Control of hot water and central heating - Control of central heating pump so that the hot water doe

Now more specifically. I am looking for a controller, simple in my opinion, for the co pump that feeds the hot water tank.
A brief description of such a controller
Based on two temperature sensors
Sensor 1 switches the pump on when the central heating temperature reaches a given temperature.
Sensor 2 switches the pump off when its temperature is higher than the temperature of the first sensor
The controllability of switching the pump on can be omitted, it is enough to switch it off when the temperature on sensor no. 2 is higher than the temperature on sensor no. 1. A working element in the form of a contactor max 2A is sufficient.
Please help

This is called a differential controller. You can also put in a reverse thermostatic valve and set it at, say, 50 degrees, then you won't let cooler water into the DHW tank.

You write imprecisely.
Which pump are you writing about?
If you mean the circulation pump, it does not feed the hot water tank. It is installed to avoid waiting for hot water and thus to save water consumption. The tank, on the other hand, is usually supplied from the mains or your own water supply, in which case a hydrophore or submersible pump is used, but this has nothing to do with the cooling down of the tank.

trance123 wrote:

This is called a differential controller. You can also put in a reverse thermostatic valve and set it to 50 degrees for example, then you won't let cooler water into the DHW tank.

Super that's one problem solved sometimes a person doesn't know what to call something.
Maybe you still know how to remedy the backflow of hot water into the central heating system because unfortunately I have a DHW tank at the height of the central heating furnace and gravity is doing its job :/ not sure about the non-return valve

Added after 10 [minutes]: .

krzysztofh wrote:

You are writing imprecisely.
Which pump are you writing about?
If you mean the circulation pump, it does not feed the hot water tank. It is installed to avoid waiting for hot water and thus to save on water consumption. The tank, on the other hand, is usually fed from the mains or your own water supply and in this case a hydrophore or a submersible pump is used, but this has nothing to do with the cooling of the tank.

.
When I wrote supply, I meant the hot water that flows into the water jacket in the hot water tank. And the circulation pump is a different story

Pryncypal1407 wrote:

I am not sure about the non-return valve

The non-return valve and possibly additionally make a siphon on the CH supply to the boiler (in practice it is a pipe from the CH boiler output lowered to the middle of the cooker or lower and only then goes to the boiler. I myself have this done because heat was escaping from the boiler.

Pryncypal1407 wrote:

Maybe you still know how to remedy the backflow of hot water into the CH system because unfortunately I have a DHW tank at the height of the CH furnace and gravity is doing its job :/ I'm not sure about the check valve

.

The aforementioned non-return valve, siphon or electric valve controlled from the pump- pump on valve open pump not running valve closed. The problem with the last one is electricity there is a whole thread about the backflow problem on the electrode search