Re: What's 0 on boiler pressure gauge mean?

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Set Square wrote:

Another thing to check is the position of that leaver on the side of the valve. In one position the valve will operate normally, in the other it will be locked into the mid position (thus allowing manual intervention to get some useful operation should the valve control electrics fail in some way).
Also check the room stat does actually generate a signal. With most it is possible to hear a click when you rotate it back and forth around about the current room temp. While the "click" is not a guarantee that it is working, not getting any would be a good indication it is not.

<snip good procedure for checking valve body>

Is your boiler overpressure release valve still leaking? If you are unsure, then tie a small plastic bag round the pipe with a rubber band and see if it collects water.
--
Cheers,

John.

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Okay guys, first thanks for your ongoing help. We're getting closer.
1) I have replaced the Danfoss 3-port valve actuator for a new one, but no difference. It works the same as the previous.
2) The valve itself doesn't appear to be stuck, as the actuator lever successfully moves it around. However, it always returns the level to a central position, no matter whether the wall timer is on CH or HW.
I am not quite experienced enough to own a multimeter, but here is what I found using an electrical screwdriver to test signals in the junction box, where the valve actuator is connected to all the other wiring:
Valve wire: Blu Org Gry Wht CH On 0 0 1 1 HW On 0 1 1* 0 Both On 1 1 1 1 *on electrical screwdriver, light was blinking not solid
Does the system appear to be wired correctly?
3) I have looked at the hallway wall stat, and provided a photo of the wiring here:
http://www.cjse.pwp.blueyonder.co.uk/images/IMAGE_00188.jpg
As you can see, the Blue is connected on the left, and the Brown and Yellow are in the *same* terminal. Is this correct? :-S Also, the Earth you see at the bottom appears to be loose and the 3rd terminal from the right is unscrewed.
Here is how the electrical screwdriver responds to the stat, which does click when turned:
Wire: Blu Brn Yel On 0 0 1 Off 0 0 1 *on electrical screwdriver, light was blinking not solid
Is this our problem?
Thanks!
size=2>...</FONT></DIV><FONT size=2>&gt; Set Square wrote:<BR>&gt; <BR>&gt;&gt; As John Rumm told you many days ago, you have a problem with your<BR>&gt;&gt; mid-position valve. The chances are that the 'wet' part of the valve is<BR>&gt;&gt; stuck in roughly the mid position, but not far enough round to operate the<BR>&gt;&gt; microswitches in the actuator. In this condition, the boiler and pump will<BR>&gt;&gt; be controlled by the HW output from the programmer and the cylinder stat -<BR>&gt;&gt; but whenever the boiler is firing, both HW and CH will get hot. The CH feed<BR>&gt;&gt; from the programmer - which goes via the room stat - will have no effect<BR>&gt;&gt; because that only controls the boiler *after* the microswitches in the<BR>&gt;&gt; actuator have operated.<BR>&gt; <BR>&gt; Another thing to check is the position of that leaver on the side of the <BR>&gt; valve. In one position the valve will operate normally, in the other it <BR>&gt; will be locked into the mid position (thus allowing manual intervention <BR>&gt; to get some useful operation should the valve control electrics fail in <BR>&gt; some way).<BR>&gt; <BR>&gt; Also check the room stat does actually generate a signal. With most it <BR>&gt; is possible to hear a click when you rotate it back and forth around <BR>&gt; about the current room temp. While the "click" is not a guarantee that <BR>&gt; it is working, not getting any would be a good indication it is not.<BR>&gt; <BR>&gt;&gt; Remove the actuator from the valve (2 screws). This will reveal the valve<BR>&gt; <BR>&gt; &lt;snip good procedure for checking valve body&gt;<BR>&gt; <BR>&gt;&gt;&gt;2)&nbsp;&nbsp;&nbsp; Boiler loses pressure slowly.<BR>&gt;&gt;&gt;<BR>&gt;&gt; <BR>&gt;&gt; Sounds like you've got a leak, like we said earlier.<BR>&gt; <BR>&gt; Is your boiler overpressure release valve still leaking? If you are <BR>&gt; unsure, then tie a small plastic bag round the pipe with a rubber band <BR>&gt; and see if it collects water.<BR>&gt; <BR>&gt; -- <BR>&gt; Cheers,<BR>&gt; <BR>&gt; John.<BR>&gt; <BR>&gt; /=================================================================\\<BR>&gt; |&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Internode Ltd -&nbsp; </FONT><A href="http://www.internode.co.uk "><FONT size=2>http://www.internode.co.uk </FONT></A><FONT size=2>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; |<BR>&gt; |-----------------------------------------------------------------|<BR>&gt; |&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; John Rumm - john(at)internode(dot)co(dot)uk&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; |<BR>&gt; \\=================================================================/</FONT></BODY></HTML>
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In an earlier contribution to this discussion,

