Automatic bypass valve

[mdrandall]

We have a new installation with a condensing boiler feeding a 2 zone radiator system. Initially we had a lot of noise and the plumbers came back and installed a Danfoss AVDO automatic bypass valve. This seems to have cured the noise but the radiators don't get as hot as they used to. However, the pipes around the valve get very hot

I have looked at the Danfoss instructions and it says the valve should be set up with the system cold and all radiators open. Then the valve should be set so it is just closed. When I do this on my system even with the valve set to maximum of 0.5 bar, it appears the valve is open already as the valve pipes get very hot immediately.

The valve control knob won't go any further and the knob on top just clicks - is this correct? Do I have a faulty valve or do I need one with more pressure range?

 

[croydoncorgi]

If the pipes around the ABV are hot then the valve is open. It should be set so that it ONLY opens when there's no alternative path available (TRVs, zone valves etc. all shut) but the boiler still needing pump overrun to cool down.

If the valve is open all the time, even on its max setting and with radiator valves, etc. open, then it's not working right. Are you SURE there's no other (partly shut) valve between the pump / ABV, etc. and the rads?

 

[mdrandall]

Fairly sure. O went round and opened all the TRVs on every radiator. Should I also open the lock valve end as well?


Has anyone tried the Danfoss automatic valve and if so, can you confirm that the adjuster knob clicks when wound right in? It just doesn't seem right somehow.

 

[PEDANTICVINDICTIVEMAN]

Think you have to loosen the screw in the middle or something to adjust and then retighten screw when finished.

 

[mdrandall]

Can't find any screw, just a large plastic black knob on the top which tunrs freely moving up/down the bar pressure scale. That is until it reaches the end when it just clicks?