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sPoNiX
 
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Default Ball valve versus gate valve

Doing mods to the central heating...

I notice my central heating has loads of gate valves (The ones with
the red handwheels) for isolating various parts of the circuit.

However, the 'fashion' these days seems to be to use service valves
(Ball valve with a screwdriver slot).

What are the pros and cons? Why should I use one over the other? (Both
are avaivalbe locally at the same price)

Personally I tend to favour the gate valve as the hole through it
looks bigger. Any other issues to be aware of?

sponix
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Grunff
 
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Default Ball valve versus gate valve

sPoNiX wrote:
Doing mods to the central heating...

I notice my central heating has loads of gate valves (The ones with
the red handwheels) for isolating various parts of the circuit.

However, the 'fashion' these days seems to be to use service valves
(Ball valve with a screwdriver slot).

What are the pros and cons? Why should I use one over the other? (Both
are avaivalbe locally at the same price)

Personally I tend to favour the gate valve as the hole through it
looks bigger. Any other issues to be aware of?



Full bore ball valves are the ones to go for. These have a hole that is
the same size as the connected pipe bore, and a flow path that is
totally unimpeded. So in the open position, it's the same as having no
valve.


--
Grunff
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sPoNiX
 
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Default Ball valve versus gate valve

On Tue, 10 Jan 2006 09:18:01 +0000, Grunff wrote:

sPoNiX wrote:
Doing mods to the central heating...

I notice my central heating has loads of gate valves (The ones with
the red handwheels) for isolating various parts of the circuit.

However, the 'fashion' these days seems to be to use service valves
(Ball valve with a screwdriver slot).

What are the pros and cons? Why should I use one over the other? (Both
are avaivalbe locally at the same price)

Personally I tend to favour the gate valve as the hole through it
looks bigger. Any other issues to be aware of?



Full bore ball valves are the ones to go for. These have a hole that is
the same size as the connected pipe bore, and a flow path that is
totally unimpeded. So in the open position, it's the same as having no
valve.


More expensive and not available from the sheds..

The gate valve is almost full bore but most "service" valves seem
considerably smaller.

Is there any advantage to using a service valve over a gate valve?

sponix
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Dave Liquorice
 
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Default Ball valve versus gate valve

On Tue, 10 Jan 2006 09:08:54 GMT, sPoNiX wrote:

However, the 'fashion' these days seems to be to use service valves
(Ball valve with a screwdriver slot).

What are the pros and cons? Why should I use one over the other?


Gate valves are notorious for not shutting off completely when they
havn't been exercised regularly (fully closed and fully opened at
least once/year). Scale or other crud builds up in the grove that the
gate slides down and stops it seating properly. Also never leave them
wound fully open against the stop, the shaft will jam. Fully open then
close 1/4 to 1/2 a turn.

Personally I tend to favour the gate valve as the hole through it
looks bigger.


You can get "full flow" ball valves.

--
Cheers
Dave. pam is missing e-mail



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Grunff
 
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Default Ball valve versus gate valve

sPoNiX wrote:

More expensive and not available from the sheds..


But well worth it imho. All plumbers merchants carry them, as do
screwfix, toolstation, bes etc.


The gate valve is almost full bore but most "service" valves seem
considerably smaller.

Is there any advantage to using a service valve over a gate valve?


Service valves are smaller in size, and also 1/4 turn. These are both
'advantages', but not huge ones.



--
Grunff


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Christian McArdle
 
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Default Ball valve versus gate valve

What are the pros and cons? Why should I use one over the other? (Both
are avaivalbe locally at the same price)


I would use neither. Gate valves are unreliable. Service valves are small
bore. I use full bore lever valves.

Christian.


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Dave Plowman (News)
 
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Default Ball valve versus gate valve

In article ,
sPoNiX wrote:
Is there any advantage to using a service valve over a gate valve?


For maintenance purposes yes. Old gate valves never shut off completely.
Although this might only be in a hard water area.

--
*Just remember...if the world didn't suck, we'd all fall off.

Dave Plowman London SW
To e-mail, change noise into sound.
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Aidan
 
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Default Ball valve versus gate valve


sPoNiX wrote:
Doing mods to the central heating...

I notice my central heating has loads of gate valves (The ones with
the red handwheels) for isolating various parts of the circuit.

However, the 'fashion' these days seems to be to use service valves
(Ball valve with a screwdriver slot).


When I were a lad, gate valves were what we used before ball valves
became commonly available.

Gate valves were used in preference to globe valves
(stopcock/screwdown-tap types) on pumped circuits because they offered
little resistance to the flow. Their disadvantage was that they often
failed to fully isolate.

That's all now history, use full-bore ball valves.

Service valves have a reduced bore and are intended for use on water
supply systems where the increased resistance is of little concern. Use
full-bore ball valves on pumped heating systems.

Any other issues to be aware of?


The gate valves' glands are liable to start dripping if you do operate
them after a long time. The glands are probably packed with asbestos
fibre material. The 15mm gate valves must be worth at least 10p as
scrap.

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John Rumm
 
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Default Ball valve versus gate valve

sPoNiX wrote:

What are the pros and cons? Why should I use one over the other? (Both
are avaivalbe locally at the same price)


Wot the others said, plus, gate valves have an endearing little habbit
of getting stuck, then the shaft breaking internally as you go to open
them. The nett result being that it feels like you just undid a tight
valve, only you didn't!

DAMHIK


--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/
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sPoNiX
 
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Default Ball valve versus gate valve

On Tue, 10 Jan 2006 14:22:22 +0000, John Rumm
wrote:

sPoNiX wrote:

What are the pros and cons? Why should I use one over the other? (Both
are avaivalbe locally at the same price)


Wot the others said, plus, gate valves have an endearing little habbit
of getting stuck, then the shaft breaking internally as you go to open
them. The nett result being that it feels like you just undid a tight
valve, only you didn't!


Unfortunately, I don't have lever ball valves available...only
'service' ball valves or gate valves.

I'm gonna use a gate valve methinks as there are already other gate
valves in the system that seem to work fine.

sponix


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Andy Hall
 
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Default Ball valve versus gate valve

On Tue, 10 Jan 2006 09:29:58 GMT, (sPoNiX) wrote:

On Tue, 10 Jan 2006 09:18:01 +0000, Grunff wrote:

sPoNiX wrote:
Doing mods to the central heating...

I notice my central heating has loads of gate valves (The ones with
the red handwheels) for isolating various parts of the circuit.

However, the 'fashion' these days seems to be to use service valves
(Ball valve with a screwdriver slot).

What are the pros and cons? Why should I use one over the other? (Both
are avaivalbe locally at the same price)

Personally I tend to favour the gate valve as the hole through it
looks bigger. Any other issues to be aware of?



Full bore ball valves are the ones to go for. These have a hole that is
the same size as the connected pipe bore, and a flow path that is
totally unimpeded. So in the open position, it's the same as having no
valve.


More expensive and not available from the sheds..


B&Q usually have a few, but not at the best prices. If you look at
BES, Screwfix,... they are reasonably priced, but not as low as
service valves.



The gate valve is almost full bore but most "service" valves seem
considerably smaller.

Is there any advantage to using a service valve over a gate valve?


Service valves are not a good idea for heating because they impede the
flow too much. Their best application is for isolating taps and
toilets on mains pressure supplies. In heating, the only useful
application I can think of for service valves is for a bypass.

Compared with gate valves, apart from also being full bore they:

- shut off flow completely
- don't leak around the spindle
- don't stick with heat or scaling.


--

..andy

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