Solar Water Heating FAQ’s

posted Dec 20, 2013, 5:43 AM by San Diego Solar   [ updated Dec 20, 2013, 5:43 AM ]
I am considering to purchase a evacuated tube solar water heater, not the flat panel type. But i have a few questions. :

1. Do these also have a link with the natural gas/electricity to do the heating in case there is no sunlight for several days due to snow, rain etc?

The SWH (short for solar water heater) is installed so in the summer you feed directly from the SWH to your hot water line (shower etc).
Then in the shorter and more rainy time of the year (winter) you turn a valve and the SHW feeds into the water line that goes to your gas or electric water heater.

For best results use gas-tank-less with a thermostat sensor (bosch or similar) …so in this case the you open the shower. The gas burner comes on and if the hot water comes from the system the gas burner turns off and you still have 100% savings in the winter.
If the water in the solar system is not hot enough (rainy week or lots of guests) then the gas heater stays on and heats the luke warm water that came from solar. If u have a gas-tank-less then you leave the setting to this all year round, you can have any number of guests and never have to worry about hot water usage.
2. How many of these have you installed? Can i talk to happy clients about these?
We ourself have installed over 40 of these. Worldwide the same heaters have been installed millions of times. The thermal tubes and Eco and Eco have been around for a while now.

3. How does the water heat at night when there is no sun?
It does not. The water is heated during daylight, not just sunlight!
At night the water sits in the water holding tank (attached or separate) and can be used at any time.
Cold water comes into the lower part of the holding tank and stays there, the next day the water will be heated again.

4. How does the water pump work? Are they electricity powered?

You don’t need a pump for systems that have the tank attached. For systems with a separate water tank you need a very small pump with a timer. It uses electricity, but very little and some folks like this to be done by voltaic solar cell.

5. What is the standard configuration? Does the tank sit on the ground floor/basement?

Simplest is a TH250, it needs no pump. And the whole system can sit anywhere, roof, ground.
It works best if its faces south. But southwest or even west facing installations perform very good.
Before installing consider
* short distance to hot water line/ kitchen or shower.
* that no tree or neighbors house blocks the sun.
* that its not in the way and you later hate to see the thing in your path.
Generally ground installations are fine too. Many of my friends always want to see how it work (again and again) and they want to check how hot the water is when they visit me (every time).

6. How long does it generally take to install one system?
We install a TH240 in a few hours.. For first timers with with the self installation CD it will take you about a day.

7. The price, is it list or net to install one system at my own place? What does it include?

End Prices are shown on our SWH catalog.
It includes the SWH with thermal tubes, frame, attached tank

We highly suggest that you install the following additions.

* anti scalding valve, in case the water gets very hot
* pressure reducing valve, in case your water pressure varies and is above 50psi

What will be its capacity (1-2 people 3-4 people, 5- 6 people……?)

A TH250 is good for 3-4 people for most of the year. In the summer it can sustain about 5-6 people.

What is a drain closed loop system?
Closed-loop system that circulates antifreeze through the solar hot water collectors and uses a heat exchanger to transfer this collected heat to household water. When the sun shines on the PV modules, the DC pump that circulates a propylene glycol solution through the pipes and collectors runs in rough proportion to how much energy the sun can provide an elegant, grid-free solution. But dealing with the maintenance requirements of periodically checking the pH (acidity and alkalinity scale) of the propylene glycol antifreeze and recharging the system held little appeal for me.


What is a drain back system?
A closed-loop drainback system that uses demineralization or distilled water as the heat-transfer fluid. In these systems, a pump moves water through the collectors and circulates it through a heat exchanger. When the pump is off, the water drains from the collectors and outdoor piping to a storage tank, assuring freeze protection.
Drainback systems are effective and reliable—some systems can operate twenty years or more without needing service. Their only downside is that larger, higher power AC pumps;requiring more energy—usually have to be used. This is especially true if you’re pumping water two stories or more, since the drainback pump has to lift the water to the height of the solar collectors.
In the pressurized loop of a glycol system, all the pump has to do is overcome the friction head of the piping itself.
Are your systems compatible to the freezing temperatures we have here?
Since there is no water in the tubes and the tank has a back-up electric heater just in case. but it will never freeze inside. the to/from water lines are a the easiest to freeze that is why we suggest is that you install a back flow pump.
meaning at any time there is small amounts of hot/warm water coming from the system, run through the line and then feeds back into the system. easy to do.
watersaversolutions or home depot offer such pumps for around $200.00.
This pump must only turn on if you don’t take hot water from the tank for longer periods. especially in cold nights.
Very good professional insulation must be installed around the tubes. That is most important and will do the job in most cases.

What are the weight/dimensions so that we can work out the freight charges? 
The total volume is 3 sqm (37ft3
the weight is 130 kg (286lbs)
We suggest forwardair shipping from terminal to terminal.

If you have any more questions feel free to call me at 1 619 822 2082 or contact us.