JWSG The steam boiler temperature will plummet by 8-10 degree after the purge
However, if I do not draw any hot water to warm the cups, the steam boiler temp only drops <1 degree
Most likely when you draw water from the service (steam) boiler, the amount of water is not enough to trigger a fill.
You then go about steaming, the water level drops and a fill triggers, sending cold water into the boiler and consequently the temperature drops.
Next time you draw water, make sure the steam boiler fills up before steaming. Usually the only way to do that is to try to make it register, by drawing more water, or pruning the steam wand until you hear the pump filling up the boiler.
