The REAL story on tankless water heaters

07.13.2008 | 8:38 am | General

Several years ago, I had done some research on tankless water heaters as a way of reducing our electric bill, while at the same time having an endless supply of hot water. The theory is that the water heater only turns on when the hot water starts to flow, unlike a conventional tank that keeps turning the heating element on to retain the temperature level in the tank. You can also set the temperature so that the hot water is comfortable when using only hot water, with no cold water mixed in. That way you can avoid any scalding problems, and you don’t waste energy by heating the water up, then adding cold water to cool it back down again.

If you are contemplating getting a tankless water heater, here are the things you need to consider:

1. The temperature of the cold water that comes from the street will govern how powerful a unit you need to buy. In Florida, the cold water is most likely in the 75 degree range, while in Wisconsin, it may get down to the 50’s or lower. The unit needs to have enough power to bring the water up to the temperature you desire.

2. The flow switch will require a certain GPM rate in order to activate the heating elements. This means you can’t have a slow trickle of hot water coming from the tap. Most units seem to need between .2 and .5 GPM in order to trip the flow switch. Typically, you will be turning the hot water tap on full anyway, so this will probably not be an issue. However, there is a caveat. Most showers have a mixing valve, and when you want to make the water temperature colder, it actually adds cold water AND reduces the amount of hot water that is used. In your attempts to get the most comfortable temperature, you may end up reducing the hot water flow too much. This will cause the GPM rate to fall below the threshold, and turn off the heater. The next thing you know, you are taking a cold shower!

3. You will need to decide if you want a whole house unit, or a point of use unit. Using the point of use units is more involved and requires additional expense and installation, but provides redundancy in the event that one of them fails. If you have 2 bathrooms in your home, and the whole house unit fails, you will have no hot water anywhere. If you use point of use units, and one of them fails, you can still take a shower in the other bathroom. With a sink, it is not too tricky to put a small unit under the sink somewhere. When it comes to the bathroom, the location of the unit becomes more difficult, and may require additional plumbing that you hadn’t planned on. 

After doing some internet research, I chose a unit from SETS in Miami Florida, and picked the whole house unit, which cost roughly $750 USD. I had an electrician run the 220v lines (two required), and I did the plumbing myself, since I am pretty handy with solder and a torch. The unit looks similar to this one, and mounts flat on the wall.

After the intial tweaking, I got the system to work fairly well and was pretty satisfied with the way it performed. Then, about 2 years later,  I had a problem.

I noticed some drips coming from the bottom of the case, and the temperature of the hot water began to be inconsistent. I opened the case up and found that the internal copper pipes had sprung a leak. Here is where things get really ugly.

I called SETS to arrange to have it fixed since it was still under warranty. Over the period of 5 days or so, I made repeated calls to them, trying to find a technician who could authorize me to get the unit fixed. The guy who answered the phone kept telling me they were busy, and that he had been giving them the messages for me. Finally, I got hold of a tech, and after I described what was wrong, he told me I needed a new unit, which I already knew!! Needless to say, my frustration level was maxed out by now.

The problem was that they don’t make house calls, and their warranty policy is that I uninstall the unit, I pack it up and pay for the shipping to them, I pay for the shipping to have the unit sent back to me, I reinstall the unit when I receive it, and I live without hot water during the entire process, which is already 5 days long! Needless to say, this did not sit well with me, and I decided to skip the whole tankless water heater thing and go back to a conventional heater. I went to Lowes, bought one, and put it in.

The theory of a tankless water heater is a wonderful one, and it does save on electricity. When it works correctly, it is great. However, I cannot in good faith recommend SETS based on my experience with them. I suggest that anyone who is considering getting a tankless water heater do their homework and make sure they know exactly what the manufacturer’s warranty consists of before they buy it.

If I were to do it again, I would go with point of use heaters so that I have hot water in the event of a failure of one of the units.