Inside a Central Heating Zone Valve Actuator

[@peteg5389]

Thank you so much for such an excellent and well presented video. I knew nothing about central heating systems or how they worked until I watched your video. My boiler would turn on when required but wouldn’t turn off. By watching your video I had the confidence to look inside my HW flow valve actuator to discover that both plastic lugs holding the springs in place had snapped, so the springs weren’t attached and so unable to close the valve / micro switch when the power went off and hence leave the boiler running. Rather than pay the £300 that I was quoted to have it diagnosed and fixed - I diagnosed it myself & with 2 plastic coated screws fixed it myself - even if this doesn’t last I know how to replace the whole actuator for about 40 pounds but more importantly I know far more now about how my central heating system works so feel I have been well educated thanks to your clear and concise video! many thanks

[@theoldgod9]

congrats!

[@chester6343]

Your vids are so helpful, seriously if we internalised everything you teach we wouldn't need to go on any courses lol, people take the piss out of watching KZbin videos for trade related problems and applying that knowledge at work but it's so narrow minded, back in day if you had a problem on your car you had to get a Haynes manual and fuck around, these days literally any problem you have you can just KZbin it and watch a video of someone dealing with the exact problem you're having. So lucky.

[@richardstone9224]

Hi John, I’m currently studying towards my level 3 plumbing and found these videos on 2 port valves very helpful. My tutors aren’t giving us much insight into how things work and how to diagnose problems, so thank you for all your help. Keep them coming 👍

[@brianmatthews9049]

Followed the strip down and found 1 spring had become unattached. That’s why it seemed to be working but wasn’t. Brilliant description John

[@MrImarcus]

I watched your vid last night and have subsequently fixed my heating which would have been impossible for me to do without understanding how the valve worked. absolutely brilliant. Thankyou very much for going to the trouble of doing this. I am in your debt sir.

[@tonysmith1736]

I've just fixed ours thanks to this video. What helped in my case was the part number on the microswitch visible at 04:59, which cross references to RS part 161-6640. The switch was unmarked on ours, so this saved me measuring everything and hunting around for a physical match. The RS part is an exact fit and only £2.70.

[@theoldgod9]

Great stuff!

[@eldridism]

Thanks. My boiler and pump were running continuously. Watched this and opened mine. The microswitch was half way pushed in all the time and had some black gunk on it. Pressed it in and out a few times with a screwdriver wiped the gunk off with a cotton swab and all good now its working as intended.

[@markhummerstone7206]

Many thanks for this JW. We have had problems with our CH for the last 20 years. Turns out it was incorrectly wired plus a residual voltage from the Y valve firing up the boiler. A head scratch and suppressor later, all is well.

[@colinhoward9402]

Brilliant video which allowed me to diagnose the fault with my valve. One of the springs had detached because the plastic peg it had originally been fixed to had broken off. A small self tapper araldited into place solved the problem. Many thanks for his invaluable information, John.

[@WonkyWoodworker]

Thanks for this, brilliant. Helped me prove the valve mechanism in the pipes was sticking and the valve electronics were all working properly.

[@Spaldingcrow]

Hi John. Watched this vid cos I was having to manually close the valve. It opened OK but would not shut off. Then the little black plastic bit snapped off so I had to take the cover off to get to the bit of metal and push it down to close the valve. Watching this vid made me realise that the bit of metal I was pushing should have had a spring attached but it was missing. I found it on the floor, attached it with a cable tie (the plastic pin had snapped and left a handy hole) and hey presto - working actuator valve. I know it won't last forever but I brought some time. Thanks for the vid.

[@abdulh63]

love your channel! the fact that you take things apart makes it so much easier to understand how it works

[@roberthuntley1090]

I think that the manual lever only opens the valve half way because it is a common part with a three way valve (in which it is desirable to do this). Having both output ports open on a three way valve makes it easier to bleed air from all parts of the system.

