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Float valves for roof tank - on/off

Does what it says on the tin
Hardgrafter
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Float valves for roof tank - on/off

#409028

Postby Hardgrafter » May 3rd, 2021, 4:55 pm

I need a 1/2" float (ball) valve for my 4' x 2' roof tank that operates as either fully closed or full bore. I don't want any dribble flows etc. The tank feeds 2 bath /showers and 3 wc.

Reason? I have a new water softener that requires a minimum 10 l/minute flow rate. If the flow rate is less than that the water channels (i.e. bypasses) through the resin, and doesn't soften much. The existing traditional ball valve dribbles in water when the tank is nearly full. So when a toilet is flushed (9 litres) the water level only marginally falls ( about 1/2"), only slowly refills.

Float valves I have seen in Screwfix and Wickes don't have any information on this matter.

Suggestions for a better valve please (and web link).

jfgw
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Re: Float valves for roof tank - on/off

#409088

Postby jfgw » May 3rd, 2021, 8:04 pm

A "part 4" valve should do the job. These are servo valves - the float arm opens and closes a tiny hole which causes water pressure to open and close the main valve. I would go for one with a brass shank.

https://www.screwfix.com/p/fluidmaster- ... alve/49088

You may find that the pipes bang when it closes if the pipes are not clipped securely.


Julian F. G. W.

88V8
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Re: Float valves for roof tank - on/off

#409128

Postby 88V8 » May 3rd, 2021, 10:50 pm

Hardgrafter wrote:I have a new water softener that requires a minimum 10 l/minute flow rate.

As a matter of curiosity, why? I mean, what made you choose that softener?
In our previous house, for 28 years, we had a Kinetico... the salt dosing controlled by a water turbine... worked at all flows.
https://www.kinetico.co.uk/products/water-softeners/premier#moreinformation
It was a lot of money, but 28 years is a long time.

V8

jackdaww
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Re: Float valves for roof tank - on/off

#409165

Postby jackdaww » May 4th, 2021, 8:06 am

i installed Fluidmaster 747 side entry valves about 7 years ago.

no issues so far .

:)

scrumpyjack
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Re: Float valves for roof tank - on/off

#409188

Postby scrumpyjack » May 4th, 2021, 9:18 am

A bit off topic but in order to get good pressure in our water system, so no shower pumps are needed for example, we many many years ago installed a pressurised water system. This has been brilliant, does away with the need for tanks in the roof and gives excellent pressure on all the taps all the time. Our mains pressure was not good as we are 150 yds from the road.

DrFfybes
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Re: Float valves for roof tank - on/off

#409192

Postby DrFfybes » May 4th, 2021, 9:30 am

scrumpyjack wrote:A bit off topic but in order to get good pressure in our water system, so no shower pumps are needed for example, we many many years ago installed a pressurised water system. This has been brilliant, does away with the need for tanks in the roof and gives excellent pressure on all the taps all the time. Our mains pressure was not good as we are 150 yds from the road.


Is this one where you have a pressurised cold water tank in (say) the garage, with its own pump and expansion vessel? Has it been good and reliable, and what sort of pressure does it provide.

We are looking at such a thing as whilst static pressure is 1.5 Bar, our incoming main only supplies 11l/min on the garage tap (the first on the run after the meter, which is on the boundary about 30m from the building. Flow drops to 9l/min once it reaches the kitchen sink. Flow isn't helped by the entire house being plumbed in 15mm from the stop cock in the kitchen, which immediately goes to a cartridge filter designed for supplying a cold tap only.

With this and header tanks we end up with pumps for shoewrs (and the sink in the garage for some reason, probably as it was easier to tap it off one of the shower feeds), and would like to do away with it all when we replace the heating system and HWC later this year. The Heating guy suggested one, but at thick end of £3k we wondered if it was worthwhile.

Thanks

Paul

88V8
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Re: Float valves for roof tank - on/off

#409198

Postby 88V8 » May 4th, 2021, 10:35 am

Pressurised... can be OK, but it can also make the system very noisy :( so that every time a tap is opened there's a swooshing din that resounds throughout the house.
Especially if the pipes are small.

All three of our houses have had static systems, but we've been in some old hotels where the pressurised systems certainly alert you to your neighbours' bathroom habits....

We have lower pressure since recent 'improvements' by the water co, mainly a problem for garden watering, jolly annoying.

V8

scrumpyjack
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Re: Float valves for roof tank - on/off

#409199

Postby scrumpyjack » May 4th, 2021, 10:35 am

DrFfybes wrote:
scrumpyjack wrote:A bit off topic but in order to get good pressure in our water system, so no shower pumps are needed for example, we many many years ago installed a pressurised water system. This has been brilliant, does away with the need for tanks in the roof and gives excellent pressure on all the taps all the time. Our mains pressure was not good as we are 150 yds from the road.


Is this one where you have a pressurised cold water tank in (say) the garage, with its own pump and expansion vessel? Has it been good and reliable, and what sort of pressure does it provide.

We are looking at such a thing as whilst static pressure is 1.5 Bar, our incoming main only supplies 11l/min on the garage tap (the first on the run after the meter, which is on the boundary about 30m from the building. Flow drops to 9l/min once it reaches the kitchen sink. Flow isn't helped by the entire house being plumbed in 15mm from the stop cock in the kitchen, which immediately goes to a cartridge filter designed for supplying a cold tap only.

With this and header tanks we end up with pumps for shoewrs (and the sink in the garage for some reason, probably as it was easier to tap it off one of the shower feeds), and would like to do away with it all when we replace the heating system and HWC later this year. The Heating guy suggested one, but at thick end of £3k we wondered if it was worthwhile.

Thanks

Paul


Yes cold pressurized tank in garage and expansion vessel, and also hot water tank and expansion vessel for the CH system. The pressure is brilliant. Effectively provides full mains pressure whatever volume you take. Showers, taps etc all provide excellent flow rate throughout the house. The plumber removed all the shower pumps assuring us they would not be needed and he was right.

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Re: Float valves for roof tank - on/off

#409244

Postby Hardgrafter » May 4th, 2021, 1:40 pm

To 88v8,

My previous water softener (35 years) like yours was indeed a mini Kinetic, which had a twin tank duplex design. As the tanks were only about 6" dia, the minimum flow rates requirements were low. Anyway the water driven valve finally gave up. I disassembled it to see if there was anything obvious (dirt, worn cogs), but it was just old age I reckon. Even refurbished valves from US were £300 plus shipping, duty and VAT. When I went to the recycling facility (dump!) I found there were three other identical ones already in a large bag, clearly having life expired.

So I went for a new normal domestic single tank design (8" dia), which was quite inexpensive (£480) from BWT /Screwfix. I am quite aware of the effects of low flow rates on softener resin, having been another sector of the water treatment business for many years.

I think changing the tank inlet valve should remove the minimum flow problem. We shall see!

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Re: Float valves for roof tank - on/off

#409669

Postby Hardgrafter » May 5th, 2021, 9:07 pm

To Jackdaww

I replaced the fill valve with a Fluidmaster 74G (same as 747, but the Pro version with brass shank). Works brilliantly, and the tank fill rate has gone up to 6 l/min from a dribble to 3 l/min at best with old Part 2 fill valve. Mind you, the old valve did require a new diaphragm. Water hardness now 0!


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