Causes for fireplace insert not heating house
Fireplaces (insert or not, though insert is typically better than not) are usually a poor choice for heating a building, and are generally not intended for that purpose, but rather as an entertainment device.

As for the thermostats, they will simply stop circulating hot water if the fireplace is helping - making a dent in alternate fuel use - the temperature will only rise if the fireplace is supplying more heat than the building needs, which might require a very mild day and a hot fire, depending on the construction and insulation of the building.

As a rule, a woodstove is generally a far more effective heater than a fireplace of any sort. Some with a good window setup can still be pyrotechnic entertainment as well.