Glowworm Boiler Firing control problem & Permanent Live

[Broondog]

I have recently changed my central heating programmer from an ACL Lifestyle LS522 to a Drayton LP522 - as I understand it - a direct replacement.

However, my Glowworm economy plus 50FF boiler now fires continuously as if it has a permanent live.

The Drayton installation guide simply says refer to the boiler installation manual for wiring. I have the installation and servicing manual for the boiler and unfortunately it is not clear how to wire the system from scratch.

Before going into a raft of questions on the exact wiring, I wish to say that there is a change the DHW 2 port motorised valve could be mechanically blocked due to solids in the heating system.

<Q> On any Honeywell V4043 22mm valve;
i - How does the microprocesser work (at both ends of the valve range)?
ii - What actually are the orange, grey wires for?

Upon inspecting the wiring, the Drayton guide (fully pumped 2 port system, dia 3) appears very similar apart from the following;

1) The permanent live in my system connects to (junction box ref #7). This is the ORANGE wires feeding both Honeywell 2PORT V4043 22mm valves. This also connects to the red (3core plus earth) cable to the boiler (&pump).

The grey connections from both CH and DHW valves in my system therefore have no live input as per the Drayton diagram. The two grey wires are both connected to the YELLOW cable (3 core plus earth, see para above) to the boiler SLAVE/AUXILLARY.

<Q> Economy PLus 50FF GLOWWORM BOILER;
This is a pump overrun boiler, I cant clear in my mind how this afects things as there is a yellow cable to the boiler AUX/SLAVE

Finally, all the other wires appear the same as the drayton sysetm.

* To recap, the DHW valve is mechanically suspicious....

* When calling for Heat and/or HW with the programmer live but OFF, the boiler fires when the gas is not set to OFF via the control thermostat....

i.e. something is faulty and calling for heat or the boiler is permanently live.

Either way, its bugging me.... Any help very welcome, photos avail if you require to see the junction box wiring.

 

[giblets]

The grey and orange wires on the HW 2-port powerhead are the switch contacts; L, N & E are obvious; white (if you have one) is not used on the 2-port valves.

Dealing with the heating valve only (the DHW one is the same) the valve is opened by a switched supply from the room stat. When the valve is fully open the microswitch contact make and switch on the boiler and pump via the switched live connection on the boiler. The pump should be wired from the boiler control not the juncton box. There should be a permanent live feed to the boiler to operate the pump over-run when the switched live is off. When the programmer is off there should be no feed on the grey wire from either valve.

It is not unknown for the auxillary microswitch contacts in the powerhead to stick shut causing the boiler & pump to run continuously. You can check with a multi-meter or disconnect the grey wires in turn (with the programmer turned off).

 

[ChrisR]

might help ... - might not...

 

[namsag]

Also although clock maybe straight replacement jumpers on back of clock need setting the same as previous

 

[Broondog]

All,

Thanks to contributions above. Upon removing the grey DHW wire the system appears to function properly.

As such, it is likely to be a failure of the microswitch on Honeywell 2 port DHW valve.

Now......

Can you replace the Honeywell V4043 spring return valve head assembly without draining the system????

 

[gas4you]

Yes very easy, but make a note of the terminals and colour of each wire going to them

 

[Broondog]

Thanks - Can you quickly talk me through the replacement?

 

[gas4you]

Isolate mains supply to heating

Locate small screw on one end of zone valve head (can't remember which end right now )

Loosen this and pull silver case off.

Locate two brass phillips screws one top left, one bottom right

Undo and remove

Pull head off

Fit new head in reverse of above, taking care to engage shaft correctly and carefully.

Disconnetc old wiring and wire new one in, as said either write down before disconnection, or do 1 wire at a time

 

[Broondog]

Thanks to gas4you!

 

[giblets]

Before you remove anything just check that the top of the silver cover of the valve motor has a raised pip at the end where the cable goes in. If so then a replacement head can be fitted. If not then the system will need to be drained and the valve replaced as you cannot replace the motor as described above - you will get wet if you try.

 

[Agile]

Yes very easy, but make a note of the terminals and colour of each wire going to them

Dave should have remembered that it can only be done without getting wet on the later dimpled ones.

Perhaps the "wink" was at the thought of him getting wet if it was old!

Tony

 

[gas4you]

Forgot about the very old ones I've only come across one of these. The thought of somebody getting wet would have produced a

 

[Broondog]

All,

There is a raised pimple but at the non cable end. I presume this still means its ok to replace.

Additionally, if I did buy a new valve - should I buy normally open or normally closed?
(I would ideally just take the valve and ask for a direct replacement to plumbers merchant)?

 

[giblets]

Yep, sorry - meant non-cable end. That will be OK to replace.

Honeywell valves are normally closed. Just ask at the merchants for a 22mm(?) Honeywell Zone Valve. No need to take the old valve along. You will get the whole bit including the powerhead (the silver box). AFAIK you can't get just the brass valve body on it's own from a normal merchant.

 

[werewolf]

Little tip.

If you get a new head it`s supplied with the lever in the "locked" position .Before removing existing head lock the lever in the open position. Makes the alignment of shaft into hole on valve much easier.

Paul