3-Way Valve Woes

[BobSTR]

So the 3-way valve on our central heating system has been sticking (stuck on hot water - nothing coming to the radiators). Need to frequently manually move the valve. A common problem right?

Well - a few years ago I replaced the actuator (Danfoss Randall HSA3). That seemed to help for a while - but didn't fix things entirely so I had the valve body itself replaced. But now it's sticking again!

What could cause this recurring problem? The actuator is only 4 years old - the valve body probably 3 years old now. Could it be debris in the system jamming the valve?

It's sticking a couple of times a week - usually in the middle of the night so we wake up to a cold house!

 

[Agile]

The first thing to do it to look at the condition of the water.

A drinking glass is good for looking at the colour.

Tony

 

[BobSTR]

Water from a radiator bleed is pretty clear - perhaps a slight straw colour. Having said that I've no doubt there's a fair amount of debris lurking at the bottom of some of the radiators. Last time I drained the system was probably about 3 years ago - and got some nice black stuff out then. (Yes I put inhibitor in afterwards!).

But it sounds like you're thinking it could be debris? So perhaps a flush plus the installation of magnaclean is the answer?

(I should explain - my skill level is limited to removing, flushing and refitting radiators, gravity draining and refilling the system, and changing the actuator motor - anything else and it won't be DIY for me).

 

[45yearsagasman]

Those valves are prone to failure. My advice is to get rid and replace with a Honeywell v4073 3 port valve. That will require a part drain down and simple wiring connections.
If you can remove and replace a rad, then replacing the 3 port should be within your capabilities.