New pop-up drain control limiting overflow capacity?

[Underwater]

We've just had some new bath taps fitted and, as a nice little surprise for me, Mrs Underwater had the
plumber install (in my absence) a pop-up drain plug, operated by a shiny rotating control mounted in the overflow hole.

Although it looks nice and neat, I'm concerned that there is very little room around the control for the overflow to actually drain excess water.

I tried turning on both taps full on, and the level seemed to reach equilibrium at about 5mm below the point where the bath would actually overflow into the room - not a comfortable margin.

The taps are gravity-fed from loft tank, so pressure should (in theory) be constant, and flow rate shouldn't vary (at least not upwards) over time, but what do forum members think about this arrangement? I'm concerned that any minor accumulation of debris in the overflow will erode this safety margin to the point where the bath could actually overflow.

As an additional concern, the new taps have a lower flow rate than the old ones, meaning that people are now more likely to walk away whilst the bath is filling.

Does anyone have any experience of this type of control causing the oveflow to fail to work when needed?

Thanks

Underwater

 

[Riley]

If the fitting worries you then get your plumber back to change it but expect to pay again. I've fitted loads of these and they have never been an issue.

 

[Alex Knight]

Fitted loads and never heard of any problems also.

 

[lame plumber]

bit of common-sense here, don't fill your bath on full flow from both taps and walk away to have tea..

 

[Underwater]

Yes - very helpful.

If only I could guarantee that everyone else would follow this rule, then I wouldn't need an overflow at all. Why does anyone bother with them, when they can just adopt your simple rule? Do you have an overflow on your bath? If so, why bother?

 

[Riley]

That's not really the attitude to get yourself more help is it. With many things like this common sense takes a massive stance. You have had a number of people say on here that they have fitted them with no problem I think you may be overthinking it

 

[Stigster]

In reality you'd be lucky to find an overflow (in your case you've actually managed it as you say you have tested it and it didn't overflow) that can take the full flow rate of both taps away quickly enough to prevent overspill. You've likely got around 2 metres of head (or more) to the taps, probably in 22mm tube, which is going to produce a flow rate of more than the 22mm sized single pipe can take away under the best possible conditions.

Simply put, it is unfortunately normal that a bath (or sink/basin) overflow will not cope with both taps on full tilt. You can go and try this at your basins and sinks and will likely find that you can overflow those with the taps wide open too.

There are products on the market that can allow your plugged waste to open up if the bath is overfilled though. Here's just one Magiplug

Maybe something like this could alleviate any worry without altering any systems? What do the folks on the forums think about this?


Edit to add - The Magiplug will not work with the pop-up waste mechanism, unfortunately. If you want to use a device like this you'll need a standard waste fitted instead.

 

[joni os]

Too much concentration on flow rate from taps. My bath overflows when missus gets in it.

 

[Stigster]

On doing a bit of research this afternoon on the subject of bath "overflows" I found this very interesting article, albeit from a US site, which I think explains the bath overflow situation and how they don't actually exist!

Here is an excerpt from the article -

Home buyers and new homeowners believe that bathtub overflows will prevent their bathtubs from overflowing due to an unattended filling operation.

This belief is also held by many building inspectors and building code officials.

This belief is a myth.

Here is how bathtub overflows came to be:

100 years ago manufacturing molds for cast iron bathtubs had a hole for mounting a tub spout inside the tub. In other words, the original purpose for the hole was as a mounting point for the tub filler spout. It was later learned that water from the tub could back siphon through the spout into the water supply. Plumbing codes made this installation illegal. With the tub spout moved up on the wall, manufacturers were left with a hole that had no purpose. The molds for the tubs were so expensive that the manufacturers could not afford to change the mold to remove the hole. Their first idea was a solid plate mounted in the hole with a chain attached to the plate and a rubber drain stopper at the other end. Second idea: A trip lever to move the tub stopper up and down. The lever is attached to a rod which went down the backside of the tub and then under the tub to the drain where it attaches to the stopper. This assembly required a housing to enclose the trip lever rod. Once this housing was in place some trip lever plate manufacturers cut a slot in the plate. The slot allowed a very small amount of water to flow down the housing when the water level in the tub reached it. People later dubbed this assembly an overflow even though it would not prevent a tub from overflowing due to an unattended filling operation. There was no intention at the time for this to be a real overflow and no code work (standards creation, engineering calculations, testing protocol, or listing) was ever done to make this setup a real overflow. Nothing has changed from then to now - we are still installing trip lever housings - not overflows.


Are bathtub overflow drains required

 

[clarky101]

I was worried about the exact same thing & came up with the solution.....ripped out the bath & put a shower tray in.....job done...

 

[lame plumber]

Yes - very helpful.

If only I could guarantee that everyone else would follow this rule, then I wouldn't need an overflow at all. Why does anyone bother with them, when they can just adopt your simple rule? Do you have an overflow on your bath? If so, why bother?

no overflow can cope with both taps on full flow anyhow, so as before dont walk away from baths and basins with taps on, train your friends and family, why bother posting on here if your going to be a rude blighter

 

[Allgoode]

For the poster with the query.

Unfortunately too many people have lost this gift of common sense and if there IPhone/smart phone does not tell them something then it goes above there heads & does not register with them.

Common sense tells you not to leave a filling bath unattended to prevent overflow or similar events.

Come on, Its not rocket science................

Thanks,

Andy

 

[Radioman]

I was always taught to regulate the flows so the overflow could cope. Sometimes this means the bath would take too long to fill so custard would ask for full flow back. I have fitted auto switches that stop the supply at a certain depth and sound an alarm. We used to do this for folks with little or no vision. Aqualisa do a system that you can program to fill the bath to a set depth and temperature. Another solution would be to cut a second overflow into the bath with a separate outlet.