Re: [SolarHeat] More on energy-efficient showers; was: Re: coiling copper tubing heat scavenger
John Allen
I have a shower head that works fine at 2 GPM and it has a shut off valve that allows me to throttle it down and up without affecting the mixture/temperature. At 1 GPM it is sort of OK. but below that it just dribbles.
I resurrected a prior shower head that did not have a built in valve, and added a ball valve to it. This one has more of a needle like spray and can still project a couple inches at about .5 GPM, but it is hardly satisfying at that rate. It is acceptable to me at .8 GPM but my family prefers to run it at it's max of 1.5 GPM
What flow rates do you all live with? Does anyone care to recommend their shower head?
John Allen
__._,_.___If you want the most energy-efficient shower to make the most of your solar hot water, in addition to the shower heat recovery device you might also look at the shower design itself.
While I am not a particular fan of their overpriced refrigerators, the Sunfrost people have a fascinating take on showers on their website at http://www.sunfrost.com/concepts_sustainable.html
Their design makes great sense, I believe, and I am seriously contemplating using it in the house I am designing for my family now.
David
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John A Allen
John Allen
I also agree that a key parameter is staying very warm. I think I am going to replace my shower curtain with a sliding glass door and seal off the area above that, and the half of the widow that will then be outside this new shower stall within my tub. I doubt that I will eliminate the ceramic tile, but I'll let the project evolve. I love hot showers and hot baths. I used to enjoy the steam room they had at my college so if this sealed enclosure gives a similar experience I'm all for it.
On a sunny day, I'm almost producing all the hot water I need via one 4x10 collector and I think I can make it to 100% by reducing flow rate in the shower. I'm particularly motivated because I have an old gas water heater that I want to completely eliminate. I estimate it is only 50% efficient and that it's daily stand by loss is about 20 degrees * 40 gallons * 8.3 pounds per gallon or ~7,000 BTUs. In addition I estimate it is using 12 cubic feet of natural gas per day for the pilot light. (another 12,000 BTUs), this 19,000 BTUs is roughly the same as my daily hot water need - 50 gallons * 40 degrees * 8 .3 pounds = ~ 17,000 BTUs
Can anyone confirm these estimates or point out a likely error?
My idea for the replacement non solar heater, which I only expect to need for about 14 full days per year, is an electric supplement to the hottest of my unpressurized storage tanks. I've already tested this and it works. I intend to upgrade the immersion heat exchanger in that tank so the unpressurized water does not have to be as hot. Currently it needs to be 20 degrees hotter than the shower water. Of course if I manage to lower the flow rate, this will reduce the differential needed to do the job. BTW my water bill is rather high so that is another reason to reduce flow rate.
ja
--- In Sola...@yahoogroups.com, "John Allen" <johnaallen@...> wrote:
>
> I like the enclosed shower idea, and I was attracted to the mention of 1/2
> Gallon of water Per Minute, GPM, shower flow rate.
>
> I have a shower head that works fine at 2 GPM and it has a shut off valve
> that allows me to throttle it down and up without affecting the
> mixture/temperature. At 1 GPM it is sort of OK. but below that it just
> dribbles.
>
> I resurrected a prior shower head that did not have a built in valve, and
> added a ball valve to it. This one has more of a needle like spray and can
> still project a couple inches at about .5 GPM, but it is hardly satisfying
> at that rate. It is acceptable to me at .8 GPM but my family prefers to run
> it at it's max of 1.5 GPM
>
> What flow rates do you all live with? Does anyone care to recommend their
> shower head?
>
> John Allen
__._,_.___I have a sneaking suspicion that the very low rates don't rinse well, so actually take more
total water. Of course, one of the best ways to save a lot of water in the shower is to get
wet, then turn off the water while soaping down. The design of the subject shower stall,
with its fairly tight construction and the metallized bubble-wrap walls would be very
comfortable while showering in this way.
Bill
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John A Allen
John Allen
ja
---------- Forwarded message ----------
From: John Allen <johna...@gmail.com>
Date: Apr 4, 2007 9:27 AM
Subject: Re: [SolarHeat] More on energy-efficient showers; was: Re: coiling copper tubing heat scavenger
To: Sola...@yahoogroups.com
> Doesn't the pilot light heat the water?
Most certainly. But the tank still gets about 20 degrees colder over a days time if I turn it off.
This is tricky to measure or estimate due to occasional small flows, that is why I'm looking for confirmation or correction. My heater is a Reliance brand model NORT6 made in Dec 1983. I'm plenty interested in data points for other heaters. As we work to make something better it makes sense to me that we should have a real good understanding of what we are replacing.
ja
--- In Sola...@yahoogroups.com, "John Allen" <johnaallen@...>
wrote:
...
>
> On a sunny day, I'm almost producing all the hot water I need via
one 4x10
> collector and I think I can make it to 100% by reducing flow rate
in the
> shower. I'm particularly motivated because I have an old gas water
heater
> that I want to completely eliminate. I estimate it is only 50%
efficient and
> that it's daily stand by loss is about 20 degrees * 40 gallons *
8.3 pounds
> per gallon or ~7,000 BTUs. In addition I estimate it is using 12
cubic feet
> of natural gas per day for the pilot light. (another 12,000 BTUs),
this
> 19,000 BTUs is roughly the same as my daily hot water need - 50
gallons * 40
> degrees * 8 .3 pounds = ~ 17,000 BTUs
> Can anyone confirm these estimates or point out a likely error?
