Unskyld at jeg skrive på Engelsk, men min Dansk er desværre ikke so god, fordi jeg er flyttet til Danmark.
We bought a house last december with a Baxi multiheat 2.5 for heating and water. It is a big house but it is well-insulated and has floor heating everywhere. The pillefyr was running okay, but the ash was always black and clumping together. So mid april we called in an expert to have a look at it. He explained a lot about the pillefyr, and how you need to clean it every week. We only removed the ash once a month until then. He removed 4 of the metal zig-zag bars from the tubes, to increase the temperature in the chimney. He increased the water temperature from 60 to 70 degrees. He changed the pump from lowest to highest speed. And he also changed the settings on the Baxi so that the ash would be gray. I'll put the settings in the bottom of this post.
The result now is that the ash is grey, but we also get a lot of black tar in the upper part in front of the tubes.

This picture was taken only a few days after the settings were changed.
Below are the zig-zag bars. The one in the bottom was one of the removed ones, so that is how they used to look before the settings changed.

After a few weeks I decided to change the settings back to the old values, but then I got an A1 alarm, so then I went and put the new settings in again. Sometimes I got an alarm after cleaning (last time it was A11), but I did not think much of it, I thought it was just me who had not started the fire correctly.
Today we got an A1 alarm in the morning, and I do not think that should happen, because it has been running for a day without me doing anything to it. It needs to run without alarms when I am at work, because the wife will get nervous otherwise

In general now, I think the house is just not asking for any heat during day, so the pillefyr is just smouldering. Looking at the smoke coming out of the chimney, it is black and smelly. The chimney temperature is 80 degrees or so. The O2 level is 0 and the fan is OFF, at least most of the time. Ash is grey. Tar is still building up, but not as much as in the beginning (I think).
What I am not sure of is if the old settings would have worked better, because we only used those when it was cold outside. Now summer is here and I can imagine that it is not ideal for a pillefyr to only ask it for very little warm water.
So I'm hoping someone here can give some advice on how to prevent alarms from going off, and how to keep the tar away, while still keeping the ash grey.
(The expert we used is not answering calls, I think he got tired of us. He also did not send an invoice yet.)
((Sorry for the long post, but I figured giving all the details may help fixing this...))
Settings:
Old New
PROM version 110 110
max pause @ low use H24 H24
min pause @ high use L50 L40
max blower @ high use b50 b60
reversing time spindle r0.0 r0.0
min air blower -40 -40
spindle time @ high use H0.5 H0.5
spindle time @ low use L0.3 L0.3
blower time @ pause P05 P05
O2 setting @ high use 8.0H 6.5H
O2 setting @ low use 7.0L 7.0L