Gas heating lockout resst - Carrier XHB123D X/Y Series Heat/Cool Air Conditioner

Just press the Reset button to reset the hard lockout, but if it does not work even after that, it means the lockout condition of your boiler needs to be cleaned. So better contact a Registered Gas Engineer in Essex to get the work done flawlessly.

replace ignition control board, use only OEM psars

If you have a dual fuel system - gas/heat pump the heat pump should lock out at around 41 degrees depending on what the outside lockout sensor is set at. It may be that both the heat pump and furnace could be running at the same time if the outside lockout isn't working or there could be a problem with the thermostat. Best bet would be to have a service tech check it out. However if you want to check it out here are the terminals Terminations: R,Y1,Y2,W2,E,G,O,B,L,C. W2, E and B are the heating terminals for 2nd stage heat and emergency heat. First stage heat, compressor Y1 with B (reversing valve on heat pump) energized together. 2nd stage W2 energized for gas or electric heat . No power to Y1 and B when W2 is energized if gas. E can be energized with Y1 and B if you have electric heat or if you switch over to emergency heat, E will be energized.

YOUR FURNACE IS IN LOCKOUT MODE DUE TO A SAFETY FEATURE OF UNIT. USUALLY THE HIGH LIMIT HAS BEEN TRIPPED, OR YOU PRESSURE SWITCH FROM DRAFT INDUCER MOTOR FAULTY OR PLUGGED. IT WILL CONTINUE LOCKOUT MODE UNTIL THIS IS FIXED.

Ignition Lockout on this unit means #1 that it is set up on propane. If you are low on propane, or were low on propane and just refilled, low/no gas pressure could be the issue. If you ran out of propane, thre is now air in the gas line that needs to be fully blead out.
If propane level is not the issue, replace the ignitor.

The ignitor on these units is also the flame rectifier (flame sensor). If the unit is firing up, but the computer thinks that it is not, then it is not sensing a flame. Replacing the flame rectifier/ignitor will fix the problem in this case.

The FV lockout varies by brand of heater... some require simple cleaning, while Rheem requires part
Following link has rundown for various models:
http://waterheatertimer.org/troubleshoot-flammable-vapor-on-gas-water-heater.html

Burner going out could be FV lockout, low gas pressure, or gas control valve thermostat:
Following link has troubleshoot for pressure and various models of gas control:
http://waterheatertimer.org/troubleshoot-gas-water-heater-thermostat.html

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

I would check out the flame sensor it needs cleaning

check the gas valve under neath souns like it is still in lockout position

I had the same problem when I bought it and it just happened again; the problem is solved by ressting the control panel: Hi Temp ---> Heated Dry two or three times. It kind of goes into a testing cycle and the clean blinking light goes off.