[@Graham_Langley]

I've just had to fit the mid-position version of this valve to replace an old blue Switchmaster that suddenly developed a 1l/week leak from the spindle. From the hand-written date the motor on it it's been in use for 37 years and I somehow doubt the new one will last anywhere close to that. The base moulding of the new Drayton looked identical to the one you show here, so it seems they've designed the moulding for use across the range of 2 port, 3-port mid-position and diverter valves. If you look there are slots for the vertical snap-in PCB used on the mid-position valve and this commonality probably explains why the manual actuator only opens the valve half-way - on the mid-position version it opens it to the mid position for filling and bleeding the system.

[@hjhogg6381]

Excellent, Now I know how the springs are fitted, the plastic pegs had broken. Will strip it down & a DIY fix should cure the problem. Thanks again.

[@MrM1neill]

Just watched this video and then proceeded to fix my valve assembly. Thanks for making this video. I watched the video and then took mine apart and the plastic lug that holds the spring in place had snapped. I made a little repair and its working fine now. Understanding and seeing how the valve worked made the job much easier. Thanks again

[@ColinRichardson]

Thank you, I don't particularly care much about boilers, but this whole series has informed me so much. I kinda wanna take my boiler apart just to see all the parts... But my other half would kill me.

[@alassady78]

Great video, thanks to you I was able to fix my jammed actuator and actually put it back!

[@richardmarkham8369]

Just had one of these fail open so CH was on all the time. One of the return springs just fell off! The plastic peg that it should be attached to broke off. I guess they use plastic that can't cope with the heat without going brittle. What a great design!

[@Graham_Langley]

I see this one has a one-piece motor and gearbox so you can't replace the motor on its own. They do seem to work on a thermal knife-edge, particularly when installed in an airing cupboard next to the hot water cylinder as they usually are. If anything makes them run a little bit hotter the motor coil goes open-circuit - a towel dropped on them usually does the trick IME. At least on this one they've added a heatsink, although cooling the motor via the gearbox isn't the best arrangement.

[@Jammoko]

Yer, thanks for that... most interesting; just fixed my MA1. The spindle on the valve was dry and siezed; some WD40 and then some oil freed it up enough for the MA1 to move it. I was surprised to see that tyere is not much movement on the spindle... only about a 20% throw! But I can feel the stops so I presume that's normal! it appeared the the MAi was OK. Oh, is that an M102 in the background :) I have the A100... perhaps I should have used some Hammond turbine oil? lel

[@sukie230]

A Fantastically informative video. A great public service as these are very commonly used valves and seem to commonly fail!! I replaced the motor about 3 months ago & now I think it's the micro switch!! What ever next!!? I regrettably blamed the missus for leaving the heating on all day!! Thanks again.

[@AnthonyFrancisJones]

Absolutely brilliant - problems with ours - I feel I now fully understand this simple but annoying device when you need to be warm on a cold night!

[@harmandeepcom]

Your video saved my £100. I managed to fix heating issue without calling any expert. :) thanks!

[@paulmorris8068]

Excellent video John, heating is now back up and running.. thank you very much.

[@jacktheplumber7164]

Are you this funny in real life? Or just have this canny knack at making your tutorials so enjoyable! I use your videos for training students and always end up smiling Jack the Plumber - Birmingham

[@SimonGipson]

Another happy viewer! Your video gave me the confidence to take the cover off and take a look at why it wasn't switching fully. It now seems to be working properly again.

[@barrywatts8501]

Thats the valve i need to change or fix. Excellent video just what i needed. Thank you very much for up loading 😀

[@erikboens960]

Hello, I am from Belgium and thanks to your video I have been able to make our heating this morning. Your video was very clear.

[@nicodavies3725]

Grey is the perm live for the micro switch Brown is wired to the same terminal as the room thermostat so once the room drops below the set temperature it allows current to flow down the brown which then powers the motor which then activates the live switch (orange) and allows the perm live to send current down the orange which then tells the boiler to ignite and get going

[@SteveMayne1]

Had wondered how much power was used to keep the valve open, though what a terrible waste of energy. I guess the spring return keeps the manufacturing cost of the device down. Thanks for explaining how the device functions.

