At work, our offices are heated by a Vaillant Ecotec 831 boiler which is controlled by a VRT392F controller. We are constantly plagued by the fact that the boiler spends most of the day giving out a low heat output. Typically the gauge on the boiler reads 40 degrees, although on rare occasions it goes as high as 60 degrees. The controller is in a cool location where the temperature is maybe 18 degrees or so, and is set to request a temperature of 28 degrees. So why would the boiler give out such a low heat output when there is a demand for heat?