ᐅ Guntamatic Pellet Heating System: Supply Water Temperature Too High

Hello everyone,
apparently my pellet boiler is set up incorrectly. I’ve tried and checked quite a few things but can’t figure it out. The supply temperature goes above 50°C (122°F). I’m worried my floor tiles might crack 😉 (underfloor heating).

It’s a Guntamatic with 10 kW.

What I’ve already checked:
- Mode is Eco-Ideal, which should be correct
- Operation mode is Normal
- Temporary setpoint temperature at 18°C (64°F) made no difference in lowering the supply temperature
- Heating curve was adjusted from 0.6 to 0.5 (0.6 should be fine)
- Screed heating is of course switched off
- Max supply temperature is set to 37°C (99°F), so it should never get that hot...

Attached are some pictures:

Hello

Is the boiler connected to a buffer tank? From the buffer tank, does it go through a mixing valve and mixing valve motor?
Is the mixing valve operating correctly, or is it possibly set to manual mode?

Olli

Hello Oli,
Yes, I have a mixer; at least it was still functioning yesterday.

In the picture, you can see the mixer. It is set to the lowest setting. Does that mean it adds only a little heat, or a lot?

Regarding your other questions, I find it difficult as a layperson, but I’ll try to explain. You will understand what I mean 😉

The pellet heating system heats the large buffer tank responsible for the domestic hot water. The underfloor heating line runs through this buffer tank 😉 What do you mean by boiler? The large buffer tank, I suppose.

To my (layperson’s) knowledge, I don’t have a buffer tank specifically for the underfloor heating.

Hello
Based on the position of the mixing valve actuator, almost exclusively water from the return line should flow into the supply line.
First, check whether the mixing valve actuator is mounted correctly on the valve.
You can also try pressing the round button and then turning it fully to the right.
Does the supply temperature drop then?


Olli

So, the mixer doesn't move. I opened it up earlier and noticed that the screw holding the "knob" is loose. I've just read that you also need to push in to adjust it manually. I'll try that again later.

Apparently, it wants to take the water from the return line (to reduce the flow) but can't, maybe because the component is not seated correctly.

I'll take another look at it later. I currently live about half an hour away...

Should the red ring be visible when the system is regulating? Or should I press it in?