Potterton prima randomly turning on

[West Counrty DIYer]

Hi all

I posted a few days ago with what I thought was a confroller problem. With some advise from someone on here I changed my old switchmaster for a hive mini. The hive is working fine but it hasn't fixed the original problem. My Potterton prima boiler fires up randomly when the heating/hot water is off. It can do it for a few seconds or just 1 second, sometime I just hear a noise like gas coming on but not igniting. I have to switch off the power to the boiler to stop it. Can anyone help please.

 

[CBW]

Sounds like you have a faulty motorised valve.

 

[Harry Bloomfield]

1. Might it have a built-in program, to exercise itself every so often, if it has no call for heat? My Vaillant does that.

2. Might it be triggered by the cold weather? If the boiler senses a temperature lower than 5C, some fire themselves up to protect themselves from freezing.

 

[West Counrty DIYer]

Thank you both for taking to time to reply, unfortunately I don't think it's either of those suggestions.

The fault dirs not sound like something that is meant to happen and happens regardless of the temperature. It happened last night when the house was 19 degrees.

The motorised valve is only a year old, I'm not discounting it because of that, I heard it close this morning as the heating turned off and the boiler stated its odd noises.

I should have given more detail. My system is and old gravity-fed one, so I have HW or HW and CH. It had been working fine until last week, because the boiler seems fine when CH or HW are on then I assumed (wrongly) that it was a control problem. Which is why I changed the old rotary dial switchmaster for a hive mini, but I still have the issue. This makes me think it's a problem with the boiler making it fire up without a signal from the controller.

 

[West Counrty DIYer]

I've attached a video so you can hear the noise it makes sometimes.

 

[ianmcd]

which Hive mini ?dual channel or single channel ?

 

[ianmcd]

The motorised valve is only a year old, I'm not discounting it because of that, I heard it close this morning as the heating turned off and the boiler stated its odd noises.

Just because the motor springs back does not mean the micro switch isnt sticking

 

[West Counrty DIYer]

Dual channel, set up for gravity-fed system.

 

[West Counrty DIYer]

Just because the motor springs back does not mean the micro switch isnt sticking

Roger, but I don't think the moterised valve activates the heating. Rather it shuts off the heating when it's set to HW only.

 

[ianmcd]

Roger, but I don't think the moterised valve activates the heating. Rather it shuts off the heating when it's set to HW only.

No that is not how it should be wired, it is possible but very unusual to have gravity HW with a zone valve on the system, are you sure you have gravity HW ? post some pics of the boiler the pump and the pipes coming out of the top of your boiler

 

[ianmcd]

Dual channel, set up for gravity-fed system.

NOT Gravity fed, gravity HW they are very different, I dont think you have a gravity HW system as already said post pics of the pipes coming out of the top of the boiler

 

[ianmcd]

Where is your pump wired into ? the boiler terminals or the Hive mini receiver terminals ?

 

[West Counrty DIYer]

So here you go. Top of boiler pipe work. I have a junction box, the controls (formally the switchmaster now hive) are wired into it. Live and neutral wired to the junction box via the controller Motorised valve to the junction box, junction box to the boiler. There is also a wire from the junction box going up stairs which a assume goes to the hot water tank. The pump is on the hot water and the motorised valve on the heating. I checked and I could hear the motorised valve close when I selected hot water without heating.

.

 

[ianmcd]

As suspected you DO NOT have Gravity HW system, you have a botch, show a pic of the wiring in the boiler and the wiring centre and your hive , it is not wired correctly and not set correctly

 

[West Counrty DIYer]

I'll provide photos in the morning. My main concern is what has failed to cause the problem I have.