Standard Bath Tap hole sizes?

[jwoodwar]

Is there a standard diameter for bath tap holes in the UK?

I've recently bought a steel bath, specified with holes to be drilled for 3/4" taps. The diameter of these holes is 32mm, but the taps that I've bought (Twyford Rival side valves) are too big.

I've contacted other tap manufacturers, who also need a bigger hole.

Various on line sites refer to standard tap holes, and although the between centres dimension is 180mm, I haven't been able to find a dimension for the diameter.

Thanks

 

[chrishutt]

The 3/4" thread that all bath taps have has an outside diameter of 26mm, which should fit easily into 32mm hole. What is the problem? Are the tap tails not 3/4"?

 

[jwoodwar]

Chris,

The tails are 3/4"/26mm as you suggest.

The body of the valve is externally threaded, O/d 32mm, and fits up through the hole - snug fit, but it's ok.

The problem is that there is then an internally threaded collar which screws down from the top, onto the surface of the bath, to hold the valve in place. This collar has an internal shoulder, which has an o/d of 35mm, and a length of about 5mm. Since the shoulder won't go through the hole, the sealing surface on the bottom of the collar doesn't meet the bath.

I've seen another post about opening up holes in a steel/enamel bath with a file, but would rather have a go at getting the supplier to sort it out first if I can show that they haven't drilled standard sized holes.

Thanks for your reply

 

[chrishutt]

Are these taps intended for fitting in this manner? Can you post a link for them? They sound like they might be intended for fixing to a vertical panel or such like.

 

[jwoodwar]

Chris

I believe these are definitely intended to be deck mounted on the side of the bath.

http://www.twyfordbathrooms.com/twy_commercial/brassware/Rival.htm

The model is RL5355CP

If you look very carefullly at the line drawing, there's the hint of the shoulder on the underneath of the collar. The tail is given as 3/4" but no indication anywhere of the hole diameter required.

(As an aside, we're using the valves to feed a combined filler/waste/overflow, rather than the spout supplied, but interestingly the spout will fit through one of the 2 tap holes and install exactly as intended )

 

[chrishutt]

I see what you mean. I think you have good grounds for complaining to Twyfords that they don't advise that a larger than standard tap hole is required. Ring their tech. line and see what they have to say. I guess these taps weren't cheap, so you're entitled to expect better.

 

[ChrisR]

I've fitted this sort of handle arrangement a few times. Some have been to sets of 3 holes where everything fitted, on basins (like item 5326) and others to undrilled baths where you obviously cut what's needed.
I would infer that they aren't supposed to fit standard twin bath tap holes.

It would be tricky to drill larger holes because there's nowhere to drill a pilot hole fror the centre drill. If you clamp a piece of wood under the rim you'll have somewhere to drill a centre.

 

[Agile]

I have never drilled a pressed steel bath as I specialise in boilers.

However, with the hard vitreous like enamel I would not view it as an easy job.

These kind of problems for an apparently straightforward job is one of the reasons I keep away from showers and baths!

Tony

 

[Nige F]

we're using the valves to feed a combined filler/waste/overflow,Whose make ...I would guess that you will get your money back @ best...The debate will be as to who should have informed who as to the suitability of a 3hole tapset and a 2 hole bath

 

[jwoodwar]

Thanks for all your input

I guess the issue is knowing that 3 hole taps and 2 hole taps are different standard sizes ! Who knew? Different manufacturers have all started out saying 'standard' but when pressed, given 25mm, 32, 33 and 34 as the actual 'standard' diameter. Some standard.

Twyford technical helpline advise me that these valves need a 38mm hole. As I told them, it would be helpful to give that information on the data sheet.

Any tips for filing holes bigger on enamel baths anyone?

 

[Nige F]

Only thing I can think of would be a Die grinder, which is a bigger version of a dremmel...or even the drem. if you have one...and several clyindrical stones (carborundum)....The problem would be with the enamel possibly chipping off beyond the hole and being seen ....An acrylic bath supplied w/out tapholes would be easier to drill... the bath is new, could it be returned?...even part refund restocking charge. Hope this may help a bit.

 

[chrishutt]

Any tips for filing holes bigger on enamel baths anyone?

I think ChrisR gave you the best tip above. Clamp wood below to provide something for pilot drill to engage and use hole saw.