Helpful? 0

Using a heater to raise the bathroom air temperature: a moisture question

In my home I use a small, electric kickspace heater to raise the temperature in the bathroom during showering. The elevated air temperature allows for the air to hold more of the moisture and raises the window glass temperature, reducing condensation on that glass.

I am assuming that this elevated air temp gives the exhaust fan and the HRV exhaust more time to exchange that air and the moisture it holds. My question is this: by increasing the ∆T am I really just increasing vapor drive through poorly-sealed areas? The house was built 15 years ago and probably is not as well sealed at the window perimeter as I'd like. This is a timber-framed house with a SIPs enclosure.

Asked by Todd Stanley
Posted Mon, 12/31/2012 - 11:22
Edited Tue, 01/01/2013 - 06:54

Tags:

2 Answers

Select your preferred way to display the comments and click "Save settings" to activate your changes.
1.
Helpful? 0

I seriously doubt that this is an issue. If you have an exhaust fan and/or HRV pulling air out of the room at an adequate rate, and run it for long enough, you're totally covered. Example, an exhaust rate of 40 CFM will change the air in a typical 5x8 bathroom with 8' ceiling in 8 minutes. That's a bare minimum scenario, you may well have more ventilation than that. Use a thermo-hygrometer and see how quickly the RH returns to normal in the room after use, Raising the air temp a few degrees only raises the moisture storage capacity of the air a small amount.

Answered by David Meiland
Posted Mon, 12/31/2012 - 11:30

2.
Helpful? 0

Vapor diffusion loading of the susceptible wood is all about the averages, not the extreme moisture events. Unless you're running the shower for hours per day, the 10-15 minute peaks aren't going to add up to enough to matter.

Answered by Dana Dorsett
Posted Mon, 12/31/2012 - 13:56

Other Questions in General questions

How to protect shallow mono footer during winter construction, zone 5

In PassivHaus | Asked by Lucyna de Barbaro | Oct 1, 14

Breaking thermal bridge between concrete porch and brick wall?

In Green building techniques | Asked by Paul Gorcey | Sep 26, 14

I'm getting two different opinions about foam insulation in the attic

In Energy efficiency and durability | Asked by Rus Pearson | Sep 30, 14

Windows for my Pretty Good House

In Green products and materials | Asked by Matt Mesa | Sep 29, 14

Grid-tied without independence … what’s the point?

In General questions | Asked by flitch plate | Sep 29, 14
Register for a free account and join the conversation


Get a free account and join the conversation!
Become a GBA PRO!