"The production of carbon monoxide is a byproduct of incomplete combustion and there are numerous possible causes. If you are reading this in the vent (which I assume) it may not necessarily be a leaking heat exchanger (of course it could be). If…"
"The previous comments have addressed a lot of good possibilities and areas to look at, but I would like to expound a little further. I hope it helps. As mentioned in several of the other comments sealing a building can cause the inside RH to…"
"Obviously all of the prior recommendations could be correct however there is another possibility. In the HVAC industry it's typically referred to as "Dirty Sock Syndrome". It occurs in heat pumps and shows up in the heating cycle. The…"
"In your original entry and in your replies to other's comments you said a number of things that rule out some options - but also rule out some potential issues. The homeowner's request to add another supply (by itself) would provide…"
"Regarding the venting, the question is: how tight is the house? There are several issues with this 80% furnace being installed like this. In addition to the question of sufficient combustion air you also run into the issue of proper…"
"Unfortunately there is some missing information here, which of course you'll have a chance to gather. I also would take a look at the basement and what the humidity levels are there. It's interesting that he gave you the RH…"
"I'm not sure there is enough information to positively identify the problem. For instance, what were the outdoor ambient conditions and how long were the existing systems not functioning (were both broken)? What were the thermostat set-points…"
"Like most subjects this one is more complicated than a brief reply leaves gaps but...
Heat pumps are a great option and are used throughout the US. Heat pumps have received some bad press, but a lot of that is because of installation/service/design…"
"There are a number of possible solutions, but don't rule out a heat pump. A conventional heat pump should be able to provide the heat needed, even if auxilliary heat is required to supplement. While this has a higher operating cost it may solve…"
HVAC design, Manuals J, S, T, & D, Duct leakage, Air flow, ENERGY STAR new home requirements, and more. Since heating & cooling are such a big part of home energy use, understanding HVAC is critical.See More
Combustion Appliance Zone Testing (CAZ) Made Easy (March 24, 2016)
-Adapting to the new BPI standard
-RESNET testing requirements
-NFPA testing requirements
-Best practices for best results