OSO Spare Parts
Electrical Deals Direct supplies genuine and compatible OSO Hotwater spares and replacement parts for their stainless steel unvented hot water cylinders. Order online with trade pricing, fast dispatch and expert phone support from a team who know unvented hot water systems inside out.
About OSO Parts
OSO Hotwater is a Norwegian manufacturer, founded in 1932, and is the world's largest maker of stainless steel unvented hot water cylinders. OSO products first reached the UK market in 1989 as the first widely available stainless steel unvented cylinders, and OSO Hotwater UK was formed in 1994, growing into one of the leading suppliers in the UK unvented cylinder industry. Ranges such as Super S, Delta and Multipoint are found across domestic, commercial and marine hot water installations. Because these cylinders run at mains pressure and fall under Building Regulations Part G3, their safety and control components — thermostats, relief valves, expansion valves and tundishes — need to be kept in good order and replaced with the correct part when they fail.
Looking for the cylinder itself? Browse the OSO Hotwater range, or find related valves and cylinder spares in our Heatrae Sadia Parts and Reliance Parts sections.
Common OSO Parts We Stock
- Thermostats & fitting tools — rod thermostats (including high-temperature versions for Super S iQ and Delta immersion heaters), surface-mounted and case-mounted boiler thermostats, and box key spanners for fitting immersion heaters
- Pressure & temperature relief valves — T&P relief valves, expansion valves, and valve service kits covering the PRV mechanism, strainer and mix mechanism
- Expansion vessels — potable expansion vessels with wall brackets in a range of sizes for Multipoint cylinders
- Tundishes & accessory kits — angled tundishes and direct/indirect accessory kits with flexi hose, tundish and elbows
- Hoses & flexible connectors — braided hoses for expansion vessels and Y-type corrugated flex tubes
- Fittings & adaptors — non-compression adaptors, drain cocks and sensor pockets
- Casing & electrical parts — top lids and cable strain reliefs for the electrical box
How to Find the Right OSO Part
OSO parts are matched to the cylinder range and model, so start by identifying whether your unit is a Super S, Delta, Multipoint or other range, then cross-check the part number on the component you're replacing. It matters whether a thermostat or accessory kit is for a direct or indirect cylinder, and safety components such as relief and expansion valves must be the correct pressure and temperature rating for your unit. We stock both genuine and compatible options on many parts, so you can choose on price and preference. If you're unsure which part you need, use our Can't Identify Your Spare Part? service, or send our trade counter team the model number or a photo of the old component and we'll match it for you.
Why Buy OSO Parts from Electrical Deals Direct
- Trade pricing on all OSO parts, with account pricing available for regular buyers
- Same-day dispatch on in-stock parts ordered before cut-off
- Genuine OSO parts, plus compatible options on selected items where they offer better value
- Expert phone support to match the right thermostat, valve or kit to your specific cylinder
- Deep unvented cylinder and G3 knowledge on hand, not just a parts list
Related Categories
Browse the full OSO Hotwater range, our Heatrae Sadia Parts, Reliance Parts, or all spares and accessories. Not sure what you need? Try our Product Advisor or browse the Advice Centre.
OSO Parts — Frequently Asked Questions
What's the difference between Super S, Delta and Multipoint parts?
These are different OSO cylinder ranges, and their thermostats, valves and accessory kits are not always interchangeable. Check your cylinder's rating plate for the exact model before ordering, or send us the details and we'll match the correct part.
Are these genuine or compatible OSO parts?
We stock a mix of both — genuine OSO components alongside compatible alternatives on selected items, so you can filter by part origin and choose based on price and preference.
Can I replace a relief or expansion valve myself?
Unvented cylinders are covered by Building Regulations Part G3, and their safety components — pressure and temperature relief valves, expansion valves and the discharge arrangement — must be the correct specification for your unit. Fit like-for-like and use a G3-qualified installer where required.
Which thermostat does my OSO cylinder use?
This depends on the cylinder range and whether it's direct or indirect — for example, Super S iQ and Delta immersion heaters use specific high-temperature rod thermostats. Match the part number on your existing thermostat, or send us the model and we'll confirm.
Do you stock spares for older OSO cylinders?
Yes — alongside current ranges we stock parts for older models such as the Delta MK1. Send our trade counter the model number or a photo of the data plate or failed component and we'll do our best to match it.
Not sure exactly which part you need? Use our parts finder to search by model. If you'd rather talk it through, call our team on 01934 253600 or use live chat and we'll help you get the right OSO spare first time.
From Splash Backs to Drip Plates to Air Filters, if it's not in the list, don't hesitate to call us on 01934 253600, or send an email over to [email protected]. We are confident that we can source your replacement part or accessory.
