Automatic Bypass Valve After Mid-Position Valve

[lloydh]

I've just replaced a couple of radiators in my Y plan system which now means that every radiator has a TRV. I don't have a good candidate (such as a towel radiator) to leave with two lockshields so I need to install an automatic bypass on the heating loop.

My boiler/pump/mid-position valve installation is very cramped so I just wanted to check that it makes no difference installing the bypass valve a bit further along the heating loop, after the mid-position.

Does that sound OK?

 

[ShaunCorbs]

doesnt need an auto bypass as its a mid position

 

[lloydh]

doesnt need an auto bypass as its a mid position

Hi Shaun. What about if the main stat is calling for heat (but not hot water) and the TRVs are all closed down?

I understand it's common to have a rad without a TRV so there's always flow but that doesn't suit this situation.

 

[ShaunCorbs]

Hi Shaun. What about if the main stat is calling for heat (but not hot water) and the TRVs are all closed down?

I understand it's common to have a rad without a TRV so there's always flow but that doesn't suit this situation.

even the bathroom rad has a trv ? and makes no difference if you install it further down eg end of line

 

[lloydh]

even the bathroom rad has a trv ? and makes no difference if you install it further down eg end of line

No bathroom radiator, in fact only one rad upstairs — it's an old property renovation in progress.

Ok, that's what I thought. As long as the bypass maintains flow it will do its job.

 

[John.g]

Depending on the type of circ pump installed you may find it very difficult to set up the ABV properly to give a minimum flow rate without either excessive by pass or none at all, you could consider just installing a mini ball valve (screw driver slotted) in the bypass and adjust this to give your minimum flow when all TRV's are fully shut.

 

[lloydh]

Thanks for the help. I did install an ABV and in fact managed to fit it in between the pump and mid position valve as seems to be most common. I think it's adjusted about right because the pipework beyond the valve stays cold when the heating comes on but quickly heats up if the rads are closed down.

 

[Chuck]

Ok, that's what I thought. As long as the bypass maintains flow it will do its job.

Check the boiler's installation instructions; there is often a minimum volume of water (or length of pipework) that must circulate around the ABV loop for it to do its job properly.