ICOS/Ideal HE18 Hot Water but No Heating

[David Ward]

I would recommend doing some tests before replacing the valve head, the motor must be working so the problem is either microswitches in the valve head faulty, mechanism in valve head faulty, or problem with the wiring to the valve.

At the very least carry out this test to avoid wasting money on an unneeded new valve head.

With hot water off at the programmer and central heating on with room stat turned up, you should have:
240V on the valves white wire
240V on the valves grey wire

If you don't have the above, the fault is external to the valve.

When it's all working there should also be 240V on the valves orange wire to power the pump and boiler, this probably isn't happening at the moment.

All tests will need to be carried out with a 2 probe AC volt meter, with one probe connected to neutral for all tests. A neon screwdriver or volt stick is not suitable and will give incorrect/misleading readings.

I'm going to guess there is no power to the grey wire when the hot water is off.

I never even got to open the connection box as when I moved it from under the floorboards in the airing cupboard the heating burst in to life. I'm guessing (hoping) that there is a loose connection in there somewhere but I'm not going to touch it just yet as the house is warming up and we're sitting at 15c with blankets on. If it goes off again at least I'll have a starting position.

How can something so simple cause so much work?

Thanks you all for the help

 

[Echo the husky]

It should be fixed to a surface not jammed under a floor!!! Almost certain to be a loose connection then. When you are warm again, check all the wires are secure paying close attention to the terminals with the grey and orange wires.

How can something so simple cause so much work?

Shoddy wiring such as what you have described above can cause all sorts of faults which would not be present if the wiring was installed in a way that met British standards. But don't worry, you are not alone. Almost all the other threads about heating controls on here have poorly installed wiring.

 

[David Ward]

I'm going to check all the wiring and make sure all the connections are tight but at the moment it's working and I don't want to risk losing heat again.
When I do it I will attach it to the wall as well. Thank you for all your advice.

 

[David Ward]

Keeping this post bookmarked - it has some useful info on it.

 

[David Ward]

Right, heating has gone again. I've done some tests. It doesn't look like a loose connection.

Problem has not been solved. Looks like it was a temporary fix.

Hot water is still coming on but heating won't. The pump appears to be working.

The motorised valve works when the water comes on and moves all the way to the right. But if I turn the hot water off the valve stays where it is. If I manually move the valve all the way to the left the heating does still not switch on and it won't move of it's own accord.

Any suggestions

I would recommend doing some tests before replacing the valve head, the motor must be working so the problem is either microswitches in the valve head faulty, mechanism in valve head faulty, or problem with the wiring to the valve.

At the very least carry out this test to avoid wasting money on an unneeded new valve head.

With hot water off at the programmer and central heating on with room stat turned up, you should have:
240V on the valves white wire
240V on the valves grey wire

If you don't have the above, the fault is external to the valve.

When it's all working there should also be 240V on the valves orange wire to power the pump and boiler, this probably isn't happening at the moment.

All tests will need to be carried out with a 2 probe AC volt meter, with one probe connected to neutral for all tests. A neon screwdriver or volt stick is not suitable and will give incorrect/misleading readings.

I'm going to guess there is no power to the grey wire when the hot water is off.

Multimeter says:
Grey = 240+V
Orange = 0
White = 0
These tests were done with the water off at the programmer - but get same results with it on.
One of the probes was connected to the relevant terminal the other was connected to the pump (is that OK?)
All terminals are tight - and a very neat wiring job inside too
I've tested with stat all the way up and all the way down - no difference
I've checked continuity from stat to connection box - all is ok

My header tank and valve are full and working.

Are there any more checks I can make to determine the problem?

Any help and advice would be appreciated.

 

[dilalio]

These tests were done with the water off at the programmer - but get same results with it on.

What make and model programmer and wireless roomstat do you have? Fault could be with programmer if you get same readings at different settings!

 

[David Ward]

Honeywell ST6400C - works fine for Hot Water
Drayton Digistat RF1 and SCR

 

[Echo the husky]

Where on the pump? The other lead should really be on the neutral terminal (blue wire on valve)

If you are getting the same reading when HW on and off, the cylinder must already be up to temperature.

The problem will either be with the programmer not sending the heating on signal to the room stat, or the room stat is faulty/or the wiring to/ from it is.

Is the red light lit on the SCR?

If the thermostat is calling for heat, the green light on the SCR should be lit, is this happening?

If not push the override button on the SCR and see if the heating comes on then (programmer must be set to heating on too of course).

Edit, these only send the wireless signal out every 5 minutes, but I would expect it to send out a signal straight away if the user has changed the thermostat setting.

 

[David Ward]

Put it on the actual pump casing itself. I can test again putting probe on valve neutral/blue wire.
Cylinder/Hot Water is hot
Green light is on SCR - when I reduce temp on stat it flashes red then goes off when increase temp flashes red and then goes green as it should
Pressing Override button makes no difference

 

[Gas2Air]

Jesus Christ. Take the SCR unit off, link live into call on the wiring backplate. If heating works it's the SCR, if not it's the actuator.

 

[David Ward]

With HW Off
Grey 240/250
Orange 0
White 0

With HW On
Grey 130
Orange 250
White 0

Jesus Christ. Take the SCR unit off, link live into call on the wiring backplate. If heating works it's the SCR, if not it's the actuator.

Gas2Air - Please explain - bit of novice here

 

[Echo the husky]

Jesus Christ. Take the SCR unit off, link live into call on the wiring backplate. If heating works it's the SCR, if not it's the actuator.

As there is no power to the white wire surely it will be the SCR or programmer?

Well it sounds like the SCR is receiving the signal.

Gas2Air - Please explain - bit of novice here

Power off, remove SCR from mounting plate.
Take wire out of terminal 3 and connect it with the other wire in terminal 1.
power on, programmer set to heating on, heating should then work if SCR is faulty.

If it doesn't work, check for power at the white wire now.
If not 240V the problem will likely be with the programmer.

 

[David Ward]

Just getting my head around what you said. I understand. Pretty certain there's a label inside the SCR showing which wire is which

 

[Echo the husky]

The terminals should be marked in this order N,L,1,2,3,(and 4 which is not present/used) you need to connect the wires in 1 and 3 together. 1 should come from the heating on connection from the programmer, 3 should go to the white wire of the valve. Depending on who wired it they may be reversed, but it makes no difference to the operation.

 

[David Ward]

Right off to test this out. Will be a little while.