Wiring to Boiler

[jaram]

Hi,

In need of advice/help please. Our gas boiler is wired as per the attached diagram. Boiler is controlled by a basic programmable timer which can run the CH and/or HW. Timer works fine in this respect and CH and HW both working fine.

The problem we have is that the boiler seems to have a permanent live feed - as even when timer programme positions are off, the boiler fires up for about 2 or 3 minutes every 15-20 minutes or so. Doesn't seem right to me - it's annoying and will also be using up gas.

I don't understand the attached wiring - the arrows in the diagram are wires off that have been cut but perhaps were once connected to a thermo/frost stat. Wire colours are as shown in the diagram.

Any help or advice much appreciated - easy fix or get a sparky in?

Thank you in advance. J

Untitled

• jaram
• 26 Sep 2011
• 2

 

[flameport]

The problem we have is that the boiler seems to have a permanent live feed

That isn't a problem, and is probably specified in the installation instructions as a requirement. Don't change the wiring.

- as even when timer programme positions are off, the boiler fires up for about 2 or 3 minutes every 15-20 minutes or so.

Plenty of boilers do this, however on most, this function can be disabled or at least turned off at night etc. Even if not, the amount of gas used is tiny.

What make and model of boiler is it?

 

[jaram]

Thanks. When British Gas guy came to service the boiler he told me it shouldn't be happening but as it was wiring would not help further?

Boiler is an Ideal Classic FF 380. Sorry I can't be more help with regard to more specific information.

The wiring diagram shown is the only wiring that is external to the boiler if that helps?

J

 

[flameport]

Boiler is an Ideal Classic FF 380

Ancient.

That boiler doesn't have any functions to preheat or whatever, and is of ye olde type which does NOT require a permanent supply.

If power is applied to the boiler, it will operate. Therefore you were correct initially - when controls are set to off, there should NOT be any power at the boiler at all.

The problem is either with the wiring, or the timer/valve etc.
What other controls are there - programmer, timer, thermostat? Should also be at least one motorised valve, possibly two.

 

[bernardgreen]

If the boiler only has permanent live, neutral and earth then there is no way the boiler can be told when to fire up by the control system. It will try to fire continuously and that is a safety hazard.

Turn it off and get a heating engineer to look at it.

The short firing every 15 minutes suggests the boiler is firing up when the pump is not running and there is no flow through the boiler. The water in the boiler is getting over heated and the safety thermostat is shutting the boiler down before the water boils. The water then cools down and when it is cool the safety thermostat resets and the boiler fires up again.

 

[jaram]

Thanks for the thoughts and advice so far. Here's a pic of the gear in the airing cupboard if that helps at all?

Untitled

• jaram
• 26 Sep 2011
• 2

 

[flameport]

Looks like a standard Y plan system. The valve and pump are not original, although the cylinder thermostat probably is.

Likely that when the pump and valve were replaced, the wiring was messed up, causing the problem.
This should be an easy fix for someone competent with heating system wiring - which is not necessarily a gas or boiler person.

 

[jaram]

Sounds plausible. Thanks for your time and advice Flameport - much appreciated. J