How JustAnswer Works:
  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site. Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.
Ask Rick Your Own Question
Rick, HVAC Supervisor
Category: HVAC
Satisfied Customers: 22024
Experience:  40+ yrs. experience as a licensed oil & gas technician.
Type Your HVAC Question Here...
Rick is online now
A new question is answered every 9 seconds

I just ran out of propane and my heat hot water combo

Customer Question

I just ran out of propane and my heat hot water combo furnace won't relight. It a Bosch zwb 42-3
Submitted: 2 years ago.
Category: HVAC
Expert:  Rick replied 2 years ago.

It won't relight because there is air in the line since you ran out of propane. The safest option is to keep power cycling the unit. Turn the power off once it locks out due to failed ignition then wait a minute and turn it back on, keep doing this until it fires up. It can take a long time to do it this way. The other option is to close the gas shut off valve to the unit then disconnect the gas line then turn the gas back on until you can smell the gas (no open flames anywhere in the vicinity) then turn the valve back off. Then reconnect the line turn the gas back on (put slightly diluted dish detergent on your connection to check for leaks) then cycle the power again after waiting 10 or 15 minutes. The second option is how we would do it but if you aren't comfortable with disconnecting the gas line then stick to the first option.