Central Heating has a mind of its own !

[Knight2135]

Hi Guys,

I have a central heating system that has a mind of its own. It decides to turn on and off whenever it feels like it. I thought my 2 channel programmer was the cause of the fault so I bought a new one. To my shock, the boiler still does its own thing. My next plan of action was to turn my thermostate down to 0 in my house and monitor. The heating still turns on. Im very confused .

I have had to turn the power to my boiler off to stop it coming on and off when it feels like it. I have the clinder tank up in my bedroom and have played with a 3 port value and that seems to have some effect on whats happening but I don't know enough about why this would turn on / off my boiler downstairs.

Can anyone point me in the right direction to what further investigation I can do ?

Thanks in advance.

 

[gas_man_gaz]

prob the 3port, could do with a better description of the fault tho

 

[Knight2135]

Cheers Gaz,

Sorry this is my first post on here so I was unsure what info people would want. Ill start from the begining and if you need anything answered let me know and ill post straight back.

I have an ideal classic boiler with a danfoss 2 channel timer. I went away for a week and my dad noticed I had VERY hot water half way though the week, even though the two channel control unit was set at OFF for water and heating. Thinking this was odd and the unit was old, I bought a brand new one. I fitted the control unit to the same backplate as not to distrub the existing electrics. This unit did the exact same thing, both controls are set to OFF and I was finding I had hot water when I came home from work. I have checked and double checked the timer controls and they are all set to OFF. Today I have spent in the house to check the heating. To my surprise the boiler just fires up and down by itself, again even though all the controls are set to off. I have had to turn off power off to the boiler to stop it turning on again.

I started to investigate further and have turned the room thermostat down to 0. The boiler still kicks in and out during the day turning the central heating on and warming the water.

I went to the hot water tank, checked the pump, that seemed ok (im no expert) but when I play with the 3 port valve, I can hear my boiler kick in and out and am not sure why or whats wrong with it.

This is where Im really looking for some advise. I don't understand enough about the valve to know why it would cause my boiler to come on and off and what I can do to fix it, IF it is this at fault. At the moment I really don't know what is causing these problems.

 

[gas_man_gaz]

it sounds like the 3port valve is stuck in the hw position, what make is it?

 

[nogoodatfaultfinding]

Cheers Gaz,

Sorry this is my first post on here so I was unsure what info people would want. Ill start from the begining and if you need anything answered let me know and ill post straight back.

I have an ideal classic boiler with a danfoss 2 channel timer. I went away for a week and my dad noticed I had VERY hot water half way though the week, even though the two channel control unit was set at OFF for water and heating. Thinking this was odd and the unit was old, I bought a brand new one. I fitted the control unit to the same backplate as not to distrub the existing electrics. This unit did the exact same thing, both controls are set to OFF and I was finding I had hot water when I came home from work. I have checked and double checked the timer controls and they are all set to OFF. Today I have spent in the house to check the heating. To my surprise the boiler just fires up and down by itself, again even though all the controls are set to off. I have had to turn off power off to the boiler to stop it turning on again.

I started to investigate further and have turned the room thermostat down to 0. The boiler still kicks in and out during the day turning the central heating on and warming the water.

I went to the hot water tank, checked the pump, that seemed ok (im no expert) but when I play with the 3 port valve, I can hear my boiler kick in and out and am not sure why or whats wrong with it.

This is where Im really looking for some advise. I don't understand enough about the valve to know why it would cause my boiler to come on and off and what I can do to fix it, IF it is this at fault. At the moment I really don't know what is causing these problems.

I have maybe read this wrong but i am guessing the boiler is kicking in as it should be and forcing the pump to turn periodically on the CH side, now for your hot water have you checked to see if you have an immersion fitted and if so is it turned off as this will heat up your HW, without looking at it it could also be the Cylinder stat wrongly controlling both the CH and HW

 

[gas_man_gaz]

why should the boiler fire without demand?

 

[nogoodatfaultfinding]

why should the boiler fire without demand?

Known alot of sparkys to fit in a pump over run (believe its called) to stop CH pump seizing up in the summer.
It could also be that thy ar confused with how thier stat works as alot of people get confused with what it does.

 

[D_Hailsham]

How a mid-position valve works will tell you all you need to know.

 

[TicklyT]

I traced a similar problem to a broken return spring in the 3-port valve. Without the return spring the valve stopped wherever it felt like stopping when the timer was off, usually in the mid position, instead of positively moving to it's 'off' position and operating the microswitch in the valve head that controls the boiler.

With all power to the system turned off, the valve should move to it's default position. you should be able to move the lever on the side by hand, and it should run back when released. If the lever just flops about, or doesn't run back, the valve head is suspect.

 

[Knight2135]

Thanks very much for all help so far guys, being a novice it really helps.
(plus it gets me out of watching the x factor lol )

Next to the pump and the 3 port value I have a white danfoss MB12 box which the wires from each (the pump control speed and 3 port valve) go into.
I can not get the the front of the vavle to have a look to see if anything is labeled on the front.

Not sure this helps what so ever but the vavle is very dark blue.

 

[gas_man_gaz]

can you unclip the actuator from the body? did bg install maintain the sys under homecare?

 

[Knight2135]

ill pop and have a look.
I bought the house not long back so Im not aware of the home care or BG installation :-s

I have added a photo album to my profile and have added two pictures so you can see what im talking about. it might help, it might not.

[/img]

 

[Knight2135]

Yes, I have managed to unclip it.

I have two things to play with -

1) on the bottom I have a plastic handle I can force from right to left and i can feel it turning something in the actuator.

2) on the left hand side, I have A and B with the slider in the A position.

The Actuator is a BGMVPS - 2

 

[Knight2135]

typo

its a

BGMVSP - 2

 

[gas_man_gaz]

looks the same as bg's (a re-badged drayton), depending on how old it is ya might be able to remove the head. if ya can they will be a black button on the side, push it in n pull it away from the body.