More proof it's HVAC that causes humidity issues

[charles Tauber]

Originally Posted by ruby50

The HVAC system does not raise or lower the the amount of water in the house. A duct system or radiator system is closed - there is no water being removed or added as the air in the house gets sucked into the return, through the system, and out the supplies, or as it passes through a radiator.

While I appreciate your expertise, this isn't necessarily true.

Some homes have a humidifier installed adjacent to the furnace, in-line with the furnace and ducting. A typical version of such a humidifier allows air to blow over a pad that has water trickling over it. As the air passes over the pad, the air picks up moisture and the moister air is then distributed throughout the home.

In the summer, "air conditioners" cool the air by blowing the warm, moist air over cold surfaces. As the air passes over the cold surfaces, some of the moisture in the air condenses on the cold surface, removing moisture from the air. The cooler, drier air is then circulated through ducting to interior spaces.

While many associate "air conditioning" with making air cooler, the more general sense of "conditioning" is to bring the air temperature and humidity into "comfortable" conditions. Anyone with a window air conditioner is aware of the constant dripping of condensed water on the outside end of the air conditioning unit.

Sealing first then insulating second is the way to solve the bulk of the humidity problem.

Insulation reduces condensation on cool surfaces of moisture in the air, thereby keeping more moisture in the air, itself, rather than on cold walls, windows, pipes, etc.: condensation on surfaces can lead to mold growth.

To be clear, there must be some exchange of fresh air to the home. The goal, from a health standpoint, is not 100% recirculated air.

[rokdog49]

Originally Posted by charles Tauber

While I appreciate your expertise, this isn't necessarily true.

Some homes have a humidifier installed adjacent to the furnace, in-line with the furnace and ducting. A typical version of such a humidifier allows air to blow over a pad that has water trickling over it. As the air passes over the pad, the air picks up moisture and the moister air is then distributed throughout the home.

In the summer, "air conditioners" cool the air by blowing the warm, moist air over cold surfaces. As the air passes over the cold surfaces, some of the moisture in the air condenses on the cold surface, removing moisture from the air. The cooler, drier air is then circulated through ducting to interior spaces.

While many associate "air conditioning" with making air cooler, the more general sense of "conditioning" is to bring the air temperature and humidity into "comfortable" conditions. Anyone with a window air conditioner is aware of the constant dripping of condensed water on the outside end of the air conditioning unit.



Insulation reduces condensation on cool surfaces of moisture in the air, thereby keeping more moisture in the air, itself, rather than on cold walls, windows, pipes, etc.: condensation on surfaces can lead to mold growth.

To be clear, there must be some exchange of fresh air to the home. The goal, from a health standpoint, is not 100% recirculated air.

Having come from a background in Plumbing/ HVAC, this is all quite accurate. The thing is, if you don’t have a “built-in” furnace humidifier that part is null. If you have a forced-air furnace, it’s the greatest invention since sliced bread.