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Changing the SMR Mini Valve

Mini Valve 3794R (Replacing Earlier 3308R)

Note: This change in valve specification has been introduced by your tap manufacturer.

This post on changing the SMR Mini Valve is organised into four sections

1: Outlines the key design and functional changes to the Mini Valve throughout its production history, along with the tools required for safe removal and replacement

2: Before replacing the valve in your tap, make sure the problem has been accurately diagnosed to confirm that the valve is the root cause.

3: Instructions for removing and replacing the valve, with a reminder of the tools required for the job.

4: Useful Guides and Links

Section 1: The key difference between the earlier 3308R and the later 3794R 

3308R Valve (aka SP3308)

• Has white (or black) seals which is a little thicker than later 3794R.
• It is stamped ‘San Marco’ plus date.
• Flat sided nut which can make it harder to remove. You can try a mechanics long socket and ratchet tool to remove the Valve from this Tap, or a 12mm spanner, or buy a special tool from us.  Be careful not to force any tool on this valve and thereby damage it so much that you cannot then remove it with the correct fitting tool.
  

  San Marco SMR Mini Valve 3308R , showing flat sides on nut

• We supply a tool 4013R for this purpose which you can order here.
  

  Valve Removal Tool 4013R

3794R Valve (aka SP3794)

SMR Mini Valve 3794R Pair, 6 Sided Nut

• Has red / blue seals
• It is stamped SMR plus date.
• 6-sided nut so can be extracted using a size 14 hex key or an adjustable spanner.

For both of these mini valves :

• These valves are slightly smaller than standard ceramic disc valves, making them more susceptible to issues caused by debris in the water supply. We generally do not recommend this type of valve for use in hard water areas—unless a reliable limescale treatment system is in place. Even then, the effectiveness can vary depending on the type of treatment used, and debris can still accumulate within the ceramic discs, potentially leading to valve failure.
• Both valves are interchangeable in your Tap i.e you can replace the 3308R with a 3794R and vice versa. However, for older Taps we would recommend you continue with the 3308R.
• A Hot Valve opens Clockwise.  A Cold Valve opens Anti-Clockwise.
• If you do not know which Valve is at fault this blog here should assist you: How to tell which Valve needs replacing – Hot or Cold?
• No Brass Bush is usually required with the mini SMR Valve. 
• Both Valves are quarter turn with ceramic discs, also known as Glands. They will have SMR or San Marco stamped on them.
• Measurements: Height 38mm, Diameter at thread: 20mm, Splines: 28

Section 2:  If you are replacing your Mini Tap Valve, then this is because:

Your Tap is dripping from either the end of the Spout (Aerator end) or from the Handle.  If water is dripping from the base of the spout, it’s not a valve issue—it’s likely due to worn spout O-rings or a fault with the spout itself.  Please contact us if you need help identifying these parts.  Here is our general Post on ‘My Kitchen Tap is dripping‘ for further explanations on the main reasons why a Kitchen Tap Drips and how to fix.

Section 3:  How to remove your Tap Handle & replace the Valve ?

Knowing which version of the valve is in your tap before attempting removal is important, especially when ordering replacement parts. If you have the earlier 3308R valve, you’ll need the 4013R Removal Tool to take it out. Ordering this tool at the same time as the valve helps save on shipping costs.

If your tap uses the later 3794R valve, which has a six-sided nut, no special tool is required. You can remove it using a 14mm hex key, available at most DIY stores—or even better, borrow one if you can.

• Remember to turn off the water supply before attempting any repairs and consult a professional if you are unsure.
• We recommend placing a cloth or towel underneath to catch the screw as they are tiny and you don’t want to lose it.  But if you lose it you can buy the grub screw here.
• You usually need a 2mm allen key (screw is located underneath the handle) But there are a few models that uses a 2.5mm handle grub screw.  Please don’t attempt to try to guess the size of your Allen Key because if you damage a grub screw you might not be able to remove it.  Click here to buy the pack 2mm allen key for Handle and 2.5mm allen key for Spout.
• Turn the screw anticlockwise to loosen it.  There is a usually small white handle insert (separate part) that covers the top of the valve.  If your own needs replacing you can purchase that part SP3530 here.
• You can buy handles from us but we would need details e.g pictures of your own Tap to identify which Handle you require.   All our Handles come complete with Grub screw.  Here are the Handles we currently stock.  If you can’t find your own Handle there, just contact us for assistance.
• Here is our video showing how to remove a Handle that is fitted with a grub screw.
• You screw out a valve ‘anti-clockwise’.   As you loosen the valve some water may start to seep out. Don’t panic. It’s just some water left in the Tap chamber.  When the valve has been removed clean this chamber.
• Screw in the new valve, turning clockwise.
• Then repeat the above steps in reverse.
• Tightening your new valve: Don’t over-tighten this valve.  As a rule of thumb, tighten as far as possible by hand, and then tighten 1/4 turn with an adjustable spanner.
• Finishing with tightening back the grub screw of the Handle.
• Turn back on your water.

Whichever Valve is in your own tap, you will receive the SP3794 if you order here.  If you want the earlier version with the flat sides on the nut, you can click here to order it.

Still need help?

If still in doubt, please contact us before buying because so we can advise you on the correct part.  You can email pictures to us sales@tapsandsinksonline.co.uk or use the Contact us Page.

Section 4: Useful Guides and Links

Here are all the Tap Brands we do Genuine Spares for.

• Valve:  Dripping from the spout? How to change your tap valve
• O-Rings:  Leaking where the spout meets the base? O-ring replacement guide
• Aerator:  Water splashing or uneven flow? How to remove your aerator
• Spout:  Need to replace the spout? Spout removal guide

Our general Help Section is here

See our Trouble Shooting Guide here for the most common problems.

After Sales Advice

Our Sales Team offers excellent after-sales support. Contact us before buying, and we’ll help you choose the correct part—so you / your plumber has everything needed to fix your tap.