Vaillant 246/5 controlling 2 heating circuits - Euroster or Calormatic?

Hello,

Please assess the correctness of the installation of the heating circuit control.
I have doubts about the correctness of execution, due to a number of other manufacturing errors of the company I commissioned to install the water and sewage system (including confusion of cold and hot water, one heating loop for the bathroom and the office ... which unfortunately came later) , and also due to the high gas consumption (600m3 for last month).

The house has an area of 300m2 - ground floor and first floor. Warming 25 cm polystyrene, recuperation.
The entire house has underfloor heating and radiators in bathrooms and in the garage (in the low-temperature floor circuit).

The house is heated by a Vaillant 246/5 boiler. The Stiebel Eltron WWK 300 sol heat pump is used for heating tap water in the spring - autumn season.

The boiler feeds warm water to the coupling, from which it is distributed to two heating circuits. Each with mixer and pump.
Circuit I - the ground floor includes 10 heating loops (including two bathroom heaters) + two garage heaters
Second circuit - floor includes 12 heating loops ((including one bathroom radiator)

Each room has thermostats that control the solenoid valves.

The operation of pumps and mixers is managed by the universal Euroster Uni2 controller.
It is not connected to the boiler, and the supply temperature is taken from the temperature sensor in the clutch.
The boiler is also connected to this sensor and the temperature sensor in the heat pump's storage tank.

The boiler works all the time and the possibility of regulation is limited to setting the set temperature.

In the Euroster controller the heating curve can be set for both circuits, but the burner cannot be modulated etc.
The manual provides the ability to control the activation of hot water (priority settings, etc.), but in fact (maybe due to the lack of appropriate connections?) It is not possible. You can only control the circulation pump.

Hence the question:

Is such heating circuit control correct / in line with the art?
If so, is it worth connecting the euroster controller to the boiler and where to connect it to Vaillant?
The controller scheme allows you to control the hot utility water charging pump - where is the connection in the boiler?

Is it worth replacing Euroster with a dedicated Calormatic 470 controller?
If so, please let me know what equipment you'll need. Certainly the mixer module VR 61/4, from what I read (only 1 or 2?).

Thank you in advance for your answers, which will definitely prove helpful before meeting the next installer (or maybe the matter is not very complicated and thanks to the tips on the forum I can do it myself ...?)

Euroster does not work with Vaillant automation, therefore it will not modulate the burner, so the control is OK.
Euroster plug into the boiler in the place of the thermostat 0/1, unfortunately I do not remember what color the plug but it should be described on the plate.
Euroster may not control the charging pump, e.g. because the tank is being loaded by the boiler pump. I can't see the pump behind the clutch.
Is it worth putting in a dedicated driver? In my opinion, in the case of a cooler installation such as this one, it's not worth bothering with eurosters.
If I remember correctly, you can buy one solar or VR71 mixer module probably 70 or two and it will enter two heating circuits with mixers.

As for connections in the boiler, it would be useful to remove the circuit board or diagram at least for me because I can't help by memory. If you have a minimal idea of cables and a set of fingers then you should do it yourself

Thank you very much for your answer.

I am inclined to replace Euroster with a dedicated CM470 + VR70, I wonder if, apart from the comfort of controlling the boiler through a dedicated factory controller, I will get something more ...?

At the moment, Euroster controls mixers based on a heating curve and indication of the outside temperature sensor. It is not connected directly to the boiler (which is probably an error), and the boiler switches on / off after reaching the set temperature (according to the indications of the temperature sensor attached to the clutch).

Euroster has an output for controlling the charging pump, but it is slow. The boiler heats based on indications from the sensor in the tank, and I would prefer that the control goes through Euroster, since it is possible. I'm not only sure where to connect the Euroster in the boiler - so when it comes to controlling the boiler on / off as well as the operation of the loading pump (diagrams attached - I will be grateful for a lopological explanation of where to connect the Euroster cables in the boiler).

If I replace the controllers, I know that I will get burner modulation, but what else will control the boiler on / off?

In your case, we will not make Euroster use a tank charging pump because the tank is loaded with a boiler pump.

Since the mixers are old on the basis of the heating curve and the boiler heats to a constant temperature, it is a little pointless because when the mixers close and the heat reception is small, the boiler will heat up quickly and will be treated. If I were to do such a system at home, I would take a dedicated controller with a module for 2 circuits, not put mixers, but set a low heating curve on the controller and end. Possibly rebated thermostats to protect against overheating "if needed".

I do not know this controller and I do not know if it will work with the boiler like a regular on / off thermostat but if I was to try to connect it I would aim at a "24v dc room thermostat" but this is just a shot on my part, I have no experience in this topic.

