Potterton Profile Boiler - Temp Sensor Kicking In??

[lulu73]

Been reading a few of the posts in here and I think my problem is either my central heating pump (WILO GOLD) or my 3 way valve thingy (Danfoss).

I drained the system, cleaned and re-filled because a couple of rads were not working. I have bled air from everywhere I can see, yet the boiler will light and work for only 3-4 minutes.

I'm assuming the temp sensor is kicking in - the feed and return pipes from/to the boiler are both hot, but none of the rads get the chance to get warm.

Pump whirs away but is making a clicking sound and the 3 way valve lets me change it from auto to manual.

I hope this is enough info - please help!

(EDIT: Forgot to say that I am not getting any hot water either...)

 

[chrishutt]

I would guess an air-lock. Look for likely air venting points - section of pipework that will not vent air naturally to an open vent. You may find one near hot water cylinder - a small brass fitting on the end of a short vertical pipe? If it has a screwdriver slot or something, open it a little to release any air.

 

[lulu73]

Thanks Chris
There is indeed a vent point near the cylinder - this was the first thing I tried, it seemed to let a lot of air out. Now it is only letting water out...

 

[chrishutt]

Put motorised valve into position for hot water only, with heating circuit shut - do you get proper circulation then? Also is there a by-pass ( a pipe and valve linking flow and return pipes, usually near boiler)?

 

[lulu73]

By putting the valve to HW only do you mean slide the lever to manual?

Yes there is a llink pipe between the flow and return in the airing cupboard - it has a gate valve (I think that's what it is - but without the red handle)

 

[Agile]

DIYers can do the weirdest things, like repeatedly draining and refilling a system. A professional would do the minimum! If you drain it you risk airlocks!

Check pump valves are open, bypass is closed, pump shaft is vented, header tank is full of water etc.

Gate valves can shear off inside and seem open but be shut! better left untouched!

Tony Glazier

 

[chrishutt]

Manual setting on a 3 port valve is "mid position" open both ways. Better to let it shut under spring return. It will then be open in one direction only, which will help clear air locks. I think the default position is to hot water (?).

You have identified the by-pass (with red gate valve). It will help if you temporarily close this, since flow is probably only passing through this at the moment. Count the number of clockwise turns to shut, so you can restore the setting, just in case it's been properly set in the first place (unlikely).

 

[lulu73]

Chris and others,
I have done as suggested, moved the 3 way valve halfway and let it move back to auto again, I have closed the by-pass (well it was closed anyway) and I have bled air from the vent in the airing cupboard and all the rads.

Since cleaning the system, the water coming out of the rads is all clear - which is good, but not good if they can't be used!

Please help..!

 

[kevplumb]

are you sure the pump is running and vented

what speed is it set at

 

[bathjobby]

1

rads were not working.

2

the boiler will light and work for only 3-4 minutes.

3

Pump whirs away but is making a clicking sound and the 3 way valve lets me change it from auto to manual.

4

Forgot to say that I am not getting any hot water either.

Number 4; is this with both HW and CH selected from your prog ? I bet if you select HW only, you will get HW, try it.
HW only, returns the 3 way valve into its 'at rest' (no power required) position under a physical spring tension.
Selecting either CH or HW & CH drives the motor in the 3 way valve to mid or full position. When the valve gets there a micro switched signal is returned to the boiler telling it all ok. If that signal is not received after a short time (3 to 4 minutes = Number 2), the boiler assumes a problem and shuts down to prevent possible over heating.
Number 3; I bet that is the motor in your motorised valve failing.

Take the cover off the valve and watch it to prove this, or just change the little motor. Even B&Q stock then for around £9. 5 minute job...

 

[kevplumb]

Pump whirs away but is making a clicking sound and the 3 way valve lets me change it from auto to manual.

are you sure its the pump not the valve

 

[Agile]

If the pump was working AND pumping water then he would get either heating or hot water regardless of the position of the mid pos valve.

Nowhere has he ever said he has bled and spun the pump shaft or seen if it is turning on its own accord.

All the symptoms are typical of a pump not working. Even if the pump itself is Ok there could be a blockage or air in part of the system.

The poster MUST check the pump AND the pump valves ( if they want to get it going! )

Tony

 

[kevplumb]

are you sure its the pump not the valve icon_question.gif

as in the valve clicking

 

[bathjobby]

If the pump was working AND pumping water then he would get either heating or hot water regardless of the position of the mid pos valve.

Wrong.
If the valve does not get driven to its correct position, it will not make the safety microswitch, which will not signal 'OK' to the boiler, which will then shut itself off to after a short predetermined time to protect itself and the system.
Just like the symptoms he has described.

 

[lulu73]

A lot of info there...!
I undone the bleed screw as you have shown and all that happened was that it came out in my hand - no water or air - should there have been either?