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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
  • View more information

Switching/contact rating: 6A. H x W x D: 112 x 153 x 33mm. Backplate fit: 9-way (included). Not suitable for underfloor heating.

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Horstmann 425 Tiara Programmer Instruction Manual


4.25 5 20

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Horstmann 425 Tiara Programmer 4.3 5 20 20
basic timer I bought and fitted this timer for my mother ,who is 75 years old.i know if I bought an all singing all dancing timer I would be round at her house every day showing her how to use it and what each button did.she doesn't need a 5/2 day timer or one that knows when you're on holiday.its simple it does the job 19 Dec 2014
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. 14 Dec 2014
Compatable replacement. I'm an electrical contractor. I was called to a house that had a Horstmann Diamond programmer built in the 60's which was now sometimes sticking. I Spoke to Horstmann technical who suggested Horstmann 425 Tiara Programmer. What an excellent choice, a breeze to install and all working o.k.. If this one lasts as long as the old Horstmann Diamond, the customer will be well happy. This item was cheaper from Screwfix than any of my electrical wholesalers. Well done Screwfix. 23 Jul 2014
Horstmann Tiara 425 I was initially quite impressed by this programmer: it seemed to work satisfactorily, and appeared to be good value for money. However, after approx 18 months of operation, I experienced erratic operation of my heating system: domestic hot water (DHW) worked OK, but central heating often failed to start. (My heating system uses a motorised 3 port valve, and both DHW and CH are pumped.) After much investigation, I found that the fault was caused by intermittent closure of the DHW switch, when in the "off" position. I have dismantled the mechanism, and the fault is caused by poorly toleranced plastic in the switch leverage system. I would NOT recommend this product. 5 Nov 2013
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Brand Horstmann
Model No 425 Tiara
Pack Size 1
Product Depth 33 mm
Product Height 112 mm
Product Width 153 mm
Total Product Weight 0.43 kg