Who knows?! An electrical screwdriver with neon indicator is about the *least* reliable way of determining what's live. [In the absence of a voltmeter, copping hold of the bare wire is far more accurate - but not to be recommended <g>]
With HW-only on and the cylinder stat not satisfied, the *only* live wire should be the orange. When the cylinder stat is satisfied, orange should go off, and grey should come on.
With CH-only on, Grey should be on, White (or brown/white depending on the actuator) should be on when the room stat is not satisfied, and should go off when the room stat is satisfied. Orange should follow white - being switched by the actuator itself.
Don't worry about both together yet - let's sort the basics first!

Not the best of photos, is it! The brown and yellow should *not* both be connected to the same terminal. This is simply by-passing the stat so that it is effectively in the not satisfied state regardless of setting and room temperature. The yellow wire should be one or two places to the left depending on the internal workings of the stat.

Well that just demonstrates how useless an electrical screwdriver is! Brown and yellow are connected togher, so how can one be live and the other not live, for God's sake?

From what I've seen so far, I wouldn't trust *any* of the wiring without going through it with a fine tooth comb and working out exactly what is connected to what - particularly in the 10-way junction box, assuming there is one.
I fear that you're going to have to get someone who knows what he's doing to look at it. What part of the country are you in - someone here might like a challenge, or an excuse to escape from the Christmas spirit?!
--
Cheers,
Set Square
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I tried that and nothing happened <g>

This appears to be what happens. We can ignore the "1*" above as I think that means it is picking up a weak signal nearby, not actually from that terminal, so I have:
Valve wire: Blu Org Gry Wht CH On 0 0 1 1 HW On 0 1 0 0 Both On 1 1 1 1

This ties in with you realising that the room stat is permanently satisfied as it had been wired to be so.

I have now tried yellow on both places, and the stat still has no effect on the new valve which remains in the central position at all times, serving both HW & CH.

Sorry, it was implied that Brown was on as it was connected to Yellow, my mistake was at first I thought Brown was on the terminal to left of yellow, which was "0" off.

There is a 10-way box, but I'm not up to analysing it :-S
I'm hoping from the new info above, and that the new valve stays midway even with the stat wired apparently correctly, you will be able to give me some things to try?

