Buffer tank on base ROTEX

[loop]

Hi Mickael,

if I start from the work of RAMSES for the manufacture of my exchanger having a diameter 25 at my disposal.
If I stay on 38/40 meters of exchanger is it ok for heating ?? knowing that its work concerns the construction of a DHW exchanger
In manufacturing, is it better to have a double spiral (spiral one inside the other?
or a simple spiral?
the difference between the spirals is it important? if so what gap should be favored?
is it better to tighten the spirals towards the top of the balloon? and space them down ??

1 meter of smooth tube of diameter 25 has a surface of 0.08 m2.
40 mx 0.08 = 3 m2 is good, it is the surface of the solar exchanger of my 500L buffer tank.
The corrugated stainless steel has an even larger surface, thanks to the undulations, this will only improve the exchange.

For me your 40m will be well suited, still it is necessary that the circulation is done with a certain flow, to be turbulent. But I am confident because the heating circulators are adjustable in power.
For the realization of the coil, do not take the head. Keep it simple with a homogeneous vertical distribution. The space between the turns will promote circulation by thermosyphon in the volume.

A+

[loop]

Anyway, I didn't know what a ROTEX oil tank was, now I'm looking for one; =)
why in the end you only keep one exchanger?
you do not intend to connect solar panels?
Are you planning to inject the heat from the boiler? how high ?

The Rotex balloon from mi16 is not an oil tank, but a mixed solar buffer tank.
It is a water reserve at atmospheric pressure made of plastic (or composite?) Which allows the solar circuit to be connected in self-draining, by circulating the water directly to the collectors. The heat exchanges for consumers (DHW and heating circuit) are made from separate exchangers.

The absence of pressure in the tank is an advantage, but as the oxygen supply is permanent, the tube which constitutes the sensors must withstand the shock. I do not know of any negative feedback on complete Rotex installations, but the "oxygen" parameter must be taken into account in the aging of the solar circuit.

A+

[jonule]

thank you for your answers Looping;

To avoid overheating, there are a lot of solutions

for overheating I read a long time ago that a radiator dedicated to this application was sufficient to evacuate the heat, in a cold place like outside, connected to a temperature limiter on the circuit? ... it makes the birds laugh but it should work?

Be careful when working on an enamelled DHW tank, if the enamel jumps after drilling or welding, the life of the tank is greatly reduced in DHW use (attack of steel by dissolved chlorine).

for the enameled balloon I take note, but even if the "recovered" balloon dies, remaking it costs less than a new one anyway? or else I do not have access to certain prices ... I will look at "solar diffusion" and purchasing groups on the forum Sunscreen ...
Otherwise I tell myself that a surface treatment could do the trick, like gel-coat paint or other suitable paste / putty? in any case, I assume that hot water is not made to be drunk;

For the connection of the boiler, no need for an exchanger, the circuit and the tank are pressurized. Changing it to solar is possible with an exchanger fixed to the inspection hatch.

are you talking about a buffer tank that has a visit hatch, on which we can place a heat exchanger for DHW?
and inside the water circulates the radiators, and therefore the boiler stove, so yes 1 only exchanger, but 2 for the DHW, which will lead me to ask myself the same questions as mi16man on stratification and exchanges of heat, good I thank you; =)

A DHW tank can be converted into a buffer tank, but the orifices being quite small (usually 3/4 = 20/27), it must be checked that this does not disturb the loading / unloading.

I imagine that in this case it is necessary to work with this same section on all the installation?
by the way I did not tell you: this balloon is double shell, intended to be heated with water from the radiators ... what would be the best use that I can make of it, according to you?

For the use of radiators, unfortunately I fear that the result will be poor because of the inertia of the steel + water assembly.
The best collectors contain little water and are made of aluminum / copper because these metals are very good conductors of heat.

even with "flat" steel radiators? if not a mix with panels made of copper, what really to extend the surface?

The Rotex balloon from mi16 is not an oil tank, but a mixed solar buffer tank.
It is a water reserve at atmospheric pressure made of plastic (or composite?) Which allows the solar circuit to be connected in self-draining, by circulating the water directly to the collectors. The heat exchanges for consumers (DHW and heating circuit) are made from separate exchangers.

as much for me I thought it was a self-built tank;
self-draining ... does this keep the fluid contained in the caps + pipes, off reserve, at t ° C so that it does not cool? is that the only advantage?

thanks again

[mi16man]

hi Jonule
good with regard to ROTEX it is a buffer tank, which comes in different variants with more or less exchanger inside.

Rotex is a brand type on google their site details the concept well


there are even rotex buffer tanks on which a gas boiler is mounted
my last acquisition is precisely this "GSU" gas solar unit model
I found only the tank in which I will redo an exchanger which will be under pressure and connected to the heating system in parallel with the boiler and the boiler stove.

I see you do a diagram but there I am a bit taken aback by the winters that arrive and the making of my buffer balloon, so not for now


finally on the ROTEX the water which is heated serves just as accumulation it does not circulate in the heating system and is therefore not under pressure
the tank is filled once it's like a "bain marie"
except that this same water is sent into the solar panels called self-draining.

a pump draws the water from the tank and sends it into the panels when there is solar gain once the solar supply is zero the water returns to the tank and the panels are empty

advantage: no antifreeze, no pressure in the panels, if too much solar gain no need for a discharge loop because in this case the panels are left empty, positive feedback
brand still on the market which implies a sponsored design ??

inconvenient O2 intake in the system as pointed out by looping,
charging time of the panels, compulsory slope (the tank must be lower than the panels) for emptying

to respond to looping the tanks are made of double wall plastic injected with 7 cm of polyurethane foam

[mi16man]

hi Gérald

good for the exchanger I will keep it simple it is often what works the best you will tell me!

