Hello,
I have an issue with the gas boiler. I have a buffer tank connected to the heating circuit and a dhw tank. The issue I have is that when using it for heating it does not maintain the set flow temperature for more than ~20 minutes. I have set the flow temperature to 60C (it reaches that), but the buffer tank temperature cannot reach even 55C, because the boiler turns off after about 20 minutes. It turns on again after 4-5 minutes, but the buffer tank temperature is dropping to ~45 during that time, so it runs again for about 20 minutes and turns off. This cycle repeats until I turn it off. I have also observed that when heating DHW it stops serveral times for about 1 minute, before it reaches the set temperature.
I cannot understand why it is stopping the heating cycle. My understanding is that it should run at constant flow until it is turned off. I see that it is not modulating down properly to keep the flow at 60C when the return temperatures rise, it just turns off. Please help me with some advice or whatever, because I'm out of clues, as also the installers are. If I want higher temperatures in the buffer I can increase the boiler feed temperature, but this does not seem right to me, because when I turn on my underfloor heating and set the feed temp to 40-45C, it does the same, so I have to increase the feed temp, which puts it out of condensig mode (return temps go above 53-55C) and the whole idea for economy goes out of the window. I think the issue may be related somehow to the fact that the boiler does not know about the buffer tank, which works as a low loss header, but in the configuration. there is no option to set that I have low loss header/buffer tank and DHW tank directly connected to the boiler (not upstream of the low loss header).
Please help with some advice.
Best Regards.
