I recently had a high efficiency furnace installed, what is the reason it needs a fresh air intake?
The furnace sometimes has a problem firing and the installer(not hvac) thinks it is not getting enough air to fire. It eventually does fire. He removed a plug on the side of furace (about the size of a hockey puck) to allow more air in. It seems to work better but this is not how it is supposed to work. The intake is 3″ pvc, 2 elbows, 18 ft long. He also measured gas pressure at two places. He thought the gas pressure coming in may be too high(12). he adjusted the internal pressure to specs. The intake pvc is not clogged. But if you remove it at the furnace it seems to fire normally. He seems to think that removing the plug is good enough. I want to make sure this is not bad for furnace and safe to run this way. Would an adjustable gas valve fix it? Also, the gas water heater is still vented into chimney, it is in center of house. I have a slate roof so it is difficult to access chimney. The chimney has an elevated cover. Any suggestions are appreciated.
The new high effiency furnaces need to draw their combustion air from outside the house. it’s all about the negative pressure like mentioned above.And also as a safety to keep the combustion sealed from the ambient air in the house. And like redbird mentioned your intake piping may be too restrictive, and may need to be replaced with a larger diameter pipe.
But everybody has overlooked the obvious. Have you looked at the intake pipe outside? It could be that the exhaust and intake are too close together causing the furnace to recycle the exhaust gases. Since there is little to no O2 left in the exhaust it can cause the symptoms you’ve mentioned. The exhaust should be turned up and away from the intake or straight out from the house and the intake should be turned down, to keep them at a minimum of 18″ apart. Check your manual to find out how far apart they should be and how they should be terminated. Is it blocked by something? Sucked up leaves etc etc. A couple of leaves in the pipe can restrict it just enough without making it appear blocked.
I made a service call on a furnace one night for the exact same problem as yours and found the guys 6 yr old kid had stuffed a plastic bottle down into the pipe with a stick.
Just a couple more ideas for you to look at.
Honour PVC on Kinky Chain Suspender Dress Esme
The Blanket Lift Bar is made of plastic-coated steel. It creates a free space of about 30 x 16 x 12¨ (76 x 41 x 30 cm). One side slips under the mattress and the other side supports the blanket.
Dimensions are 16 x 12 x 16¨ (41 x 30 x 41 cm) high. Dimensional size packaging….
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