Gate valve as a bypass valve

[Fallout]

Hey if using a gate valve as a bypass valve how far open should it be so its working as a bypass, but not letting too much water flow through to affect the heat to the raditors?

 

[denso13]

Open it a quarter turn and see if everything heats up ok.

 

[dcawkwell]

If you have something like a bathroom radiator that is always open.
The bypass is completely pointless so have it shut.

 

[Fallout]

Open it a quarter turn and see if everything heats up ok.

Thank you does quarter turn usualy allow enough flow through to be an effective bypass?

 

[Dan Robinson]

Depends on the length of string.

Try a quarter turn no more than half.

 

[Fallout]

Thanks does the auto bypasses not allow any flow through untill there needed i.e all the valves/ zone valves are shut?

 

[denso13]

Basically yes. They adjust flow as required.

 

[Fallout]

Basically yes. They adjust flow as required.

Do these come pre-set or do they need setting?

 

[xr4x4]

Ok, what if you have a 3 port valve, a rad can't act as a bypass in this situation?

I.e when it shuts,

 

[GasBod]

only need a by pass on an s plan with pump over run

 

[xr4x4]

Ok, s plan? Two zone valves?

Am I right in thinking a three port rests in an open position?

 

[Jezthered]

Ok, s plan? Two zone valves?

Am I right in thinking a three port rests in an open position?

Yes, but still better to have an auto bypass valve because it's designed to maintain constant differential pressure as well as allow flow, this prevents noises.

They normally are best set at 0.2 bar

 

[Dan Robinson]

only need a by pass on an s plan with pump over run

Sorry, that's rubbish.

You need a by pass to comply with regs and as mentioned- provide a minimum flow through the boiler.

There are a few exceptions, like a thermal store system or boiler where a variable output pump can be used. However even here you need a bypass. Regs say automatic IIRC, but a manual here would be better.