My first attempt to descale my C85. I followed the procedure outlined in an old post of 11/5/2005 "Water, Scaling and Descaling in a HX machine".

I drained the boiler of as much water as I could by bring it up to operating temperature, shutting it off, and opening the hot water valve. I disconnected the machine from water mains, removed the resin column and and connected it to 5 gallon bucket. After that I mixed about 2.5 gallons of 1.5 tablespoons citric acid per quart of water, filled the softener column with the solution, and let the auto-fill fill the boiler with the citric acid solution to its normal mid point on the water level gauge.

As I was waiting for the boiler to come up to temperature, I could hear noise from the boiler which sounded to me like boiling. When the boiler pressure, about 1.4 bar, I heard what sounded like the heater relay opening, 1.4 bar is the normal cut off point. After what was maybe 15-25 seconds, something in the machine shut the power off as the red operating light went off. I am making a possibly unwarranted assumption that for some reason the over pressure switch shut off the power. Even after the boiler dropped to 0 pressure the power will not come back on.

Three questions;
Any ideas what the "boiling" sound from the boiler might be and should I be concerned?
Does the over pressure switch have to be manually reset?
Or have I really screwed up?

David

If the safety switch on the boiler did activate, you do have to reset in manually by pushing it back in. It's the red switch on the heating element.

If that doesn't do it, I would check the heating element. It's not clear from your description that it has been damaged, but it's not uncommon after a descale.