Adding solar hot water to existing hot water tank?

Ralph III · 04-07-19, 10:21 AM

Hello All,
Can anyone give advice or provide a link with specific details/pictures for adding solar hot water to an existing natural gas hot water tank?

My hot water tank is in the garage and on the south side of our home. So it would be easy to add vacuum tubes on the outside wall and then connect it to the NG hot water tank on the inside. However, exactly how do I do this because I can find no step by step scenarios for a simple setup as I desire. I don't want to go off the grid or anything complex. I just want a simple setup in order to lower my hot water heating costs.

1) Whatever I do will be mounted on the side of our house and not on the roof. That area is inconspicuous and it gets a lot of sun.

2) I simply want to heat some water via solar and add that to my existing NG hot water heater system.

3) I could add a second holding tank and use it to preheat water prior to going into my natural gas hot water heater, if a better design? I can get individual vacuum tubes at an affordable price so I suppose I would need a holding tank of some sort?

God Bless,
Ralph

jeff5may · 04-08-19, 07:55 PM

Option 3. If you have the right conditions you could set up a thermosiphon. This would yield the most heat per sun. If everything is not perfect, you'll have to run a pump and a control of some kind. The solar collector has to have its own loop of water. Nobody with a hint of sense runs tap water through the solar collector.

Ralph III · 04-09-19, 12:10 AM

Thanks Jeff.

I most definitely need a second tank that will act as a pre-heater. I drew out a diagram of what I would need and then came across the image below which looks really similar to what I had envisioned. I would be using vacuum tubes to heat water though.

1. No potable water enters the vacuum tubes. The tubes simply heat up the water in a header of sorts.

2. I have a circulating pump with a built in timer already. So I could set it to circulate the water every hour for a few minutes during daylight hours. My pump would be just as the one pictured in the image.

3. I would be looking into getting a used or cheap hot water tank and using it for a pre-heater. I'm assuming I could utilize the check valve and drain valve as my 3rd and 4th water outlets?

4. I have an expansion tank on the cold side already. Would I have to install a second expansion tank and I assume I would need to re-install the check on the holding tank somehow or in the pipe?

Thanks,
Ralph

Xringer · 05-16-19, 06:26 PM

Quote:

Originally Posted by Ralph III

3) I could add a second holding tank and use it to preheat water prior to going into my natural gas hot water heater, if a better design? I can get individual vacuum tubes at an affordable price so I suppose I would need a holding tank of some sort?

My first solar assisted system was a storage tank that fed into the cold-water input of my oil-burner (that supplies our hot water).
The system used an antifreeze/glycol loop from roof panels feeding down to a typical 1970s heat exchanger, with pumps for input and output.

https://www.history.com/topics/1970s/energy-crisis

The hard-water slowly destroyed the heat exchanger. After 5 or 7 years oil prices came back to the affordable range and I uninstalled (dumped) the leaky system. The problem with solar hot water system (and electric hot-water) is they don't last very long before they start leaking..

Up in here MA, gas hot water is the cheapest way to go. Adding a bunch of plumbing might be more trouble than it's worth.
If I had gas on my street, I wouldn't being working on a leaking hybrid solar PV / Heat pump this week. The stupid anode thread is leaking and it's not looking good. Just what I don't need is a flood in my basement shop..

CrankyDoug · 05-16-19, 08:21 PM

Take a look at this thread......

https://ecorenovator.org/forum/showthread.php?t=6711

I haven't installed the device yet so I can't give you any facts, other than reports from people who have one and are satisfied. One thing is certain, a solar panel and this device is much less headache than hydronic solar collectors. It is probably less expensive as well. Best of all, it won't freeze and break. It is immune to variations in outside temperatures.

04-07-19, 10:21 AM	#1
Ralph III Lurking Renovator Join Date: Oct 2011 Location: Alabama Posts: 5 Thanks: 0 Thanked 0 Times in 0 Posts	Adding solar hot water to existing hot water tank? Hello All, Can anyone give advice or provide a link with specific details/pictures for adding solar hot water to an existing natural gas hot water tank? My hot water tank is in the garage and on the south side of our home. So it would be easy to add vacuum tubes on the outside wall and then connect it to the NG hot water tank on the inside. However, exactly how do I do this because I can find no step by step scenarios for a simple setup as I desire. I don't want to go off the grid or anything complex. I just want a simple setup in order to lower my hot water heating costs. 1) Whatever I do will be mounted on the side of our house and not on the roof. That area is inconspicuous and it gets a lot of sun. 2) I simply want to heat some water via solar and add that to my existing NG hot water heater system. 3) I could add a second holding tank and use it to preheat water prior to going into my natural gas hot water heater, if a better design? I can get individual vacuum tubes at an affordable price so I suppose I would need a holding tank of some sort? God Bless, Ralph

04-08-19, 07:55 PM	#2
jeff5may Supreme EcoRenovator Join Date: Jan 2010 Location: elizabethtown, ky, USA Posts: 2,431 Thanks: 431 Thanked 619 Times in 517 Posts	Option 3. If you have the right conditions you could set up a thermosiphon. This would yield the most heat per sun. If everything is not perfect, you'll have to run a pump and a control of some kind. The solar collector has to have its own loop of water. Nobody with a hint of sense runs tap water through the solar collector. Last edited by jeff5may; 04-08-19 at 08:48 PM..

04-09-19, 12:10 AM	#3
Ralph III Lurking Renovator Join Date: Oct 2011 Location: Alabama Posts: 5 Thanks: 0 Thanked 0 Times in 0 Posts	Thanks Jeff. I most definitely need a second tank that will act as a pre-heater. I drew out a diagram of what I would need and then came across the image below which looks really similar to what I had envisioned. I would be using vacuum tubes to heat water though. 1. No potable water enters the vacuum tubes. The tubes simply heat up the water in a header of sorts. 2. I have a circulating pump with a built in timer already. So I could set it to circulate the water every hour for a few minutes during daylight hours. My pump would be just as the one pictured in the image. 3. I would be looking into getting a used or cheap hot water tank and using it for a pre-heater. I'm assuming I could utilize the check valve and drain valve as my 3rd and 4th water outlets? 4. I have an expansion tank on the cold side already. Would I have to install a second expansion tank and I assume I would need to re-install the check on the holding tank somehow or in the pipe? Thanks, Ralph Attached Thumbnails Last edited by Daox; 04-09-19 at 01:56 PM..

05-16-19, 08:21 PM	#5
CrankyDoug Apprentice EcoRenovator Join Date: Jul 2016 Location: Georgia Posts: 100 Thanks: 6 Thanked 14 Times in 11 Posts	Take a look at this thread...... https://ecorenovator.org/forum/showthread.php?t=6711 I haven't installed the device yet so I can't give you any facts, other than reports from people who have one and are satisfied. One thing is certain, a solar panel and this device is much less headache than hydronic solar collectors. It is probably less expensive as well. Best of all, it won't freeze and break. It is immune to variations in outside temperatures.