Curious heating behaviour? (boiler does not fire up on demand)

[Harry Bloomfield]

It is either wired up wrongly, or the valve is sticking despite your suggesting it is doing what it should.

 

[fixitflav]

If it's any help, here is the internal wiring of the mid-position valve

 

[Tanel]

Disable hot water at the programmer and then try increasing the room thermostat temperature to double check that the boiler is still not coming on for heating-only, ie valve at H position.

When at H position give the lever some help to go as far as possible in that direction, just in case it's a bit sticky and not going far enough. It needs to go far enough to operate the internal microswitch which turns on the boiler.

The valve goes over to H and has stayed there even when I re-enable hot water and/or turn on the hot tap. It's right across under H and won't go any further.

What is interesting though, that I didn't notice before, is that even when the hot water is set to "Off" on the programmer, the red light comes/stays on, if the heating is on:-

In other words, I can set hot water "Off", "Once/Twice" or "On", and that doesn't affect the heating side, but if I put the heating "On" (or set it to "Once/Twice", during the "On" hours), the red light under hot water comes on with it, even though the little arrow indicator stays at "Off" (see picture). Is that supposed to happen, or is there an issue with the wiring in the programmer? Could that have any bearing on the main issue of the heating working independently of hot water usage?

 

[ianmcd]

Although you have a fully pumped Y plan system, someone has set your programmer to gravity you need to set it to fully pumped, you remove the programmer and move the little jumper to pumped

 

[Tanel]

Although you have a fully pumped Y plan system, someone has set your programmer to gravity you need to set it to fully pumped, you remove the programmer and move the little jumper to pumped

That's interesting - it links back to a comment John D made earlier about a setting at the back of the programmer.

I take it then that the dark red gizmo to the right of the boiler and below the motorised valve is a pump, and that even though I have a water tank in the loft and cylinder in an airing cupboard (which again, as a layman, I thought were the hallmarks of a "gravity system"), someone at some point fitted a pump in there. Not come across the term "Y-plan" before but am interested to research it now!

I'll have the jumper setting checked and report back and thank you very much for your input here.

 

[ianmcd]

by the looks of your older pipe work it looks as if it was origionally gravity HW, someone has converted to Y plan, but not set the programmer , very simple job to do

 

[JohnD]

as for the green corrosion, you can clean it off with a green nylon pan scourer and an old toothbrush, with washing up liquid and a little water.

sponge off the residue and clean with a cotton rag, it will look quite shiny. If it is still leaking, limescale and green corrosion will be visible in a few weeks, and you will probably be able to see the joint it is coming from.

 

[Tanel]

Managed to get the boiler casing off and access the programmer, and took it off the wall.

The jumper was indeed set to "G" instead of "P", and I therefore changed this.

This has solved the "red light" issue, and both hot water and heating now click on and off independent depending on setting, as hoped. Thanks for all the guidance on that.

In the process I took the precaution (made the mistake?) of turning the electrical switch off on the wall and it seems the pilot light is now out.

Relighting instructions on the boiler casing say to turn the boiler temperature dial to 0, and turn off electrical supply, before doing the "press and click", yet elsewhere (in a downloaded Glowworm manual) I have read that the ignition process involves the fan running, which presumably cannot run unless there is power.

Thermostat is way down and programmer set to OFF. Should I have the electrical switch on/off when relighting the pilot? Does it matter?

 

[Harry Bloomfield]

Relighting instructions on the boiler casing say to turn the boiler temperature dial to 0, and turn off electrical supply, before doing the "press and click", yet elsewhere (in a downloaded Glowworm manual) I have read that the ignition process involves the fan running, which presumably cannot run unless there is power.

I suspect you may be reading a wrong manual..

All of the 'press and click' boilers I have come across, need no power to maintain the pilot light lit, nor to re-ignite the PL if it goes out. All you do is press the gas valve button, and click the igniter, until it lights, then hold the gas button pressed for several seconds, until the PL holds in.

 

[ianmcd]

your boiler has an electronic pilot, so sounds like when you turned the power off the boiler was running and the over heat thermostat has operated, tur n the power back on, to the right hand side of the boiler thermostat is a little button, press it and see if you feel a slight click, if you then that is it reset and everything will come back on