Where to install the pump on the supply or return in an open system?

It is safest on the supply, MUST after the branch from the tank. Accordingly, modifications are required. Or on the return, if you have the reservoir at the correct height. I would let go of the tee for the tank instead of the first knee and then give the pump with a bypass. A good valve can handle it even horizontally.
Although it might help just to balance the installation. And the pump would not be necessary.

nautes wrote:

It is safest on the supply, MUST after the branch from the tank. Accordingly, modifications are required. Or on the return, if you have the reservoir at the correct height. I would let go of the tee for the tank instead of the first knee and then give the pump with a bypass. A good valve can handle it even horizontally.
Although it might help just to balance the installation. And the pump would not be necessary.

Would that be OK?

Ok, but don't install the pump itself, just the entire pump bypass. First, buy a bypass, then a pump (or together with the other, there are different connections) and only then redo it. The bypass immediately has the necessary filter and valves.

nautes wrote:

Ok, but don't install the pump itself, just the entire pump bypass. First, buy a bypass, then a pump (or together with the other, there are different connections) and only then redo it. The bypass immediately has the necessary filter and valves.

Of course I will buy the whole system ready .. this is just a pictorial picture about the solution option.

Jerzykowski wrote:

Maybe instead of installing the pump, try to lower the stove? The photos show that the return pipe does not go downhill, but rises upwards, which is not conducive to the proper operation of the gravity system. As for the pump, I'd rather give it back. It will have a safer life in the event of boiling water.

I will keep this in mind when it comes to the height of the stove when doing some major renovation of the room. As for the service life, I have heard that it is rare to boil water in the furnace when there is a pump because, after all, the water is constantly pumped. But these are only reverbs and life is life

For this, among others these are the minimum heights so as not to boil the water so easily. Apparently, the pump works longer in the return (how much longer? Maybe a year - maybe two?), But the pressure system is certainly better when it is on the supply.

nautes wrote:

For this, among others these are the minimum heights so as not to boil the water so easily. Apparently, the pump works longer in the return (how much longer? Maybe a year - maybe two?), But the pressure system is certainly better when it is on the supply.

The pressure system is better when the pump is on the return.
1) there is no chance of air entering the pump.
2) minimally increased pressure in the boiler improves heat reception.
3) reduces micro-boiling, which bubbles often cause damage to the pump when it is on the supply, because then the pump, producing a slight suction from the boiler, increases the size of these bubbles.

The pressure system is better when the pump is on the supply:
- it seems to me that the air bubbles go up, so downstream, but rather the pump should not air out at all;
- for better heat removal: a slight difference, within the error limits, you can look the other way: higher system pressure improves reception
- I think it is about cavitation - so it is important to respect the right height.
On the other hand, thanks to the pump on the supply, we have considerably limited airflow to the radiators on the top floors with irregularities in the installation.
And a great convenience with placing the tank lower.
The durability of the pump is definitely slightly reduced due to the higher temperature. But I often encounter too much demonization of placing the pump on the power supply. This is not a bug. The most important thing is to do the installation correctly.

Edit: in the era of lower and lower design temperatures, the argument that the operating temperature of the pump is higher in the supply is less and less important.

nautes wrote:

The pressure system is better when the pump is on the supply:
- it seems to me that the air bubbles go up, so downstream, but rather the pump should not air out at all;
- for better heat removal: a slight difference, within the error limits, you can look the other way: higher system pressure improves reception
- I think it is about cavitation - so it is important to respect the right height.
On the other hand, thanks to the pump on the supply, we have considerably limited airflow to the radiators on the top floors with irregularities in the installation.
And a great convenience with placing the tank lower.
The durability of the pump is definitely slightly reduced due to the higher temperature. But I often encounter too much demonization of placing the pump on the power supply. This is not a bug. The most important thing is to do the installation correctly.

Edit: in the era of lower and lower design temperatures, the argument that the operating temperature of the pump is higher in the supply is less and less important.

First of all, the installation should be done correctly.

You write that the pressure in the installation is important, but at the same time you give as an argument that with the pump on the supply, you can give the tank lower (lower pressure).
Instead of making extra mistakes and messing around with the installation even more, you should correct what is wrong.

I already wrote about it in this thread in an earlier post.
After all, the tank connection point is the "0" point of pressure ...

Let me explain it to you this way:
it works for my peasant reason that the supply pump pushes water, the return pump pulls. It doesn't make a difference, but it does. If he is pulling, there may be a lower pressure than if he is pushing.

Well, you guys, a 10m tank. over the cottage, because instead of smoking normally, someone goes crazy. (Of course, keeping an eye on the maximum allowable pressure, as if someone had such an idea ...)
Let me explain again: in order not to boil the water at a temperature of

nautes. I read your posts and it looks like you know what's going on, but weird / incomprehensible / etc ... and you explain it. You use mental shortcuts and then the flowers that "collected" by colleague Jerzykowski come out.
There is nothing to be in a hurry. People and fahofcyi are smarter and they will install thermostatic valves in the installation with a coal-fired boiler or the latter + thin tubes (colleague Grzegorz Siemienowicz wrote great - drinking straws) + panel heaters, because if there is a lot of water in the installation, you need to heat it and are ... losses (?!)
It is better to put the pump on the supply (there is no need to worry about the temperature with today's pumps) because, as a rule, the operation of the pump causes smaller fluctuations in the water level in the expansion vessel.
Hardly anyone takes into account the increase in the capacity of the vessel needed when installing the pump.

nautes wrote:

I repeat again: the point of connection with the tank is the zero / starting point of the system pressure.

