Contact Anthony
Anthony
Horstmann 423 Diamond Mechanical Timer ~ Ultra Rare
Kippax, West Yorkshire
£50
1 of 6
- Posted
- 16 hours ago
Description
Horstmann 423 Diamond – Rare, Obsolete Central Heating Programmer – Excellent Condition
Condition: Used – Fully tested
Step into reliable, old-school engineering with the Horstmann 423 Diamond.
This highly sought-after central heating programmer is long discontinued, making it a rare find for anyone replacing an existing unit without rewiring or changing backplates.
Perfect for those who want to keep a proven system running smoothly, this unit has been tested prior to listing and is ready to install.
---
Features
Compatible with existing 423 Emerald/Diamond backplates – easy swap.
Simple mechanical controls – no confusing menus.
Built to last with solid construction.
Ideal replacement for ageing or faulty 423 models.
---
Condition Details
Fully working, tested with live wiring before removal.
Clean faceplate with minimal wear.
All switches, dials, and indicators function correctly.
No cracks, chips, or missing parts.
---
Why Buy This Model?
The 423 Diamond has a reputation for robust reliability. Many owners keep these running for decades, making them the heating control equivalent of a classic car – timeless, dependable, and easy to service.
---
Included
Horstmann 423 Diamond main unit
Original backplate (if applicable)
Fixing screws
Ad ID: 1502045298
Stay Safe
"Be wary of buyers asking to use 'Gumtree delivery' or 'Payments on Gumtree' because Gumtree doesn't offer these services currently. Requests from Whatsapp or SMS could be scams"
"Only access Gumtree from gumtree.com and do not follow links sent by other users"
"Share photos and ask lots of questions about the items you are buying and selling"
"If an ad or reply sounds too good to be true, it probably is"
"Use the 'Reply to ad' button for your safety and privacy"
"Don't reply to email addresses hidden in text and pictures"
"Trade in person, use PayPal 'paying for an item or service' to transfer money"
"Beware of fake Gumtree, eBay or escrow sites and invoices"
1 of 8