[@longinus3333]

Thanks very much, understanding the operation gave me the confidence to investigate. Found both motor screws very loose and so the motor was not always engaging on to mechanism. This also explained the loud clunk when it lost engagement during operation. All now working correctly thanks for taking the time with this vid.

[@whitefields5595]

It is important to stress that these valves must be open before the boiler and pump fire up. If somehow that microswitch signals the boiler and pump with the valve shut then the hot water has nowhere to go and it all ends in tears! You are right to suggest changing the whole motor head as a unit as if the motor has failed other items like the switches may have failed too. Once on the bench you can figure out what the fault was and salvage some spares.

[@mickkitcher1273]

John, Great video, really helpful. I'm having trouble diagnosing whether or not my mid position valve is operating correctly, do you or can you do a similar demonstration for the three port one, it would be really helpful?

[@jeremylister89]

So, fully open the motor is effectively stalled, so just sits there getting hot? Excellent video. My fear has left the building! 20 mins later.... My problem: one valve that fills hot water cylinder does not appear to close fully, so when central heating is on, I also end up with scorching hot water, and I'm wasting money. Will replace the motor assembly...maybe on both. The guarantee ran out 15 years ago! Also checked that the mechanical valve is not seized. this seems ok, nice and smooth.

[@jwflame]

Make sure the valve does actually close without the actuator on - they normally have a rubber disc or ball inside which is what seals when closed, they can deteriorate so the valve never closes properly.

[@jeremylister89]

@@jwflame Thanks John. When I manually opened the hot water valve it didn't shut properly compared to the identical central heating valve maybe springs..? I've ordered two replacements at a very reasonable £39 each Inc vat. When they arrive I can check if there's any difference in valve resistance/ smoothness. If there is it's drain the system time and change the body as well as actuator.

[@thomasfrancis5747]

My Drayton MA1 packed up - motor ran, lever moved but central heating boiler would not fire. Turned out to be worn cam/microswitch. Found it cheapest to buy actuator with brass valve rather than just the actuator.

[@e.g.systems6146]

Brilliant. Clear and accurate, and covered everything I needed to know. Thank you!

[@Phiyedough]

My own valve is a Drayton MA1 which is a mid position actuator but I only use it to switch between hot water and central heating. It works if I connect mains direct to the motor but not if I connect it normally. It has 2 microswitches and I suspect one of those has failed but I don't understand what they do. From what you say the motor remains powered up but stalled when in the right hand position. If this is the case I could ignore the other wiring and just connect new wires from hot water thermostat to the motor(when the hot water reaches temperature the stat powers the diverter valve).

[@jwflame]

3 port valve explained here: kzbin.info/www/bejne/fGbQaZlsfbNli9U you can't just connect the motor directly as that valve has 3 positions and one of the switches in the valve is what activates the heating.

[@Phiyedough]

@@jwflame As I said, I don't use the mid position setting anyway. I have wired the thermostat direct to the motor and the valve is now working fine.

[@hiralpatel9518]

Hi John, thanks for this video. My radiators keep running and giving heat despite the heating being turned off from the thermostat and programmer. What could the issue be?

[@jwflame]

Valve has jammed open

[@zapfish63]

A few notes after a bench test of a new actuator in case anyone finds them useful: the manual selection lock DOES NOT close the microswitch; the microswitch does not close until power is applied to the motor. I don't think the documentaion makes that clear. This means that, although the manual selection lock will (partially) open the valve, it will not cause the boiler to come on. Also, applying of power overrides the manual selection which is lost when power is later removed.

[@robertjohn819]

Hello John I found your video on the central heating actuator switch very useful as my switch is at the very back of the heater cupboard and facing the wrong way. So finding your work was a blessing. Thank you. Oh I subscribed to look at more of your vlogs . Plenty of useful things there. Cheers Rob.

[@davidhume5454]

Thank you for a clear demo. The microswitch can also be a problem ? - central heating continues to run despite thermostat control switched off

[@jwflame]

Yes, if the switch sticks closed, the heating will run continuously even if the programmer and thermostats are off.

