Bosch Aquastar 240 FX tankless water heater

Posted on Thursday, March 1st, 2007 at 3:11pm CST by 6fc69fa3

Company: Bosch Aquastar 240 FX tankless water heater

Category: Other

Bosch FX 240 LP by

Bosch sells an expensive ($1000.00) unit that is fraught with problems. Maybe that is why they have replace it with a newer model, but I am reading reviews that say otherwise.

1.) Takes countless gallons of water to get to a stable temperature. If you are on City water this will create higher water and sewer bills not to mention gas and electric useage being elevated. If you are in the country, you will put added strain on your septic system.

2.) Water temp drops to cold or becomes scalding hot, whenever there is a fluctuation in the water pressure. (i.e. when the pump activates, or a toilet is flushed) I am afraid to allow my grandchildren or my elderly parents to take a shower at my house. Techs will tell you it will not heat above 120 degrees, but I have measured my water at over 130 degrees at times.(Where is the Consumer Safety Agency) I feel that this unit is dangerous.

3.) These units get a buildup of lime or calcium on the burners, that cause it to be noisy, rattle, and to trip the overtemp circuit breaker. When the breaker is tripped, you get cold water, and a blinking light on the circuit board. Because of this buildup, the sensors that control temp do not work reliably. The techs are more than willing to send you additional circuit breakers, but I now have 3 on hand, and it is obvious that replacing the breaker will not fix the underlying problem.

4.) There is no literature mentioning the need to purchase an electric pump and hoses to flush the unit monthly with white vinegar, but that is what the factory tells me I need to do. Finally the factory tech told me to use CLR or Limeaway to clean the unit, however, the literature says that your warranty will be voided by using such chemicals. I flush the unit for 8-10 hours a month, and it still will not work properly.

5.) In 5 years we have had our unit factory replaced twice, and the latest unit is now being replaced with a conventional tank model. 5 years of hot and cold showers, of having to run the hot water between every cycle of the dishwasher, and of just plain frustration, have prompted me to replace the unit with a conventional tank model water heater. I could have purchase 2 conventional units for what the initial purchase price was, let alone all of the expense since. Let the buyer beware.

Feel free to contact me: Colleen Franke



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2859f764, 2009-08-04, 02:53PM CDT

I have really enjoyed my FX 240 NG, however we have continued to lose water pressure only on the hot water side...and now so much so that it doesn't get enough water flow to turn the hot water on sometimes. I cannot find a way to remedy this other than get a new unit of a better brand.

35ffbe97, 2009-09-22, 02:16PM CDT

Ever hear of a water softener? Or cleaning the inlet filter? Finding a Tech with a brain?

Yes, when you flush the toilet AHEAD of the unit it will stop but that's a house pressure problem which demands re-piping and also piping the toilet away from the water heater. Should have tried Descaling with a 20% CLR or Lime-Away solution not 100% white vinegar. Scaling occurs only on BAD water and it occurs in the Heat Exchanger not the Burner.

A internally clean unit should come to temperature while only passing less than 2 gallons of cold water. If you scaled a unit this bad, any Tech replacing it under warranty is an idjit.

The noise, popping and cracking is boil out caused by hot spots in the heat exchanger caused by calcium and iron deposits.

Circuit breakers???? the item controlling temperature is called a flowmeter and a Thermister.

At this level of incompetency, none of you should have been allowed to play with the baby (tankless unit).

1661a650, 2009-09-28, 06:03PM CDT

I don't have a complaint with the unit tself but I do have a big issue with Bosch's tech support .They are nonexistant.My problem started 3 weeks ago with the unit lighting up sporaticly.I called Bosch and was given a reference number and then transfered to another area to wait on hold for over an hour.There was an option on the hold measage that said" if you leave a callback number ,we will call you back when its your turn."So I took this option.I never did get a call back.I called every other day for three weeks always getting the same results.@ days ago the heater died for service techs on saturday and sunday so we heated water on the stove to get a tepid bath.Finally this morning while waiting on hold I saw an internet posting that said that the Aquastar 240fx was built by a company called Kakagi and it was model TK1.I looked them up and found a tech support number , No waiting on hold, a nice guy named Robert talked me through the fix and My water heater was up and running in 15 minutes.Robert,I love you man.

Don't waste your time with the Bosch people .I understand that things break, but with a name as prominate as BOSCH in the market at least offer good customer service.I know that from here on out because of the lack of service I recieved I will avoid BOSCH products at all cost.Well thats my rant.

Thank you


4d77a82b, 2010-04-19, 03:20PM CDT

I have one. It is a piece of junk. It has to be reset constantly and the tech support is no help. I am replacing it with another brand.

92cae5d8, 2010-12-21, 08:00PM CST

I purchased this Bosch AquaStar 240FX, quite expensive water heater based on Bosch reputation for quality. I wanted to do my part to save energy, so spent more than twice

the cost of a conventional water heater. It functioned well for 2.5 years,

then stopped working. I thought "no problem", the warranty was a reasonable

5 years, similar to a "normal" water heater. I failed to read the fine print however. 5 years was for the heat exchanger ONLY. The rest of the parts were

warrantied for ONE YEAR ONLY!?. The failed part, the main circuit board was FIVE HUNDRED DOLLARS!!, almost half as much as a new unit.

Even the cheapest conventional water heater lasts more than a couple years. This is my second bad experience with Bosch, as I had an early

failure of a dishwasher as well, where the replacement parts far exceeded

the value of a two year old appliance. I'll not consider purchasing another Bosch product. Beware an advertised warranty length to be sure it's on the whole product before purchase. To add one more complaint, I was on hold for over 2 hours for tech support to diagnose the problem

6046d413, 2011-01-31, 03:36PM CST

Have a Aqua Star 340 FX unit since 2004. No problems. I even have a whole house water filter attached to the incomming water line to the unit. This is to reduce the fine grit and calcuim from the water. No pressure problems and the water comes to temperature in about 5 seconds of turning it on even with another shower or dishwasher going.

The unit is approximately 25 feet away ffrom the showers.

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