Doesn't the pilot light heat the water?
--
Bert Menkveld
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John A Allen
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John A Allen
John Allen
It sounds like you are suggesting a additional water heater that acts as an on demand heater to bump up the tap water temperature after it leaves the heat exchanger in the unpressurized tank. Is that so?
I am trying the approach to use supplemental energy to raise the temperature in the unpressurized storage tank. I figure this can be done on a "trickle charge" basis, esp during the night. Currently I use a 700 watt silicone rubber heating pad under the 55 gallon drum that is the hotter of the two drums I use. It can raise the temp of that drum about 5 degrees per hour. Worst case, I can heat that drum from 60 to 120 in 12 hours. This gives me my minimum shower requirements during the very occasional stretch of bad weather here in San Jose CA. And it leaves me a 2x safety margin. It takes no space and cost me $70. Another $30 for thermostat and timer. As I migrate to a larger tank I expect to use an over the side immersion heater.
I call this approach a solar electric hybrid water heater. Does anyone else have any experience with doing it this way?
I just measured my shower drain water during a 14 minute shower at 1.5 GPM, and it was 96 F as it left the tub. Since my input is about 60 degrees I am definitely interested in capturing some of that 36 degrees! Unfortunately my lower floor drain is a long tight crawl space away from the cellar that has my heat vault. Maybe someday. I'll be following the discussion and progress and let some one else do the pioneering on this front. Is anyone thinking of combining heat recovery with use of the gray water?
John Allen
Ho JohnYes a small electric hot water heater is all you need to back up your solar hot water system. Heat recovery from the drain ( as David neley mentioned) is also a good idea. Very small water heaters may be purchased from people who sell mobile homes or you could make your own with heat tape and a copper coil.John
----- Original Message -----From: John AllenSent: Wednesday, April 04, 2007 9:44 AMSubject: Re: [SolarHeat] More on energy-efficient showers; was: Re: coiling copper tubing heat scavenger
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John A Allen
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John A Allen
John Allen
Speaking of homework, is it appropriate to ask here for recommendations on shower heads? I really like the idea of performance beyond flow rates and I'm quite ready to buy a better one. I do find it a little hard to compare marketing claims so I'd particularly like to know what you use if you like it.
About the ceramic tile, this gentleman will likely defer to his lady.
ja
Various people mentioned a concern about reduced flow showers having poorer rinsing ability.
Most modern low-flow shower heads do surprisingly well in this, since they mix a large quantity of air with the water. This increases the apparent volume as well as the motion of the water, allowing it to do more than it would if it were a mere stream of water.
I suggest doing your homework before you purchase your next shower head, to get ones that are well rated in performance as well as being low in flow rates. Even some surprisingly inexpensive ones come out quite well in this regard.
For the gentleman who "doubts he will get rid of his ceramic tile"--be aware that this kind of mass is exactly what works against comfort in the shower. It simply takes too much energy to warm the tile and keep it that way. That energy must either come from some sort of heat source or from the water itself.
One key to the original design is the low mass of the enclosure combined with the insulation around that low mass. It could easily get warm and tend to stay that way. Thus, if you ignore that component you are not likely to have results as good.
David
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John A Allen
John Allen
I am VERY interested in your suggestion about "geothermal heat pump with desuperheater option that uses the waste heat from the cooling cycle to heat domestic hot water rather than pumping that heat into the ground."
I'm helping one of the solar decathlon teams and I''m wondering about using that approach with their solar input absorption cycle air conditioner. Do you, or anyone else, have any experience with using a heat pump in connection with solar hot water to provide, heating, and cooling, and Domestic Hot Water?
I suppose I'm naively optimistic but it seems like we should be able to use the heat pump, as needed, to maintain a sufficient differential between a cold tank and a hot tank, such that we can use the cold tank for cooling and the hot tank for heating. The primary source of energy acquisition into the hot tank can be solar and the cold source can be a ground loop and/or or nighttime radiation through the solar collectors.
ja
John,
Have you not added an insulation blanket to your heater?
If you have a conventional, tank-type heater, these insulation blankets can help immensely. They are available for less than $20 in most big-box stores like Home Despot, and from small hardware stores as well.
If you insulate sufficiently, you can make up some of the difference between the conventional heaters and the tankless ones. If you have the budget, a tankless heater designed to function as a backup for a solar heating system is likely the best option for most--although if you are in a cooling climate and desire air conditioning, it is hard to argue with a geothermal heat pump with desuperheater option that uses the waste heat from the cooling cycle to heat domestic hot water rather than pumping that heat into the ground.
David
On 04 Apr 2007 09:27:17 -0700, John Allen < johna...@gmail.com> wrote:
> Doesn't the pilot light heat the water?
Most certainly. But the tank still gets about 20 degrees colder over a days time if I turn it off.
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John A Allen
John Allen
John,
Since your shower appears to be over a crawl space, you may be able to install a GFX unit there. Rather than running the heat to your heat storage tank, it is much more sensible to run the shower drain heat back into the cold input line to the shower--actually, running the cold line to the GFX before it goes to the shower is how it is usually done. This raises the "cold" side temperature, so you use less from the hot supply.
Typically, the GFX unit is said to capture about 65% of the waste heat from the drain. If your base water supply temperature is 60 degrees, and the drain is at 98 degrees, one would expect the supply to become about 84 or 85 with the use of the GFX on the "cold" side. This reduces the amount of hot water you would need to bring the water to comfortable temperature in the shower.
david
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John A Allen