Increasing hysteresis of boiler stat

[Richard Owen]

Hi guys,

I have the oversight of a friends holiday home. It has an oil fired boiler (Worcester Bosch Greenstar Camray.)

The boiler feeds a thermal store which (in addition to a hot water coil) has two radiator loops, on towel rail loop and one UFH loop fed off it.

The system works well in terms of keeping everything warm. The presence of the UFH loop ensures the return temperature is low which is good for condensing.

The problem is that with the heating running the boiler fires every couple of minutes for a minute or so. Which isn't going to be great for the efficiency.

Currently, the boiler is controlled by its internal stat.

A quick google gave me some designs for stats with adjustable hysteresis but I'm not going to build something for someone else (I reserve the prerogative of wanton electronic destruction for my own place.)


Does anyone know either of a tank stat with large hysteresis or a way of rigging up a system with a large hysteresis?

[Brandon]

i use a pair of stats latching a relay to great effect.  search on here.

[Richard Owen]

Found it.

Sorted.

Thank you.

Can't work out how I missed all the discussions on this before.