Rinnai tankless water heater takes too long

Everybody writing these posts here, are really missing the point. Tankless units are great, because you never run out of hot water. Period. End of story. That alone makes them worth it. And two in series is smart too because you can run many fixtures at once.

The problem from the original post is a common one: It is the waste of water down the drain waiting for the hot to arrive. I am on the third floor of an old Victorian. It takes about 30-40 seconds. Water costs a fortune in San Francisco. Well I solved it.

This can be solved one of two easy ways.

First, you can add that pump and return gizmo, (D'Mand, Gundfos, etc.) but that still wastes energy, and it’s a pain because when you turn on the cold, not the hot, but if you turn on the cold you have to wait for the warm water to flush out for the cold to arrive.

Second solution, and a far better solution in my opinion, is this: Hook up an in-line small hot water tank under the sink. All hot water flows through that tank to get to your hot faucet. I have mine under the kitchen sink. That gives you instant hot water on the third floor for washing hands, dishes, quick face wash, etc., even a load in the dishwasher. Those are the scenarios when you really need hot water fast. For a shower, it allows the incoming cold water a chance to blend with the already hot tank, until the real force of hot from the tankless arrives.

And you aren't paying to heat cold water in the tank. The tank always has an influx of hot water from the tankless several floors below.

And in any event, I always turn on the hot shower while I'm undressing so it will be perfectly steamy when I get in. That's when a tankless delay isn't all that big a deal. I am always in awe of the IQ scores of people who get in a cold shower stall, close the door, stand naked and THEN turn on the spigots. Who does that?? Really, stop already.

Doing this solved my issues. Will you spend a few bucks a month on electricity for the in-line hot tank? Sure. But you don’t waste water, and you don’t spend $500 on a recirc pump.

See? Easy solution.

Thank you for listening to my Ted Talk.

Tankless water heaters are a great investment for your home or office. Not only are they highly efficient, but they can also save you money by heating water only on-demand. Although uncommon, issues can arise if something isn’t working correctly within your water heater.

Here are six of the most common problems and maintenance concerns for tankless water heaters:

• Mineral Buildup
• System Overload
• Cold Water Sandwich
• Air Supply or Exhaust Blockage
• Ignition Failure
• Flame Failure

Keep reading to learn what signs to look for when identifying these issues and how to fix them!

Whether you use a traditional or a tankless water heater, you need to keep an eye out for mineral buildup inside your water heater. Hard water (in contrast with soft water) is water with a high mineral content, and the harder your water, the higher the potential for damaging mineral buildup. Calcium and Magnesium are the two minerals that most often cause scaly buildup, and this can impair the function of your water heater if you don't address is. If you own a tankless water heater or are upgrading from a traditional tank water heater to tankless, it is also important to check the water filter in your water heater, especially if you have well water. Tank water heaters do not have to be cleaned as often, if ever, but tankless water heaters require more care for a long-lasting life. Well water can cause a quicker buildup of debris in your tankless water heater making it difficult for water to travel through the long, narrow path to the heat exchanger. If you are not regularly checking your water filter, debris can become trapped in this long path if not stopped by your water filter. To avoid damage, flush your water heater every six months with the Eccotemp EZ-Flush System Descaler Cleaning Kit.You can also use a water softener to slow the buildup.

If you do not have the hook ups to clean your water heater you need a valve bypass kit to assist with the cleaning process. 

Problem 2: System Overload

Depending on your tankless water heater's capacity, too many simultaneous hot water applications (such as multiple showers running) can overload your water heater. Your water heater may struggle to supply the hot water needed or shut down altogether if it becomes overloaded. If this happens, you should reduce the demand for hot water by limiting simultaneous applications, and you may want to consider resetting your unit. However, if your tankless water heater frequently becomes overloaded, you should consider either upgrading to a tankless water heater with a higher capacity or adding a second unit. Although a second unit might seem like a large investment, it can actually save you money in the long run since you’ll use less water while waiting for hot water to arrive and less gas to heat the water. Not sure which product is the right addition to your home? Check out the Product Selector on our website to narrow down which product is right for you based on intended use, number of applications, and energy source!

Problem 3: A Cold Water Sandwich

If your household frequently takes back-to-back showers, you may be familiar with the "cold water sandwich." Suppose a member of your household just finished showering and now it's your turn. You turn on the shower and feel warm water at first, but then get blasted with several seconds of cold water before the temperature slowly climbs back up. Here’s what happened: When the first shower ended, some hot water was remaining in the pipes on the way to the shower. When the second shower began, the initial warm water you felt was the trapped water. Tankless water heaters are also called "instantaneous water heaters” and they have earned that name! Any cold water that you are experiencing in your shower is due to cold water living in the pipes between your water heater and your shower. The further your water has to travel from the water heater to its destination, the more noticeable the gap. Unfortunately, there's no way to prevent this, but now that you're aware of the problem, you can avoid jumping in the shower until the cold water has passed. 

Problem 4. Your Air Supply or Exhaust is Blocked. 

For most tankless water heaters, the display with present an error code to inform you that your air supply or exhaust is blocked. This means your water heater is having issues with either combustion air or venting. First, inspect all vent pipes to ensure they are connected properly and free from puncture holes. Refer to your product manual to make sure the clearance requirements are being met, as installing your water heater too close to other objects can block the air supply and create a fire hazard. Birds nest, rodents and wasps nest can also block your venting, so be sure to thoroughly examine all vents that are located or lead outside your home.

Problem 5. Ignition Failure.

There are several reasons your water heater could fail to ignite. Often, this issue is caused by the gas supply, so check to make sure your propane tank is full before you do anything else. If your gas valve or water valves are not fully opened, this could also cause the ignition to fail. Check and open gas and water valves fully. If these steps do not resolve the ignition problem, then either your ignition pack has failed or there's a bigger problem. You should contact technical support to help you trouble shoot the issue and order replacement parts if necessary. 

Problem 6. Flame Failure. 

Flame Failure is generally caused by either a gas pressure problem or an electrical issue. Just like ignition failure, you should first rule out simple causes such as a low propane tank or an unpaid gas bill. Other possible causes of flame failure include a gas line that’s too small, regulator failure, combustion issues, venting and more. Contact technical support for help with troubleshooting the issue further. 

Having a Tankless Water Heater Problem, But Unsure the Exact Problem?

Tankless water heaters are generally low maintenance and very efficient, but problems can still occur. This list includes some of the more common problems that people have with tankless hot water heaters, but it is not all inclusive. Eccotemp Protection Plans are available for purchase within 60 days of your water heater purchase. 

If you don’t see the tankless water heater problem you’re having here, or if you need technical support with your water heater, please visit our help desk to schedule an appointment, or call us at 866-356-1992.

This article was originally published by Robinson's Plumbing Service and edited by Eccotemp. Try our Product Selector to find the perfect hot water solution for all your needs.

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