Solar system drainback drainback: why it's better?

[Christophe]

Quite unknown and very little installed, the thermal solar water heater with drainage nevertheless has many advantages!

So I created this subject to present these systems of which we have a "copy" with us!

Here is a list of pros and cons that come to mind:

Most:

a) no glycol = more ecological (the heat transfer fluid is pure water!)
b) no risk of overheating of the fluid and therefore of suppression
c) no risk of frost
d) for reasons b) and c): longer lifespan of the panels (ours are 25 years old and have not been used for at least 5 years: no conventional pressure system would withstand an "abandonment" of 5 years unless it has very good safety devices against overheating ... but no one is safe from a failure on the network and therefore from destruction or shutdown, electrical failure during a summer storm, possible!)
e) cheaper per m² therefore with solar power recovered
f) annual yield a little better because the fluid does not cool down at night (so in the morning, it starts a little "faster")

The lessers:
a) may be noisier (depends on configuration, risk of hot "knocking")
b) the circulator must be more powerful to mount the fluid in the solar circuit
c) "horizontal" inclination of the panels necessary (so that complete emptying is possible)
d) little known so little mounted ... and little offered by industry therefore rare. Example of a draining solar station by PAW

Pole has a drain back system trailer demonstrator. He will present it later in this topic.

[elephant]

Why is it cheaper per m²?

[Christophe]

Several reasons for this:

a) no need for glycol (from a certain surface / L ca how to make expensive)
b) no need for a safety group (expansion tank, removal ...) = bcp less connection and labor = reduced cost
c) no thermal load shedding required
d) no need for pressure test / expel air (quite chiatic and requires special equipment) = additional cost MO
d) longer service life = influence on long-term cost

In short with a drainage system, we can, a priori put more m² for the same investment! But beware it does not make a very important difference (I would say 20% at best ...)

Ah, I forgot in the "plus" the fact of not using glycol = greener!

[poleau]

For information https://www.econologie.info/share/partag ... U3O24I.doc

[poleau]

Hello,

In addition it is not useful to have an air intake outside the circuit.
poleau

[Christophe]

In addition it is not useful to have an air intake outside the circuit.

? I don't know what you mean? Can a diagram be?

[gegyx]

Good idea that this topic.
If it is simple to build and maintain, inexpensive, reliable and respectful.

That of Cuicui, works the same?

If the specialists could make a diagram, with the necessary material.
The power of the circulator for a water height, section of the tubes (big I think).
Does the drained water fall into a separate reserve?

[fthanron]

Yes, it's interesting.

Is it possible to obtain comparative returns with other solar collector systems?
Figures, data, grain to grind?
Thank you in advance.

@+

[Cuicui]

The lessers:
a) may be noisier (depends on configuration, risk of hot "knocking")
b) the circulator must be more powerful to mount the fluid in the solar circuit
c) unrecognized and therefore little mounted ...

You forget a "minus": the need to respect the slope of the pipes so that the sensors are emptied perfectly when the circulator stops, otherwise, in case of frost, squeak! (I speak from experience). A glycol sensor does not have this constraint.
On the other hand, the circulator should not be too powerful, otherwise it will make noise in the pipes.
"Drainback", what is this horror? An alien? Why not chat French?

[Christophe]

Yes Cuicui you are right for the tilt, but is it really a disadvantage? I mean: you have to think about it during the installation and after it's settled!

For the noise, as you know with us it is still not resolved (noise of waterfall on the return, which is 34 mm). I still have 1.5 months to get started this year before the 1st risk of frost ...

Drain Back is the other name for a drain system. At Apper they often talk about it.