Re: Takes long time to heat then goes from hot to cold.
I know that this is a great answer but with out being there its hard to answer you call there tech support they are great, I have had to call they from jobs before they can help
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1. Cross Connections - this occurs when cold water leaks into the hot water system through a fixture. In order to check for a cross connection: 1) turn off the cold water to the tankless 2) open up hot water fixtures in the home. The water should shut off at all hot water fixtures; if there is a continuous flow of cold water, then you have a cross connection. The most common place to find a cross connection is on old shower cartridges.
2. Ask the customer to check to see if the burner indicator is continuously lit during operation.
3. When the water goes cold at one fixture, try another near by fixture to confirm it is also cold there. If its hot at one fixture but not the other, then you have some issue with you plumbing. Tankless heaters can't pick and choose which fixtures to deliver hot water to.
4. Tankless water heaters all have a minimum flow rate that must be maintained in order to continually fire (.5 gpm for Noritz). Ensure their hot water fixtures flow at least this amount, or that the customer isn't mixing too little hot water at their fixture.
5. If they see the cold spurt during initial firing, they may be experiencing a cold water sandwich. When the heater moves from a standing state to a firing state it takes a short period to ignite and heat water. During this time it will be passing cold water through the system. Usually this cold water mixes with hot water in the line as it travels through the plumbing system, but if their fixture is very close to the heater, there won't be enough time to mix.
6. If debris has gotten into the flow sensor, this can prevent the unit from registering flow and cause intermittent firing.
The manual says to hold a match near the pilot while the ignitor is
trying. It says that if the unit lights the pilot orifice may be dirty
or clogged. Then the manual says to check
the voltage on the igniter. It should be 1.3 volts DC minimum if it is not means the electronic control box is defective.
Aquastar 1600H NG Natural Gas Tankless Water Heater Bosch AquaStar Model 1600H NG Natural Gas Whole house tankless gas water heater, 117,000 Btu input, natural draft with hydro-generated ignition. Provides endless hot water for one major application at a time . Can replace 40-gallon storage tank water heater. Optional Accessory: Model AQ1- Power vent with built-in... More freeze protection when venting horizontally. Capacity: 1 to 2 Bathrooms Dimensions: 8.75D x 18.25 W x 29.75H Weight: 40 Max GPM @ 45F Rise: 4.2 Energy Factor: NG .80 LP .84 Minimum Input: 28,000 Maximum Input: 117,000 Vent Size: 5 Gas Connection: 3/4 Water Connections: 1/2 Warranty: 12-year warranty on heat exchanger, 2-year on parts Features: Endless hot water Can save up to 50% off utility costs annually Perfect for one major application at a time No standing pilot, hydro generated
If you are using a 3/8" copper line for your gas, get it replaced ASAP. It will fail. 1/2" Black Iron is required with natural gas. 50 gallons is a lot of water to heat. Look on the heater label for the recovery rate.
it sounds to me like the dip tube has failed. this is a plastic tube that is inside the water heater on the cold side. It is designed to put the incoming cold water at the bottem of the tank allowing heated water out at the top. when this tube deteriorates the cold water mixes at the top of the tank instead of the bottom. a new dip tube is about 5 bucks but must be inserted on the cold side by someone with plumbing experience.
Hi Ken Tankless Water Heaters typically heat to a 80 deg temp. rise. Per a set time it takes the water to pass through the heat exchanger. Matter of seconds So at 130 deg F. Your heater is working fine. Did you take a heat measurement or are you looking at the set points inside the cabinet? To get the 130 deg F you need to upgrade the sensor available from your Bosch Dealer. Typical output water temperature would be 110. There are scalding issues over this set point. As long as you have 3/4 id pipe in and out and have insulation on the discharge side of the heater at all exposed points of the pipe. Your system was likly installed properly. Look it is only my opinion but Bosch it the best you can get in Tankless heaters. As for the dishes. Use the sanitize setting on the dishwasher or alittle extra bleach in the dishwater. And don't forget to rince with fresh water only. For the shower or tub. Use less cold water in the mix. Tankless water heaters were designed to use less resorces aswell as energy. And I want to thank you for that.