Tuesday 5 February 2019

Boiler

For the last couple of weeks I have been living in a cold house with occasional tepid running water. This week I finally had my boiler replaced. As I was standing in my kitchen watching the plumber he asked me what I did for a living. "Computer Programmer". Long awkward silence. "I'm a heating engineer" he said eventually as he drained my heating system and took my boiler off the wall. No Shit!

My house has a combi boiler so as well as heating water for the radiators it heats water for the hot taps on demand.  When you turn on a tap it senses the flow, lights the burner and heats the water that is heading to the tap. My last combi boiler had a preheat function so that heat exchanger was always hot and you got hot water at the taps more quickly. I'm careful with my money, I live alone and I don't use that much hot water so it would infuriate me that the boiler would burn gas every hour or so just to keep the hot water ready. You could turn the preheat function off, but then I would waste a load of (metered) water between turning the tap on and it running hot.

For nearly a decade I have wanted the combi boiler to have an external input that switches between eco and preheat.

My first job was designing consumer electronics and I worked closely with the software engineers on user-interface. I've spent over 20 years as a software engineer and, although I am not one, I have worked with technical authors who had to describe what I have made to the general public. I am spectacularly well placed to be able to read the user manual and the electrical section of the installation manual for a new combi boiler.

I was delighted to read that my new combi boiler has an electrical input to control the preheat function, and display modes to show you what state it is in. I asked the plumber about fitting an external timeswitch to control preheat and he said "it doesn't work like that." I showed him the page in the manual and he insisted "it doesn’t work like that" I showed him the page in the electrical interface manual and he said "That's just because it's the same circuit board as the system (non-combi) boiler."

As soon as he left I tool the boiler apart and ran some dangerous tests connecting live mains to the various inputs. I was right, he was wrong, and I now have timer controlled hot water preheat. Woohoo!

Richard "This is my manor" B

1 comment:

  1. I would wager that your so called heating engineer is about as qualified to call himself an engineer as I am to call myself a concert pianist

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