Horstmann 425TIARA Programmer, Black

Product Information

Is it the programmer or could it be something else??? Everything else seems to be working, thermostat, pump... So there you go. It's given me some confidence to look at the Heatmiser wifi-connected thermostats next. 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. There's a baseplate which is fixed to the wall/hole in the wall onto which the controller should plug, and is secured with two screws on the top. Hey guys, it seems like you are all very helpful, and as I know very little about central heating/boiler systems (I still can't figure out whether I have a "Fully Pumped" or "Gravity Fed" system), I thought I would ask for help. For instance, I *hope* the cabling to each thermostat allows for me to install the NEST power supply (supplies?) in the hot tank cupboard (where the timer currently lives) and power each thermostat (remotely) that way.

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. The problem only started this week, I have never had any problem before..I have been using set on HW for the past 2 months now that summer is upon us!!!!!!!!!! Some people will, incorrectly, refer to your type of system is a "gravity" one. The term should really be used only for systems where the circulation through the HW coil is due to the change in density of the water when heated; i.e it is not pumped through the HW coil. As for your easy to understand explanation about my system, that was great, I'm a lot happier now I understand what is actually happening in my home. Thanks - I read that earlier but even trying that suggestion feels like I'm pulling the baseplate off the wall too.I have got a small problem with my programme, I think, when it's set for CH it comes on but when it's on for HW ( which is what it it is currently set during summer) it It seems to have a valve on the top pipe that goes into the cylinder. I have 6 cables going to the timer. I can get a screwdriver between the wall box and the stand-off but there's no way they are going to separate without my breaking one of them. I am wondering if the stand-off comes away from the main unit. I can pull the main unit away from the stand-off enough to get a screwdriver into the gap but it's not coming away consistently - only where I exert pressure so much that the plastic deforms. HORSTMANN (SECURE) 425 TIARA PROGRAMMER - Now use 4210051 or 4210056 Our Part No 4210005 MPN NU0550301000

The HORSTMANN (SECURE) 425 TIARA PROGRAMMER - Now use 4210051 or 4210056 is a genuine, brand new Horstmann Controls product, covered by a Horstmann Controls manufacturer's guarantee. 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.Our house experiences brief power outages from time to time. 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 large tank in the loft is the cold water feed to toilets, wash basins etc, and to the hot water cylinder, which is thing in the cupboard.

The heating controller was held in place by nothing more than the electrical blade connectors. But it need that leverage - very surprising. Tiara, two channel programmer with 16/10 programme setting for fully pumped or gravity hot water/pumped CH systems.Select ON/OFF twice a day, ON all day,or permanently ON or OFF with advance switch and 9 pin wall fixing plate.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 Could any of you identify the model of my parents Horstmann timer as in attached pic? I am after a wiring diagram for it as would like to replace with a Horstmann H21XL two channel timer but am unable to find this particular model online... Not what you're looking for? Try our unique Spares Finder tool or you can view all Horstmann Controls products.