BOSCH 250SX Whole House (JUNK) Tankless Water Heater

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RANDELL

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I bought a Bosch 250SX tankless water heater in 2007 hoping it would save me money. Had it installed by a gas company after home addition was finished in 2008. The unit cost $834 then I think I paid $150 or $200 for installation. The thing has never worked as advertised. It lights, turns off, lights, turns off, then lights the third time and either stays lit or if it goes off this time has to be reset. This is not something that happeds occasionally but ever time we turn on the water. This has happened ever since it was first installed. I called Bosch and they sent me a part, which was a wire that wraps around the heat exchanger, with instructions on how to replace it. I replaced the wire but the unit still did the same thing. Every time we want hot water we waste several gallons of water before we hot water or have to reset the water heater then waste more water going thru the cycle again. I called them several more times and they gave me the run around, first they said I didn't have it vented properly. I had went by the instruction manual which clearly said the fresh air intake could be vented with just a 90 degree elbow on the top of the unit. After They told me it was not properly vent I installed a vent through the roof for the intake. Still the same old water and time wasting piece of junk. I called them several more times and they told me that it was probably not getting enough gas. They would not connect me to a technician because I was not a licensed plumber or gas tech. I called several plumbers and gas people but nobody would even come out since it was a Bosch brand. One plumber told me that Bosch wanted a licensed plumber out here so that they could take the blame for whatever went wrong. Like I said we got this thing installed in 2008, and our water bill has been about double what it was before we got this installed. And I have been close to taking it off the wall and throwing it away many, many times. Finally I got a plumber to come out, he charged me $85 but couldn't fix it because he was not trained to work on Bosch water heaters. I called Bosch again and was told to email their resolutions department , which I did. The email I sent was basically the same info as I am giving here. I got an email today saying that Roto Rooter would come out and service the unit but that I would be responsible to pay for all repairs. With the cost of the water heater, installation, service calls, wasted water and gas ( the water heater is the only gas appliance we regularly use). I would say that hot water has cost us about $7200 for the past 7 1/2 years, that's about $80 per month. Now it looks like I will be paying Roto Rooter. even more. I have heard so muh how tankless water heaters generate huge savings. I just don't know how much more I can afford to save. I get overheated just thinking about Bosch and their water heaters, I guess I need a cold shower, but that's kind of the norm around here.
 

Jadnashua

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Any good HVAC tech would have the tools to verify how much gas was getting to the unit, but the first thing I'd do is look at the installation instructions and see what they require for gas service. Having too small of a supply pipe or excessively long run with lots of elbows, or a meter not capable of providing the volume required will give very erratic operations.

A couple of things that can prevent the thing from turning on properly: failure to get flame, and failure to detect water demand (flow sensor). There's probably an outlet water temp sensor that also looks for overheating, and maybe one on the heat exchanger to determine if that is overheating. A faulty flame sensor (could be as simple as it's bent out of position) may not recognize that it actually lit when it should, and a bad igniter would prevent it from lighting at all, at least some of the time. There are also likely air flow sensor(s) that determine if there's enough combustion air and if the exhaust is obstructed. IOW, lots of little things, but if it has been doing this since new, it may be something that the installer did, or a bad unit from the get go.

While their concept is good, I'm not convinced that they actually end up saving people much in the long-term, with the extra installation costs, maintenance costs along the way, and just the way they operate (like not turning on when you only need a small volume of hot water).
 

BadgerBoilerMN

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Your beef is with the gas company. Be sure the RotoRooter guy is licensed. Ask to see it.

I would go to the original installer and ask Bosch for a local installer/service agent.

If the unit was poorly installed and never serviced by qualified techs you likely need a new water heater. Whether the new water heater is Bosch, Rinnai, Takagi, Noritz or Navien should be determined by the local support and the particular application. If your water is hard, 5 years would be a long time running.

We install tank and tank-less water heaters trying always to fit expectation with performance. Sometimes the manufacturer lets you down but more often the installer fails to install and the owner fails to service.

A professional must be on the other end of the line for the factory service tech to help.

