Bolier Control Wiring Query

[Matthew Humphreys]

Hi everyone!

I have a Danfoss Controller (FP715) connected to a Honeywell 3 way valve via the Danfoss wiring box.

I installed it a while back, but it is only now the days have become warmer that I had spotted a problem.

If I, via the programmer, turn the central heating on, the rads get hot.

If I turn the CH and hot water on, the rads get hot and the water is heated.

Now that the warmer days are here, I only wanted the hot water heater, with no central heating. Unfortunately both the hot water and central heating are switched on!

This isn't really what I wanted to happen!

I have read, and re-read, the FAQ on 3 port valves, and can only assume that I have wired it incorreclty.

Can anyone else who has a honeywell 3 port valve please confirm what colour cable I should have where?

I have my hot feed to AB, my CH is port A, the HW is port B (is the OK)? (As I am writing this, I think the ports should be the other way round?)

The connections for the wiring box are:

Green Earth Blue Neutral White CH Call for heat Grey HW off Orange HW on (via the cyl sat)

Does this sound correct?

From the FAQ (which makes me think I have the valve the wrong way round).

Green/Yellow Safety Earth Brown Not used. Orange Go fully to 'B' when live. Grey Live when at 'AB' or 'B' White Go to 'AB' or 'B'.

If I have the valve the wrong way round, can I just swap the Grey and white connections over?

Many thanks for your help, and apologies for my ramblings!

Matthew

[Lurch]

On Sun, 11 Apr 2004 10:35:27 GMT, in uk.d-i-y [e-mail] (Matthew Humphreys) strung together this:

Nope, thats fine.

Yes.

No. I think your wiring fault is elsewhere in the system, assuming it isn't a faulty component somewhere. You might want to read these.

the system through, with a test meter, for the correct voltages at the right places.

[Matthew Humphreys]

Many thanks for that SJW.

Thanks for the links.

Looks like the plumbing is correct, perhaps I have a wiring fault elsewhere.

Any ideas where to start?

If I call for heating only, the CH side of the pipework get hot. If I call for both, both sets of pipework gets hot - if I lower the seting on the tank stat the HW side of the pipework cools down. If I call for HW only, both sides get hot, and adjusting the stat switches the pump off so both sides cool down!

Does this help?

Thanks again,

Matthew

[Set Square]

Make sure that the layout and wiring is as per the Y-plan details given in

think A is ok for heating and B for hot water - check the Honeywell references which someone else has given.

If you *do* get them the wrong way round, you can't easily correct it with a simple wiring change. This is because - when installed correctly - the hot water wiring requires an ON *and* OFF signal from the programmer, and requires the cylinder stat to have change-over (as opposed to just on/off) contacts. If you swap this round, the heating would need a "not required" signal from the programmer, and the room stat would have to be the change-over sort. It also means that the valve actuator would be consuming power rather than sitting at its home position throughout the summer when only hot water is required.

Under these circumstances, it is far better to turn the valve round - even though it means partially draining the system.

[Set Square]

Check the wiring in your junction box. When hot water only is switched on, pins 1 and 6 in the junction box should be live. When you turn the cylinder stat up to a high temperature, pin 8 should be live (and pin 7 not live). When you turn the cylstat down to a low temperature, pin 8 should cease to be live and pin 7 should become live instead.

The boiler and pump (or just the boiler if the pump is connected via an over-run stat on the boiler) should be connected to pin 8 - so the boiler should fire when the cylstat is turned up.

Check these things, and let us know the score.

[Matthew Humphreys]

Thanks for the help - not bad support for an Easter Sunday! OK,

If I ask for HW only, pins 6,7,8 and 9 of the Danfoss wiring box are live! This doesn't sound right!

If I drop the stat temp, then 8 and 9 go off.

The boiler is on pin 9, which in turn is linked to pin 8 (as per the installation sheet) - which seems OK.

Pin 7 is the "HW off" from the stat, I think

Hope this is starting to make sense to someone!

[Set Square]

I was referring to the pin (connection) numbers in the 10-way junction box shown under Y-plan in

sounds like you have a different wiring scheme if the boiler is on 9! Do you have a reference to a diagram which covers your setup? [On the Honeywell diagram shown in my reference, 9 and 10 are not used!]

That aside, if - as you say - 8 and 9 are live when calling for HW only, and the boiler is on 9, I'm at a loss to know why the boiler isn't coming on and heating the water.

[Lurch]

On Sun, 11 Apr 2004 15:56:17 GMT, in uk.d-i-y [e-mail] (Matthew Humphreys) strung together this:

I think from what you say pins 8+9 are the boiler and pump.

That sounds right.

I think this might help.

I'm assuming the wiring you have is as this diagram is, if it's different then what I said could be totally wrong. If I were you I would check the wiring at the clock, stat etc and ensure it is all right.

