new heat pump as a replacement for oil heating with existing radiators

Is it possible to do both with one heat pump? What type do you have?

No, each outdoor unit only runs with one refrigerant. I have the Vaillant Arotherm plus VWL 55/6, and the cooling is provided by Fujitsu with 4.4 kW cooling capacity. Cost is 35,000€ vs. 7,000€ with everything included, including two new radiators and 2 indoor air conditioning units. One outdoor unit is in front of the house, the other behind the house.

So you can cool with a heat pump, but only via underfloor heating, and you have to take care of the dehumidification of the air yourself. The air conditioning standardly disposes of the condensate outside.

But of course, both can heat.

Now something strange has happened. Enpal wanted to make me an offer. When I told them my data by phone, the employee said that their system showed everything in "red," which means that the project is not feasible as is. I gave her the tip to enter 6,000 times 3,000 liters per year instead of oil consumption, and then it worked. They want to create the offer that way. Yesterday the boss of a heating company was here and looked at the heating system. He was horrified. Everything was completely misconfigured. No wonder the oil consumption was so high. He advised me to set the flow temperature to 45 degrees experimentally and then see if everything in the house still gets warm. If not, I should gradually increase the value. That way, we could see if and which heat pump would be possible. Only, I do not know how to do this. Does anyone here have a similar burner? It is a Fröling Wärmecenter 16/30 MyPromat 2000 Series 03. I can see that the boiler temperature is set to 80 degrees (almost at the limit) and the burner starts when this value is undershot. The timer is set day-by-day for the times heating should be on. And that for the main heating circuit (practice) with mixer and the secondary heating circuit (apartment) according to the second weekly timer. Where should I now change something to lower the flow temperature? In the manual I only see how to set the maximum limits (maximum flow temperature limit). Or should I turn down the boiler temperature regulator? Or change something on the controller’s characteristic curve?

Fröling Wärmecenter 16/30 MyPromat 2000 Serie 03

Oh dear, the company has been insolvent for a long time now, pellet heaters are now sold under that name. The MyPromat 2000 controller is identical to the RVP75.230 from Landis&Gyr as well as Oertli. The operating manual for the latter can still be found online. You need to adjust the heating curve with ADAPT, which is described on page 7 for Oertli. Specifically for both heating circuits 1 and 2 separately. It is best to get an infrared thermometer and measure the pipes yourself to see what the setting achieves after a certain reaction time. It always depends on the outside temperature. Hopefully, your system has an outdoor temperature sensor. By the way, Enpal is also just another network marketing company, similar to DWW, but with better devices.

Thanks! That helps me a lot. I sent the DWW away and did not sign it. Now I am hoping for Stadtwerke Jena. They installed the photovoltaic system for me. It went smoothly like clockwork. On that occasion, they also cleaned my roof with a pressure washer, as a favor. The price was quoted once at the beginning and stayed the same until the last electrician left. When they install the heat pump for me, I have complete confidence. The service contract partner also called me right away. They are located 4 km away, two towns over. In case of a breakdown, they would be there in 10 minutes if a technician were in the house.

Your system hopefully has an outdoor temperature sensor.

Yes, it does. Pipe sensors (supply, return) are attached to the pipes and are easy to read. As already mentioned, the burner starts depending on the boiler temperature. I have never observed the supply temperature playing a role in this. For example, supply 50 degrees, boiler 30 degrees, the burner still starts.

Yes, the burner keeps the boiler temperature on course. However, this initially happens independently of the flow temperature.

If the outdoor temperature results in a flow temperature of 50°C, a mixing valve mixes the return flow from the radiators with the boiler water so that approximately 50°C warm water is produced for the flow. If the boiler water gets too cold, so that the mixing valve can no longer achieve 50°C, the burner must assist. However, you never actually have the boiler temperature in the heating circuit.
On the other hand, the combustion process requires a minimum flue gas temperature for the condensing technology to work. This can then also trigger the burner demand. A low boiler temperature of 50°C is not allowed in some cases depending on the design. Therefore, it is not a problem if the boiler has much more heat than the heating circuit needs.

Have you found the settings for the heating curve? What is currently set there?