Bypass Valve confusion

[rjm2k]

Bit confused about the Bypass valve on my system, it's a Gloworm Ultimate 80ff boiler. I have read that the manual bypass is pointless if you have rads which are always on (eg bathrooms). I believe it's a 3 port valve that we have and there are at least 3 rads without TRVs that will always be open, it's an open vented setup

The installation manual says

A bypass is usually unnecessary on systems using a 3 port
diverter valve since one port will remain in the open position at all
times. This allows satisfactory operation of the pump overrun.
However if thermostatic radiator valves are fitted to all radiators
or two port valves are used a bypass is required

However, the manual also then goes onto say (in the adjustment section)

UNDER NO CIRCUMSTANCES SHOULD THIS VALVE BE
LEFT IN THE FULLY CLOSED POSITION.

So which is?

TIA

 

[Armo74]

If the installation manual says fit one then one should be fitted,fairly sure it's regs now anyway and on low water content boilers. What happen's if someone removes the by-pass rad for decorating purposes not knowing any different.

 

[denso13]

It means you probably don't need a bypass valve but if you do the system should be commissioned with it closed and then opened to suit the temp/flow conditions. If you have one don't leave it closed after commissioning - seems pretty clear?

 

[Oozoid]

Boilers, in my very limited experience, always have an internal automatic bypass valve, the purpose of which is to add a bit of hot water when the water returning from the radiators is cold enough to cause condensation of the flue gases (and thus corrosion). This ABV closes when returning water is warm enough. An external bypass to maintain some minimum flow is a separate issue. I asked the people who installed my system if they had installed a bypass and they looked at each other and said yes, it is under the floor. Later I crawled under the floor and confirmed what I suspected, that they were lying. Not a problem, I leave the bathroom radiator fully open all the time. If the flow were ever to fall below the minimum required, I would expect the flow switch to open, shut down the boiler and raise an alarm.

 

[muggles]

Boilers, in my very limited experience, always have an internal automatic bypass valve, the purpose of which is to add a bit of hot water when the water returning from the radiators is cold enough to cause condensation of the flue gases (and thus corrosion). This ABV closes when returning water is warm enough. An external bypass to maintain some minimum flow is a separate issue. I asked the people who installed my system if they had installed a bypass and they looked at each other and said yes, it is under the floor. Later I crawled under the floor and confirmed what I suspected, that they were lying. Not a problem, I leave the bathroom radiator fully open all the time. If the flow were ever to fall below the minimum required, I would expect the flow switch to open, shut down the boiler and raise an alarm.

Welcome to the forum. Did you not notice the giant red box at the bottom of this thread telling you it was four years old and didn't need adding to?

 

[Terrywookfit]

Boilers, in my very limited experience, always have an internal automatic bypass valve, the purpose of which is to add a bit of hot water when the water returning from the radiators is cold enough to cause condensation of the flue gases (and thus corrosion). This ABV closes when returning water is warm enough. An external bypass to maintain some minimum flow is a separate issue. I asked the people who installed my system if they had installed a bypass and they looked at each other and said yes, it is under the floor. Later I crawled under the floor and confirmed what I suspected, that they were lying. Not a problem, I leave the bathroom radiator fully open all the time. If the flow were ever to fall below the minimum required, I would expect the flow switch to open, shut down the boiler and raise an alarm.

 

[Razor900]

Boilers, in my very limited experience, always have an internal automatic bypass valve, the purpose of which is to add a bit of hot water when the water returning from the radiators is cold enough to cause condensation of the flue gases (and thus corrosion). This ABV closes when returning water is warm enough. An external bypass to maintain some minimum flow is a separate issue. I asked the people who installed my system if they had installed a bypass and they looked at each other and said yes, it is under the floor. Later I crawled under the floor and confirmed what I suspected, that they were lying. Not a problem, I leave the bathroom radiator fully open all the time. If the flow were ever to fall below the minimum required, I would expect the flow switch to open, shut down the boiler and raise an alarm.

You seem familiar, you didn't work for the BBC did you???

 

[AGAS]

WTF

 

[Steelmasons]

If the flow were ever to fall below the minimum required, I would expect the flow switch to open, shut down the boiler and raise an alarm.

Surely in a situation of 'minimum flow' the 'flow switch' would CLOSE and as a result CLOSE the switch contacts in order to 'raise an alarm'....
How would this 'internal bypass' fair when used on a condensing boiler?...would raising the return temp increase efficiency???

 

[Oozoid]

Oh dearie me, yet another forum full of morons.

 

[Steelmasons]

****t.

 

[AGAS]

Oh dearie me, yet another forum full of morons.

takes a moron to know one

 

[D_Hailsham]

Boilers, in my very limited experience ...

You are right there. The rest just shows how limited it is.