EcoRenovator  

Go Back   EcoRenovator > Improvements > Solar Heating
Advanced Search
 


Blog 60+ Home Energy Saving Tips Recent Posts Search Today's Posts Mark Forums Read


Reply
 
Thread Tools Display Modes
Old 03-01-10, 02:48 PM   #1
bennelson
Home-Wrecker
 
Join Date: Sep 2008
Location: SE Wisconsin
Posts: 546
Thanks: 3
Thanked 165 Times in 96 Posts
Default Pressure tank as solar hot water tank?

Hey Guys,

What do you think of using a well-pump pressure tank as a solar hot water tank and heat exchanger?

First take a look at this photo.



On the left is a pressure tank I just found on the curb that one of my neighbors is throwing away. On the right is an old 50 gallon electric water heater with the heating elements and some insulation removed.

As you can see, the pressure tank looks like it's about the same size as the water heater once you take the insulation into account. So, I think the pressure tank is close to 50 gallons also.

The pressure tank has larger ports on it than the water heater, and all the ports use standard pipe thread. The heating element ports on the water heater are a straight thread - so a special adapter would be needed to use those with regular pipes anyways.

The pressure tank is the "old-fasioned" style - just a big metal tank. It doesn't have a rubber bladder inside. You do have to add pressure to the tank, maybe once a year, to make up for air that dissolves into the water over time.

I am guessing this tank was thrown away because of some other upgrade to the neighbor's water system, and a new, rubber-bladder pressure tank was installed.

I could run water in to the pressure tank through the lower side port, and out through the very top (the hottest point!) The middle port could be used for a temperature gauge for tank average temperature, or for future expansion. A coil of copper pipe could be wrapped around the outside of the pressure tank to exchange heat from the solar fluid to the water. A layer of insulation would go over the entire tank.
This would most likely be a layer of radiant barrier, then Great Stuff expanding foam or similar, and then some sort of protective cover.

The water heater in the photo has some rust on it, but it also has a lot of calcium build up in it as well.. The drain port on it is cheap plastic, and seized in there, I can't unscrew it.

I could buy a new electric water heater and modify it, but even a basic 50 gallon model runs several hundred dollars. This like all my projects, only has a budget of whatever I can scrounge together. Also, the less I spend on the project, the faster the economic ROI.

Another possibility would be a used water heater through Craigslist, Freecycle, or other sources. I might be able to find something pretty decent for $50? Maybe. Who knows.

So, what do you think would be the advantages and disadvantages of using this pressure tank for my solar hot water transfer and storage? Would the old electric tank work better? Some other possibility I am not even thinking of?

Please note that I have more or less ruled out building my own tank from scratch, I just don't have any room available, other than what would fit a standard tank anyways, so I am not going to re-invent the wheel.

Here's a couple more photos.

-Ben

__________________

To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.


To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.

Last edited by bennelson; 03-01-10 at 02:51 PM.. Reason: middle port note.
bennelson is offline   Reply With Quote
The Following User Says Thank You to bennelson For This Useful Post:
buffalobillpatrick (06-12-14)
Old 03-01-10, 03:03 PM   #2
Daox
Administrator
 
Daox's Avatar
 
Join Date: Aug 2008
Location: Germantown, WI
Posts: 5,525
Thanks: 1,162
Thanked 374 Times in 305 Posts
Default

I don't see any reason why the pressure tank wouldn't work. But, I do think the electric water heater tank will be easier to use since its already nicely insulated.
__________________
Current project -
To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.



To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.
&
To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.
Daox is offline   Reply With Quote
Old 03-07-10, 08:34 PM   #3
Joe
Lurking Renovator
 
Join Date: Jan 2010
Posts: 21
Thanks: 0
Thanked 0 Times in 0 Posts
Default

I think it would make a good batch heater, or maybe something to set on a wood stove for a boiler setup, other than that I think you are better off with an electric like doax said.
Joe is offline   Reply With Quote
Old 03-07-10, 09:16 PM   #4
Xringer
Lex Parsimoniae
 
Xringer's Avatar
 
Join Date: Feb 2009
Location: Woburn, MA
Posts: 4,918
Thanks: 114
Thanked 250 Times in 230 Posts
Default

No special adapters needed for the pressure tank?
Can you get heating elements that will screw into those standard threads?
(If you wanted to use one).

I like the looks of the pressure tank. It appears to be heavy duty hardware.
If you seal up the exterior paint job real well before insulating, that thing might last a life time.

The tank could be insulated a few difference ways, and it shouldn't be too hard to DIY and get a good low loss tank.

The exterior of the insulation doesn't really need to have a sheet metal jacket.
But, some bright metal foil in layers to reflect IR might be a good idea.

I say, Go for It!
Xringer is offline   Reply With Quote
Old 03-07-10, 09:34 PM   #5
bennelson
Home-Wrecker
 
Join Date: Sep 2008
Location: SE Wisconsin
Posts: 546
Thanks: 3
Thanked 165 Times in 96 Posts
Default

The pressure tank appears to have all typical (tapered) pipe threads.

Electric water heater heater elements have straight threads, and seal with a flat o-ring. This means you can't just screw a pipe right into the heater element port, or a heater element into a standard pipe port.

I don't think that I would want to set up my solar tank with a supplemental electric heating element anyways. I believe it is more advantageous to have two separate tanks, as it promotes improved heat transfer from the panel to the storage tank. Also, I don't need to heat water with an electric element that may just be heated by sunlight later in the day anyways.

I DO like how the pressure tank has a big port right at the very top. Seems like that is the absolute best place to take hot water from!!!

__________________

To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.


To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.
bennelson is offline   Reply With Quote
The Following User Says Thank You to bennelson For This Useful Post:
buffalobillpatrick (06-12-14)
Reply


Tags
heater, pressure, solar, tank, water

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -5. The time now is 09:40 AM.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2024, vBulletin Solutions Inc.
Ad Management by RedTyger
Inactive Reminders By Icora Web Design