My problems with a tankless water heater

Old 07-20-08, 11:49 PM
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Unhappy My problems with a tankless water heater

My problems with the Aquastar 240FX water heater. The 240FX is the prior model to the Aquastar 250FX. I want to document the issues I've had with this heater so people will realize all is not rosy in the "tankless" heater world.

I had heard about tankless, or demand, water heaters and it all sounded good to me. The efficiency, and the fact that you would never (theoretically) run out of hot water, fit my needs. I have three teenaged sons and finding enough hot water for showers, the dishwasher, and laundry was difficult to do. Our conventional electric 50-gallon water heater was always running out of hot water.

In February 2003 I checked at my local building supply stores and found the Aquastar 240FX at Home Depot. I asked the Home Depot employee in charge of plumbing for a list of contractors to install it, and got what was, in retrospect, my first warning. He knew of no one that installed the tankless water heaters, just the conventional water heaters. I didn't let this stop me, I figured I could just return it if I couldn't find an installer.

I called a number of plumbing firms before I found someone that was willing to take on the project. He hadn't done a tankless install before but was willing to try. He came over and did an estimate. He wasn't sure how long it would take but guessed the cost would come in at $600.

The install was kind of rough; the main problem was finding the 1" copper gas line this unit needs to feed it's huge appetite for gas. We had to special order it and when it came it was very expensive. We had to dig a big trench in the backyard to bury the tubing. The final cost for the install was $900! So far I had invested $900 for the unit, plus $100 for the special vent hood, plus the cost of install. This was getting very expensive very quickly.

But it was in. Now to reap the benefits of the unit! Or so I thought. First, the hot water never got that hot. The default temperature setting for the 240FX is rather low at 122 degrees and after the temperature drop from the plumbing I could never get any more than 110 degrees at point of use. This is no good for dishwashers as they need very hot water to cut the grease on dishes. My dishwasher has a water heater but it would have to heat the water for up to an hour before it would proceed with the wash cycle. You can increase the temperature setting on the Aquastar by spending another $100 dollars for a remote unit, but I decided I had spent enough money.

Second, it is really annoying to wait for hot water every freaking time you turn on a faucet. I think everyone has had an experience when in the early morning you had to stand around and wait for hot water to make it's way through hot water pipes that had cooled overnight. Just imagine this every time you turn the hot water on. Rinsing off dishes is the worst, you end up leaving the hot water faucet on so the hot water will keep flowing, wasting the energy you were supposed to be saving.

Third, the shower water temperature changed from hot to cold to back again. I never had this trouble before the tankless heater. After making the first of what was to be many phone calls to CEC (Controlled Energy Corporation) tech support I found out my private well was the problem. In a well system the water pressure varies as the well pump stops and starts. This pressure difference causes the hot and cold water to go through the plumbing at different rates, plus the hot water heater needs to vary the burners to "catch up" with the increasing speed of the water when the pump starts. The net result is you have to keep fiddling with the hot and cold faucets to keep the water temperature comfortable. CEC's suggestion was to have the high and low pressure setpoints on the well pump set close together.

I called a well service (another $120) and got the guy out to my house. He told me CEC's suggestion would jeopardize the life of my well pump. The pressure set points they wanted were too close together. I had him raise the pressure a bit and get the set points a little closer together. But it didn't really help.

We were not happy with the Aquastar heater, but we put up with it. At least we were saving energy. But then we had some serious problems...

In Fall 2003 we started to notice the unit would not fire up every time there was a demand for hot water. The dishwasher occasionally ended up with a load of cold water instead of hot water. It was a rare occurrence at first, then started to get annoying frequent. I called CEC tech support and they suggested I clean the flame sensor of the unit. They sent e-mail with a .PDF file showing the procedure. I was able to clean the sensor but was shocked at one aspect of the heater's construction. The cover to the burner area was held on by little metal tabs stuck through slots and bent over. Just like little toy cars were made back in the '60s. This concerned me because this type of arrangement would never hold up to repeated cleanings, the tabs would break off. They must have never thought service would ever be needed in that area. What else had they overlooked?

