Using attic heat for wtr htr feed.

[HeelSpur]

Has anyone ever tried any method similar to this blurry drawing (sorry).

In the attic would be 2 coils of 3/4" pipe of some kind and they would need to stay coiled for winterizing purposes.
Plus there would be a condensation pan of some sort too.
Where the 2 coils connect would be at a 45* angle for drainage.
The main cold water valve to wtr htr would be closed during attic use
and the top 2 vlvs opened.
Heating the feed water before it goes to the wtr htr would hopefully save one a few bucks a month.
I put the drain points below the winterizing vlvs in the pic but there suppose to be above the top 2 vlvs.
When winterizing, simply close top vlvs, turn main feed vlv back on and open the drain points. All the water should drain with no problem.
Whatcha think, worth it or not?

 

[R6 Racer]

Sounds like a viable idea. Not sure how much it would save. You would need another shut off valve between the cold water feed & the drain for winterising. Without one there all you would have would be a cold water tap & not a winter drain. I would put both your winterising drains above your turn off valves.

Interesting to see what kind of costs vs savings you get.

Steve

 

[jrsulo]

Same thing used for solar pool heat....youtube
it !!!!!

 

[71flh]

Why not put a water tank up there (above a wall)?

 

[Outlawmws]

Why not put a water tank up there (above a wall)?

Weight and thermal mass; You need surface area to absorb heat, a tank would not take in as much for the surface area vs. the volume.

Why not a solar panel feeding a smaller tank with a night time cut-over for after the sun goes down? Done right the panel will feed the tank on the "Heat rises" principal.

 

[Toymeister]

I have a 50 gal
Tank. In my attic for this very purpose. It saves a c note every year for me.

 

[PassnThru]

Always factor in the cost of the parts you use to build it against the savings.

 

[ddawg16]

The heat gain from the attic is not going to be much.....contrary to popular myths...the temp up there rarely goes above 140. You would need a really large coil to absorb enough heat to notice a difference.

The only reason toy is seeing a 'c note' difference is because there is no heat loss from the heater...attic is as warm as the water.....and he is most likely using electric.

If you want to save money on hot water...you need a solar collector on the roof.

 

[kbs2244]

The use of “tempering tanks” is a somewhat common plumbing thing.
It is just an un-insulated tank plumbed in before the water heater.
They usually put a drip pan under them to catch any condensation.
The water sits in the tank to get close to room temperature before entering the heater.
This save you from heating the cool water fresh from the underground feed.

 

[sirsloop]

The physics say it will work, but I don't know how practical it is or how much money is up for savings.

If you had an uninsulated tank in the attic with a volume of water in, sealed... then put a coil through that tank... it would be very efficient. All day the water in the tank is heating up. When your heater valve kicks open you will be transferring much more of the heat from the attic into the heater water. The water sealed in the tank acts as a "heat reservoir" and water transfers heat much better than air! Better yet place the tank on the roof and paint it black.

I use the inverse of this to cool down boiling hot beer during the brewing process. I have a volume of hot beer we need to chill. I drop a 50'x1/2" coil into the boiling wort. I pump cold water into the coil, and in under 10 minutes I have 5-10 gallons of liquid cooled down to 70F from 212F.

Joe at Princeton Homebrew is all into solar... he has some neat installs based on solar heating.
http://www.solarhomebrew.com/

Another neat thing you could so is place some copper wire inside the coil before coiling it up. This acts to disturb the water in the coil and evens out the water temperature maximizing the temp delta between inside and outside the coil.

 

[admranger]

My house had to be replumbed due to a problem with the brass fittings (Kitec fittings, for those who are curious). The house is slab on grade construction so they ran the water lines in the attic and then dropped them down the walls.

Right now my cold water isn't. In fact, it is screaming hot and stays that way for quite some time, depending on how much plastic hose is in attic for the run I'm using.

I don't know if it saves me anything, but it definitely gets hot up there and it stays hot for >6 months per year.

 

[dirttracker18]

The use of “tempering tanks” is a somewhat common plumbing thing.
It is just an un-insulated tank plumbed in before the water heater.
They usually put a drip pan under them to catch any condensation.
The water sits in the tank to get close to room temperature before entering the heater.
This save you from heating the cool water fresh from the underground feed.

