Boiler & cylinder firing up randomly

[Jarofjam]

Hi everyone,

We recently had a new Vailant ecoTec Plus 630 boiler and Joule unvented cylinder installed, and overall everything works - we get hot water and heating at the right times.

But a few times now we've noticed the boiler and cylinder both loudly firing up in the middle of the night, when there is no demand for hot water or heating.

The boiler is clearly running, with the temperature display going up and a solid 'radiator' icon on the display (our setup has the radiator icon for both heating and hot water - no tap icon). At the same time, there is noise/activity from the cupboard housing the unvented cylinder, and from putting my ear against it, this appears to come from the cylinder itself rather than just the pipes. The radiators stay cold.

We've noticed this 2-3 times and there don't seem to have been any ill effects (apart from the annoying noise at night) but it does make me nervous. Last night, after about half an hour, I turned off the boiler from the front panel, although the unvented cylinder continued making noise.

Is this normal? What could be causing it? I'm no expert but to me it seems to go on too long just to be some sort of maintenance mode.

My best guess is that it wrongly thinks there's demand for hot water... does that sound right? Could it be a wiring fault?

Thanks.

 

[Riley]

My best suggestion would be to get the installer back and explain your worries

 

[Jarofjam]

My best suggestion would be to get the installer back and explain your worries

I am planning to do this but want to be armed with as much information as I can first.

 

[Riley]

Well it could be a number of things
Faulty control component
Controls not set up properly
Controls set up correctly but wrong times
Someone fiddling with boiler settings the list goes on
If you trusted the guy to fit the boiler etc, trust him to be able to sort it satisfactorily

 

[Jarofjam]

Thanks Riley - the main thing I want to confirm is that this isn't expected behaviour?

 

[Riley]

This is the difficult thing it could be, it could not be, it could be doing exactly what the controls are set up to tell it to do. This is why you need someone to take a look at it. Sorry I'm not trying to be unhelpful but some of these things you actually need eyes on to be able to understand what the system is doing

 

[Jarofjam]

This is the difficult thing it could be, it could not be, it could be doing exactly what the controls are set up to tell it to do. This is why you need someone to take a look at it. Sorry I'm not trying to be unhelpful but some of these things you actually need eyes on to be able to understand what the system is doing

By controls do you mean the thermostat and hot water timer? I can confirm that these are definitely set correctly and there is no demand for heating or hot water when this happens. I even manually switched heating and hot water off at the controls to confirm. It is a Tado system.

 

[Darren Jackson]

Is there a back up immersion heater fitted? and if so has it inadvertently been left switched on permanently? This could explain the cylinder noise but not why the boiler is running. As above you need to double check that the controls are set up / installed correctly.

 

[Jarofjam]

Is there a back up immersion heater fitted? and if so has it inadvertently been left switched on permanently? This could explain the cylinder noise but not why the boiler is running. As above you need to double check that the controls are set up / installed correctly.

The immersion heater is definitely off, and the controls are definitely set correctly.

Im guessing that it's a wiring issue - e.g. perhaps the hot water is set to come on where there's no demand and vice versa (we wouldn't notice the rest of the time because it cold outside so the boiler is on much of the day)

 

[Darren Jackson]

Sounds like you need to get your installer back. Fully explain the problem to the engineer on site, Not just over the phone to whoever answers. Ask the engineer to check all the wiring again and ask them to check each setting is performing as it should do.

 

[deg]

As above really but could there be a frost stat kicking in these cold nights or set too high?

 

[townfanjon]

I know its a long shot but it does happen , if your immersion heater has a neon on it, it doesnt light , yep its off , if its a normal switch they can be upside down . Like I say longshot !!

 

[Frog67]

Zone valve motor switch sticking?

 

[wozelbeak]

Eco setting kicking in?

 

[Jarofjam]

As above really but could there be a frost stat kicking in these cold nights or set too high?

According to the manual, frost protection should heat up to about 30 degrees, but this was heating up to 60. But good thought!

 

[sparkie30]

Did you check which 2 port valve was open when found the boiler on.

 

[Jarofjam]

Did you check which 2 port valve was open when found the boiler on.

It's going again now… there are two 2-port valves next to the unvented cylinder, and both of them resist when I pull the lever.

 

[sparkie30]

It's going again now… there are two 2-port valves next to the unvented cylinder, and both of them resist when I pull the lever.

That means it is wired correct and not calling for heat so it seems boiler settings need looking at.

Good luck.

 

[Jarofjam]

That means it is wired correct and not calling for heat so it seems boiler settings need looking at.

Good luck.

The pipes going through those 2-port valves to the cylinder are hot, and there is noise from the cylinder cupboard and I think the cylinder itself. Does that make sense with the valves being inactive?

 

[sparkie30]

The pipes going through those 2-port valves to the cylinder are hot, and there is noise from the cylinder cupboard and I think the cylinder itself. Does that make sense with the valves being inactive?

To be honest if lever is not moving freely that means the valve is closed and boiler shouldnt fire but as you said the boiler is on. As others have adviced best get the the guy who installed the system back in.

Thanks