Trying to fault find Honeywell Y-Plan system
- Thread starter The Jeep
- Start date
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They've been floating around the internet for quite a few years now!
There's a little more to it, in that a 4073 has about 4 resistors in it. I drew it once a long time ago in a far off place... I'll have another go. Something interesting to do in front of the telly.
There's a little more to it, in that a 4073 has about 4 resistors in it. I drew it once a long time ago in a far off place... I'll have another go. Something interesting to do in front of the telly.
I got them off this site about a year ago. There was a long thread - you might find it if you search here on mid-position valves and check out the long threads. Apart from the diagrams there were many words of wisdom - I wish I'd kept a link.The Jeep said:
I've had a quick glance through the drawings and am a bit puzzled in places, perhaps unsurprisingly as, though I know something about electrics, I am new to these controls.
It seems that the opening and closing of the room stat is not indicated (it seems to remain closed), though the red voltage line does that, I guess: just a tad confusing.
It would be very useful to have accompanying text describing what's happening, particularly to the valve position, at each stage. And in particular with relation to the 'valve hold' mode.
The two switches within the valve head are presumably the micro-switches, but it's hard to relate them to the ball position/port opening, as this is not shown.
Anyway, all very interesting and I shall study the drawings in more depth later. Any and all further clarification most welcome!
It seems that the opening and closing of the room stat is not indicated (it seems to remain closed), though the red voltage line does that, I guess: just a tad confusing.
It would be very useful to have accompanying text describing what's happening, particularly to the valve position, at each stage. And in particular with relation to the 'valve hold' mode.
The two switches within the valve head are presumably the micro-switches, but it's hard to relate them to the ball position/port opening, as this is not shown.
Anyway, all very interesting and I shall study the drawings in more depth later. Any and all further clarification most welcome!
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Looking at the diagram, I cannot see how we can end up with a low voltage eg: 100-180v on the orange boiler feed, because the diode would be disconnected on one of the Xover switches in the valve head. Are you sure the diagram is right or have I missed something?
Thanks for the link, I'll check it out shortly. I have just acquired a damaged power head to play with. Apparently the electrics are fine, just the mechanism is sh@gged.
By the way, the only place I've seen mention of 100V on the orange wire is in Honeywell's own blurb. Could be a mishtake...? Still waiting to hear from them regarding that issue - no reply to my email yet though.
By the way, the only place I've seen mention of 100V on the orange wire is in Honeywell's own blurb. Could be a mishtake...? Still waiting to hear from them regarding that issue - no reply to my email yet though.
Hi guys - done my cutting and pasting (finally got drawings in correct order, with correct blurb - thanks). However, in trying to identify my client's problem, the sequence is somewhat reversed. Let me explain:
If he starts with CH only on, then it seems the valve will be fully diverted to Port A open due to the 240V on the grey wire (from DHW off). The 240V from the room stat will go via the microswitch(es) on the valve to the orange wire and hence power the boiler/pump.
If the timer now switches on the DHW then the 240V on the grey wire disappears, the valve starts returning under spring force and is stopped at the mid position due to the first microswitch and 240V on the white wire from the room stat going to the diode then the motor (interesting stuff about the DC braking effect on an AC synchronous motor in linked post!).
So there we are at the illustration from Chrishutt on the previous page, both CH and DHW calling for heat and the valve held mid position. But now suppose the room stat is satisfied (cylinder still calling) and the 240v on the white wire disappears. All voltage to the motor will also disappear, causing the ball to return to it's default Port B DHW only open position (thus it seems that the valve hold function only applies to the cycling of the cylinder stat - am I right?).
Now this is exactly where the problem kicks in: the room stat 'on' indicator stays a-glow - even when the dial is turned down manually - and the CH goes up & up uncontrollably (i.e. the house gets too hot). This must mean that the valve is still open to Port A, despite the room stat being satisfied, and the 'on' indicator would indeed suggest voltage still on the white wire, and therefore the diode circuit.
This is beginning to sound like a fault with the room stat, though this has been changed since my client inherited this problem when he bought the house.
Or perhaps the valve is sticking in mid-position....now that I think about it, whenever I moved the power head lever from auto to manual, I don't recall feeling any resistance for the first half of the lever's travel. Being new to this, I never gave it any thought, but now that may indeed indicate a stuck ball. Sound feasable?
