Solar Hot water - Page 2

iamgeo · 07-15-11, 03:19 PM

I'm not ragging on anyone here. I feel I have to mention this.
It seems some of you did not read my original post.
I stated that I have a tankless water heater.
I stated that I will put a hose bib where the pipes go under the house in order to drain water in case of a hard freeze.

iamgeo · 07-15-11, 03:27 PM

Quote:

Originally Posted by strider3700

the pvc probably won't last long in the sun like that, even painted it'll breakdown pretty fast. It will also add a plastic smell/taste to the water, most people using PVC heat exchangers have switched to pex since it doesn't seem to change the water.

Well, I have been here 4 years now. The water supply line to my house is 1 inch PVC. About 25 ft of that is exposed from the water meter to my driveway since I could not dig a trench till I got to the bottom of the hill.
To me the water tastes the same. I do use a reverse osmosis water filter. Even just the tap water tastes the same to me, but I could be conditioned to it already.
Anyway, the hot water is not really used for any other purpose than to wash dishes, clothes and myself.
I do like the idea of using PEX but I do not think they make it in a 1 inch diameter.

iamgeo · 07-15-11, 03:29 PM

I will have to do this.
In place of the Standard Water Heater I have a Tankless.

strider3700 · 07-15-11, 08:41 PM

Quote:

Originally Posted by iamgeo

I do like the idea of using PEX but I do not think they make it in a 1 inch diameter.

PEX Tubing , Plumbing PEX Tubing , Aquapex Tubing , PEX Pipe - PexSupply.com

they sell up to a 3" if you really wanted it. 1" is pretty common though

Ryland · 07-16-11, 10:27 AM

Quote:

Originally Posted by iamgeo

I stated that I have a tankless water heater.
I stated that I will put a hose bib where the pipes go under the house in order to drain water in case of a hard freeze.

For solar hot water you need a storage tank of some sort and a storage tank will work great with an on demand water heater, really solar hot water heaters work best with on demand water heaters because they allow you to only use fuel to heat water that needs that bump in temp.

iamgeo · 03-24-12, 07:32 PM

I just picked up a gas 40 gallon water heater.
Now I need to figure what would be the best way to use it.
Would it be too much weight to make this :

and put it on the roof. That is the only place that gets full sun.
I think it would better to build this:

Indyplumber · 04-08-12, 01:09 PM

Don't think that will work the way you want. Tankless water heater depend on a flow sensor to turn on and off so the way you want to set it up would require you to pipe in cold water to the loop before it gets to the TWH. Because of that, you run the risk of scalding because of the water not moving in the pipes and overheating, not to mention the PVC or PEX melting because it exceed the design temps. You would be better off with a drainback system going into a storage tank with the cold water supply for the TWH looped through a heat exhanger in the tank.

Another thing to consider is that tankless water heaters have a MINIMUM tempurature rise before they come on. If your setpoint is 120 degrees then the max incoming temp necessary for the unit to run is generally 40-45 degrees lower than that. Thats because the minimum BTU input is about 12k. That means that at minumum flow the outlet temp on the unit won't exceed the setpoint.

At the moment I can't think of any setup that you can use with a tankless water heater to cut down on energy usage.

07-15-11, 03:29 PM	#13
iamgeo Apprentice EcoRenovator Join Date: Aug 2010 Location: Lakehills, Tx Posts: 168 Thanks: 4 Thanked 10 Times in 9 Posts	I will have to do this. In place of the Standard Water Heater I have a Tankless. Last edited by iamgeo; 07-15-11 at 04:28 PM.. Reason: I misquoted.

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07-15-11, 03:19 PM	#11
iamgeo Apprentice EcoRenovator Join Date: Aug 2010 Location: Lakehills, Tx Posts: 168 Thanks: 4 Thanked 10 Times in 9 Posts	I'm not ragging on anyone here. I feel I have to mention this. It seems some of you did not read my original post. I stated that I have a tankless water heater. I stated that I will put a hose bib where the pipes go under the house in order to drain water in case of a hard freeze.

03-24-12, 07:32 PM	#16
iamgeo Apprentice EcoRenovator Join Date: Aug 2010 Location: Lakehills, Tx Posts: 168 Thanks: 4 Thanked 10 Times in 9 Posts	I just picked up a gas 40 gallon water heater. Now I need to figure what would be the best way to use it. Would it be too much weight to make this : and put it on the roof. That is the only place that gets full sun. I think it would better to build this:

04-08-12, 01:09 PM	#17
Indyplumber Lurking Renovator Join Date: Jan 2011 Location: Indiana Posts: 18 Thanks: 3 Thanked 1 Time in 1 Post	Don't think that will work the way you want. Tankless water heater depend on a flow sensor to turn on and off so the way you want to set it up would require you to pipe in cold water to the loop before it gets to the TWH. Because of that, you run the risk of scalding because of the water not moving in the pipes and overheating, not to mention the PVC or PEX melting because it exceed the design temps. You would be better off with a drainback system going into a storage tank with the cold water supply for the TWH looped through a heat exhanger in the tank. Another thing to consider is that tankless water heaters have a MINIMUM tempurature rise before they come on. If your setpoint is 120 degrees then the max incoming temp necessary for the unit to run is generally 40-45 degrees lower than that. Thats because the minimum BTU input is about 12k. That means that at minumum flow the outlet temp on the unit won't exceed the setpoint. At the moment I can't think of any setup that you can use with a tankless water heater to cut down on energy usage.