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UK diy (uk.d-i-y) For the discussion of all topics related to diy (do-it-yourself) in the UK. All levels of experience and proficency are welcome to join in to ask questions or offer solutions. |
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#1
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Ball valves - whats the difference
Hi all,
Whats the difference between a part 1 :- http://www.screwfix.com/app/sfd/cat/...14542&ts=32264 and a part 2 http://www.screwfix.com/app/sfd/cat/...11518&ts=32264 Alan |
#2
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Ball valves - whats the difference
"Alan Campbell" wrote in message om... Hi all, Whats the difference between a part 1 :- http://www.screwfix.com/app/sfd/cat/...14542&ts=32264 and a part 2 http://www.screwfix.com/app/sfd/cat/...11518&ts=32264 Alan google is your friend A part 1 is a copper alloy body piston valve type part2 is a copper alloy body diaphragm type. part 3 is a plastic body diaphragm type (cold water services only) part 4 compact valve for WC mrcheerful |
#3
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Ball valves - whats the difference
"Alan Campbell" wrote in message
om... Hi all, Whats the difference between a part 1 :- http://www.screwfix.com/app/sfd/cat/...14542&ts=32264 and a part 2 http://www.screwfix.com/app/sfd/cat/...11518&ts=32264 Alan 90 pence! No seriously it looks to me as though it is the way the ball is connected, one straight on the end of the arm and one at a right angle, for a narrower cistern perhaps. HTH John |
#4
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Ball valves - whats the difference
"Alan Campbell" wrote in message om... Hi all, Whats the difference between a part 1 :- http://www.screwfix.com/app/sfd/cat/...14542&ts=32264 and a part 2 http://www.screwfix.com/app/sfd/cat/...11518&ts=32264 Alan Hi Alan, It's all to do with the air gap between outlet and water level when fitted to the cistern. The airgap is required for backflow prevention. The part 1 valve has the outlet on the under side of the valve. This is not suitable for fitting to WC cisterns where the inlet hole is at the same level as the overflow hole. In the event of the valve failing, the water level rises to the overflow level and the outlet of the valve ends up under water, thus the required air gap for backflow prevention is lost. The part 2 valve has the water outlet via an upstand. If this valve is fitted in a cistern where the inlet and outlet holes are at the same level, then in the event of an overflow situation, the airgap is maintained. In general if the inlet hole and overflow holes are at the same level then Part 2 valve is required. If the inlet hole is above the overflow hole and the airgap is maintained in the overflow situation then part 1 can be fitted. A part 1 valve can be replaced with a part 2 valve with no problem. But a part 2 valve can't be replaced with part 1 unless you first check that the air gap will be maintained in overflow situation. Part 1 valves usually found on potable water cisterns, cold water tank in loft. Part 2 valves usually found on WC cisterns and CH feed/expansion tanks. BillP. |
#5
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Ball valves - whats the difference
"BillP" wrote in message
... "Alan Campbell" wrote in message om... Hi all, Whats the difference between a part 1 :- http://www.screwfix.com/app/sfd/cat/...14542&ts=32264 and a part 2 http://www.screwfix.com/app/sfd/cat/...11518&ts=32264 Alan Hi Alan, It's all to do with the air gap between outlet and water level when fitted to the cistern. The airgap is required for backflow prevention. The part 1 valve has the outlet on the under side of the valve. This is not suitable for fitting to WC cisterns where the inlet hole is at the same level as the overflow hole. In the event of the valve failing, the water level rises to the overflow level and the outlet of the valve ends up under water, thus the required air gap for backflow prevention is lost. The part 2 valve has the water outlet via an upstand. If this valve is fitted in a cistern where the inlet and outlet holes are at the same level, then in the event of an overflow situation, the airgap is maintained. In general if the inlet hole and overflow holes are at the same level then Part 2 valve is required. If the inlet hole is above the overflow hole and the airgap is maintained in the overflow situation then part 1 can be fitted. A part 1 valve can be replaced with a part 2 valve with no problem. But a part 2 valve can't be replaced with part 1 unless you first check that the air gap will be maintained in overflow situation. Part 1 valves usually found on potable water cisterns, cold water tank in loft. Part 2 valves usually found on WC cisterns and CH feed/expansion tanks. I usually find and almost always fit plastic valves to WC cisterns - the Y fork at the end of the arm allows the float ball to be angled to one side or the other which is usually necessary to get past the flush valve. You can use brass part 2 valves, and in fact I did so with one today: one handy thing with brass part 1 and 2 valves is that you can leave the 1/2" BSP tail of the valve attached to the cistern and pipework and unscrew the big brass nut coupling it to the valve body and just replace the body - including replacing a part 1 with a part 2. |
#6
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Ball valves - whats the difference
It's all to do with the air gap between outlet and water level when fitted to the cistern. The airgap is required for backflow prevention. The part 1 valve has the outlet on the under side of the valve. This is not suitable for fitting to WC cisterns where the inlet hole is at the same level as the overflow hole. In the event of the valve failing, the water level rises to the overflow level and the outlet of the valve ends up under water, thus the required air gap for backflow prevention is lost. The part 2 valve has the water outlet via an upstand. If this valve is fitted in a cistern where the inlet and outlet holes are at the same level, then in the event of an overflow situation, the airgap is maintained. In general if the inlet hole and overflow holes are at the same level then Part 2 valve is required. If the inlet hole is above the overflow hole and the airgap is maintained in the overflow situation then part 1 can be fitted. A part 1 valve can be replaced with a part 2 valve with no problem. But a part 2 valve can't be replaced with part 1 unless you first check that the air gap will be maintained in overflow situation. Part 1 valves usually found on potable water cisterns, cold water tank in loft. Part 2 valves usually found on WC cisterns and CH feed/expansion tanks. BillP. Thanks all. I need to replace a fault valve in my parents CH header tank. The existing one wont shut off properly and is slowly filling up and overflowing. The one they have is a part 1, but when the tank fills, it is under the water level, so I guess I will replace it with a part 2. Cheers Alan |
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