Help - Reverse draft from water heater CO monitor going off
I have a 15 year old home with a regular venting hot water heater. It is a 3" B vent to the roof that goes through the wall upstairs wall, through the attic above the garage and out the top of the roof.
The water heater is 3 years old and we have never had a problem before. In late October we had our house reroofed due to a hail storm. Problems with CO began to occur off and on around Thanksgiving. It seems if temperature is below 10 deg F. We get a reverse draft in the vent causing CO to leak into the house. You can also smell the combustion gases.
The water heater vent had a 24" striaght up run then a 90 another 24 inch run then another 90 to the pipe going straight up to the roof. I changed this this week to go to 2 45's to straighten the run and always keep an upslope. This helped until last night after both kids baths and a cold clear night I had the CO monitor going off. I cracked a window in the basement and kept fans going to lower the level.
Because of snow/ice I can not really get on the 9/12 pitch roof safely and check the outlet cap. I am also concern I may have the house too tight. I recently installed a new patio door because the other one had several leaks around it and we went from traditional box attic vents to ridge cap. Could this have tightened the house that much?
Should I invest in a power vent water heater when I have a perfectly good one. Should I invest in a power vent kit for my hot water heater? Should I put in a make up air vent - Not exactly sure how these work, where to get them. Any help would be greatly appreciated.