Okay, or that option is good :) I'm in SW London (near Richmond, Surrey) if anyone is up for sharing their expertise. Will make it worth their while ;) ;)
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Hi guys
You will recall my great photo of the wall stat wiring here:
http://www.cjse.pwp.blueyonder.co.uk/images/IMAGE_00188.jpg
When the BG engineer fixed the wiring the other day, as well as changing some wires in the junction box, he also moved the red/live wire from pin 2 to pin 1.
When installing a new stat today, I removed the blue wired from pin 4 of the old stat, and the stat still operated the heating perfectly, with just the red and yellow wires in place.
My new stat only requires 2 wires also - ON and COM (N/L).
My question: What is/was the Blue wire for, and can I just put some electrical tape round it and tuck it into the wall?
Thanks :)
size=2>...</FONT></DIV><FONT size=2>&gt; Set Square wrote:<BR>&gt; <BR>&gt;&gt; As John Rumm told you many days ago, you have a problem with your<BR>&gt;&gt; mid-position valve. The chances are that the 'wet' part of the valve is<BR>&gt;&gt; stuck in roughly the mid position, but not far enough round to operate the<BR>&gt;&gt; microswitches in the actuator. In this condition, the boiler and pump will<BR>&gt;&gt; be controlled by the HW output from the programmer and the cylinder stat -<BR>&gt;&gt; but whenever the boiler is firing, both HW and CH will get hot. The CH feed<BR>&gt;&gt; from the programmer - which goes via the room stat - will have no effect<BR>&gt;&gt; because that only controls the boiler *after* the microswitches in the<BR>&gt;&gt; actuator have operated.<BR>&gt; <BR>&gt; Another thing to check is the position of that leaver on the side of the <BR>&gt; valve. In one position the valve will operate normally, in the other it <BR>&gt; will be locked into the mid position (thus allowing manual intervention <BR>&gt; to get some useful operation should the valve control electrics fail in <BR>&gt; some way).<BR>&gt; <BR>&gt; Also check the room stat does actually generate a signal. With most it <BR>&gt; is possible to hear a click when you rotate it back and forth around <BR>&gt; about the current room temp. While the "click" is not a guarantee that <BR>&gt; it is working, not getting any would be a good indication it is not.<BR>&gt; <BR>&gt;&gt; Remove the actuator from the valve (2 screws). This will reveal the valve<BR>&gt; <BR>&gt; &lt;snip good procedure for checking valve body&gt;<BR>&gt; <BR>&gt;&gt;&gt;2)&nbsp;&nbsp;&nbsp; Boiler loses pressure slowly.<BR>&gt;&gt;&gt;<BR>&gt;&gt; <BR>&gt;&gt; Sounds like you've got a leak, like we said earlier.<BR>&gt; <BR>&gt; Is your boiler overpressure release valve still leaking? If you are <BR>&gt; unsure, then tie a small plastic bag round the pipe with a rubber band <BR>&gt; and see if it collects water.<BR>&gt; <BR>&gt; -- <BR>&gt; Cheers,<BR>&gt; <BR>&gt; John.<BR>&gt; <BR>&gt; /=================================================================\\<BR>&gt; |&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Internode Ltd -&nbsp; </FONT><A href="http://www.internode.co.uk "><FONT size=2>http://www.internode.co.uk </FONT></A><FONT size=2>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; |<BR>&gt; |-----------------------------------------------------------------|<BR>&gt; |&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; John Rumm - john(at)internode(dot)co(dot)uk&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; |<BR>&gt; \\=================================================================/</FONT> </BLOCKQUOTE></BODY></HTML>
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Richard Marx wrote:

Hmmmm, fuzzzy ;-)

> in the junction box, he also moved the red/live wire from pin 2 to pin 1.

> and the stat still operated the heating perfectly, with just the red and yellow > wires in place.
It would do.... although not as well as before!

Probably a neutral connection. The old bimetal stats have a small compensating heater built into them. This improves the accuracy and stability of their operation. In order for this to work they need a neutral connection in addition to the live. So without it, they still work but not as well.

Yup. (or put a chockie block on it before taping it up - that way there is nothing waiting to stab you in the finger when you manhandle the tape! ;-)
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Cheers,

John.

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...

Thanks for the excellent info. Have now done all the tests, topped up the pressure from 5 PSI to 10 PSI, topped up the water to 1 bar when cold. When warm it rises to just below 2 bar, *but* when cold again it drops to zero, doesn't remain at 1 bar.
What does this indicate and what can I do?
Thanks.
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In an earlier contribution to this discussion,

I guess it's one of 3 things: * Faulty pressure vessel [re-check to make sure it's *still* at 10psi] * Faulty pressure relief valve [find where it discharges to the outside world, and hang a plastic bag on it to see whether it collects any water when the system is running - it shouldn't!] * Water leak elsewhere [inspect all pipework, junctions, radiator valves, etc.]
--
Cheers,
Set Square
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