20 Most Recent Bosch & Tankless LP Hot Water Heater - Page 8 Questions & Answers

check for pilot but im sure that the pilot is on demand thats what makes these things so cool and inexpensive to operate. try having someone turn on the hot water while looking for ignition. if there is nothing it may be a relay. im not sure but if you open it up check for a 3 amp fuse its green. all the new furnaces with mother boards have a fuse. I am not really a heating guy but i have been looking into on demand systems and sat in a training session at the plumbing supply. never hurts to try and help.
if its not a fuse or the ingniter isnt functioning you may need to call a heating person who knows on demand or check Bosch on line maybe they have the trouble shooting guide if you dont.

sorry that all i can suggest hope it helps

Hi,

With these types of heaters there can be a harmonic sound that is produced at certain firing rates....the heater is a variable fire and it will run the burner at the heat needed to produce the temperature water needed...
The only way to reduce the sound is to change the firing rate of the boiler or the hot water temperature so that it runs at a higher fire and stops the sound...

This all becomes very complicated to do and it will take an experienced tech. to get the job done safely...

heatman101

MAY BE THE STAT IS BAD.. TAKE VOLT METER AND CHECK FOR POWER AT THE HEATING ELEMENTS. COULD BE A BAD ELEMENT ,WICH MAY BE A HOME DEPOT PART ABOUT $10.. IF NOT THESE CAN BE KINDA TRICKY TO REPAIR.. GOOD LUCK HOPE I WAS OF HELP..J

I would check to make sure thermocouple is in proper position in pilot flame. If so and pilot won't stay lit I would replace thermocouple. Thanks

Hello. This is strange unless you have a timer on the unit that prevents it from firing at night. Call your LP provider as most companies have technicians who will come out for free to keep you as a happy customer. Joe

4 thumbs up please. ty

I say it's Thermostat based, either the sensor, the thermistor, or the actual Thermostat itself, or possibly even both. You will have to perform the troubleshooting procedures to isolate and tell. usually this is accomplished, if one has NO instruments, by simple substitution. One should also obtain a service manual, for your exact make and model, if you cannot find one on the 'net, then approach the manufacturer directly, they will be only too happy to supply one.
To do any work on a unit such as this one really must obtain a service manual.
It is my professional opinion, that really one should get a professional to attend to these matters, as sometimes they can be the start of an underlying problem, that maybe quite serious?
In any event, be careful, and stay safe.

Look at eReplacementParts.com and the parts diagrams

Hello. Use a small stiff brush and a vacuum cleaner with hose to thoroughly clean the entire mechanical area of the water heater. Then go through the steps to light it once again.

Many times a little dust is the problem with these heaters. If the cleaning does not solve the problem the next step is to change the thermocouple. This is a common item available at any hardware store. Joe

Hi Greg. The problem is either a dirty thermocouple or a worn out thermocouple. You can try cleaning it with a small brush and a vacuum or you could try pushing it a little closer to the burner. that said, thermocouples do have a life span, you can go to a local hardware store and buy a universal thermocouple for less than 10 dollars.

I had the EXACT same problem (installed my tankless last winter and worked fine, now this summer it fluctuates, have to turn the shower completely off and then on again to get any hot water and then it only lasts for a couple of minutes!) Argh - it is frustrating!

Here's what I found: the demand for hot water is lower during the summer (hot) months because the "cold" water coming in is already quite warm. You don't need as much hot water to make the shower temp comfortable. SO, my tankless was shutting off due to low flow demand. I've removed the flow restrictor from my shower head and it helped alot but didn't completely solve the prob. Next step is what has been recommended to me by several people but is much more expensive - change the pressure valve on your shower to a temperature valve. Or just wait til winter and it should work ok again :)

In order to clean the unit you need to connect a small sump pump to the cold inlet, and run a hose from the hot side into the same bucket. Pour about a gallon a white distilled vinegar in the bucket, and turn the pump on. Let the solution run through the unit for about 15 minutes, then reverse the hose connections and run the pump for another 15 minutes. Reconnect the water supply and outlet. Turn the water on in the bathtub first on the hot side and let ir run for a few minutes before turning the power back on to the heater. While the water is still running turn the power back on and reset the thermostat. If you get a lot of debris in the bucket, you may need to consider installing a water-softener to prevent scaling.

Turn the Gas off at the main supply to the unit and contact Bosch ASAP. Do not try and refire the unit.

when your tankless starts cycling hot and cold water, then there is probably scale buildup inside the unit.
flushing the unit will remove the scale and any other debris inside the unit.
you can do this yourself, do you have the instruction book that came with the tankless heater?
it is recommended to flush the unit once a year especially if you have hard water.
it takes an hour or maybe a little longer to flush the unit completely.

A fault often found with these units is due to insufficient water flow. Usually this causes specifically the shower to run hot and cold. Try turning on more than one hot supply; if this fixxes the fault you will need to try and increase water flow. Most new tapware/showerware have water flow restictors built in. These are the cause of many problems with continous flow heaters such as the Rinnai. In taps they are usually located in the spout if it unscrews. In showers try the shower hose. Find them and take them out. Also make sure your mains supply to the house is on full.
There are more technical faults but this is something you can easily try first.

no. they are manufactured specific to the type of gas they burn at the factory

you need a water flow sensor.

time to flush out the heater. do you have the instructions?
lime and scale build-up will cause this

takes a little time, and requires about 5 gallons of vinegar, and a small pump.

if this is for residential, then you probably don't have the space or amps available in your breaker panel to use one of these. you will need to call an electrician to replace your panel.

a side note... these are VERY expensive to opperate. I wouldn't use an electric tankless unless you have no other choice. Use a tank style electric unit, much much less to opperate