We had an Atag IC Economiser 35 boiler and One Controller (opentherm) installed in Feb 2018.

Generally so far we've been very happy with it, but it did replace a 20 year old Glowworm system boiler, cylinder and tank which was making all sorts of strange noises (so a low starting point!).

We run this set up using weather compensation and the "more" influence setting which does a good job of responding to the external temperature (via the One Controller/Internet, not a weather sensor on the boiler). Generally this keeps the temp in our hall where the One Controller is to the desired temperature, although this can drift upwards to +1C over several hours which I think is a combination of warm air circulating from other rooms and perhaps a slightly oversized boiler that can't modulate as low as perhaps required. I'm playing with the heating curves to try and stop this happening.

My main bugbear really is that the One Controller never kicks in to pre-heat the house ahead of schedule (similar to Nest's "True Radiance"?). The boiler comes on only at the pre-set time which we manually have to judge, normally 45-60 min before we get up in the morning.

Does anyone else have any problems with this feature?

We have the pre-heating setting currently set to 1 hour, although we've tried 2, 3 hours and automatic to no effect.

I initially had some good contact with Atag here in the UK who suggested that we might be better of without weather compensation and using plain old thermostatic control. However we found that mode didn't control the house temperature very well and made the boiler switch on and off more regularly. The opentherm/weather compensation mode of constantly circulating warm water of varying temperatures seems to be much better than on/off.

However Atag have stopped engaging and responding to my emails :-(