Does anyone remember a boiler piggy heat saver?

[JonathanM]

I'm in the process of upgrading my controls, and recently started thinking about an energy saving device my parents used to have. I can't find anything on Google.

It was fitted in about 1990. It was small white box on the wall, next to the wiring centre for the S-Plan. When it was on, a red pig would light up, and it would override the other controls. It was my dad's idea, but my mum hated it because she couldn't get the heating on when she wanted, and after a couple of years it was removed.

Does anyone remember this, and what is was supposed to do and how it worked? Sadly, neither Mum nor Dad are still here to ask. My uncle thinks it might have been linked to an external temperature sensor, so maybe some sort of primitive weather compensation? I'd just like to know, for nostalgia's sake.

 

[JonathanM]

The external sensor is still there! I can't think what else it would be for.

Looks exactly like this one, Danfoss ESMT V1

 

[Exedon]

Seem to recall Danfoss made a unit like you describe with the light up pig! Did have a external sensor.
We fitted one or two as you describe some customers loved them others hated them.

 

[JonathanM]

Seem to recall Danfoss made a unit like you describe with the light up pig! Did have a external sensor.
We fitted one or two as you describe some customers loved them others hated them.

Thanks, that helped me track it down. It's a Danfoss Boiler Energy Manager, probably a 4000 model. From what I've just read, I think it worked by measuring the flow temperature, and the outside temperature, and would then seek to optimise the flow temperature, by cutting the burner, but keeping the pump running. But with non-condensing boilers, back in those days, I'm not sure where the savings came from? So pleased to find it!

There's a few threads on here about them, but not for a few years, I think.

 

[ianmcd]

They were a complete con, what they did was interuppt the boiler thermostat wiring and salesmen claimed massive savings they were a complete waste of time

 

[BlindChaos]

Has anyone come across these units before they seem to be very similar to what are being described above. We have recently moved home and we now have these and the heating only gets luke warm at best all the rads get luke warm no cold spots etc.