Horstmann 425 Tiara Programmer Product Code: 18470

Common timing. 3-wire installation. Override facility. BS EN 60730-2-7: 1992 and 8182 / 8319, BS EN 50081-1 and BS EN 50082-1: 1992.


  • 24 Hour Programmable
  • 26 Pre-Set Programmes
  • 2 On/Off Periods per Day
  • Suitable for Gravity-Fed & Pumped Systems
  • 2 Year Manufacturer's Guarantee
  • 3-Wire Installation
  • Energy Saving Trust Approved
  • 2 Year Manufacturer's Guarantee (T&Cs Apply)


Switch/contact rating: 6A. H x W x D: 112 x 153 x 33mm. Backplate fit: 9-way (included). Not suitable for underfloor heating.
Additional Information
Technical Specification
  • Brand : Horstmann
  • Product Height : 112 mm
  • Product Type : Programmer
  • Programme Facility : 24 Hour Programmable
  • Central Heating Control Type : Programmers
  • Model No : 425 Tiara
  • Product Width : 153 mm
  • Product Depth : 33 mm
  • Pack Size : 1
  • Suitable System : Suitable for Gravity-Fed & Pumped Systems
  • Installation Type : 3-Wire Installation
  • Manufacturer Guarantee : 2 Year Manufacturer's Guarantee (T&Cs Apply)
  • Pieces in Pack/Case : 1
Product Contents
Delivery & Returns


Standard delivery: €15

Free delivery on all orders over €70.00

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Hopefully you won't need to return an item, however, if you do, it is our aim to make this as simple as possible. By following the guidance below you can help us to help you when a product is not what you expected, or is faulty. Your statutory rights are not affected by this guidance.


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€67.95 Incl. 20% VAT

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Horstmann 425 Tiara Programmer is rated 4.3 out of 5 by 44.
Rated 5 out of 5 by from Great Great product , easy to install and easy for customers to understand
Date published: 2019-04-17
Rated 5 out of 5 by from Brilliant Easy Replacement Couldnt believe they still make this control unit. My old one after 30 years, yes 30 years , started to misbehave with wear on one of the switch off noddules. Found that its still made, and was an easy change over for the front panel, wiring didnt need to be touched.
Date published: 2019-04-12
Rated 4 out of 5 by from horstmann 425 tiara programmer dead easy to fit, straight swap for existing programmer.(check on web site first for suitability) very little to go wrong should last long time and not hard to set ,very simple to use.
Date published: 2019-02-27
Rated 5 out of 5 by from Good Product A perfect programmer for those people who find modern digital clocks too difficult to program or adjust. Easy to install with good, clear instructions.
Date published: 2019-01-26
Rated 5 out of 5 by from Horstman timer Good quality. The last one lasted for over 9 years.
Date published: 2018-02-08
Rated 4 out of 5 by from Horstmann Tiara 25 The Horstmann Tiara 25 timer packed up after many years of trouble free service so I needed a quick replacement, so power off, undo two screws and pulled off timer front then replaced with new one, two screws tightened, power on and we were back to trouble free heating and hot water. Screwfix click and collect proved excellent and they offered the cheapest price therefore they come well recommended
Date published: 2015-04-11
Rated 4 out of 5 by from Horstmann 425 Generally a very simple to use CH programmer. Don't make the mistake of model types if you want the neon 'on' 'off' indicators which are not on this model. The step forward is a very useful function although the step numbers are difficult to see if you are installing for someone who may not have good vision.
Date published: 2015-01-17
Rated 4 out of 5 by from Ok programmer A basic non digital programmer for people that don't like setting digital over complicated timers.will suit the old that have basic boiler/ pump central heating systems.
Date published: 2014-12-14
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