CF100 Questions
phillb
storage tank is rusting and the control box is on the frits to often..
I want to change to a storage tank that has a heat pump within it, but
no one makes this
Seems like the only thing to do is get another storage tank and also
get a tank-less water heater
I have tried to find manuals for the CF100, I think they have all been
recycled...
Any pointers of what could be done from someone out there
Or just sell the collectors, and upgrade?
Bob F
> The Grumman Sunstream CF100 Solar Hot Water heater I have is old, the
> storage tank is rusting and the control box is on the frits to often..
> I want to change to a storage tank that has a heat pump within it, but
> no one makes this
Heat pump water heaters certainly exist. They wouldn't normally have much to do
with solar panels, I suppose.
phillb
True
Be good for efficiency though
Use less of the Heat Pump
Josepi
Possibly make the solar hotwater heater system usefull 100% of the year.
A small heat pump shouldn't make that much of a cost increase from the usual
price gouging.
"phillb" <pblo...@hotmail.com> wrote in message
news:89680e28-809c-4163...@i25g2000yqm.googlegroups.com...
True
Be good for efficiency though
Use less of the Heat Pump
Malcom "Mal" Reynolds
<imLmn.9370$3D3....@newsfe19.iad>,
"Josepi" <J.R.M.@invaliid.con> wrote:
> I am surprised we haven't seen much of this.
>
> Possibly make the solar hotwater heater system usefull 100% of the year.
>
> A small heat pump shouldn't make that much of a cost increase from the usual
> price gouging.
>
>
> "phillb" <pblo...@hotmail.com> wrote in message
> news:89680e28-809c-4163...@i25g2000yqm.googlegroups.com...
> True
> Be good for efficiency though
> Use less of the Heat Pump
That may be true, but remember that the
other side of the heat pump is pumping
out "cold" that can be vented into your
HVAC which makes it run less
Robert Scott
>Heat pump water heaters certainly exist. They wouldn't normally have much to do
>with solar panels, I suppose.
Well, here is one way in which solar energy can help out a heat pump:
Heat pumps operate with a Coefficient of Performance (COP) of between 1.0 and
maybe 5 or 6 at the maximum. The COP is ratio of heat produced to electrical
energy consumed. When COP equals 1.0, you essentially have straight resistance
heating. When COP is 4, then you get hot water using only 1/4 the amount of
electrical energy that simple resistance heating would require.
The main factor affecting the COP is the temperature of the source where the
heat is being pumped from. That source can be either ambient air or water from
a well or some other source. For example, for my space heating I have a
geothermal heat pump using a closed loop with 2000 feet of plastic pipe buried
in my landscaping. When the incoming water from the loop is 50 degrees F, then
the COP of my heat pump is about 4.0. When the incoming water drops to 33
degrees F, as it does in late January, then the COP is down to about 1.4. And
if the incoming temperature drops much less than that, then the heat pump simply
stops working.
So imagine a heat pump system where low-grade solar heat (say 60 deg. F) is used
by the heat pump to keep the COP up. Under some conditions, such a hybrid might
be cost-effective.
Robert Scott
Ypsilanti, Michigan
Josepi
allowed to.
Usually the control circuits are set to stop the heat pump below 1.2 - 1.7
as there is no point wearing out the complex mechanism when there is usually
a backup source involved in most installations that has very few moving
parts for lot of heat.
A small heat pump in a solar thermal system could go a long way for
extracting heat. Think of the heat gain when running solution through a
solar thermal panel at +1 C. Piece of cake for heat gain.
"Robert Scott" <no...@dont-mail-me.com> wrote in message
news:4b9c2b2b...@news.eternal-september.org...
phillb
Now I am really thinking of a small heat pump water heater, after the
solar thermal water heater
For obvious use of rainy weeks, and during winter
Bob F
I acually got a quote on just such a system many years ago. It was basically a
geothermal heat pump system with pipes buried in the ground for a heat source,
and a couple solar panels on the roof to "recharge" the ground heat. I believe
the solar panels were added partially to get some type of solar tax credit that
existed at the time.
Josepi
environment it may freeze up and then you have no source. The ground is not
an infinite heat source in most cases.
