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Water source heat pump Q.

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Posted by Ed Earl Ross on May 4, 2007, 4:44 pm
 
Water sources recommended for ws heat pumps are ponds, lakes,
buried coils of pipe, buried flat plate collectors, and water wells.

I've seen neither solar collectors nor evaporative water chillers
recommended to condition a water source.

Heating: Some solar collectors can heat a tank of
heat-storage-substance for evening use while other collectors can
supply water directly to a heat pump for daytime use.

Cooling: With 100% humidity, a water chiller should achieve about
the same efficiency as an air source heat pump. With low humidity
evaporation chills the water supply, and should achieve better
efficiency than an air source heat pump.

Is my analysis flawed? If so why? I cannot imagine these ideas have
been missed by scientists and engineers.





Posted by daestrom on May 6, 2007, 9:04 pm
 


For cooling I think you mean an 'air sink' :-)


Solar-assisted heat pumps have been discussed here before.  IIRC, the
question boils down to whether the solar collectors can collect enough heat.
If they are large enough for heating the home, then the heat pump adds
little and costs a lot.  Conversely, if the heat pump is supplied with some
other source such as a ground loop, then the solar collectors add little to
the equation.

Bottom line is, "Does adding solar collectors to a water-source heat pump
increase the efficiency enough to pay for itself?"

daestrom


Posted by Lee on May 7, 2007, 7:41 am
 Heating seems to be cost effective but for some reason it takes a lot
more solar collector area to drive air con - about 3 times as much.  I
understand it's about 35 sq meters to cool a 25 square house.
Apparently water cooled doesn't need as high a temp so is better for
solar.

Lee.





wrote:


Posted by Ed Earl Ross on May 12, 2007, 3:20 am
 daestrom wrote:

 > daestrom

Where I live in south Texas, total cooling costs are higher than
heating. My house is 50 years old, and does not have central heat
and air, and ductwork would be expensive. Moreover, a central unit
typically does not provide zones, some of which can be off and
others on. A heat pump allows each room to be a zone, and energy
can be used frugally by heating or cooling only a few rooms.

A ground source heat pump is more efficient than an air source.
However, drilling the required wells is very expensive. Solar
collectors that use air to transfer heat are inexpensive, but some
rooms in my house would be nearly impossible to heat in this manner
because of the required ductwork. A heat pump can transfer heat
without ducts, making one seem attractive for my application.

Would an evaporative water chiller and water source heat pump be
better than an air source heat pump running as a refrigerated air
conditioner?


Posted by TheDoc on May 14, 2007, 6:00 pm
 

Your "ideas" have not been missed, they are generally too expensive to
realise in a market
saturated with mechanical heat pump systems.. as an engineer, i did take
time out to design
a "minature" 3 ton dessicant water chiller based off a 100 ton design from a
few years ago.. and it will cost you about $0,000 USD more than a
comparable heat pump.. also, most people do not have the required space for
the heat exchangers.. so town usage is not practical..
if you live in a country setting with land then these things become more
attractive..
but cost is still a major factor..




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