[@flypic1098]

Superb video. Very clear and easy to follow. Thank you very much.

[@addz91]

The Grey is a permanent live, and the Brown is a switch live (demand).

[@agaw3484]

Hello, I have the MA1, what does it mean if it's stuck in CH (and can't be moved manually either by pushing the lever at the back)? It fails to move to DHW position when CH is no longer being called for and when only hot water is being called for, as well as not returning to DHW position when the motor's deenergised (power to the circuit box in the water tank cupboard is turned off by flipping the fuse switch next to it). There is no hot water in the tank so that side of things is not 'satisfied'. Both the heating and cylinder stats are on. I would REALLY appreciate if you could give an idea what might be wrong as I can't figure out whether it needs to be replaced or not, many thanks! 🙂

[@jwflame]

Either the actuator has failed, or the valve has seized. Remove the actuator, the valve spindle underneath should move freely. If it does, then it's just a new actuator. If the spindle doesn't move easily or at all, then the whole valve will need to be replaced.

[@agaw3484]

Thank you!

[@hal-rekabi6724]

This part failed three times on me on as much years it really got me crazy! The micro switch keeps burning out

[@TheF774]

# You can replace the micro switch, Maplin have a suitably switch Part No GW69A you have to superglue the new switch in after soldering the two wires. The cost of the switch...£1.99 which makes me very happy.....

[@evanofelipe]

Thanks for your detailed explanation of how a two port valve essentially operates but I am trying to understand one aspect and that is, when the synchro-motor has fully moved the actuator lever to open the valve and turn on the micro-switch, that in turn powers up the pump, what prevents the motor gear from continually rotating, it having reached the lever’s full extent? Is there an internal clutch within the motor that allows the gear wheel ‘to slip’ and prevent it from mechanically damaging the cogs? Is that why, when the motor is operating it generates heat?

[@jwflame]

It's just the mechanical stop which prevents the lever moving further, the motor is stalled. There is no clutch.

[@100SteveB]

What was rattling about inside, John? Did not see anything that was loose.

[@jwflame]

+100SteveB Motor mounting screws were loose.

[@carolflynn1889]

my zone valve activator is on the 'A' signal but the hot water continues to flow through it into the water tank and the water is getting too hot. It seems to be heated both directly when the hot water 'boiler 'function is on but also when the central heating is on and the hot water part is off. does this mean that the pipe below is jammed open or could it just be that the valve is broken and reverts to close on the plastic switch while the port in the pipe remains open. Is this likely in the case of a hot water feed pipe.??? Any comments would be appreciated

[@bcp64no]

Cheers John. Watching the video helped my understand the mechanics of the 3 position valve which was only setting to W and M and not getting to H. Some how I managed to free the valve using the lever and now we are set to H only but at least we now have hating and hot water which we haven't had since coming back from a holiday! Have I managed to manually override the valve/switch? And it is now always open? I have a Drayton similar to what you demonstrated but a three way. Cheers.

[@jwflame]

Manual should be M which is both outlets open. If you have both heating and hot water it isn't actually at H even if the indicator is, so it's likely the internals have been damaged in some way.

[@7john7able]

I watched this video because my valve was warm and making a humming sound, but everything still works. Was interesting video set my mind at rest because if I understood everything correctly this is normal.

[@antok1794]

Thanks John, replaced my 2 port valve head as the old one seized, the original valves orange & grey wires didn't have any connection just L N & E. So no signal back to my boiler i guess, I have 3 of these valves in the house, upstairs, downstairs & hot water all wired the same, also have two wall thermostats one up one downstairs. Does this mean my boiler only gets a signal to turn on from the timer control or the thermostat? And is this S Plan wiring done wrong?

[@kevinbeck6785]

Thanks John had to watch a couple of times but video very helpful.

[@dechristi]

Thanks John, another brilliant money saving video, really appreciate these, cheers.

[@omgffsification]

Next you could do the 3 port mid position valve. Its got slightly more complex electronics and fails even more often!!

[@montydod]

well done again jw

[@SuperLittleTyke]

Does a Danfoss HS3A actuator look very similar to this Drayton brand inside? Thanks for the video!

