Bypass on primary flow and return to indirect cylinder

[Mgrant]

Hi if fitting a bypass on the primary flow and return to an indirect hot water cylinder I know this needs to be positioned between the pump and zone valves as once the zone valve shuts off the pump will have an over run. Is this correct? Also do people now fit automatic bypasses instead of a gate valve that may have been used in the past.

 

[Killy Bing]

.....hmm let me think about that one...

 

[AWheating]

building regs require a bypass to be an auto now. your logic is sound.

 

[Mgrant]

Thanks do these shut down totally when there's sufficient flow through the system?

 

[kirkgas]

Yes generally when the system is cold there isn't enough pressure to open it, as the system heat(therefore pressure) builds up the by pass opens

 

[stevetheplumber]

Yes generally when the system is cold there isn't enough pressure to open it, as the system heat(therefore pressure) builds up the by pass opens

stick to gas, kirk as the system heats up the pressure rises the same on both sides of the bypass its trvs shutting that increase the available pump presure to open the bypass and of course if both motorised valves shut the pump over run will open the bypass

 

[stevetheplumber]

if set right theres no flow through the bypass when starting from cold assuming all valves are open

 

[Mgrant]

Ones I've seen say there adjustable from 0.1bar to 0.6 bar. Is that just what they let through when open. And they shut them selfs

 

[Ermintrude]

It's a but like a prv, except the relief is variable by compressing the spring inside. There are many different sizes of bypass .