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

Hi guys, to avoid confusion I have uploaded some pics of the valve:

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Also I have now identified that the one thermostat in the hall has no effect on the central heating whatsoever. That said, all the rooms (except hall strangely) have a stat on the rad itself. Does this negate the need for a central stat? (Surely not.)

So, to recap, current issues:

1) CH switch on/off has no effect either way. HW switch makes radiators and water hot just fine.

2) Boiler loses pressure slowly.

3) Wall stat has no effect on system. All rads have stats on except hallway.

Does this help us? :-S

Thanks!

Reply to
Richard Marx
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The valve is a Danfoss 3-port mid-position valve designed to provide just HW, just CH - or both at the same time. This is the heart of a Y-Plan system.

Even if most radiators have TRVs (thermostatic radiator valves) you still need a central stat to turn the boiler off when the whole house is hot. The radiator nearest to the room stat shouldn't have a TRV - so what you've got is right.

As John Rumm told you many days ago, you have a problem with your mid-position valve. The chances are that the 'wet' part of the valve is stuck in roughly the mid position, but not far enough round to operate the microswitches in the actuator. In this condition, the boiler and pump will be controlled by the HW output from the programmer and the cylinder stat - but whenever the boiler is firing, both HW and CH will get hot. The CH feed from the programmer - which goes via the room stat - will have no effect because that only controls the boiler *after* the microswitches in the actuator have operated.

Remove the actuator from the valve (2 screws). This will reveal the valve operating spindle, the end of which is D-shaped in cross section. The flat of the D will almost certainly be at an angle of about 45 degrees with the body - which is the mid position. See whether you can rotate the spindle through plus and minus 45 degrees. In the unlikely event that it's *not* seized, you should be able to turn it with finger and thumb or - at any rate - with light pressure from a pair of pliers.

Then, with the valve in the mid position, and the actuator still off, put the actuator through its paces. Use the programmer and thermostats to generate all possible combinations of HW and CH demand and see what the actuator does in each case.

Then report back!

Sounds like you've got a leak, like we said earlier.

Explained above!

Reply to
Set Square

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.

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.

Reply to
John Rumm

On 0 0 1 Off 0 0 1

*on electrical screwdriver, light was blinking not solid

Is this our problem?

Thanks!

Reply to
Richard Marx

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 ]

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?!

Reply to
Set Square

I tried that and nothing happened

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 ;) ;)

Reply to
Richard Marx

Hi guys

You will recall my great photo of the wall stat wiring here:

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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?

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:
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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!

Reply to
Richard Marx

Hmmmm, fuzzzy ;-)

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! ;-)

Reply to
John Rumm

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