Hvac package unit the heat is not working - Tylo COMBI-U7 Heater

It may just be something it does when you happen to turn on the sink. I don't think there is a problem with the water heater coming on when you use cold water. It may just be heating the water back because the water is much colder than normal. You could talk to an HVAC guy and see what kinds of things they can do to help the situation. SERVICES Marv Plumbing Bellingham WA

Another infamous question where the inquiry is not well stated.
Are we talking HVAC as this is posted in Water Heaters?
And,gosh, doesn't it make sense that when the T-Stat is on.......amazingly the unit works?
As opposed to when it's off and the unit is still energized?

http://waterheatertimer.org/How-to-fix-water-heater.html

What kind of water heater do you have? Boiler, indirect?
What brand and model?
Or is this a HVAC unit?

Gene

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

The unit you state is a Sauna heater/humidifier. I do not understand how or why it is connected to a heating ventalting air conditioning (HVAC) system, please explain.

1) No.
NO.
Do NOT store combustibles close to a water heater, fireplace, or any source of ignition, including HVAC, space heater, microwave, appliance, etc.
http://waterheatertimer.org/Troubleshoot-Rheem-Tankless-water-heater.html#bang

2) Tankless water heaters do not have FVIR safety features found in tank-type gas water heaters rated less than 60,000 BTU.

3) Tankless water heaters draw large amounts of air into combustion chamber from surrounding room, and this air feeds directly into the burner flame with no barrier.

4) If flammable vapors enter tankless, then it can cause fire, explosion, conflagration.

5) Read product manual and safe a life.

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

Look at rating plate on side of unit for Volts, Amps, Watts.
Volts x amps = watts.
If unit is 240Volts, then you need double-pole 240Volt breaker
If unit is 8500 watts at max power, then 8500 watts divided by 240Volts = 35 amps.

What size breaker for 35 amps?
When electricians figure load rating for breakers, they use the 80% rule.
40 amp breaker x 80% = 32 amp safe maximum load for 40 amp breaker. Use 8 gauge wire with 40 amp breaker.
50 amp breaker x 80% = 40 amp safe maximum for 50 amp breaker. I use 6 gauge wire with 50 amp breaker.
60 amp breaker x 80% = 48 amp safe maximum for 60 amp breaker. Again, use 6 gauge wire with 60 amp breaker.

How to connect wires to unit.
First of all, all outdoor HVAC units require power cut off located next to unit.
This lets the mechanic, or service tech turn power off to work on unit, even if the mechanic does not have access to main breaker box.

Next, open unit to see where wires connect.
If unit has wires, then connect both hot wires from 240 breaker to the wires inside unit. Connect bare ground wire to green ground screw.
If unit has terminals. The terminals will be labeled L1 L2. Connect each hot wire from 240Volt breaker to either one of the screw terminals. Then bare ground goes to green ground screw.

Copy following links for basic illustrations connecting wires to terminals, and to breakers, and selecting wire size.
http://waterheatertimer.org/How-to-wire-Tankless-electric-water-heater.html

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

1) Post the brand name of the thermostat with as much detail as possible so folks can possibly find a manual to read alongside you.
2) Call local HVAC (heat-air conditioning) supply house and ask them for information about your thermostat.
3) Call HVAC repair company
4) Take a photo of your thermostat over to HVAC companies
5) Once you find out information, do a web search for that brand and model number

You may have to dig around a bit, but programming a thermostat can save money on monthly bill.

The manual says:
http://www.coinwash.com/temp/rinnai.pdf

"For the name of the Authorized Distributor or Installer nearest you, please contact your local HVAC dealer or gas service technician, visit the Rinnai website (www.rinnai.us), call Rinnai at1-800-621-9419 or write to Rinnai, 103 International Drive, Peachtree City, Georgia 30269"

Manual says that the remote is for setting temperature.
When you turn on hot water spigot, tankless water heater will heat the water to the set point temperature.
If water heater is not set up to use remote, then tankless unit will heat to 140 degrees F.
"With the MCC-45-4US remote control installed the water temperature is adjustable from 96
to 180°F. The water temperature cannot be set to a temperature other than 140°F
without the use of the MCC-45-4US remote control unit. If you require a temperature
other than 140°F you must install the MCC-45-4US remote control unit."

"Error messages are displayed on the remote control units, simplifying service calls."

Page 9 of manual shows hot to set temperature using remote.
Water taps must be shut off to set temperature.
Circulating pump must be turned off.
"Simply press the H or C button until desired temperature is displayed"
"green in-use indicator will display"

If your unit is not working, the manual says to contact local plumber.
Fixya has specialists who will talk to you by phone about your problem for a fee.

This is a circuit board problem you will need to contact rheem

U cannot put it back together it is a fail safe if the unit over heats from a plugged inlet the spring loaded damper is released by one of two way solder retainer melts or vial melts either way the the unit is bad contact Rheem with the 1800 number on the tank and depending on the age they will replace the tank. You will have to uninstall it take it back then install the new tank all not covered by them or if you can't do this a local plumber or hvac company can do it for u