Boiler control - Can anyone make sense of this?

checjb

checjb

checjb

Soldato
Joined
18 Oct 2002
Posts
2,793
Location
Royston, Herts
Hi folks,

I bought a Hive2 (with installation) because I read that my controller (a British Gas UP2) was a straight swap out, by simply taking off the front cover and installing the Hive controller onto the existing backing plate. Nice & easy.

Now, I've never been able to run my hot water and heating separately, even though the controler should allow it. It annoys me in summer but I've never got round to sorting it out. It's a fully pumped CH system with cylinder and room stats.

My problem is that when I opened up the cover, instead of six wires all neatly going into individual slots as per the Hive manual, I get this:

Any of you fine folks know what I'm looking at? Large image, btw.
l46KA5X.jpg
 
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First question, is your Hive2 receiver dual channel or single channel?

I'm guessing dual (2 buttons on the front, one for CH one for water) but just in case as that changes the wiring and what each of the 6 pins means...
 
Hi and thanks for the reply. Yes, I bought the dual channel version as my goal is to have the ability to use the HW and CH separately. It's always been a bug bear that I have to have the CW on in summer if I want some HW to wash up.
 
OK, well in that case pins are:

N - Permanent Neutral
L - Permanent Live
1 - Hot Water OFF
2 - CH OFF
3 - Hot Water ON
4 - CH ON

As I understand it, most new boilers don't need the OFF signals, they just work when the ON signal is detected, so your current wiring makes perfect sense at the receiver end, the question is where do those two brown wires connected to pin 3 (Water ON) and the single brown wire connected to pin 4 go at the boiler end!

The purpose of these wires will depend on your system layout (i.e. do you have zone valve controlling the hot water zone etc.).

This page explains the typical CH designs used: http://wiki.diyfaq.org.uk/index.php...ols_and_Zoning#Always-on.2FBathroom_radiators you'll need to work out what you have and then follow the wires, sounds like something is crossed or if you have a plan that uses a zone valve, perhaps the valve is stuck in the open position, in which case you'll need a new one of those.
 
It seems to. I had to replace it about a year ago after the original was found to be inoperative due to a leak dripping on to it. TBH, I'm not really all that good with such systems and it's worked OK so I've kind of left it alone. The update to a Hive was the first 'real' work I've done on the CH system since I moved in.
 
A good starting point is, does the central heating come on with the water or vice versa (or both?)

My guess is that the wiring isn't quite right... or the replacement zone (diverter) valve you had installed was faulty to begin with or badly installed...
 
If its a drayton head my early bet is that hes failed to pull the level out of its pre packaged position which is by default mid position
 
OK. So, a few points to address.

I can use the HW on it's own but CH only works if I have HW on too (I got it the wrong way round in the post above). It's a Honeywell 4043H 2-port valve and it's set to AUTO. There is a slight resistance when I move it to MANUAl so I assume it working OK. Here it is in situ.
px0uWRj.jpg


Here is a photo of the airing cupboard so you can see the layout. I think it's an S-plan but it's kind of odd. There is only one 2-port valve, the pump and the Magnaclean in the system.
5t9uzrh.jpg
 
Ok, next question then, follow the black wire from the zone valve, the brown wires from the receiver should be somehow connected to the valve (which in itself also has return wires)

All told the valves are simple really, they have a permanent live and a signal input and they output a signal that goes to the boiler when a microswitch is activated by the mechanical movement of the valve opening (assuming it's a usually closed valve of course...)

The fact you can only use the CH with the hot water suggests that the boiler is only controlled by the zone valve output signal, which begs the question, where do all those brown wires go!
 
Having dug around under the floor of the cupboard, here is another photo.
B88UMVR.jpg

The black wire from the valve goes to that junction block where is is joined to the white white that then disappears down through the floor (preumably towards the controller on the ground floor). The other white wire you can see is separate and goes to the pump and also goes down through the floor. There seem to be no other wires heading down to the controller.
 
