Re: ballcocks and water tanks

And make sure the overflow will cope with the additional flow.

It will also reduce pressure to other fittings if there is any restriction on incoming flow.

The one I was pulling apart the other day - and I think every one I've ever seen - has a nozzle of maybe 4mm squirting water against a rubber diaphragm a few mm away. It will be the limiting factor, not the pipe.

That's why they supply 2 nozzles - a fatter one for low pressure (from tank) supplies.

Andy

Thanks for the replies; the majority seem to think there will be some improvement. The tank does not run dry but the pipes whistle for hours when the tank fills up, so I like it to fill and go silent sooner. I think it's worth a try.The tip about the overflow is a good one.

Thanks again.

Yes, but why would you want to?

Cold water tanks are there as a reserve supply of water, so you don't really care how long they take to re-fill. Toilet cisterns are there for immediate use, so you do care. If it's a cistern, then fit a different _type_ of valve (Torbeck etc.) that fills with the full flow rate all the way, then shuts quickly, rather than the traditional old Croydon float valves that closed gradually.

Maybe. But *both* valves would have to fail open before you needed the extra overflow capacity - which ain't all that likely.

I've seen enough cases where duplicated equpment has failed simultaniously to consider catering for it where failure would be severely detremental, as in the case of a flood in the loft.

Perhaps our posts crossed?

"the pipes whistle for hours when the tank fills up, so I'd like it to fill faster and go silent sooner." (edited to read better than before!)

Re. the overflows: would you need one 21mm pipes for each ball c*ck or could one manage? I thought that both failing together would be unlikely but for the cost of a pipe against the cost of a new roof, it doesn't seem worth taking the risk.

The only problem would be crawling to poke another pipe through the eaves. Could I be naughty and tee a second overflow into the CH overflow pipe. What's the likelihood of all three valves (2 in water, one in CH) failing together?

OTOH, I think I've talked myself out of that: I suppose there's a very slim possibility of contamination working from the CH header tank up the overflow to the HW tank, so I guess it's against regs and I shan't do it.

I did start a new thread but no-one seems to have noticed ;(

I was going to add a second ball c*ck and see what difference it made but I am confused about type 1 and type 2 valves. I have searched google but the sites seem to contradict each other. What are type 1 and type 2 and which is used where?

Thanks.

Could also try using fluidmaster type float valves. They only ever open at full flow rate and then maintain full flow until full, whereas a typical ball valve will turn on and off gradually according to the position of the ball. With a normal ballcock valve the tank could be half empty before the water supply is at full flow to refill it.

Perhaps working pressure? A header tank would normally come from the mains but older toilets using this sort of valve might be fed from that tank so low pressure.

FWIW, they're normally called float valves these days.

Can you get these for water tanks? I've only ever seen them for toilet cisterns.

Thanks.

Is that for reasons of political correctness? ;)

I see no reason why a side-entry valve intended for a cistern wouldn't work on a water tank - provided the overflow pipe isn't a lot lower than the entry pipe. If it is, the tank will overflow before the water level reaches the float!

I think the torbeck ones work the same way (as in full on/full off only)

Thank you. These always seem to be advertised for toilets so I thought they were only for toilets and that there was a reason they could not be used on water tanks, perhaps regulatory rather than technical. However I guess it's just that they sell more to people for toilets and that is why they are marketed as such. I see the SF description of one of the links given in the other reply does say for both toilets and tanks. Thanks.