As for saving money, most people buy tank-less water heaters for the "endless hot water" feature promised by Paul Harvey so many years ago when he peddled Rinnai.
 

RANDELL

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The Unit is vented with 3" vent thru the roof for the intake. and the factory recommended special vent pipe for the exhaust. The Unit requires 11 to 14" water column gas flow. It has been checked with 2 different gauges. It runs between 12 and 13" until lit and hold steady around 12" after it lights. Once the unit get lit it usually works fine until you turn off the water. After it is lit you can turn off the water for a minute or two and turn it back on and it does the same as when it hasn't been on for a while. It lights for 1 few seconds, goes off, hesitates then lights again for a few seconds, goes off, hesitates, then light a third time at which point if it goes off again it has to be reset. The unit is properly installed, it is just defective and has been since day one. I originally ordered one from the Home Depot at over $1200, then I came home and found the exact same model online for $834 tax included. I ordered online and canceled the Home Depot order. I am thinking maybe I got a better deal because they new the unit was defective. Regardless of why it's not working properly I hold Bosch responsible for not putting me in contact with an authorized repairman. I called several plumbers and gas companies in my area and none of them would even come and look at it until last week. He was a licensed plumber and gas fitter and he did check the venting and gas supply but would not take the unit apart as the Bosch Tech suggested. Bosch should have authorized service people in any area they sell their products. They gave me contact info for a service provider somewhere in Georgia. One that I would be responsible for paying even though this unit has been defective from day one. I won't buy anything else with the Bosch name on it , not even a spark plug.
 

Jadnashua

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It really sounds like the flame sensor is either dirty, misadjusted, or bad. 3x trying to light before declaring a failure is fairly common on gas appliances. Some of them are easy to test, and there is probably something in the user's manual about it as well. The flame sensor must be positioned properly and the leads attached tightly with no corrosion for it to work. Many of them are essentially a bimetallic strip, and applying heat causes a small electrical voltage to be produced proportional to the amount of heat. This voltage is fairly small, and the input to the electronics board and the leads to it must all be in good shape. Sometimes, they use one that adjusts the internal resistance based on how hot it is, and those are also easy to test with a good multimeter and a thermometer...they should have a certain resistance at a certain temperature, and you can change the temp and watch the resistance change while testing.
 

sku99

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I have also had this unit installed since 2007 (manufactured in 2005 or 2006). Early on I had similar experiences. I personally dealt with with tech support, even though I am not a plumber or HVAC tech. They were quite helpful. I guess I just got the right techs.
The flame appeared to "blow out" as soon as it tried to light. These are the steps we took to fix the problem:
Replaced the control board. this didn't help.
We added an air intake "limiter". Helped for a while, didn't solve the problem.
Replaced the flame sensor. Helped for a while, didn't solve the problem.
I purchased a CO detection tool and balanced the air input--this is like tuning a carburetor. This was the cure! I found a tech manual somewhere on line with the instructions.
I later had a temperature sensor quit working, after the warranty was up. Purchased one on line and it works perfectly.
About once or twice a year we will get an error code that needs to be reset--usually when the weather changes. Other than that this unit is everything that was advertised. Trouble shooting was frustrating for the first 2-3 years, but now we are very happy with this unit.
I agree that Bosch has had less than ideal support. This is a very complicated unit to trouble shoot. I'm cheap, but I figured it out.
 

BadgerBoilerMN

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All good arguments for professional installation. If you want to DIY and conventional tank-type water heater is your best bet. It makes clear the reason Home Depot no longer sells Bosch water heaters and why they have gone to conventional distribution, like Rinnai, Takagi, Noritz and Navien have always done. You can still buy these units on-line, but for the most part, you do so with a certain level of risk, including; negating any warranty and more important, no professional help when you need it.

By the time you buy a combustion analyzer, a multi-meter that will read milli-volts and spend a few days teaching yourself HVAC basics, you would be money ahead to by from an authorized service agent to begin with instead of rolling the dice and trying to find someone to fix your mistake after-the-fact. All the more important when purchasing a propane burning appliance.

Well done sku, I would give you a job.
 
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