h a l f b a k e r y
Like you could do any better.
add, search, annotate, link, view, overview, recent, by name, random
news, help, about, links, report a problem
or get an account
Jim has noticed that ground source heat pumps are the fashion in low carbon heating and cooling. He thinks this is great for those with some ground and not really practical for those without. In fact the traditional method of rejecting heat into the atmosphere has become impractical for those individuals
living in cities (have you ever tried to get planning permission for an external feature...) Currently living in a flat without any ground to dig up and unwilling to pay for the privilege of rejecting heat into the atmosphere Jim needed another (better) solution...
Jim contemplated using the fish tank as a heat sink but could not bring himself to boil the fish during summer... Anyways Jim has decided that water is the answer to this problem since he can reject heat down the drain.... ah actually he can reject heat into the hot water cylinder.
Using the time taken to boil the kettle as a guide Jim reckons there is about 5mins of 2Kw cooling per litre of water. Great Jim reckons the fridge and the air conditioning should be plumbed into the hot water tank...
Like a heat pump water heater?
[ldischler, Jul 03 2009]
||Unless your water source is cooler than the outside air, and
stays that way (not the case for a water heater) this is going
to be considerably less efficient than an air source unit. If
you need the hot water, per [ldischler]'s link it's a good idea,
but not otherwise. The advantage of ground loop (or open
ground water) is the ground is ~55F, considerably cooler than
the air you'd normally be dumping to during cooling season,
and warmer than the air you'd be dumping to in heating
||actually no, water/refrigerant AC condensers are very efficient and could easily be included in a supply loop for the hot water heater. I would propose a reservoir system for a moderate volume of water to accommodate the variability in hot water consumption. The outlet water on the water units that I have owned took cold water on the inlet and made thermostatically regulated hot water on the outlet so I imagine you could build a system that basically took care of your hot water needs, in the summer.
||And water conducts heat about 4 times more efficiently, or "quicker", than air. I reckon it's a fair play to dump heat out of your environ and into your drain, or geyser. But I think this has been proposed on the 'bakery before...
||Again, I said if you need a hot water heater, it makes
sense, if you don't, that's where the problem comes in.
||Heat pumps depend on energy input to create a
temperature differential. The larger the differential, the
more energy you have to put in, and this is not a linear
relationship. Cold water is great, hot
water is not. In this system, there is a problem:
Either you are dumping to a finite volume of water, or you
are dumping to an infinite volume of water. In the first
case it will quickly reach a temperature where it is more
efficient to dump to air (I suspect the 125+F of domestic
hot water heaters is well past this point on all but the
hottest days). In the latter case, you are going to run a lot
of water through the pipes, and unless you have a non-
drinking water source, the cost of water, and the energy
used to purify it will greatly surpass the energy savings
from saved versus air.
||If you do have a non-potable water source, this is an open
loop or ground water source heat pump, and is thoroughly
baked, but that has all its own problems, and is not likely
available in an apartment.
||You might have a non-potable water source, without an open loop or ground water source heat pump.
||Specifically, if you have a rain water collection system, then that water (until you treat it) is non-potable.
||Of course, unless you have an infinitely large storage system for the water, you can't simply use it as your heat sink and dump it down the drain... you'll just run out, and then where will you be?
||However, if you have a sufficient quantity of non-potable water (or if your regular water is sufficiently cheap), you can buy an after market misting device, which sprays water your the air conditioner's condensor. This results in evaporation, which lowers the effective temperature of the condensor.
||I should have said continuous flow non-potable water
source, I guess.