Horstmann 425TIARA Programmer, Black

Product Information

Hi all - no I haven't managed to remove it. Gave up after failing last time but it's more urgent now because the timer needs resetting almost daily now. The Tiara has all the capability and features of the 425 Diadem, but without the indicator lights. The Tiara is ideally suited for both gravity systems and fully pumped systems with either mid-position or zone valves. I could buy a new programmer and change it but i want to be certain this is what the cause of the problem is... I also don't really understand how each of the two-way valves operate - whether the timer "job shares" between the two zones and whether two NEST thermostats can replace that functionality. Or if each thermostat demands heat and the timer is on for each zone, both valves just open and they get served with hot water equally. The Horstmann 425 Tiara Mechanical Programmer offer a easy to use and simple way of controlling hot water and central heating systems, it uses a 24-hour rotating dial with 2 on/off periods indicated by the red and blue pins.

Twin circuit hot water and central heating programmer. Offers 16 programmes for fully pumped systems incorporating motorised or mid-position valves and 10 programmes for gravity H.W./pumped heating systems. There are way too many options out there, so we have taken on ourselves to find the 10 absolute best reviewed central heating controllers. This would not allow your system to work properly on the CH, so I have to assume you have already 'had a go'. The small tank in the loft is the Feed and Expansion (F/E) tank for the central heating. The purpose of this tank is to supply water to the CH system when it is first filled or if any gets lost. It also provides somewhere for the CH water to expand into when heated. I haven't touched the wiring at all - in fact, while waiting for a reply I wanted to switch the water on and figured I could work out for myself how to turn it on using the controls on the H37XL unit in place - by switching "Zone 1" Heating on the unit to "ON", it switched the water on as I had hoped - you can see this quite clearly if you compare the wiring diagrams, pin 1.A piece of plastic which may act as some sort of stand-off or interface - it's the piece that has the 2 screws in the top (not any more though). I suspect this is integral to the main unit - I only mention it because it is a separate moulding

The 425 Tiara is a two circuit programmer for hot water and central heating and is ideal for use with gravity systems and fully pumped systems with mid-position or zone valves. It has 16 programmes available for fully pumped systems, including independent programming of heating and hot water as well as 10 programmes for gravity hot water/pumped heating systems. Will have another go when the need for heating diminishes in a month or so. Wife wouldn't be happy if I broke it at the moment. 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. I really would not advise that this is done on your system without changing the HW cylinder and other changes to accomodate expansion. Our 425 series of mechanical programmers are the simplest way to control hot water and central heating in the home. The heating controller was held in place by nothing more than the electrical blade connectors. But it need that leverage - very surprising.Thanks - I read that earlier but even trying that suggestion feels like I'm pulling the baseplate off the wall too. It seems to have a valve on the top pipe that goes into the cylinder. I have 6 cables going to the timer. The Tiara has all the programme capability and features of the 425 Diadem but without the indicator lights. CarGurus UK Limited, c/o Legalinx Limited, 3rd Floor, 207 Regent St, London W1B 3HH, United Kingdom