Having our boiler replaced I was happily going along with the recommendation of a WB Greenstar 18Ri with HoneywellCM927 until I came across the concept of OpenTherm and modulating direct boiler controls.
It appears that WB don't offer an OpenTherm boiler, (at least not in the size we need - haven't looked at the larger ones), so we'd have to look elsewhere.
Would modulating controls be worth considering?
They are probably most worthwhile when combined with an external temperature sensor to give full weather compensation. That way the system can not only take into account the actual room temp and the desired temp, but also how cold it actually is. However, even without external sensors you ought to get tighter temperature control and increased comfort and some gain in efficiency, since the boiler will be running the lowest temps it can for the circumstances.
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