Horstmann 425TIARA Programmer, Black

Product Information

One number makes a huge difference, as my system only has two "channels" - hot water and central heating. The whole idea is that the expansion of the hot water in the radiator / boiler pipework is taken up by an air pocket in the primatic hot water cylinder.

The 31 and 37 3 channels use same backplate but different wiring, live is not available/linked L-2-5 as 2 and 5 are used for switching. The heating controller's "life-long" battery must be dead (9 years old) because it regularly displays the incorrect time, leading to cold water at bath/shower time. The purpose of this tank is to supply water to the CH system when it is first filled or if any gets lost.

But I think a modern electronic clock that has options to choose exact on/off settings and 1, 2 or 3 hour on cycles, is best. Having checked thousands of central heating control reviews, we can say that the Horstmann is the best choice for most people. i just would like to be able to programme at least 3 times aday and what exactly does using the existing backplate mean. I'm sure it's not that complex but I like to know how things work in my head before I spend the cash.

By pulling outward and generally downward I can clearly see the single wall box because I am dragging that towards me too. Handy for some circumstances, but as you say, room stats are really the way forward these days for lack of complexity and wiring.currentley have the Horstmann 425 Coronet single circuit timeswitch and the thing can lose an hour or more over a few days, so we are constantley messing with it. Although it says "not user serviceable" I thought I'd have a looksee anyway - I'm not without some skills in the repair and replacement of PCB components - however I can't get the bloody thing off the wall. It might be possible to introduce a motorised valve in the primary circuit (pipes going from the boiler to the HW cylinder). The Tiara is ideally suited for both gravity systems and fully pumped systems with either zone or mid-position valves.

The list shows the best reviewed central heating controls from a much bigger list of selected products. Thank you KIAB for the tip, - I never have seen those Horstmann lights and certainly will keep an eye out for them. I'd prefer not to break it as a replacement is some 90 quid, not to mention the loss of any hot water for the days it takes to turn up.

The hot water and CH is usually made separate by fitting a pump and dividing the flow of hot water coming from the boiler using a motorised valve. You can have things like one or two hour boost during an OFF period or addition to an ON time, 7 day control or 5+2 day, 2 or 3 on times per day, holiday timer, single button daylight saving adjustment.