"Bob F" <bobn...@gmail.com> wrote in message
news:hnk2ig$31d$1...@news.eternal-september.org...
daestrom
> The heat pump doesn't stop at 1.0 COP. The COP will go much below 1.0 if
> allowed to.
>
I don't think the COP of a heat pump can go below 1.0. At 1.0, the only
heat being delivered is the energy it takes to run the compressor.
Just where could the energy to run the compressor go if not to the
condenser? It certainly wouldn't go to the evaporator (on the suction
side of the compressor).
daestrom
Josepi
condensor or the evaporator. There are losees from the compressor and other
mechanisms, involved. The fan energy alone would be a dead loss of energy
moving air if the coil is the same temperature as the target zone.
The heat lost from the case of the compressor is not being delivered to the
desired target. A compressor could run all day, wasting energy, with it's
refrigerant valves closed. COP = 0
"daestrom" <daes...@twcny.rr.com> wrote in message
news:hnmee...@news4.newsguy.com...
phillb
tube from outside channel in, and release the cold in the basement
well, during summer that is
How about hte main idea though
What are the possible benifits of heat pump/solar hot water tank...
On Mar 17, 12:29 am, "Josepi" <J.R...@invaliid.con> wrote:
> The energy to run the compressor does not need to be delivered to the
> condensor or the evaporator. There are losees from the compressor and other
> mechanisms, involved. The fan energy alone would be a dead loss of energy
> moving air if the coil is the same temperature as the target zone.
>
> The heat lost from the case of the compressor is not being delivered to the
> desired target. A compressor could run all day, wasting energy, with it's
> refrigerant valves closed. COP = 0
>
> "daestrom" <daest...@twcny.rr.com> wrote in message
Robert Scott
>well, during summer that is
>How about hte main idea though
>What are the possible benifits of heat pump/solar hot water tank...
The benefit is increased COP of the heat pump as compared to geothermal. Here
in Michigan, a geothermal heat pump closed loop system drops to about 30 deg. F
in the middle of winter, which lowers the COP of the heat pump to less than 2.0.
If the inlet water could be raised to 60 deg. F, the COP would be closer to 5.0.
A solar heating system can easily create 60 degree water. The efficiency of a
solar collector goes up if it can be designed to work at lower temperatures.
Seems like the two technologies fit very well together.
daestrom
> The energy to run the compressor does not need to be delivered to the
> condensor or the evaporator. There are losees from the compressor and other
> mechanisms, involved. The fan energy alone would be a dead loss of energy
> moving air if the coil is the same temperature as the target zone.
>
> The heat lost from the case of the compressor is not being delivered to the
> desired target. A compressor could run all day, wasting energy, with it's
> refrigerant valves closed. COP = 0
Just about all refrigerant compressors are cooled by the refrigerant, so
the heat *does* go to the condenser.
The fan circulating air passed the evaporator would be a loss, but
rather small compared to the whole unit (what's a common ratio of fan
power versus compressor power?) With conventional heat pumps, the fan
circulating air passed the condenser is not a loss since it's energy is
delivered to the house air.
As far as running a compressor with it's valves shut, yes well the
idiotic can't be helped. Same would be true for a seized compressor
that doesn't have overload protection, or no refrigerant, or any number
of other idiotic scenarios.
In any realistic situation, the COP can't go 'much below 1.0' (guess it
depends how you define 'much below 1.0'.)
The bigger issue is that most home heating heat pumps are only designed
for a few tens of degrees rise (say about 40F) and heating water to
120F+ using 60F or less outside air is just not within its design. So a
solar 'boost' to raise the evaporator end to 80F+ has some merit. Of
course there are common heat pumps that can run with 70F+ temperature
difference (one in most homes is the food freezer, although they are
much lower capacity).
An issue comes up if the heat pump capacity exceeds the solar input.
Then it naturally cools the collector down and this reduces heat pump
capacity and reduces ambient losses of the collector. So its somewhat
self-regulating.
A simple thermostat could be used to shut off the heat pump when the
collector temperature drops too low. Where 'too low' is not very
critical unless the collector might be damaged by freezing/frost.
daestrom