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Heating, Air Conditioning, Fridge, HVAC/Brand New Concord Furnace Doesn't Work In Cold Weather



I purchased a 90% efficient condensating Concord furnace, model number 95G1UH090CP16 in mid-October of this year with a Honeywell programmable thermostat. When it was installed in October, the weather was mild (in the 50s) and the furnace worked great. However, now that it's December and has gotten quite cold in New England, the furnace is on the fritz despite being brand new. The plumber who installed it (and another guy from the same company) has been out to try to fix it, and cannot figure out what's wrong with it - an HVAC repair guy from a different company was out, and cannot figure out what's wrong with it. The plumber called Concord Tech Support, and they couldn't figure out what was wrong with it - but I haven't had heat for 2 weeks despite temps below freezing, and I have a 1 year old son, so I'm getting a little desperate here. Here's what I know:

- There is 18 feet of piping and 4 elbows (5 elbows allowed with up to 19 feet of piping, so we're below that)
- Everything is properly pitched toward the furnace
- The drain piping etc appears to be installed correctly, and drains into a condensate pump that appears to be functioning properly
- By all appearances, there is nothing wrong with this furnace

The symptoms:
- If the temps outside are mild, the furnace works fine and keeps my house at the set temperature with no issues. If it gets cold, the following happens:
- Fan turns on, burners ignite, everything works properly for 30 secs-3 mins. Then everything shuts down, blower turns on. It doesn't get nearly warm enough to get the house up to temp, but everything turns on and appears to be running properly while it's running
- Sometimes a pressure switch error that indicates the pressure switch trips while the inducer is open (3 blinks) gets thrown. Other times, it's just a solid light, indicating no problem at all (even tho there clearly is one)
- There is water getting into the inducer fan. I do not know where it's coming from. According to the Concord tech support guys, it's not possible.
- The furnace doesn't drain while it's running, but I believe it should... It drains after the burners go out and everything shuts down
- There is no lock out; if I set the thermostat high (in the mid-70s or 80s) the furnace will kick on and off every half hour or so, but it only runs for a little bit before going out. If I turn the temp down on the thermostat until the request for heat turns off and then turn it back up so the request for heat comes back, it turns the furnace on - I do not need to manually turn power on and off to the furnace, the thermostat does its job, but the furnace only listens for a little while
- It is not a thermostat issue, as jumping the wires doesn't solve the problem
- The pressure switch appears to be operating properly, as does the sail switch and the rest of the furnace. There's clearly a drainage issue due to the water in the inducer, but everything is installed properly and the condensate pump is working - also, if it wasn't hooked up properly, it wouldn't work fine in warmer weather

I'm not even looking to DIY this, but I'm not sure what to do at this point - 2 plumbers, an HVAC guy, and the Concord tech support dudes are stumped, and I'm frickin freezing. I have a brand new furnace and no heat - the place I bought it from has a guy who's Concord certified, but he's on vacation for another week (of course). Do you maybe have ANY insight that I can pass along as to what could possibly be wrong with this furnace? Thanks in advance.


goggle " Concord 95G1UH " then find the pdf file on the installation guide and start from page one and read and check what they recommend. Having a plumber install would not be the right way to go for starters. You need a HVAC Professional. Plumbers deal with piping.Typically do not know how to set the gas pressures.I live in New England also and plumbers are not licensed to set up furnaces, ( troubleshooting for starters )How experienced was the HVAC guy you hired? No mention from you if the gas pressure was checked and adjusted to manufacture the gas valve and checking the incoming gas pressure in your residence. Your altitude has a lot to do with setting up the gas pressure.If your altitude is above 4500 you need to change to a high altitude pressure switch ( page 39 ) In the install guide instructions it says no lower than 60 degree return air consistent temperature across the Heat Exchanger.If you have a non direct venting , do you have enough surrounding air for complete combustion? Where is your furnace located, basement,attic, closet??, horizontal mount,vertical mount? Flue pipe piped exactly as stated and terminated minimum of 12" above highest anticipated snow level? Do you have propane or natural gas? if propane page 31 talks about a inlet pressure switch needing to be installed. Gas pressures for natural gas 3.5" propane 10" , below 4500 ft. altitude. above 4500 altitude instruction says call Tech. Rep. I believe if you hire a SENIOR HVAC Tech. who is trained in Concord gas furnace ,along with following the install guide ( that I referenced ) and read it carefully page by page and follow it to the T you will find your problem.The install guide also talks about if the furnace is installed in a cold environment ( below 35 ) to insulate the vent pipe with 1/2" armaflex insulation or if any part of the pipe goes through a unconditioned area. To me all this should be covered under warranty, including labor, if you went with a reputable Contractor. Also many times furnaces have what are called Technical Bulletins meaning there is some issue with the furnace and parts may need to be changed on new units. Basically a recall. So ask your Contractor or Tech. Rep. or goggle your model and brand to see if there were.

There is water getting into the inducer fan. I do not know where it's coming from. According to the Concord tech support guys, it's not possible.
- The furnace doesn't drain while it's running, but I believe it should... It drains after the burners go out and everything shuts down,.......Try checking the drain line hook up it may be located for a horizontal configuation vs a vertical or vise versa. usally the drain lines has couple taps depending on configuration.Your problem may be with the drain system, or flue,or negative pressure preventing the pressure switch from closing consistantly. Suggest taking photos of your furnace and piping and send to Tech Support so they can see your install. If this is a propane furnace hopefully they installed the correct gas valve conversion kit which consists of springs and burner orifices . The springs go inside the existing gas valve. the orifice ( made of brass ) replace the natural gas orifice and mount at the ends of the burner main header.

One last thing pages 46 and47 has a detailed start up checklist, was it followed???? suggest having the Contractor fill it out ,then call Tech. Rep to compare

A95UH, A93UH, 95G1UH & 92G1UH
Warm Air Gas Furnace
Upflow/Horizontal Left and Right Air Discharge says " THESE INSTRUCTIONS MUST BE LEFT WITH HOMEOWNER."

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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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