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Heating, Air Conditioning, Fridge, HVAC/Mysterious boiler main burners problem


Mystery time. 20 year old Weil Mclain VHE has cycled as it should untill one week ago when temps took a dive to @ 7 degrees. Cycled properly all day but @ 5 PM and AM after 5-6 OK burner cycles main burners unlit and gas coming in (strong smell rising through house) so I switched off at the boiler and called service man, when he arrived two hours later and switched boiler on it cycled as it should. The gas valve was replaced 1 year ago, and when checked now worked as it should. Service man left after all checks found no problems. Next morning @ 5 AM same thing. The burners had cycled OK for sometime as the house was warm, but now burners unlit, gas smelling up the house. Called another tech and again no faults found when switched back on. He suggested low gas pressure to house and calling gas company to check meter and regulator. Gas man found no faults but raised pressure from 6" to 7". Boiler has cycled as it should since then but outside temps have been 20-30 degrees warmer since failure occurred, and a big drop is coming and I am not confident the problem has been fixed.
So, any ideas why the burners fail (twice a day at around the same times)to light after apparently doing so for 5-6 cycles? I sat watching and never saw the no-light condition but did see the burner flames very weak after 5-6 OK cycles. Any suggestions most appreciated.

eyeballed the boiler


Looked briefly at your unit via pdf file, says minimum gas pressure to unit 5" max 13" 3.5" at gas valve ( natural gas ). No mention from you if either of the techs checked the gas pressure at the gas valve.possible you have issues with the flame sensor or spark ignitor. Says lack of primary air causes yellow tips on the burners, underfire causes small flame, overfire causes large flame.I would check the gas pressure at the gas valve first. clean the flame sensor or replace along with the spark ignitor. When was the last time unit had a PM check ? In the instructions it says a yearly cleaning ,removing the flue pipe and cleaning, cleaning the burner tubes, I would download a pdf file on line and read what they recommend.

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40+ years diversified experience.An HVAC/Refrigeration Self Employed Contractor since 1986. NATE Certifield. Answer questions pertaining to Residential and Commercial Air Conditioning , Warm Air Heating, Heat Pump systems.Mechanical and Electrical troubleshooting of these systems.Be as detailed as possible when describing problem.Packaged unit or split systems.No appliance questions.


Installation and Troubleshooting, Mechanical and Electrical, in following areas, Refrigeration ( Walk In and Reach In Coolers and Freezers ) Commercial Roof Top and Packaged Heating/Cooling ( Natural Gas,Propane, Electric, and Heat Pumps ) Computer Room Air Conditoning Systems,Commercial Residential Packaged and Split Systems Air Conditoning and Heat Pumps.Warm Air Oil , Natural and Propane Gas Heating systems.

Graduated from Private Technical School in 1975. An HVAC/Refrigeration Contractor . Have Unlimited Heating/Piping and Cooling Contractor License.Limited Sheetmetal Contractors License.NATE Certifield. York Certifield Master Heat Pump Technician 1986. Served 33 years combination Active Duty Air Force , Air Force Reserves and Air National Guard in the HVAC/Refrigeration Shop/Mechanical Shop. Troubleshooting/Installing HVAC/Refrigeration Equiptment Worldwide. Retiring in 2003 as a Senior NCO ,and a Mechanical Superintendent.

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