This is the easiest way to calculate, but who does it ??? On the other hand, with thermostatic valves on radiators, all the calculations go to the head, sometimes along with the "departing" overheated installation.

Jerzykowski wrote:

And what if someone puts on thermostats that close and the pump has nowhere to pump water? And what if there will be a strong wind that draws the flames inside the chimney and burns so intensely that the excess heat has nowhere to go? I know an extreme case, but it is possible.

The case is not so extreme! I have dealt with him personally.
PS. I don't remember where does this requirement of 0.7 pump head come from ???
Why not 0.9 or 0.6 ??? After all, what pressures appear in the installation depends on the flow resistance and the size of the flow. And they are added or subtracted from the static pressure "caused" by the length of the expansion pipe.
Maybe someone will enlighten me.

With a properly made gravity installation, the height of the tank to the pump lifting height is important for two-pipe connection of the tank (riser and return), so that there is no flow through the tank.
With one-pipe connection of the tank, water level fluctuations in the tank are only caused by inaccurate deaeration of the system, mainly radiators, which are not designed to allow 100% deaeration.
In most radiators, the connection is approx. 1-1.5 cm below the upper surface of the radiator, so that air remains in it, and despite the subsequent compression of this air with pressure in the system, the pump expands it a bit, raising the water in the tank. In addition, there is a typical increase in the volume of water after heating it and an increase in the volume of residual air trapped in the radiators.
These two factors must be taken into account when calculating the tank capacity, but this capacity only counts up to the overflow level, not the total capacity.
The air closed in the radiators is absorbed over time, - dissolved in the water and will not reappear in the radiators if the installation is working properly.

The more accurately the installation is made and the better the grading of the pipes, the smaller the fluctuations in the water level in the tank, and the better the gravity installation is made, the more the pump is redundant.
The pumps are used in long installations where it is impossible to keep slopes due to distance and gravity will not be able to distribute the water in the circuit, or the cross-sections of the pipes would have to be very large. In private homes, there are probably no such extensive installations, they are only poorly made.
In such extensive installations, smaller cross-sections and circulation pumps are used, and in the case of solid fuel boilers, a part of the installation that allows circulation in gravity is taken into account as a protection in the event of a power failure, which is to give the smoker some time (several to several minutes) to extinguish the boiler before the water becomes cold. will boil.

Finally, I agree with pleasure .
So that there is no flow through the tank, you can make a little circulation below. It is not always desirable, of course, but it is sometimes a solution.

Col. Jerzykowski, I did not really mean boiling the water in the boiler. And you will find saturated steam pressures depending on the temperature everywhere.

The minimum height is measured from the bottom of the tank, not the top.

From the bottom of the boiler, you almost never have to measure anything. Perhaps the maximum allowable static pressure and, in rare cases, active pressure.

When I wrote that the pump pulls and pushes, I meant that if it pulls, the pump creates a vacuum. They are eliminated by placing the tank high enough, depending on the pump head. If there is hypertension, a minimum of 30 cm is enough. You can see it nicely on the pressure chart.

And why 0.7? I think I read about it somewhere before. When I remember, I will write it. Unless I forget .

Hello.
I would like to join the topic.

For me it's probably more complicated :(

I would need professional help in planning the arrangement of pumps and valves in the installation, which is time to replace with a new one after the house is expanded.

Now the apartment will be a two-family apartment - the ground floor with an attic will have 240-250m2, the stove is "fine" 38kW

I would like to perform installations on four-way afriso valves (or maybe Esbe better?) And energy-saving pumps Wilo Pico - here I also wonder whether Yonos for about PLN 350-370 or Stratos for well over PLN 500 per piece - electricity consumption is the same, but the more expensive is an electronic knob and a cheaper manual one.

If the furnace has 2 "approaches and the main distribution pipes will be copper 28mm diameter, is it enough to use 4-way valves with a diameter of 1" and pumps 25?

Does each of the pumps have to have its own differential valve or is one main valve on the furnace enough?
I do not know if it seems good to me, but I would like to install a 2 "cross on the power supply from the furnace, from which 2 four-way valves will come out to the sides and pumps from them, above the output for the DHW tank (here, for the summer season, I would also like to attach a junker heater "for propane butane cylinders so as not to smoke in a hot water stove in summer) which will have its own circulation pump and circulation pump, somewhere along the way make an exit to a box for underfloor heating and, at the very end, an expansion vessel.

All radiator pipes from the ground floor go in the floor and at the height of the return exit from the radiators in the old part of the apartment, and into the attic under the ceiling above the plasterboard.

I would like to do the main exits to the attic and the ground floor with shut-off valves so that in the event of any failure or reconstruction of the network, not to drain all the water from the circuit, e.g. only from the attic if I do something there.
In addition, I would also like to plug in thermometers that will show the temperature on the supply and return in both branches

Could someone be able to draw me a diagram of how to route the pipes to this installation at the stove?

Of course, the box with the floor heating distributor has its own pump and bypass