[@samrahman6413]

Fantastic video, brilliant explanation thanks made my life a lot easier

[@rodneythompson7386]

Although it's not a very good design, just replaced mine after about 17 years, water leaking up through spindle tripped rcd , can't complain. Hope this may help someone with same problem.

[@hypojames]

Thank you for your comprehensive video.

[@Kaizer10155]

Can you use orange and grey as volt free switching ? Are they separate to the 230V from the brown and neutral. for example stat powers the brown of the valve pulls its across to the SL of the orange to make a connection with grey?

[@jwflame]

Yes, the switch is totally separate from the motor connections. Example in this video: kzbin.info/www/bejne/pIC0aY17nbh_eqs

[@jc-d7886]

A really helpful video. Thank you 👍

[@paulmcgee3555]

Great video thank you. I'm trying to wire mine in. So do the grey and orange wires need to be connected to a live port in the junction box? And is that the port with the red wire or the black wire going into it?! Thank you

[@jwflame]

Wiring is covered in this series of videos: kzbin.info/aero/PLVsHvs2Suqmr5HtxgbInR4bXmH0kLseWc

[@AB-oc5lj]

Excellent as always. Thank you John

[@Tangobaldy]

Hey JW is back

[@AJ-is2dh]

Hi I have a question, please help so I know my za5 valve is faulty because it's not flicking back when my timer turns off and it's leaving heater hot.. but do I need to change motor or change full za5 valve?

[@jwflame]

Take the actuator off. If the spindle underneath is easy to turn, then it's just a new actuator. If the spindle is jammed or very stiff to turn, it's a whole new valve and actuator. The spindle only moves about 1/4 of a turn between open and closed.

[@AJ-is2dh]

@@jwflame it's the spindle it's very stiff to turn. I can change it myself but I been advised I need to flush? How do I flush?

[@bigtom1001]

Hi john,very good job☺ how important is the "actuator code"? the faulty one i have is an MA1, i have found a ZA5 at an almost giveaway price, would i be able to use it?or does it have to be an MA1?,.

[@jwflame]

You need the MA1 which is for a 3 port valve. ZA5 is for a 2 port valve and is completely different.

[@bigtom1001]

@@jwflame Thanks for the help.

[@rcairtechuk5695]

i agree clear well spoken very accurate every think i needed to know Thanks

[@musicmaestrodj]

My valve gets stuck and you can't slide the manual tab at the bottom as it won't move at all. Funny part is, if I tap the valve with a hammer, you hear a 'click' and then the ticking starts and the tab starts to move. It get stuck like this all the time. What do you think the problem is? THANKS!

[@jwflame]

Valve has probably deteriorated inside. There is usually a rubber ball or disc which seals the water inlet and when the rubber gets old, it becomes sticky and can jam in one position or the other. Solution is to replace the whole valve.

[@musicmaestrodj]

Thanks John. I figured it was most likely something like that. I wished it wasn't something that required actual plumbing so I could do it myself; oh well...

[@DJBaldPaul]

@@jwflame I have exactly the same problem, gets stuck on M, if I wiggle the head a little it "clicks" the lever moves to H, the pump starts and the boiler fires. Was hoping I could just change the head but sounds like the whole valve needs changing. It is 20 years old so guess it's getting sticky. :-(

[@BG-oj6zt]

Is it normal for the unit to be warm???

[@jwflame]

Yes, the motor uses about 6 watts, and most of that ends up as heat.

[@BG-oj6zt]

@@jwflame Thanks.

[@phlize]

You don't mention what exactly the microswitch does?? I think I have a faulty one but I'm not sure what it does?

[@jwflame]

It's a switch - joins two wires together in one position, and doesn't in the other position.

[@phlize]

@@jwflame Yes but I was wondering what it is switching in this context.

[@jwflame]

@@phlize The switch controls the boiler, when the valve is open the switch activates the boiler. Explained in other videos in this series, kzbin.info/www/bejne/jGrVf2h6YtyEf8U

[@david-ky7rt]

Great Video John. Thank you.

