Baxi 105HE

[demondriver]

Happy New Year to one and all.

I posted this message just over a year ago and the problem still persists - has anyone come across a similar issue in the meantime?

Hello folks - I hope some can shine a light onto a problem I'm having with my Baxi 105HE please.

The boiler is now 2 years old and is fitted with a remote stat and has developed a problem. When controlling the heating via the stat it decides to switch itself back on for no reason at all? So for example, the room temp is shown on the stat as 17 degrees, I turn it down to 8 degrees to turn the heating off and then a few hours later (time delay varies) the heating fires up again even though the room is still at or around the same temp (17 degrees) and the stat is still set to 8 degrees.

The Engineer has replaced the remote stat twice and the white electrical box next to the boiler (sorry, don't know its proper name) but the problem still persists??

Incidentally, when the bolier is used on 'timed' (integrated timer) it works without any problems whatsover?

Ps - I've checked with neighbours and none of them have the same type of remote stat that could be affecting the the signal.

Thanks in advance

DD

 

[gaswizzard]

Could it be due to you opening a hot tap (rads get warm)

 

[demondriver]

Hi gaswizzard,

Thanks for getting back to me, there isn't any water being drawn off - it just fires up all by itself?

Just switched the heating off by reducing the temp on the stat 1/2 an hour ago and it didn't switch off at all - it just stayed on? So I've had to switch it off using the integrated timer on/timed/off button.

DD

 

[45yearsagasman]

Deleted

 

[gaswizzard]

Has to be a fault with external controls.

 

[Ihavenojob]

Is it a normal on/off stat or a programmable one?

 

[demondriver]

It's an on/off stat - not programmable. I've just dug the paperwork out and it's a Salus RT300. Tried changing the batteries and placing the stat in various rooms sround the house (inc placing it next to the boiler) and it makes no difference.

When the installer replaced the first stat he told me he'd fitted dozens of them and never had a problem with a single one.

DD

 

[NEALDEAN]

Is it a standard 105he or the instant 105 he ?

 

[demondriver]

Hi NEALDEAN,

According to the paperwork it's just a Baxi Combi 105HE (no mention of 'instant) and it's fitted with a MULTIFIT Integral 24 hr Electro Mechanical timer (+ the wireless Salus RT300 stat).

Cheers,

DD

 

[NEALDEAN]

Pull the flap down on boiler front. Double check as it will make a big difference to the diagnosis.

 

[demondriver]

NEALDEAN,

I've checked for certain and it's deffo just the 105HE according to the wording on the flap.

Cheers

DD

 

[namsag]

When it fires up when it should not be firing look at panel and if the green demand light is on it means it is getting an external demand so faulty stat or reciever or the switched wires are touching occasionally in some way(very remote possibility).

Very easy to check if its the stat just leave eveything as you would normally have it for the day but remove batteries from stat if it still fires up at some point you know its not the actual stat


If no demand light it means there is a fault with the integral frost stat on boiler.

 

[NEALDEAN]

Possibly not 100% if just removing batteries as there could be third party rouge wifi signal triggering the base unit. Disconnect the complete stat from the boiler and try for a while.

What is lighting up on the panel when it fires up but shouldn't ?

 

[demondriver]

namsag / NEALDEAN,

Thanks for the replies.

I'll check tonight and let you know what is lighting up and not. I do know that the burner symbol on the remote stat doesn't light up when the boiler decides to switch on by itself (the symbol does appear when the boiler is on correctly).

Given that the stat and receiver have been replaced to no avail is it possible that the wiring is wrong somehow? I don't feel comfortable with trying to check it myself as I have no idea on the subject.

Thanks again DD

 

[demondriver]

Update......

Boiler was on 'timed' for a few hours today and when it switched off (at the end of the timed cycle) I left if for an hour or so. I then switched it to the 'on' position via the mechanical clock and set the stat to 8.5 degrees (the actual room temp was about 19 degrees) within a couple of minutes the boiler started on its own. The following lights were on the panel:

neons 6 - 10 (30 - 70 degree red lights, all solid, none flashing)
neon 12 - Power On
neon 14 - Central heating mode
neon 15 - Burner on

On the stat receiver both the red and green lights were on together.

I turned the boiler off and reset, and switched it back to on and took the batteries out of the stat - five minutes later it fired up and the same lights were on as above and the heating was on.

I then turned the boiler off again, reset it, kept it in the off position and tried to operate the stat. The green light on the receiver switched on and the flame signal on the stat showed up but the boiler remained switched off.

Does that help in anway?