000 BTU so we were able to determine that adding a second water heater would not be safe. If this house had a 6" flue the maximum BTU would have been 300 BTU.

In most cases you will be using a single wall connector to connect the second water heater. In most cases a 4' Y is required when combining the second water heater. If you currently have a 5x3 Y off your main flue you will most likely need to replace the boot with a 5x4 Y. 

Series vs Parallel

When installing a second water heater you can setup it up in one of two basic methods. The first method is shown in this picture is referred to as Parallel. In a parallel piping system both water heaters work independently to heat there share of the water. 

A Series piping method is setup for the water to be heated in the first unit and then pumped into the second unit. The series installation is a little easier to install and has a few other advantages. The main reason we like to install a second water heater in Series and so that you can turn the first unit down to a low temperature to preheat the water. This will still give you an increased supply of hot water but will run more efficiently than two water heaters both running at operating temperature.