[@paulhughes3524]

Very well explained

[@noblinking]

Thanks. Very good explanation.

[@sv3nsp]

Excellent explanation. Unfortunately, the design of this actuator is insufficient. Both springs are each attached to a plastic pin on one side. Plastic and heat don't mix well and the pin breaks. I hadn't noticed that when my installer replaced it. When the second broke, I was able to easily fix the first with a bolt. There was more wrong with the second. A small (internal) piece of the black lever for manual operation had broken off as a result of which a tooth of the gear has broken off or vice versa. Anyhow I reckon the design is not durable.

[@abdulhafiz6923]

Very well explained. Thsnk you

[@davidcolwell1577]

GREAT video! Thank you!

[@rodneythompson7386]

Thankyou JW.

[@stefantrethan]

Is it possible they made the manual lever like that so it resets as the motor moves once? We are chasing every milliwatt in power supply standby losses and things like this are still produced, crazy!

[@Graham_Langley]

+stefantrethan That's exactly how it's meant to work. Every one I've seen resets like this. It's really only meant for use when commisioning the system to help with filling and bleeding and, as John points out, it doesn't open the valve as fully as the motor does on this model. But it does open it enough to operate the microswitch and so fire up the boiler.

[@LWSElectricalTonedale]

Very helpful thanks John

[@dalstonjazz]

What's the power block you use? I need to get one.

[@jwflame]

Cliff Quicktest QT1, amzn.to/2ogcKqO

[@dalstonjazz]

Thanks John - I see it's a common question...

[@jeremytwigg4000]

Thanks very informative.

[@williammcgrattan9583]

Nice video john. 👍

[@SproutyPottedPlant]

Love this channel!

[@popbob4100]

Thank you very much

[@kingmonkey88]

Are these things just a bad design? Having the motor powered on to hold spring open, the valve is not spring loaded. Just have a motor that opens and closes the valve. Should be much more reliable.

[@fardellp]

Can't think why they don't just use a solenoid valve - 12V for safety.

[@fardellp]

Well thinking about it - perhaps a solenoid would bang on and off very quickly - possibly cause water hammer of some kind? At least with that motorised valve it would open slowly. Not much of an argument against solenoids though...

[@joanofarc708]

Thank you

[@mc_cpu]

my system doesn't have any valves instead it uses two pumps to control the flow.

[@Graham_Langley]

+mc349iii Pump manufacturer Grundfos did a double pump called Pump Plan but it seems to have disappeared from their product list. Its stated advantages were you could have different pump settings for CH and HW and there was no motorised valve to fail. But it seems the integral one-way valves failed instead.

[@mc_cpu]

+Graham Langley mine are just two standard pumps either side of the hot water cylinder, one pumps the boiler heat exchanger loop.the other does the CH loop. I've replaced the boiler pump twice in 20 years the other is still the original only used half the year so I suppose it gets less wear.

[@Graham_Langley]

+mc349iii That sounds like it could be a thermal store?

[@rayhumphreys9688]

Thanks very useful

[@harmandeepcom]

Great, very useful

[@TDJDriftersBoss]

Quite a poor design imo, keeping that motor powered when it hits its limit is a very primitive and outdated method

[@andynorman9738]

They are all like that, when the motor is stalled its inductance increases causing a dramatic reduction in current flow.

[@MontyVideo969]

Brilliant explanation! Thank you for taking the time to shoot this video. Our boiler makes an awful droning sound on first "heating" demand in the morning. Turning on a hot tap stops the noise for a while which then recurs. The diverter valve was replaced in September and "fixed" the noise for a month or so until the beginning of November. Just wondering whether the droning is the diverter valve actuator or something else? Here's my post from April. kzbin.info/www/bejne/aIS0p3Zqn5tjbdk Any thoughts on this annoying problem?

[@geeman3683]

Thanks sir

[@guitaraflamenco]

Why so much emphasis on the final word of each sentence?

[@sulimanmasoud9337]

You speak vary fast. We you fit back the valve should at what position was not explain.