How many of the two port valves do you have? I can only see one.

On older systems it was not unknown to simply stick a two port valve on the heating circuit to control the heating from a stat. The DHW heating coil would be on whenever the boiler fired up, but once that was on, the state of the valve would control whether the heating came on with it. Which sounds like the behavior you have at the moment.

This is what I had when I first moved in, one of the first things I did was fit a another 2 port value to the DHW coil and upgrade the controls :) . Unfortuntaly its all been ripped out now when I changed to a combi boiler
 
Hmm!

You're going to have to trace that white wire... if you were to open that black junction box you would see the wires from zone valve (some go "to" the valve, others "from" if you see what I mean but all carried in the black cable), the orange wire is the signal wire FROM the valve, this is what needs to be carried to your boiler to tell it to switch on...

Can you describe your current system? Ignoring the Hive system, I'm assuming you have (or had) from the original system:

1) Controller near to boiler to set timing for CH and Hot water
2) Thermostat in a room (is this wired or wireless?)

If the stat is wired then the white cable likely goes to that, which in turn then goes to the cabling you see at the controller end that you are trying to wire your Hive receiver into, if the stat is wireless than I can't imagine why the cable you see at the controller end is not the white cable joined up in that junction box...

Also, just for the record I am NOT a professional with any of this! I was just forced to work out the biggest spider mess of wiring that went with my S-Plus 3 zone system, so did a lot of reading...

EDIT: Or it could well be what Adam says (I had no idea anyone had that sort of set up, seems completely counter-intuitive because the hot water would need to be "active" on the controller in order for the CH to work, to me that is a system layout fault not just bad design!)

Either way, if you just stick your Hive system on all of this then you will get exactly the same behaviour as you currently have as your system doesn't seem to be wired up correctly and it may not even be plumbed correctly to have two independently controlled heating circuits by the sounds of things...
 
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As you suggest Adam, there is only a single 2-port valve on the system. I suspect I have what you had. I suspect that I'll have to return the Hive as my system simply isn't up to making use of it. :(

The thing is the system works so until it dies I'm not keen on shelling out thousands for a new heating system.
 
Manic, the system is exactly as you described. It's a wired thermostat so that must be where the wires disappear to (it also makes sense it terms of the locations of things).
 
Just thought about it again, Adam is almost certainly correct, he has to be as a properly zoned system would need either 2 2-port zone valves or a single 3 port valve, you have neither...

Personally, Hive aside, I would consider getting the plumbing corrected, at the moment you have to heat your hot water cylinder to have the CH on, that is a huge waste of energy. I'd be surprised if it cost thousands, you must have most of the needed pipework in place, converting to a "Y Plan" system should be possible I'd have thought?
 
OK. Cheers for all the help and info, guys. I've called in a local heating plumber to provide quotes for a change in pipework and/or a combi upgrade.

I really appreciate all the quick help. :D
 
When you put CH on your HW is always going to come on at the same time as at present you have nothing to turn the HW off

All you have is a tap stat on the cylinder that works like a trv valve and will shut off the tapstat when your cylinder is up to temperature
 
I am struggling to see where which pipes go where in the pictures because of limited context.

If your system is fuly pumped (as mine was) then it was just a case of adding a 2 port vave to the DHW and re-wiring the controls. Yours might be pumped heating, gravity DHW (tracing the pipes would show)

If you could draw a layout drawing of what you have then we can see. What you want to end up with is that S plan system

Your controls wiring doe need sorting out regardless though.... its an abomination. You have what looks like a DIY lash up:

Unsheathed conductors outside enclosure
Crimp spices outside enclosure
Crimp splices incorrectly used (multipe conductors in each end and oversized for conductors)
Crimps look like they have been closed with pliers and not the correct tooling
A piece of brown conductor apears to have a white trace to it, that would be a piece of a car wiring loom most likely (we do not use traces on mains wiring in order that any bi-colour conductor can easily be indentified as a protective conductor by a colour blind person)
 
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