If ball valve is so great ...

[DiyNutJob]

I am puzzled why gate valve is still used and available if ball vale is that great? What is the catch?

I am dealing with a won't-close-off-completely gate valve coming off the loft tank. I am in two minds whether I should waste my time fixing it, replace it, or substitute it. I want a completely reliable master shut off valve so that I have less need for isolation valves all over the place. Ball valve is cheaper and claims are they are better. So, how is this free lunch possible?

I want a full bore valve, that the gate valve often is, for supplying pressure to hot water tank. Can anyone point me to one? This one is mentioned in another thread. Is it any good?

Made4Trade Lever Ball Valve

• Full bore

www.toolstation.com

 

[Burnerman]

Gate valves really belong in the days of steam.....they use a sluice system of closing rather than a rubber washer.
For this reason they used to be found in oil and chemical installations.
They can jam easily, and any debris can lodge in the sluice so it doesn’t fully shut off.
The 1/4 turn full bore lever valve is great, go for a Pegler or other quality make and available in the usual sizes.
John

 

[DiyNutJob]

If gate valve is carp, then why are people still buying them, judging by the availability? Since they are full metal, does that mean they last longer, presumably with maintenance?

 

[Notch7]

If gate valve is carp, then why are people still buying them, judging by the availability? Since they are full metal, does that mean they last longer, presumably with maintenance?

gate valves are full bore and they can be set partly open, also they cant be knocked open or shut, unlike the 90 handle ones (I know some have metal locking plates)

bear in mind the one youve linked is a budget valve, I tend to prefer Pegler brand for these

 

[Burnerman]

They last well enough, being usually made of brass.
However, the valve stem can seize up at the gland, courtesy of calcium and other salts. This often results on the stem snapping off.
I don’t know anyone who uses them these days!
John

 

[DiyNutJob]

Evils of ball valve. I am suffering this on 4 old/possibly-unused valves currently.

 

[DiyNutJob]

The soft seal in the ball valve is its weakness. So, there may not be a miracle valve. Although, I think redundancy could be a passable compromise. A gate valve plus a full bore ball valve could reduce the chance of shut off failure. Here's a run through of all the valve types:

 

[DiyNutJob]

Analysing one of the failing ball valves indicates shrinking of rubber o-rings because of aging. This is reparable using mechanically superior FKM rubber o-rings that are available cheaper from china, assuming they are metric sized. China doesn't do imperial sizes. The mangled securing spring could be cannibalized from another failed valve by cutting the casing with a dremel. A repaired unit would likely be better than anything you can buy. The shrunk o-rings would be made, most likely, from the common Nitrile (Buna) rubber. There is no guarantee branded products don't use this rubber. Looking at buyer complaints, I suspect branded products also use this rubber.

 

[Madrab]

Apart from the other uses detailed - adjustable flow, screw down mechanism, gate valves are primarily used in low pressure and/or gravity fed systems, where pressure is low. Their design doesn't lean towards a high pressure seal.

There are lots of those systems still in use today, hence why gate valves are still around but for mains systems then gate valves should be avoided.

 

[DiyNutJob]

I have a gravity tank and low pressure. A full bore ball valve will work just as well. Would you say the ball valve has the same bore as the gate valve? I really need max gravity pressure.

 

[Madrab]

It certainly will work as well - As long as it's full bore then it will match the bore of the supply pipe, so should maximise available flow.

 

[DiyNutJob]

Any problems adding the ball valve at the arrow? This gives me the redundancy of 2 shut off valves. One here and the original gate valve up in the loft, which I will fix/replace. This location is the easiest to work with. The nut on the top of tank allows me to remove the pipe on one side of the valve during installation.

 

[Elkato531]

Yes its a problem. No valves are allowed on the safety vent. If you want to add a valve to the hot distribution pipe, it must go after the Tee on the downwards section of the vertical pipe.

 

[Burnerman]

If it's low shower pressure you are on about, pipe it in 22mm until the very last moment.......
Or:
Consider a shower pump or a power shower - which just looks like an electric shower but has a pump inside. Requires equal hot and cold gravity pressures.
John

 

[robinbanks]

bear in mind the one youve linked is a budget valve,

DNJ only sources parts made of the very finest Chinesium, note