Automatic Bypass Valve .. CLARIFICATION

[GomezZz]

Right , I spent the whole day arguing with my work partner about the need for an automatic bypass valve. I've been taught that its a requirement where as he says that its not and that its against the 'laws of plumbing' to install TRVS on all rads . He says you have to have one without a TRV on it ??? Is he right ?

 

[andyg0507]

yes you should leave one rad off without a trv, its good practice.

 

[Puddle]

Yes,as said , one radiator is left without a trv on it, to allow correct operation of the system interlock/room thermostat which should be located in same heating space and is not there as a bye pass,a automatic bye pass should still be fitted
This is because although the one radiator may not have a trv on it and in effect not closed down,the balancing valve on the radiator maybe in a to restrictive/closed position, not open enough to allow required circulation around boiler when that rad is the only one on and allowing circulation
This is the case on three port valve system,if two port system,then obviously auto by pass required for when valve is in closed postion

 

[diesel_ltd]

if it is a S plan system you do need an auto by-pass but you would also leave a trv off in the same room as the room stat, so that the rad with no trv cant be turned down as it will regulate the temp in the house via the room stat

 

[Toddyplumb]

And just to confuse matters even more
"the boiler is fitted with an automatic integral bypass " Baxi Platinum Combi

 

[GomezZz]

Right , thanks chaps. So looks like we were both right . You need the auto bypass (if the boiler doesn't already have on installed) And the rad sited in the same room as the room thermostat should be without TRV


cheers

 

[moony]

its only in regs that you need trv's in bedroom areas iirc. good practice to put them in every room except for the room the stat is in.

 

[buff]

why is it then that bathroom rads in the main dont have trvs when the stat is in the hallway?

 

[Toddyplumb]

Because no one ever turns off the bathroom rad

TRVs look naff on towel rails

 

[GrahamM]

its only in regs that you need trv's in bedroom areas iirc. good practice to put them in every room except for the room the stat is in.

It is CHESS basic practice to have:

1. Time switch
2. Room stat.
3. Boiler interlock
4. TRV's on all rads with the exception of room with stat. fitted.
5. Automatic bypass valve
   

why is it then that bathroom rads in the main dont have trvs when the stat is in the hallway?

There is probably no automatic bypass fitted and if there is the installer does not know the basics.
There should NOT be a stat. in room with TRV's fitted as they will conflict against each other.