Lo flow, temp a little low, both outlets. - Bunn Dual® (20900.0011)

LO standss for limit open. the most common cause is lack of adequate water flow through heater. other causes are high temp limits.

CHECK LIST

- is the BTU'S enough for the space
- is there proper flow through boiler
- should have 20'F-30'F difference between inlet and outlet temp
- is there air in the system
- is there a lock on via controls that is set to lock out under 20'F
- no matter what if boiler is working properly it should be able to maintain 20-30'F temp difference from inlet to outlet
ex. 60'F in, 85'F out = 25'F split boiler is working right, if temps do not rise means house insulation my be so bad BTUS calculated for the coldest conditions was to low

Low flow. Try cleaning the filter.

All resets and breakers trip with high heat.
Do you mean the tankless unit is tripping the 40 amp circuit breaker?
Or the thermal cut-out, located on unit, is tripping?

Is this a new installation?
Or was the tankless working before and stop working?

Copy following link to check wiring.
AE 9.5 requires 40 amp breaker and 6 gauge wire.
http://waterheatertimer.org/How-to-wire-Tankless-electric-water-heater.html

If the unit is tripping the thermal cut, -out, then product manual says to call Bosch or service technician.
Call Bosch 866-330-2729
http://waterheatertimer.org/pdf/Bosch-Powerstar-AE3.4-7.2-9.5.pdf
Thermal cut-out can trip if water flow is too low.
Try changing power selector screw from Hi to Lo so only 1 element is ON. See diagram page 6 of manual.
Adjust the 'outlet service valve:' The manual recommends that a ball valve be installed between hot outlet and faucet. Adjust the valve so more water flows to faucet.
Remove aerator, clean aerator, don't use low flow restrictions or low flow shower heads, replace leaky faucet cartridge on single-handle faucet.

If you need further help, I’m available over the phone at https://www.6ya.com/expert/gene_9f0ef4df2f9897e7

Thank you for posting your question here on Fixya.com.

A 'LO' error code for a Hayward heater is a limit string open error. If the limit string opens the heater shuts down and goes into lockout. Automatic restart is 2 minutes after the error condition is corrected and the limit string closes.

The limit string is a series of switches designed to turn off the heater if air or water temperatures exceed a safe operating limit.

The problem may be faulty a switch(es) but is far more likely to be a system condition the switches are reacting too that needs to be corrected. Low flow of combustion air due to obstructions around the heater or the vent; low flow of water through the heater allowing too high a water temp; Poor venting or sooted-over heat exchanger causing flame rollout; inlet and outlet hose connections reversed; these are all conditions that should be eliminated if they exist.

If you are not familiar with these switches or the conditions described you may want to consider calling in a professional. Hayward can refer you to someone in your area who is. Call Hayward at 908-351-5400 or try the website locator found here. It is likely to still be covered under warranty.

If this answer does not fix your problem, please comment with additional details prior to rating the answer. You may also contact me thru our website at www.arrowpools.net. Positive feedback is appreciated once your problem is solved!

John

Could be the heater bypass valve is stuck or the heater core is blocked.
I'd check the heater core first.You may have trapped air in the cooling system or the heater core may be partially plugged up. Engine coolant is delivered to the heater core through two heater hoses. With the engine idling at normal operating temperature, set the temperature control knob in the full hot position, the mode control switch knob in the floor heat position, and the blower motor switch knob in the highest speed position. Using a test thermometer, check the temperature of the air being discharged at the HVAC housing floor outlets.
Temperature Reference
Ambient Air Temperature 15.5° C (60° F) 21.1° C (70° F) 26.6° C (80° F) 32.2° C (90° F)
Minimum Air Temperature at Floor Outlet 52.2° C (126° F) 56.1° C (133° F) 59.4° C (139° F) 62.2° C (144° F)
If the floor outlet air temperature is too low, Both of the heater hoses should be hot to the touch. The coolant return heater hose should be slightly cooler than the coolant supply heater hose. If the return hose is much cooler than the supply hose, locate and repair the engine coolant flow obstruction in the cooling system.
OBSTRUCTED COOLANT FLOW
Possible locations or causes of obstructed coolant flow: Pinched or kinked heater hoses. Improper heater hose routing. Plugged heater hoses or supply and return ports at the cooling system connections. A plugged heater core. If proper coolant flow through the cooling system is verified, and heater outlet air temperature is still low, a mechanical problem may exist.
MECHANICAL PROBLEMS
Possible locations or causes of insufficient heat: An obstructed cowl air intake. Obstructed heater system outlets. A blend door not functioning properly.
TEMPERATURE CONTROL
If the heater outlet air temperature cannot be adjusted with the temperature control knob on the A/C Heater control panel, the following could require service: The A/C Heater control. The blend door actuator.
The blend door. Improper engine coolant temperature

If you're not looking specifically for temp to cook specific food items, rather what lo, med low, med etc mean . . . from the packing insert lo is 185 degrees, med low is 225 degrees, med is 300 degrees, med hi is 375 degrees and hi is 415 degrees. I just purchased this item yesterday.

One of your limits is not working or not wired up. An easy way to check the limits - Water pressure switch, Hi limits, air pressure switch all of which have 2 wires going to them. Unplug one item and connect the 2 wires together ( paper clip works fine ) Then retest, if problem does not go away remove paper clip and reconnect wires and move to the next limit. The limits are located in the black plastic header. Always make sure water is flowing through the heater at all times while checking the limits.

I just had this same problem in a 91 Camaro.It's definately the fuel pump.

The device has two different alarms: One is based on the time and one is based on temperature.

To disable the time alarm:

1. Press the Alarm button on the front until the "bell icon" on the display disappears.

To disable the temperature alarm:

1. Press and hold the "Temp Hi/Lo" button.
2. Use the arrow buttons to select the high/low temperature alarm.
   
3. Press the "Temp Hi/Lo" button again.
4. Use the arrow button to select "Off".
5. Press the "Temp Hi/Lo" button again.

Please refer to the owner's manual as a reference. Hope that helps!