[Set Square]

If your wiring scheme is like the Danfos diagram referenced by Lurch - with a 12-way junction box - then the following should apply:

With HW only selected, Pin 3 of the programmer should be live and this should be connected to Pin 6 in the juction box, which should also be live. When the cylstat is turned to high, pins 8/9/10 of the junction box should be live and pin 7 should not be live. When the stat is turned down, 8/9/10 should no longer be live, but 7 should now be live. When 8/9/10 are live, the boiler and pump should operate.

Does this make sense? If this matches your setup, please let us know what

*really* happens.

[Matthew Humphreys]

Thats the controller / wiring box I have. - I was about to post the same link!

It appears that the connection I have to pin 7 is permantly live. I will check it out in the morning to see if I have wired the tank stat incorrectly.

Can someone remind me the function of the connections on the tank stat?

Cheers,

Matthew

[Set Square]

The cylinder thermostat is in the form of a change-over switch. Pin 1 is the "common" connection and is fed from Pin 6 in the junction box which in turn is fed from the "Hot water required" contact in the programmer. When the temperature of the water in the cylinder is lower than the temperature set on the stat, Pins 1 and 2 are connected - so that Pin 2 provides a live feed to Pin 8 in the junction box (and hence to the boiler and pump).

When the water gets up to the set temperature, the thermostat switch changes over - such that Pins 1 and 3 are now connected. Pin 3 provides a live feed to Pin 7 on the junction box, and onwards to the mid-position valve actuator. This is the "hot water demand satisfied" signal and is used (via the microswitches in the mid-position valve actuator) to switch on the boiler and pump in cases where central heating is required but hot water is not.

HTH.

[Matthew Humphreys]

Of checked the wiring to the cyl stat and there was a problem! I have now fixed it.

Pin 7 is now only live when when it the tank is hot

(Note - a 240v test screwdriver glows slightly (on pin 7) when the tank is cool and then brightly when the tank is hot - is this a function of the valve?)

Which of the connections to the valve should be live for just the hw to be heated?

Cheers,

Matthew

[Set Square]

Essentially none - but the wire which is connected to Pin 8 in the junction box will be live because Pin 8 is powered from elsewhere. Some of the others may glow dimly on your screwdriver because they're connected via the motor windings etc.

The valve is least active in the Hot Water only position. It sits at its "home" (spring return) position, where it directs water only to the heating coil in the hot water cylinder. In this position, the actuator plays no part in switching the boiler and pump - they are switched by the cylinder stat.

[Dave Liquorice]

No, a function of your test instrument. Google this group on neon screwdriver for plenty of previous discussion...

[Matthew Humphreys]

Cheers Dave, will Google later and improve my education! Thanks

[Matthew Humphreys]

OK, perhaps we're getting somewhere!

I've had all the wiring double checked by a friend - we are confident it is OK.

When I ask the system for hw on pins 6,7 amd 8 are live. When the water is hot, 7 and 8 are live (7 is HW off, 8 is feed to the boiler as you explained above.

This now seems to be logical!

One thought I had was that as the system is expecting a Danfoss Randall 3 way valve, which has the CH/HW - A/B ports the other way round (doesn't it?) and I have a Honeywell 3 port valve, is the controller trying to ask the port to do the "wrong thing"?

If this is utter tripe, please tell me, I'm a mechanical engineer not an electrical /heating engineer!

Is there any way to manual operate the valve to the "rest"/ HW only position to see of the valve is playing ball.

What else can I do to check the valve is OK?

Any other ideas anyone?

Thanks for all the help over the last few days,

Matthew

[Set Square]

If you're working to the Danfos schematic, Pin 8 shouldn't be live when the water is hot - unless the central heating is also on.

When you turn all the power off to the heating system (at the main switch - not the programmer) you should hear the valve return to its home position - unless it is already there, in which case you won't.

If you want to check it's the right way round, disconnect the valve completely from the junction box but leave everything else connected. Run the system in the HW only mode. Hot water from the boiler should circulate through the heating coil in the cylinder but not through the radiators. If the radiators get hot but the heating coil doesn't, the valve is the wrong way round!

If you are using a Honeywell valve with a Danfos junction box, the valve wiring should be (as far as I can work out!): Blue - Pin 2 Green/Yellow - Pin 3 White - Pin 5 Grey - Pin 7 Orange - Pin 8

[Matthew Humphreys]

My mistake - pin 9 is dead when the tank is hot. It's been a long day.....

Will try that tomorrow.

thats what I've got too.

Cheers,

Matthew

[Matthew Humphreys]

Will it took a bit longer then planned...

The system is now running without the valve wiring connected, and BOTH sides of the valve appear to be getting hot - some of this could be conduction from the feed from the boiler, but I don't think so!

Where now?

Cheers,

Matt

[Matthew Humphreys]

UPDATE - the heating output from the valve is not hot!

BUT.... the radiators are getting hot......... HELP!!!

I have not got a clue what is going on here!