I'm going back tomorrow to work on it. The stuck ball idea makes some sense: is this a common thing to happen? If so, is it likely to require a change of power head or valve or both? Thanks again guys, I've learned a lot of good stuff here and may be close to cracking it!
If he starts with CH only on, then it seems the valve will be fully diverted to Port A open due to the 240V on the grey wire (from DHW off). The 240V from the room stat will go via the microswitch(es) on the valve to the orange wire and hence power the boiler/pump.
If the timer now switches on the DHW then the 240V on the grey wire disappears, the valve starts returning under spring force and is stopped at the mid position due to the first microswitch and 240V on the white wire from the room stat going to the diode then the motor (interesting stuff about the DC braking effect on an AC synchronous motor in linked post!).
So there we are at the illustration from Chrishutt on the previous page, both CH and DHW calling for heat and the valve held mid position. But now suppose the room stat is satisfied (cylinder still calling) and the 240v on the white wire disappears. All voltage to the motor will also disappear, causing the ball to return to it's default Port B DHW only open position (thus it seems that the valve hold function only applies to the cycling of the cylinder stat - am I right?).
Now this is exactly where the problem kicks in: the room stat 'on' indicator stays a-glow - even when the dial is turned down manually - and the CH goes up & up uncontrollably (i.e. the house gets too hot). This must mean that the valve is still open to Port A, despite the room stat being satisfied, and the 'on' indicator would indeed suggest voltage still on the white wire, and therefore the diode circuit.
This is beginning to sound like a fault with the room stat, though this has been changed since my client inherited this problem when he bought the house.
Or perhaps the valve is sticking in mid-position....now that I think about it, whenever I moved the power head lever from auto to manual, I don't recall feeling any resistance for the first half of the lever's travel. Being new to this, I never gave it any thought, but now that may indeed indicate a stuck ball. Sound feasable?I'm going back tomorrow to work on it. The stuck ball idea makes some sense: is this a common thing to happen? If so, is it likely to require a change of power head or valve or both? Thanks again guys, I've learned a lot of good stuff here and may be close to cracking it!
I think what you're saying sounds right (!)
Several odd things can happen, such as -
diode "goes" so the valve hunts to and fro in mid position instead of stopping. This can wear the spindle. That can make it leak, and that can make it stick in the middle. Sometimes it makes a little burr.
Or one or other of the microswitches can go intermittent. or not switch at quite the required position, on or off. That has odd effects. The one I may dismantle, was switching wrongly (though both switches switched) such that the valve would go from HW only to Mid, and back, properly, but after being at CH only, it only went back to Mid. So they complained that sometimes the rads got hot when they shouldn't. Whether it was actually a faulty switch , or one off the bits of tatty metalwork not quite right, I don't know.
Another bijou factoid, while I'm dribbling. You know the mending kits with the ball and plate? Well the 2 port and 3 port ones have a different part number, but I've compared, measured and swapped them, and I say they're identical.
Several odd things can happen, such as -
diode "goes" so the valve hunts to and fro in mid position instead of stopping. This can wear the spindle. That can make it leak, and that can make it stick in the middle. Sometimes it makes a little burr.
Or one or other of the microswitches can go intermittent. or not switch at quite the required position, on or off. That has odd effects. The one I may dismantle, was switching wrongly (though both switches switched) such that the valve would go from HW only to Mid, and back, properly, but after being at CH only, it only went back to Mid. So they complained that sometimes the rads got hot when they shouldn't. Whether it was actually a faulty switch , or one off the bits of tatty metalwork not quite right, I don't know.
Another bijou factoid, while I'm dribbling. You know the mending kits with the ball and plate? Well the 2 port and 3 port ones have a different part number, but I've compared, measured and swapped them, and I say they're identical.
Can you post that, Jeep, to save us having to do the same thing?The Jeep said:
With reference to your problem, it certainly does sound like a roomstat problem. Could the replacement (and even the original) have been wired wrongly so the neutral and switched live (blue and yellow wires usually) are the wrong way round?
chrishutt said:
Er, you're going to think this a bit mad in this age of word processing, but I actually cut out and pasted the text beneath the drawings using Pritstick!
However, I will do an electronic version (as it is useful and took me a while to figure out!) and post it somehow (have to figure out how to post attachments as haven't done this before).
Getting back to my 'problem', or rather my clients', I have a spare room stat which I can try out today and I will also be investigating the valve head to see if the ball ever returns fully to its rest position.
Chris R - no, I'm not aware of the mending kits...can you clarify please? Ta.
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