how to set bypass (the old, red gate valve type)

[Jennie]

Hi all,
My customer has a gatevalve/bypass off the primary flow into his cylinder.
He has fiddled with it (I think he was trying to turn off the water, and got the wrong valve).
How best to set it up?
I'll have to check to see if the system is on a three-port or two-port valves (if it's relevant).
Thanks all,
Jennie

 

[Riley]

I’d suggest that they put in a auto bypass as you can never be too sure whether a gate valve unused for a while is even functioning properly

 

[Tea-Break]

Hi Jennie,
This is an ‘old school’ method of regulating the
flow of water through the cylinder heat exchanger
(Coil) although usually fitted on primary return.
The idea is by reducing the flow, the coil will remain hotter longer. Thus heating the water quicker.
Nothing to do with modern pressure differential by-passes.
So the answer you seek, is by trial and error.
Crank it about two full turns from fully open and see how it goes.

 

[Aire]

Hi Jennie,
This is an ‘old school’ method of regulating the
flow of water through the cylinder heat exchanger
(Coil) although usually fitted on primary return.
The idea is by reducing the flow, the coil will remain hotter longer. Thus heating the water quicker.
Nothing to do with modern pressure differential by-passes.
So the answer you seek, is by trial and error.
Crank it about two full turns from fully open and see how it goes.

Given the position of the gate valve it's clearly acting as a bypass and in no way will affect the flow rate of water through the cylinder coil. I'd agree with Riley with fitting an auto bypass but would first check whether it's actually required. If the system is on a 3 way valve then I would just remove it.

 

[Tea-Break]

In the photo, you can’t make out where it’s teed from.
I assumed it was directly from either a zone or mid-position valve. However, after reading your reply Craig and looking at the photo again.
I now feel you are right and I’m mistaken
It does look too low down to be the flow??

 

[Aire]

Yeah the photo looks to me like it's at the base of the cylinder and the gate valve is is tee'd into the top of the cylinder return pipe

 

[Jennie]

Hi all,

Thanks so much for your comments. I'll have to go back and check out the surrounding pipework/zone valves/etc.

I'm a bit confused about the three-way valve versus the two zone valves. Surely both shut water off to the hot water and central heating circuits. So why isn't a bypass needed on the three way valve?

 

[Aire]

Hi all,

Thanks so much for your comments. I'll have to go back and check out the surrounding pipework/zone valves/etc.

I'm a bit confused about the three-way valve versus the two zone valves. Surely both shut water off to the hot water and central heating circuits. So why isn't a bypass needed on the three way valve?

A 3 port valve always keeps a circuit open so a bypass isn't required

 

[Riley]

Because one side is always open to dissipate heat

 

[Jennie]

Oh goodness, the penny's finally dropped. Of course the three-port valve does.