Spring 2005 we noticed the unit not firing up again. Thinking it was the same problem I again cleaned the flame sensor, being very careful to not break the metal tabs. But after I was finished the problem did not go away. I tried cleaning a second time with the same result. After calling CEC tech support they suggested I change the water flow sensor. I was game, they sent out a new sensor free of charge. I installed the sensor but it made no difference. I was convinced it was a bad igniter. They didn't want to sent one to me, fearing for my safety because it has a very high voltage. I explained I had worked as a TV and PC hardware tech in my youth and knew how to protect myself from high voltages, but they refused to send one.

I looked for a firm to work on my unit. No plumbers wanted any part of it. CEC only listed one person in my state who installed these units and he told me he had no experience troubleshooting problems, he just knew how to install them.

Things were getting ugly at home by this time. The unit would only fire up once out of ten or twenty times. I would be in the basement turning the hot water faucet on and off until I saw the unit fire up, then I would run upstairs and tell whoever needed the hot water they could use it. Finally both my wife and I had enough, it was going out the door.

I contacted a number of local plumbing firms and found one that would de-install my unit. I settled on a 60 gallon high recovery gas water heater made by Bradford White. After the install was done it was like a huge weight had been lifted off my back. It was like Christmas. Hot water instantly at the faucet. Shower temperature that was steady as a rock. No dishwasher full of cold water. No highly annoyed wife!

Home Depot, to their credit, took the water heater back giving me store credit for the $900 unit. The vent hood became a permanent part of my house. But I am still out over $1100 after this debacle.

The Bradford White unit has done everything I hoped the tankless heater would. We have never run out of hot water, even after taking one shower after the other. And our gas consumption has not increased over the tankless heater.

The firm that installed my new unit said the plumbing firms are avoiding the tankless heaters because they require too many service calls. He only knew of one firm that installed them, and they only installed one specific very expensive unit.

The "tankless" heater turned into "thankless" heater. When you look at all the complexities of these units, it's amazing they work at all. They have a computer running the gas burner and it relies on quite a number of sensors to tell it what is going on. A problem with any one of these sensors is going to cause a problem with your unit. Any minerals in your water will also play havoc with these sensors. Plus private well systems have the issues described above. I urge anyone looking at these units to reconsider buying one of these complex, expensive, finicky beasts.
Old 07-21-08, 06:19 AM
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FAQ based on my experiences with tankless units at my own properties and what I and others have seen at home inspections here in Chicago. (I like tankless heaters, but it was painful to claw our way up the learning curve on installs.)
Old 07-21-08, 04:04 PM
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Aquastar is made by Bosch and many plumbers consider Bosch to be lower on the list of preferred tankless heaters.

Myself, I wouldn't have a tankless and there are few situations where I would recommend one. I know they are all the rage these days, especially with the "green" crowd but they have too many drawbacks for me to get excited.
Old 07-21-08, 05:57 PM
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Of all your problems, one is NOT related to the tankless, and that is the delay to get hot water out through the pipes to the farthest bathrooms. That is caused by the length of the pipe run, and can be fixed by installing a dedicated return line for recir, or a remodel-type recirc with no return line.
Old 07-22-08, 05:14 AM
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I gotta jump in on this one.
Brolan, here is where I think you went wrong.
1. Any mechanical item that you buy from HD, etc is going to be junk. It is probably a second or at least, a very inferior model that you can buy at a professional supply house.
2. You asked the guy at HD for advice and a list of plumbers to install it. In other words, you asked a person with most likely limited knowledge to recommend someone to install a piece of junk.
3. Bosch is junk. Not just the tankless, but everything they make.
4. There is a learning curve when it comes to using a tankless. Once you adjust to it, most of the problems are gone.
5. You bought the unit in 2003. There have been tremendous advancements in tankless design and construction since you bought it.

I have three kids at home. A cranky wife who doesnt like glitches in anything. They all adjusted fine to the tankless. I bought the Rheem unit from a professional supply house. Since I'm in the trades (septics) I frequent the supply house a lot and was able to ask a few of the plumbers their thoughts. I put the unit in myself. I've even been in the supply house when the Rheem rep came in. Try getting that at HD. Nothing special as far as the install. The units are somewhat sensitive to water pressure and quality. Also, anti-scald valves in a shower play havoc with the units and need to be adjusted.

I guess what I'm getting at is that I like my tankless. Gas use is very more oil boiler in summer months. Have never run out of hot water. Unit is quiet and compact.

When you buy a mechanical item like this, you need to purchase it from a reputable supplier who has the knowledge and resources to make the job a complete success.

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