Regarding the 40m of interchange I started on RAMSES works but I can go up to 50m
or 50x0.08 = 4m² see a little more with the ripples ????

still it is necessary that the circulation is done with a certain flow, to be turbulent. But I am confident because the heating circulators are adjustable in power

for that I am confident also I saw that it was possible to modify the flow (because I make everything circulate in position 1 in me) and to reduce it by adding like a piece with a hole to slow down the flow (I do not know more what is it called ????


ok for the space between the turns i will make it as simple as possible the same everywhere


one or two other questions:

I go down to the bottom (stick to the bottom of the balloon) with the exchanger? or I leave about ten cm?

Is there a problem with mixing ringed stainless steel and copper?
because I wanted to make the supporting structure of the copper exchanger

do you need a car bleeder on the arrival? departure? of the exchanger
or on the 2 ???

Do I have to connect the tank by making a siphon before this one to prevent the hot water from rising by thermosiphon when the heating need is zero?

A+

[loop]

Hello everyone,

For the typical connection diagrams, you can consult this article:

http://energies-libres.net/index.php/insert-chaudiere/18-installations-inserts/insert-de-looping/289-les-schemas-de-raccordement

A+

[jonule]

thank you to you mi16man for enlightening me on the system, it must be said that I came across the "fuel" page of ROTEX and I did not look any further ..
their system looks good, I see a serpentine in a serpentine, except that I do not understand their fad of hygiene of the heated drinking water, but in short, I understand that you recovered the tank alone;
for the diagram no it does not hurry, it was by way of example and sharing, take your time to finish your work before the arrival of the cold ... who is waiting elsewhere ?!

I will take advantage of your excellent subject (sorry for the squatting but it is positive! =) to decide to open mine, your illustration allows me to design an option which I will submit to forum;

a pump draws the water from the tank and sends it into the panels when there is solar gain once the solar supply is zero the water returns to the tank and the panels are empty

advantage: no antifreeze, no pressure in the panels, if too much solar gain no need for a discharge loop because in this case the panels are left empty, positive feedback

inconvenient O2 intake in the system as pointed out by looping,
charging time of the panels, compulsory slope (the tank must be lower than the panels) for emptying

ok, so it's on demand ...
for me on the other hand it concerns solar panels, without water when there is too much sun: if they are in steel recovered from radiator it is fine, but if they are in copper brazed with tin I imagine that it is not suitable ? halala the choice is hard

PS: what would have been good for a self-built balloon, it is several indicators of t ° C "divers" inserted at different heights, to see how it is stirred according to what you inject ...

[jonule]

solar panels, without water when there is too much sun: if they are in steel recovered from radiator that is fine, but if they are in copper brazed with tin I imagine that it is not suitable? halala the choice is hard

unless you bend them, rather than braze them with elbows, yes. soldered with a soldering iron for the zinc plating on a zinc plate in several places, would it be more effective than radiators?
on the other hand it is necessary that the bending evening horizontal and not vertical so that it does not retain water for the gel ...

which section would be best? 12/14? well I could certainly do that next spring (we can't do everything!) I already have double glazing, to see the price of wood for the boxes compared to the solar panels on ebay and their performance ...

thank you for understanding the self-draining system; how is the filling / emptying technically done? do you need an atmospheric pressure vessel? a cellar vacuum pump that holds the t ° C? a valve that opens / closes? is that what the solar "fast" traps are used for, when the water fills the collectors?

[loop]

Jo,

I sent you a mp with my phone number
Give me a call on occasion, I will answer all your questions, much more effectively than in writing.

mi16

Is there a problem with mixing ringed stainless steel and copper?
because I wanted to make the supporting structure of the copper exchanger

do you need a car bleeder on the arrival? departure? of the exchanger
or on the 2 ???

Do I have to connect the tank by making a siphon before this one to prevent the hot water from rising by thermosiphon when the heating need is zero?

To my knowledge, the galvanic stainless steel-copper couple is not a problem, although there is one. See the attached document, the reference on the subject:

http://www.apper-solaire.org/Pages/Fiches/Ballons/Preconisations%20d%20installation%20ballon%20ECS%20face%20a%20la%20corrosion%20galvanique/index.pdf

a trap is necessary whenever there is a high point in a pipeline. A manual model with bleed screw is very suitable in all cases.

The thermosyphon in 1 single tube occurs with a fairly large internal diameter, of the order of 25mm.
As a precaution, you can actually put a small 10 cm counter-slope from the heat exchanger.
The thermosyphon in 2 tubes is stopped by a non-return valve or simply the closing of the circuit by a valve (3 channels or other)

A+

[mi16man]

Hello
here I am back ... involuntary absence and alas constraint ...

well I left on the structure of my buffer tank which is being made but which is progressing well ...

the structure will be in copper Diam 14 pipe to hold the stainless steel coil inside the balloon

on the other hand I dry a little on how to make hold the ringed stainless steel pipe in position in order to have turns at the same distance and a regular spiral ...

an idea????