Non concussive taps

[The Medway Handyman]

Anyone know much about these?

Place I work at has 6 'pairs' if these, installed in a new toilet block less than 2 months ago (not by me) and already 4 of the hot taps have failed by staying on - defeating the purpose of installing them.

Long story, but they can't be sent back to the supplier under warranty.

I've had one apart, no obvious scale, nothing seems wrong, tried lubricating them, no real difference.

Cheapest replacements I can find are from Toolstation @ £13 a tap, so £150+ to replace them all.

Would it be temperature or pressure related?

[Dave Liquorice]

You mean the taps that you push on and then they run for a certain amount of time then turn off automagically?

Only hot? Seems a bit odd can you find any specification for them? Though if they come with red and blue inserts I'd be surprised if the hot water was a problem, at least at hand tolerable temperatures...

I suspect they work in a similar manner to an equilibrium (torbeck type) cistern valve. As they are failing on I suspect the small (read tiny) passage way from the supply side to the other side of the diaphragm is blocked thus the pressure doesn't build up to flip it into it's other stable state and turn off the water flow. I'd also expect there to be an adjustment but if my experience of the pneumatic light switches is anything to go by a tiny fraction of a turn makes a massive difference to the delay.

[Owain]

Dunno.

But a thermostatic mixing valve under the sink would allow all sinks to use one "warm" tap, halving the number of replacements. Also would allow the hot water to be hot enough to prevent legionella but the warm would not be hot enough to be dangerous.

Can't find any infrared sensor taps for much less than =A360, but might be worth it if mechanical ones are dying 6x a year.

Owain

[The Medway Handyman]

Yup.

Others I bought come as single with red or blue inserts, so I suspect the tap is the same for both.

Didn't spot a diaphragm when I stripped one. Seems to be done by a spring.

Know what you mean. Can't find any obvious adjustment either.

[The Medway Handyman]

Good idea that. Food for thought.

Need to shut off reliably. Venue is a 'John Smiths £1.20 a pint, Fosters £1.50 a pint' place - they attract a high class clientel :-)

Favourite tricks in the old toilets were (a) leave hot taps on to waste hot water & (b) block plug hole with tissue, leave taps on to flood floor.

[ARWadsworth]

Can you remember what I found hidden under the toilet cistern lid in such an establishment?

[John]

They must be the most unreliable bit of engineering ever made. The makers should be ashamed of them. I used to think that they had been poorly set up by the installer.

[Matty F]

We had two of those. There was a tiny airbleed hole and a spring. They almost never worked properly and required constant adjustment. They were also very expensive. Someone stole them together with all the copper they could find. We don't have outside taps any more.

At another site, all taps have been replaced with taps with a sensor. They work well until there is a power cut. Then as well as being in the dark, you can't wash your hands.

[Owain]

3 sinks in the ladies and 3 in the gents?

One sink in the gents should be enough then ;-(

With a TMV they'd be wasting 50% hot and 50% cold water. Also only one tap per basin restricts the maximum flow per basin. With a spray/ aerator tap really very little water should be needed.

=A31.20 a pint though ...

Owain

[John MacLeod]

You don't say what make they are. I've dozens of them on a caravan site -- all Prestex. I suspect you may be dealing with a cheaper type. The Prestex ones are good, but didn't come out from the factory well set up. The head on some batches was under such torque that it took major effort with the tap body held in a large vice to get the head out of the body. More to the point, there was a problem with the piston in the base of the head eventually binding on the walls of the cylinder. Solved by cleaning, rubbing down with metal polish, cleaning again and lubricating with wax. They haven't given trouble for years and years since. There are two washers in that design and both are rather difficult to obtain. They need protection from frost, but otherwise they're fine.

How about describing make and obvious parts? Do they have a cylinder and piston? If so, does the piston move smoothly and easily in the cylinder?

[The Medway Handyman]

Long SS 'troughs', 4 pairs of taps in the ladies, 2 pairs in the gents.

Again food for thought. Cheers.

But its John Smiths. I'd rather drink meths.

[The Medway Handyman]

Alas no idea what make. I suspect you are right.

Little chance of finding the make due to a supply chain problem. On dismantling they seem fine. I'll try & take some pickys of one in bits.

[OG]

A place where I worked did a major refurbishment of the staff loos and installed sensor taps. Stupidly, they set them up so that taps ran for a fixed length of time; which was too long for a quick splash of wet, and too short for a proper scub with soap and a full rinse. Result is either lots of wasted water when only a splash was needed; or having to run the taps twice with even more waste of water when rinsing off the last of the soap.

I've no idea why they didn't go for a proximity sensor that only ran when it was needed

[dennis]

If they sell it for 99p a pint like they do in the cafe/pub/polish meeting place on the high street west brom you get too many fights and less profit.

[Chris J Dixon]

You need to make sure it has a maximum "on" time. Miscreants have discovered that, in some cases, if you cling film the sink, the movement of water on film can be sufficient to trigger the tap.

Chris