[Greenbuilding] [BULK] Re: rock storage + heat pump

[Keith Winston]

Just to be clear, and no offense, but this is blather. Rocks don't 
"release heat more slowly", they have different conduction/heat transfer 
characteristics and heat capacity than other materials. They have better 
conduction than water' for example, but being a solid, they can't 
benefit from convection, so net heat transfer will often be slower. They 
have lower volumetric heat capacity.

Still, your comment that they will "hold heat longer into the winter" 
has much more to do with how well insulated the storage is. Heat doesn't 
disappear, it dissipates. Either through insulation (inevitably, at some 
rate) into the environment, or via your system into your building.

Keith


Brian Hyslop wrote:
>  One reason to use rocks (I think) is that they will release heat/energy more slowly, thereby holding heat longer into the winter.  If you do pull the air directly from the rock mass and end up having a mold problem, you need to figure out  to resolve it with out scrapping your entire system.
> Brian Hyslop
>
>
> Elemental Building Design LLC
> 1042 W. 18th Pl
> Eugene OR
> 97402
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> 541-484-1220
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> ----- Original Message ----
> From: Lawrence Lile <LLile at projsolco.com>
> To: "YankeePerm at aol.com" <YankeePerm at aol.com>; "greenbuilding at listserv.repp.org" <greenbuilding at listserv.repp.org>
> Sent: Wednesday, May 21, 2008 2:50:50 PM
> Subject: Re: [Greenbuilding] [BULK]  Re:  rock storage + heat pump
>
> Exactly, this is a good idea vs. using air as a medium.  But with water, why use rocks at all?  Water is better at holding and storing heat than almost anything else.
>
>   
>> -----Original Message-----
>> From: greenbuilding-bounces at listserv.repp.org [mailto:greenbuilding-
>> bounces at listserv.repp.org] On Behalf Of YankeePerm at aol.com
>> Sent: Wednesday, May 21, 2008 4:39 PM
>> To: greenbuilding at listserv.repp.org
>> Subject: [BULK] Re: [Greenbuilding] rock storage + heat pump
>> Importance: Low
>>
>> Why not sidestep the mold problem, immerse the rock in water, and use
>> the
>> heat pump to charge or discharge (depending on thermal needs) the
>> temperature of
>> the water/rock mass? If the water were in a closed system, circulating,
>> you
>> would have no problem with mold or other contaminants.   Someone better
>> versed
>> in the mechanical end of things might chime in about exactly how this
>> is done.
>>  If you install radiators, convection can supply warm water for heating
>> in
>> the event of electric failure, common in winter in many areas.
>>
>> Dan Hemenway
>>
>> In a message dated 5/20/08 11:53:19 PM, l-shea at sbcglobal.net writes:
>>
>>
>>     
>>> We are building in Northwestern Illinois.  We want to combine a 4-6
>>>       
>> ft deep
>>     
>>> rock storage system with a heat pump.
>>>
>>>   If we pull air directly from the rock storage with no separate duct
>>>       
>> system
>>     
>>> running through the rock, do we need to worry about air quality
>>>       
>> (moisture/
>>     
>>> mold)?
>>>
>>>   Is 4-6 ft deep enough to take advantage of geothermic heat in a
>>>       
>> rock
>>     
>>> storage system?
>>>
>>>   If we use a heat pump, can this system both heat and cool the
>>>       
>> house?
>>     
>>>   One more question:  does the rock have enough thermal mass to act
>>>       
>> as the
>>     
>>> active solar collector?  We are not building a hot room/ greenhouse.
>>>
>>>   Has anyone tried this combination?
>>>
>>>   Thanks,
>>>
>>>   Greg
>>>
>>>
>>>       
>>
>>
>>
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>> 2008. The
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