Drayton MA1 3-port valve

[reluctanthandyman1]

HAPPY BIRTHDAY for tomorrow, by the way.

 

[matt1e]

Thanks!

don't worry about the multimeter, as I think I know what's wrong I can still give you some easy checks to do

Since this is being described as an intermittent fault I am presuming that normally

a) you can select and obtain hot water only
b) you can select and obtain central heating only
c) you can select and obtain both together

now how does the problem manifest itself?
how do you know when the valve is "stuck"?

Matt

 

[matt1e]

turn off at the mains and check that the valve has reset then

turn down the room stat and turn off central heating on the programmer

turn up the cylinder stat and turn on hot water at the programmer

restore power, and check the valve is still at rest
the boiler should also be firing at this stage

if the valve has moved then the valves white wire is miss-connected in the wiring centre, if it hasn't moved then carry on

now turn the hot water off at the programmer

the boiler should switch off, now check the valve
has it moved to mid position?

if yes , (this is the most likely scenario) then its likely your valves grey and white wires are mixed up in the wiring centre terminals

if no,
turn up the room stat (leave both hw and ch off at programmer)
does the valve now move to mid poss?
if so then its likely that the hot water off and central heating on connections are mixed up at the programmer terminals

Matt

 

[reluctanthandyman1]

Hello again Matt. Happy birthday again!

When this problem occurs what happens is this - The valve is stuck in mid-position.

The water continues to heat up to scalding hot levels (obviously over-riding the cylinder stat).

The heating stat becomes ineffective (ie: no clicking sound from it to effect a "call" for heat.

The cylinder stat does "click" but is completely ignored at the boiler end of things. The boiler just keeps on going.

And no matter what position I switch either the hot water OR the central heating programmes to at the programmer, the boiler just keeps on going - even when I switch both channels (heating AND hot water) to OFF!

 

[reluctanthandyman1]

When I say "the cylinder stat does click" I mean I turn it so that it clicks both on AND off - however, it has no effect in turning the boiler off. The boiler continues to heat up the water.

One thing which occurs to me - when my programmer is set so that the HW and CH are both at the same setting (ie: both of them are set at "timed", "once" or "on") then this may be causing the problem.

When HW and CH are set at different settings to each other at the programmer (ie: HW set at "on" and CH set at "timed", which is how I normally have it when the weather isn't atrociously cold) then it may be that this problem won't occur.

What do you think, if this is the case?
Is it therefore something to do with a fault within the programmer?
And if so, what could that fault be?

 

[matt1e]

When I say "the cylinder stat does click" I mean I turn it so that it clicks both on AND off - however, it has no effect in turning the boiler off. The boiler continues to heat up the water.
Is it therefore something to do with a fault within the programmer?
And if so, what could that fault be?

Nope it's a miss wiring fault
Do the tests I give you and report back with the four answers to the questions
Start here and follow it exactly

turn off at the mains and check that the valve has reset then

turn down the room stat and turn off central heating on the programmer

turn up the cylinder stat and turn on hot water at the programmer

restore power, and check the valve is still at rest, yes or no?
the boiler should also be firing at this stage, yes or no?

now turn the hot water off at the programmer

the boiler should switch off, yes or no?

now check the valve has it moved to mid position, yes or no?


Matt

 

[reluctanthandyman1]

Followed your instructions exactly.

Everything working as it should do in that scenario.

Valve indicator at its "rest"/default position at HW point when power restored and water heating up as the boiler fires up. Valve indicator stays at this position.

 

[reluctanthandyman1]

When HW is then set to "off" at the programmer the boiler goes off.

 

[reluctanthandyman1]

.....and the valve remains at its same "rest" position

 

[matt1e]

.....and the valve remains at its same "rest" position

Ok then following on from the last test
With both the hot water and the central heating turned off at the programmer
Turn up the room stat
Does the valve stay at rest, Yes or no?
Does the boiler fire, yes or no?

I'm struggling for an Internet signal here so bear with me

 

[reluctanthandyman1]

Valve stays at rest.

Boiler does not fire.

 

[matt1e]

Ok now turn both the room stat and the cylinder stat down and turn hot water on at the programmer

Does the valve stay at rest yes or no?
Does the boiler fire, yes or no?

 

[reluctanthandyman1]

Valve stays at rest.

Boiler does not fire.

 

[oilhead]

the few Y plan problems I encounter, my experience is that these actuators are the least reliable. They do not stick in mid position, but in the heating position. All the wiring checks have been O K, and it has never been a synchron fault. I've put it down to a fault on the PCB in the valve and assume some suffer from higher ambient temperatures than others.

 

[reluctanthandyman1]

Thanks for that.
As Matt1e has said - he thinks it is some sort of electrical/wiring issue. I can't believe that this problem has occurred 3 times in 6 months (with the valve changed at each occasion) and it is down to a fault with the valves themselves. Once or twice perhaps, but 3 times? No one is that unlucky.

Do also think it is a wiring/electrical issue?