Diablo

2 Port Valves Staying Powered

Recommended Posts

All,

 

My parents had a nest system installed a few weeks ago and there is something odd going on with the 2 port valves.

 

There are separate valves for HW, downstairs rads and upstairs rads.  The thing I find odd is that even when there is no demand, there appears to be current going to the valves.  Also, I have noticed that the levers sometimes feel completely floppy, as if they are not connected to anything.  I took the cover off one of them and it stiffened up, put the cover back on and it went floppy.

 

Any thoughts on what might be going on here?

 

Many thanks

Share this post


Link to post
Share on other sites

The lever feels floppy when the valve is energised.  If there is resistance when you push the lever and it then springs back, the valve is not energised.

Share this post


Link to post
Share on other sites

The lever isn't directly connected to the motor/valve. You can use it to push the valve into the open position against the spring when the motor is not being driven (and can be latched at the top of the movement to hold the valve open) but it can't be used to push the valve shut against the motor power. When the motor is driving the valve open the lever is free to be moved, hence floppy. The only purposes to doing that are to feel what state the motor/valve is in and to latch the valve open if you want it to stay open after the motor switches off.

 

In what way does there appear to be current going to the valves? Have you measured with a meter? On which connections? In case you don't realise, the motor also has a switch in it which is typically used to control power to the boiler and/or pump. The idea is that programmer and thermostat drive the motor open at which point the switch closes which then runs the boiler and pump. If the valve jams or the motor fails then the valve won't open so the switch won't operate and boiler and pump won't run against a closed valve. Are you sure the “current” you're seeing isn't the voltage on one side of that switch?

 

 

Edited by PeterW
Admin magic...

Share this post


Link to post
Share on other sites

Opps, sorry, Part 1 of that series is better on the actual operation of Zone valves. He also has another one on the insides of the actuator head. It's not immediately to me how to delete that video from the previous post.

Share this post


Link to post
Share on other sites

Hi Ed,

 

I tested the motorised valve cables with a simple voltage pen.

 

I am now back home and had a curiosity look at my own system, and notice that the two port valve for DHW is also showing current flowing to it even though there is no demand. 

 

My two UFH vales both have no current flowing to them, as there is no demand.

 

Many thanks for the responses and video link.

 

 

Share this post


Link to post
Share on other sites

Voltage pen. Work of the devil. Proves nothing.

 

Lets get back to basics. Forget voltages or currents that may be present.  Does the system work?  If not in what way does it not work?

 

PS voltage present does NOT = current flowing, completely separate things.

Share this post


Link to post
Share on other sites

I had a safety recall the other day...sure it was ref volt pens...should have read it!

 

Dangerous bloody things. Wield the tip around a flex and you might find it stops and starts.

Share this post


Link to post
Share on other sites

There are two types of zone valve, 3 wire and 5 wire. In the 3 wire you have brown blue and earth, energise to operate, de-energise and it shuts under stored energy ( integral return spring which gets stretched when the motor pushes the valve under electrical energy input ). No energy is present until a call for heat etc is made. 

The 5 wire does exactly the same but has a microswitch which gets struck by the actuator arm as it gets to 'top dead centre' of its travel. That microswitch is permanently energised by the heating systems common connection 24/7 365. When it gets struck, eg the valve has moved to the fully open position, the microswitch output becomes live also, generating the 'call for heat' signal to the boiler / other.

The lever valve is only meant for filling and draining the system when de-energised eg when new or when having maintenance / repair work carried out. If you push the lever over it may just 'bump' the microswitch and flash a brief call for heat, but it will not keep it depressed. Thats done on purpose so numbnuts plumbers can't call out and make themselves look like heroes by locking on faulty valves, to 'keep you going until the new part arrives", which would remove all thermostatic control of your unvented cylinder.

 

The title says "staying powered" and is correct, so no issue unless theres a fault.     

Share this post


Link to post
Share on other sites
20 minutes ago, Nickfromwales said:

If you push the lever over it may just 'bump' the microswitch and flash a brief call for heat, but it will not keep it depressed.

 

I think that must depend on the model of actuator head. For the ones in this house pushing the lever up turns the pump and boiler on. Just checked, turning the DHW valve on with DHW off on the programmer and indeed the pump and boiler ran. The electrician mentioned doing that as a work around in the case of a faulty programmer or thermostat when he explained the system to me.

 

The ones in John Ward's video I referenced above look different in that the external level only seems to half open the valve. He doesn't show if the cam to operate the microswitch moves far enough in that case but I suspect not.

Share this post


Link to post
Share on other sites

I am pretty sure the Danfoss ones in our old house actuate the microswitch when you move the override lever, but the Honeywell ones in the new house do not.

Share this post


Link to post
Share on other sites
3 hours ago, Ed Davies said:

 

I think that must depend on the model of actuator head. For the ones in this house pushing the lever up turns the pump and boiler on. Just checked, turning the DHW valve on with DHW off on the programmer and indeed the pump and boiler ran. The electrician mentioned doing that as a work around in the case of a faulty programmer or thermostat when he explained the system to me.

 

The ones in John Ward's video I referenced above look different in that the external level only seems to half open the valve. He doesn't show if the cam to operate the microswitch moves far enough in that case but I suspect not.

Point conceded, as I only ever fit Honeywell.  :) 

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now