If you install a dedicated controller, you have the ability to control another Vaillant device, if you ever purchase one (recuperator, heat pump, etc.), you get a cool mode of correcting the heating curve, easy access to diagnostics, vacation and other goodies modes, and probably something else but I don't remember because with Vaillant I have little in common every day

The most hot water can be controlled by Euroster UNI2 and this furnace model. In UNI2, a voltage-free output (COM-NO) and a jumper on the terminals is removed from the terminals - a 24v dc room thermostat - and this is where it connects the cable coming from the UNI2 controller. In this case, the boiler will be switched on only when there is a demand for heat, there is no timing or at least it is very limited. In the case of a gas boiler, I recommend using a 1.7k resistor which was included with UNI2 and connect it instead of the UNI2 supply temperature sensor. The output of the DHW loading pump and the DHW sensor is described in the UNI2 diagram. The boiler controls a valve that switches between the tank and the clutch so you would have to turn off the HUW control completely in the furnace, use the HUW pump behind the clutch and the control will be correct. In Eurostat UNI2 it is possible to set schedules, priority as well as the Summer-Winter season so there is no problem with the tank loading settings according to your needs. For underfloor heating, I would recommend using a regulator that will take into account the inertia of the installation. The Euroster 2026 regulator and the more advanced Euroster Q7 are doing very well. More detailed information can be obtained by contacting us at the phone number 65 5712012. Welcome.

My friend Perry Mason in your case, instead of using the Euroster Uni2 regulator, you had to immediately use Vaillant automation - it would give a greater impact on the operation of the boiler, but now I do not know if it makes sense to dump ~ PLN 2000, because you would have to buy a weather regulator, now it is a MultiMatic 700 and a module for it VR70 (cheaper because only up to 2 heating circuits with mixing) or VR71 (more expensive because it can handle 3 heating circuits). You can't use CalorMatic 470 because it doesn't work with VR70 and VR71. It works only with VR61, and in turn it only supports 1 direct circuit and 1 with mixing.

You can possibly try to "rip" your Euroster with the boiler. See what heating curves are set for both circuits and then you will know what max. temperature (at -20 ° C outside) you will need and set it on the boiler (say max something in the range of 40-45 ° C). The Euroster output described as "Volt free output Boiler" can be connected to the boiler under the connector "Room thermostat - 24VDC - strip X100 - white cube" in place of the factory jumper. You just have to check on Euroster which terminals to use because there is a changeover contact: opening the terminals in the boiler turns off the burner. In the case of the Vaillant MM700 regulator and the VR70 (VR71) module, the boiler works with the lowest temperature required for the system at the moment - the most economical.

The photo shows the control strips for servomotors on distributors. Are there actuators and such a strip on the second distributor? It is also possible to do so that if the strip has an output for pump / boiler control (turns off as there is no heat demand for this strip) then connect this output to the places in Euroster "Room controller for co1 circuit" and analogously to circuit 2 (only that there must be a potential free NO contact - as described in the Euroster manual.
Then, when we have no demand for heat from one of the strips, the pump of this circuit is turned off. When there is no heat demand from both strips, both pumps turn off and Euroster should turn off the boiler burner.

DHW tank heating can also be done by Euroster without extending the hydraulic system with another loading pump. The output from Euroster "DHW charging pump" can be used - it is a ~ 230V voltage connector - a ~ 230V relay must be connected to it and from this relay a normally open contact should be connected to the boiler under the white plug "Tank contact C1-C2" (this is the plug next to the plug which we attach the original tank temperature sensor). Just remember that we must detach this original Vaillant sensor. When the contacts C1-C2 are shorted, we force the boiler to charge the tank until the contacts are opened, and this will be handled by Euroster via a relay.

However, if I would do such an installation for myself, I would 100% choose the Vaillant MM700 + VR70 or VR71 controller - the choice is yours

As for the installation errors, I have found the incorrect short circuit of the returns from the floors, but maybe I am wrong because after these pictures 100% I can not be sure. It should be so that the return from each floor first separates to mix the 3-way valve of each circuit separately and only then they meet together and enter the clutch.

The above solution is definitely the best. I did not notice the C1-C2 connector with its use, in fact everything will work without any modifications to the installation. The floor skirting is probably Salus KL06-M skirting board and the PL07 module with NO output can be bought cheaply. Stove output 1-2 from this module simply connect instead of the controller to UNI2 in the terminals intended for the room regulator, the gas boiler must be connected to the terminals (boiler) COM and NO on UNI2.
However, please remember to replace the power sensor in UNI2 with a resistor.