[Strawbale] PEX, Concrete Slab, Fear of Death (by contractor)

[Speireag Alden]

On 2008, Jan 06, at 03:19, Ilan Ungar wrote:

> I thought that a massive floor means long charging time

     It does.

> and equally long draining time.

     It does, assuming you want to let it get all the way back down  
to where you started.  But in the winter, when it's your heat source  
and it's as massive as mine, you don't want to let it get back down  
to where it started, in the autumn, at about 17°C.  That would take  
it a long time, and during that time, you'd probably be uncomfortably  
cold.  You want it to stay a bit above comfort level, so that the  
heat radiating from it counterbalances the lack of heat from the  
nearby windows, doors, and exterior wall surfaces.

> Wouldn't the one-foot-thick slab, once sufficiently charged with heat,
> overcome long periods of cold air entering the house without losing  
> it's heat?

     No.  It has to lose *some* heat, or the cold air wouldn't warm  
up.  We could make your question an accurate statement:  A one-foot- 
thick slab, once sufficiently charged with heat, will cool very  
little while completely warming a sudden influx of cold air.

     When I said, "left a door swinging", I should have been a bit  
more specific.  I live in New Hampshire, where average daily  
temperatures at this season are around -5 to -10°C.  I'm talking  
about if a door got left swinging in the breeze while you were away  
for the day.  So you've lost a fair amount of heat (and my house is  
small).

     If someone stands in the door for about a minute, letting cold  
air in as they chat, the temperature in my two-room house drops  
noticeably.  Once the door closes, with no heat input, in five to ten  
minutes all is well again.  Technically, you've lost a bit of heat,  
but in practice all that means is that you'll turn the heat on again  
a little sooner than you would have otherwise.

-Speireag.