Combi boiler is on when no heating or hot water is being used

[Gursx]

Hi,

We’ve moved into a new build property a couple months ago, it has a combi boiler (Logic Code Combi ESP1 38).

On the actual boiler we currently have it set to water and heating and have both temperatures as minimal as possible however for some reason our boiler keeps coming on and staying on for hours at a time when the heating isn’t on and we’re not using any hot water.

We’re averaging 27kwh for gas a day even when not using any heating, when we had it on water only mode it was about half of that.

Is there a setting that I’m missing? Our thermostat is on manual mode so the heating isn’t coming on either, the boiler is just heating for some reason.

We would appreciate any help, last month our gas bill was £16 whereas it’s currently on £10 for November already when we’ve only had the heating on for 3 days - the only change we made was changing it from water only mode to water and heating.

Edit: I’ve been watching the boiler for a tad now. The temperature on the dial is usually around 52, when it reduces to 46 (takes about 20 minutes) the boiler fires up back to 52 then switches off. It’s in this cycle, I’m assuming this is what’s causing the boiler to feel like it’s always on.

I can’t seem to find a pre-heat button anywhere. Is there a way I can stop this? In theory can we just put it on water mode till we need the heating which is usually 1/2 times a week.

As the property is a new build it maintains heat very well, if we put the heating on it stays at that temperature for a day or two even with the heating off so we don’t need the boiler on at all times.

 

[Gursx]

Edit:

Just to add, every 20 minutes or so it changes ‘The boiler is operating in central heating mode’ despite us not turning the heating on.

I’m assuming the boiler is switching on due to the sound it’s making and changing modes.

 

[CountryFan]

Contact your house builder, it’s likely a link (often 24v) has been left in which will override any thermostat. It won’t be preheat as it would have done it in hot water only mode.

 

[Gursx]

Is that the case even if the heating isn’t actually on? As the boiler sets to fire when it drops to 46 and it will heat to 52 again, but at no point do the radiators actually get warm unless we have the heating on.

Can we just have it on water only mode? We only use the heating once or twice a week, can we just switch it on, use it then switch it off once we’re done?

Thank you again!

 

[Gursx]

Contact your house builder, it’s likely a link (often 24v) has been left in which will override any thermostat. It won’t be preheat as it would have done it in hot water only mode.

Is that the case even if the heating isn’t actually on? As the boiler sets to fire when it drops to 46 and it will heat to 52 again, but at no point do the radiators actually get warm unless we have the heating on.

Can we just have it on water only mode? We only use the heating once or twice a week, can we just switch it on, use it then switch it off once we’re done?

Thank you again!

 

[CountryFan]

Is that the case even if the heating isn’t actually on?

More than likely the case yes, that's what I said about it overriding any thermostat. Put it back to hot water mode and see if it still behaves this way. I've had it a fair few times now.

Are you on zonal heating? (X2 thermostats)

Can we just have it on water only mode?

Absolutely and put heating on as and when you need it, meantime get the builder back.

 

[Gursx]

More than likely the case yes, that's what I said about it overriding any thermostat. Put it back to hot water mode and see if it still behaves this way. I've had it a fair few times now.

Are you on zonal heating? (X2 thermostats)

Absolutely and put heating on as and when you need it, meantime get the builder back.

Yes we’re on zonal, both thermostats are on manual mode and not switched on.

Even after the builder comes, can we still have it on water only mode until we need the heating, then back to water? Or is there a reason not to do this?

Thank you again!

 

[CountryFan]

Yes we’re on zonal, both thermostats are on manual mode and not switched on.

I thought so with you stating the radiators don't actually heat up. Needs sorting asap otherwise it will shorten the lifespan of the boiler.

Even after the builder comes, can we still have it on water only mode until we need the heating, then back to water?

Yes, absolutely fine, but tbh you shouldn't need to when it's fixed as it'll just provide either when there's a demand.

Thank you again!

You're welcome

 

[Gursx]

I thought so with you stating the radiators don't actually heat up. Needs sorting asap otherwise it will shorten the lifespan of the boiler.

Yes, absolutely fine, but tbh you shouldn't need to when it's fixed as it'll just provide either when there's a demand.

You're welcome

Sorry what exactly is the 24v you’re on about? So I can tell the developers. Thank you!

 

[CountryFan]

Sorry what exactly is the 24v you’re on about? So I can tell the developers. Thank you!

It's a link inside the boiler on the PCB so the heating works until a control is wired in.

 

[dilalio]

Sorry what exactly is the 24v you’re on about? So I can tell the developers. Thank you!

It's very common for this to be overlooked. I did it a couple of times when I started but soon learned to always remove the link when wiring in external controls.

Most combis come with this link connected, out of the factory.

 

[Gursx]

It's a link inside the boiler on the PCB so the heating works until a control is wired in.

It's very common for this to be overlooked. I did it a couple of times when I started but soon learned to always remove the link when wiring in external controls.

Most combis come with this link connected, out of the factory.

Thank you both!

I put it on hot water mode only and it’s stopped firing up randomly so changing it to this fixes it but I’m assuming there can still be a problem with the 24v like you two said?

The only concerning part when it’s in hot water mode is that the temperature gauge goes below 1 and sits around 0.5, however as soon as I put it back on hot water and heating it goes back up to just over 1. Is this normal?

I’m trying to avoid going to developers to be honest!!

 

[dilalio]

temperature gauge

You mean pressure gauge?
That should be around 1.2 when system cold.
It needs looking at tbh.

 

[CountryFan]

The only concerning part when it’s in hot water mode is that the temperature gauge goes below 1 and sits around 0.5, however as soon as I put it back on hot water and heating it goes back up to just over 1. Is this normal?

It's not a temperature gauge but a pressure gauge. Yes that's how it's meant to work, but it's supposed to be at approx 1 bar

 

[Gursx]

You mean pressure gauge?
That should be around 1.2 when system cold.
It needs looking at tbh.

It's not a temperature gauge but a pressure gauge. Yes that's how it's meant to work, but it's supposed to be at approx 1 bar

I’m assuming something isn’t correct then as it drops to halfway between 0 and 1 when it’s in tap only mode, however when we shower etc it goes up a tad.

Why are boilers so hard? The developers are useless with this as well!