The NTI Trinity boilers are very common in the Ottawa area with parts readily available. I am installing one right now in downtown Ottawa.
Weil McLain Ultras have a reliability issues and I no longer install these. Personally I like to see a setting of 140 deg on a cast iron rad system, this being said the sentry controller in the boiler will play with this setting somewhat using the outdoor reset.
On another note, I have had no issues with the Ti-200c the boiler may be slightly over sized for heating but it is fully modulating so if it doesn't need full bore power you won't have an over sized boiler. When you consider that a tankless water heater is a somewhat modulated (Rinnai) 180,000 btu/h the 200c combi isn't that far off for both DHW and space heating.
The issue with some installer is that they don't use a primary/ secondary loop in the piping, or even use injection pumping they just go straight in and out, thus voiding the warranty.
For indirect DHW we use a Weil McLain plus 40 tank, we zone with circulators and use heat traps to prevent heat leaching into the house in the summer.
I've just registered to join this group. I am in Ottawa Canada and m interested in installing an NYT Trinity. I'd be grateful if you would recommend some names of installers. Thanks