More proof it's HVAC that causes humidity issues

[Aspiring]

Yesterday I had a new hot water heater installed.

During the day I was in my office working and noticed a bit of a humidity spike and turned down my humidifier in the room.

What I didn't catch was the temperature dropping until I woke up this morning feeling chilled.

Turns out the crew putting in the hot water heater had forgotten to turn my furnace back on and I didn't notice it until this morning.

Here is a Govee readout of the temperature and humidity. You can see where I turned the humidifier off and then turned the heat back on.

Screenshot_20210206-082053.jpg

[bsman]

Is there a Rainsong or Emerald in your future?

[Aspiring]

You mean to join the Emerald, Journey, Klos and Blackbird that I already have?
Seems like a good idea!


I have been paying pretty close attention the humidity and how it changes things. The biggest thing I've seen is how quickly the necks in my wood guitars move and how much the relief changes.

[fazool]

HVAC doesn't cause humidity problems.


This post may help understand.

[Dbone]

Lol, yes, when human error becomes HVAC then HVAC causes humidity issues...

You’re not entirely wrong though, in the sense that forced air heating lowers humidity if you don’t compensate with a humidifier....yup...

[Aspiring]

Yes clearly the temperature change was most likely the largest part of it.

I was posting mostly to show just how dramatically it changes.

Particularly with the humidifier going on and off.

[MC5C]

Temperature and humidity are completely locked together. As temperature varies, humidity varies inversely. For a given atmosphere, if the temperature drops the humidity increases, and vice versa. This is exactly why, if you take outside air at 30 degrees F and 80% humidity and warm it to 75 degrees, the humidity will fall to 20%. Hence we have to add humidity when we heat outside air for our homes.

https://www.lenntech.com/calculators...e-humidity.htm

Edit: you ever think how we did things without google calculators for absolutely everything?

[Aspiring]

Yes I understand the concept of relative humidity. You may also notice the section of the chart where the humidifier and furnace are both off the temperature is dropping and the relative humidity is not increasing.

While my phrasing of the title was not quite accurate I was trying to show the impacts that running your hvac and humidifiers can have on relative humidity from a data driven example.

Originally Posted by MC5C

Temperature and humidity are completely locked together. As temperature varies, humidity varies inversely. For a given atmosphere, if the temperature drops the humidity increases, and vice versa. This is exactly why, if you take outside air at 30 degrees F and 80% humidity and warm it to 75 degrees, the humidity will fall to 20%. Hence we have to add humidity when we heat outside air for our homes.

https://www.lenntech.com/calculators...e-humidity.htm

Edit: you ever think how we did things without google calculators for absolutely everything?

[Kerrigan]

[QUOTE=MC5C;6627031]Temperature and humidity are completely locked together. As temperature varies, humidity varies inversely. For a given atmosphere, if the temperature drops the humidity increases, and vice versa. This is exactly why, if you take outside air at 30 degrees F and 80% humidity and warm it to 75 degrees, the humidity will fall to 20%. Hence we have to add humidity when we heat outside air for our homes.

https://www.lenntech.com/calculators...e-humidity.htm



Excellent explanation... thanks for the link.
http://acousticguitarcanada.com/cabinet-project.html

[charles Tauber]

Originally Posted by Aspiring

I was trying to show the impacts that running your hvac and humidifiers can have on relative humidity from a data driven example.

I think you effectively did that.

Put a different way, if you didn't heat, ventilate or air condition (HVAC) your home, the temperature and humidity levels would be the same as outside (ignoring any effects due to human activities, such as showering, washing dishes, cooking... and sun light heating the interior space).

[charles Tauber]

Originally Posted by Kerrigan

Excellent explanation... thanks for the link.
http://acousticguitarcanada.com/cabinet-project.html

Any salient updates on your project?

[Aspiring]

Originally Posted by charles Tauber

I think you effectively did that.

Put a different way, if you didn't heat, ventilate or air condition (HVAC) your home, the temperature and humidity levels would be the same as outside (ignoring any effects due to human activities, such as showering, washing dishes, cooking... and sun light heating the interior space).

Thank you that is exactly what I was trying to say and show but phrased much better.

[Robin, Wales]

Blimey, you are obviously not paying enough for energy in the US if you can afford to control temperature and humidity in your home!

Over here in Wales humidity is controlled in the home by opening or closing a window and temperature by chucking a log on the fire or putting on a wooly hat!

[J Patrick]

Originally Posted by Robin, Wales

Blimey, you are obviously not paying enough for energy in the US if you can afford to control temperature and humidity in your home!

Over here in Wales humidity is controlled in the home by opening or closing a window and temperature by chucking a log on the fire or putting on a wooly hat!

....there are many different climates here in the US and many methods of dealing with them....energy is not inexpensive in my area...I do have a forced air system with a heat pump in my small home....in my yurt I have a pellet stove...windows fireplaces and wooly hats are not uncommon here and many people use them for temperature control...

...that said...in my opinion ...it’s true we are energy hogs...

[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. The system will raise or lower the local humidity near the registers or radiators, but by the time the warmed or cooled air gets to room temperature, the basic RH is there again.

Here is what happens - in the winter, outside air is cold and may have high RH. If your house has air leaks, then it gets into your house, and is raised in temp which lowers its RH - on a cold day, it could be in the single digit RH. However, for every cubic foot of air that leaks into your house, another cubic foot has to leak out. So your properly humidified air (shower, cook spaghetti, have plants, breathe, humidify your guitar room) gets pushed out and is replaced with drier air.

An air leaky house is drier than other houses in the winter, an air leaky room is drier than other rooms in the house.

Wood stoves and older fossil fuel heaters compound the problem because they have a chimney taller than the house, their exhaust air is very warm, and they suck air out of the house to both supply air to burning the fuel and to keep the chimney drawing. The same thing is true of leaky duct systems in the attic. (ALL attic duct systems are leaky unless you have intentionally sealed them). Leaky supply ducts in the attic not only waste money, but force outside air into the returns because of pressure differences, and leaky returns do it too. Remember if air goes out, the same amount has to come it.

My profession for the last 40 years has been residential efficiency and comfort, and we have been able to correlate RH with air leakiness. The easiest way to control excess dryness in the winter is to seal up the house. Your guitar case is like a tiny sealed room - much easier to keep the RH where you want it inside a closed case.

Your house leaks in odd locations and it is much more difficult to seal up than you might imagine. It is not your windows (except in a very few extreme cases) so don't waste any money trying to increase efficiency or reduce air leakage there. the first place to check and seal is the attic floor, because warm air rises out of the house. The second place is the foundation band area as cold air is forced in down low as the warm air escapes out up high. Third is the center of the height of the house where there are overhangs and porch roofs. Almost every house has a hole I can crawl out of hidden somewhere in the structure, and I am not a small person.

Many states and/or utilities have rebate programs that pay a portion of making your house more efficient. The most common program is called Home Performance with Energy Star. Sealing first then insulating second is the way to solve the bulk of the humidity problem.