Hmmm, that got me thinking.

I am always looking for ways to save money in the home.

 

[rlitman]

This setup is very similar to a solar collector. You can't get too much heat too quickly from it though.

What you could do, is put a small tank in the attic. Then have a loop of coil run around the attic, and connect the inlet to the outlet of the tank, with a tiny circulator pump to move the water slowly through the coil, and the tank. Eventually, enough heat will be absorbed by the coil, to heat the tank (this may take hours though). You could speed up this process by using baseboard radiator tubing (it's just pipe, but has fins).
You'll need a checkvalve in the coil, to prevent cold incoming water from bypassing the tank. Then the tank outlet would feed your water heater.

The problem is that the attic isn't quite hot enough to make this worthwhile.
If it were a true solar collector, you could do this without a separate tank. The water in the collector would be hot enough to be used to directly heat the water in your water heater (albeit, at a VERY slow flow rate), but if the attic air is at all colder than your water heater's standing temperature, it wouldn't work.

 

[sirsloop]

You could run the recirculation pump off a small solar panel. Whenever its sunny out the pump fires up. When its dark out (cold), it automatically stops. You run a closed system of water through your attic out to your roof, where you have black hose setup like Joe from Princeton Homebrew, and back into the tank. That heats up this volume of you keep in the attic using solar. You then run your cold water feed into a coil submerged in this tank of hot water. You get heat transfer and voila money saved!

 

[HeelSpur]

The use of “tempering tanks” is a somewhat common plumbing thing.
It is just an un-insulated tank plumbed in before the water heater.
They usually put a drip pan under them to catch any condensation.
The water sits in the tank to get close to room temperature before entering the heater.
This save you from heating the cool water fresh from the underground feed.

This is all I basically want to do, preheat the water going to the heater.
Well water suppose to be a constant 55* and if I could even get 100 degree water goin to it that would be great.

 

[kbs2244]

I doubt a tempering tank wil get you to 100.
But even a cool basement would be 70.

 

[spongerich]

Not to threadjack, but I'm still somewhat astonished that building codes (especially in the sun belt) don't mandate some sort of solar hot water installation for new construction. If every new home were required to have it, the economy of scale would drop the cost dramatically so the added cost per home would be minimal and the potential energy savings would be huge. In places like CA, AZ, FL etc, I suspect that we could easily reduce energy use for hot water and/or heating by 70-80%

Oil/Gas/Coal aren't getting any cheaper and solar hot water doesn't require any technology more exotic than a pump and some pipe.

 

[sirsloop]

http://www.rheem.com/product/Solar-Water-Heaters-Solaraide-Passive-Solar-System

 

[kbs2244]

Building codes are for safety and health purposes not economic.

What you are talking about are energy conservation requirements.
Those do exist but they are voluntary.
They are popular in commercial and industrial building because even a small percentage saving can be big dollars in savings.
They are not as popular in residential building simply because not that many people are willing to pay the cost increase.
There are some residential builders that advertise their “green” abilities.
But in the end the builder cannot put in something the customer doesn’t want.

 

[sirsloop]

Building codes are for safety and health purposes not economic.

Not true.

http://en.wikipedia.org/wiki/ASHRAE_90.1

Every location has different codes so requirements may vary, but to say they do not take efficiency into account is nonsense. Efficiency is one of the main points... and if a builder is not concerned with efficiency they are morons.

 

[Toymeister]

Interesting. I am the guy that is actually doing this. I have a 50 gallon tempering tank.on the attic. Ialso have a gas tankless heater. I pay for heat rise in this heater which is set at 130 degrees. The attic fan keeps temp between 140 and 110. You can see that the numbers are in my favor in My southern envitoment in the summer

 

[camarotoolman]

I was tinking of doing something like this with copper tubing painted black on my roof here in FLa. Garden hose water will almost burn your shin after a day in the sun here. Any thoughts or ideas?

 

[Toymeister]

Camarotoolman: A pump will make it much more efficient. I didn't want to make the process obvious and I have a 12/12 roof so I was not going to be climbing the roof if it broke.