Bosch Aquastar tankless water heater dripping, I have hard water

Plumbing Forums

Help Support Plumbing Forums:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.

ChicagoSuburban

Active Member
Joined
Jun 30, 2016
Messages
27
Reaction score
2
Location
Alaska
3 year old Bosch Aquastar tankless 1600 water heater dripping from the bottom.
Sometimes makes hissing sound, I made sure it is not gas leaking, it is just leaking water making the hissing sound. I have hard water. The user manual says I have to clean some parts every year. How do I take apart this unit and remove the hard water scale that may be causing the dripping? Any videos? Any quick fix? Advanced thanks for your help.
 
I don't remember him saying that. I don't have a water-softener installed. What can I do to stop the dripping? Bosch user manual says there are videos online, I checked their website and youtube, they have videos for newer models but not for my model.
 
I'd recommend calling the company directly and asking them for their suggestions.
 
I don't remember him saying that.

I don't have a water-softener installed.

It is interesting as much of the problems with the tank-less seem to be lack of communication between salesman (or his lack of knowledge or fear of loosing a customer). Any mention made they might have to be descaled annually depending on the water source?

If you can't find a SERVICE MANUAL, you might need to call in a tech.
 
Tankless water heaters have thin walls in heat exchanger to facilitate rapid heat transfer. Minerals precipitate out onto the walls of the heat exchanger which will start to clog the piping. Cleaning of the heat exchanger usually involves disconnecting it and filling it with a descaling solution, such as white vinegar, letting it sit and then flushing it out with fresh water.
If you are hearing a hissing sound, it sounds like water turning to steam. If it is a periodic sound when the burner is on, it is likely a leak in the wall of the heat exchanger dripping onto the burner tubes. That means a new heat exchanger. Look at the flames when it is running. They should be a nice blue flame with very little or no yellow.
I just searched for a manual for a Bosch Aquastar 1600 and very quickly found and downloaded the installation manual for that unit. This is a natural draft water heater. I have found many tankless water heaters improperly installed with improper venting and under-sized gas supply lines (they need a lot of gas!), both of which will lead to poor performance and premature failure.
I also see many tankless gas water heaters that never get serviced until there is a problem, and then it may be a costly fix. Follow manufacturer's recommended maintenance schedule, especially for the sealed combustion, condensing models.
 
I have a new issue. I'll post a new thread. The pilot went out so I re-lit the pilot. I stopped pressing the gas inlet to light the pilot after 30 seconds and the pilot stayed lit, however, the unit fired on as if someone was using the hot water. No one was using the water, so the unit should not fire up. Then after a minute or so I heard a ticking sound and the gas automatically shut off. I had to reset the gas slider to off, wait a few minutes and then re-lit the pilot. The whole cycle repeated again and again. The unit fires on even when the gas slider knob is at pilot-lighting position or anywhere "right" of that position. If I slide the gas knob slightly to the left, the pilot stays lit, but the unit does not automatically turn the fire on when I turn on a faucet. Any ideas?
 
I have found many tankless water heaters improperly installed with improper venting and under-sized gas supply lines (they need a lot of gas!), both of which will lead to poor performance and premature failure.

I also see many tankless gas water heaters that never get serviced until there is a problem, and then it may be a costly fix. Follow manufacturer's recommended maintenance schedule, especially for the sealed combustion, condensing models.

I just cannot understand why a plumbing outfit will not install to manufacturer's instructions or code or the salesman not mention the need for annual service?

Is it a cost savings procedure not to install as instructed or just simply ignorance? If installed inadequately or improperly, the manufacturer has no liability.
 
I read that I have to run vinegar through the system to clean the calcium deposit. Is there any place where I can borrow or rent the pump to do this? Is it cheaper just to buy the pump since it is going to be a yearly ritual from now on?
 
I read that I have to run vinegar through the system to clean the calcium deposit. Is there any place where I can borrow or rent the pump to do this? Is it cheaper just to buy the pump since it is going to be a yearly ritual from now on?

Borrow? This needs to be done at a minimum of 2x a year. Buy one. Zoeller makes a kit. And Cuno makes a descaler filter to put inline for those.
 
Borrow? This needs to be done at a minimum of 2x a year. Buy one. Zoeller makes a kit.

And Cuno makes a descaler filter to put inline for those.

;)

Who would have known?

3m-aqua-pure-ap430ss.jpg


-3M™ Aqua-Pure™ Scale Inhibitor System-

I did not know this... THANX! :D
 
The Zoeller pump is a $300 piece of equipment (with tax). Is there a cheaper or DIY option available?
 
Solution: Lower the incoming gas pressure. There is a sweet spot for gas pressure that these Bosch tankless HWHs like. Play with the red lever on the gas line coming to the unit. Turn it all the way on (straight up, full on). Slowly turn it clockwise so the gas pressure decreases. There will be a point when you'll see the pilot fire is becoming smaller. Stop right there. If you turn the red knob anymore, the pilot light/fire will start to flicker and eventually turn off and you you have to re-light the pilot. That is the sweet spot. Use a marker and put a mark on the gas pipe so you'll remember that spot.

It works like a champ for me. The pilot haven't gone off for 2 months now. It stopped the annoying dripping. I didn't have to run any vinegar or do any type of cleaning.
 

Latest posts

Back
Top