At my wits end with Heating pump continuously running!

[MrFeathersMcGraw]

Hi Anyone that can help.

I have an ICOS HE15 Boiler, in new house less than 5 years old.
The problem I (intermittently) have is that when the Central Heating is switched off - either via the programmer, or through reaching temparature and the thermostat clicking off, the pump in the cylinder cupboard keeps on running.

I've had two engineers out now, and both the Danfoss Programmer, and Danfoss HPA2 Valve have been replaced.
I have also replaced the thermostat myself .

This problem continues, and it's really driving me mad. I'm afraid to leave the heating on when i'm out because the pump continues to run and run and run and the cupboard gets hotter and hotter.

On the boiler the 'C' is lit with the burner light flashing all the time, as if it's on it's over-run programme (but it never stops)
In the cyliner cupboard you can hear the pump continue to run. The valve has closed, because the rads do not get hot, instead, the heat in the cupboard continues to rise.

The only way i've figured out to switch it of, is via the mains switch on the wall next to the programmer (switching off the boiler doesn't stop it). If I leave it off for a few hours, when I switch it back on it doesn't continue, on some ocassions though the pump starts running again straight away.

The other way i've found of stopping it is (maybe this is a clue) if I switch the valve in the cupboard (top one) to Manual, then allow it to return back to auto quite a few times (at least 20) it finally stops the pump running.

Any help is very much appreciated before this costs me an arm and a leg.
Image of Cyliner cupboard is in my album.
What's causing me this problem?

Thanks

Untitled

• MrFeathersMcGraw
• 16 Nov 2013
• 1

 

[ianmcd]

when the pump is running does the boiler get hot ? it wont fire all the time but as you say the cupboard heats up , is the boiler firing up occasionally with no demand ?

 

[steve32]

The pump continues to run after the system shuts down to disperse heat from the boiler and is controlled by the boiler stats.
As best as I can tell from the picture a bypass has not been fitted between the pump and zone valves to allow circulation to cool the boiler after the valves shut.

 

[ianmcd]

yes I know that, but the way your system works , it is called a n S plan and the two valves that you have are called zone valves they have a motor in them which when energised and fully open will press in a micro switch which will bring on the pump and the boiler and when de energised these switches break and switch off the pump and the boiler, it is common for these micro switches to stick and cause the pump to continue to run but the boiler would fire intermittantly also, if the cupboard is heating up I would suggest this is your problem

 

[newbuildinstaller]

bypass is on the first tee after the pump, Its a prepiped range tribune so it would be strange for them to miss that out

 

[steve32]

Missed that, but is it opening when valves shut off.

 

[ianmcd]

when the valves shut off one of the micro-switches is sticking in the closed position that is your problem not the by-pass

 

[MrFeathersMcGraw]

wow - never expected replies so fast - thanks everyone.

The cupboard does continue to grt hot, particularly the pipe connected to the Top Valve which has already been replaced.
What everyone is saying is making sense. When the programmer or Stat try to shut the system down, you can hear the valve close, but the pump keeps on running.

If it is a microswitch (total novice here) how do I get it sorted?
can I do it myself?

 

[Gasescape]

Them hpa2 actuators will give you loads of problems , long term I'd rip them out & fit a couple of honeywells ...

 

[MrFeathersMcGraw]

By the way..... The HPA2 was replaced with a new one only last week, is it just bad luck that this one is bust too?

Thanks again for the replies!

 

[ianmcd]

The engineer replaced the wrong actuator, either one would give the exact same symptom, only way to determine which one it is , is to remove the end switch wiring from the wiring centre when the problem is occuring and test with a multi meter, but as you say that if you manually motor one of the valves and this frees the switch then i would be looking more closely at that one

 

[MrFeathersMcGraw]

Thanks Ian

So, just for me to be clear, the HPA Actuator on the top (horizontal pipe) is the one that has been replaced, and this is the one, that if you mess with (move from auto to Manual) several times it shuts the sytem off.

Is this whole unit the problem, do I need to replace it (with a Sunvic SZ2301 for example). It's just a concern that this is a bran new one.

The Hot water (which I presume is the HPA 2 on the right of the photo) never has any problems, it's always the Central Heating.

If i'm going to buy and install (worried about the wiring) a new Actuator I want to be sure that's the problem.

thanks again Ian - appreciate your help!

 

[Gasescape]

I always lubricate the body when changing the actuator & make sure it moves freely....
Best to remove them long term..

 

[ianmcd]

when the pump is running on get a multi-meter and make sure you isolate the power at the fused spur, remove the cover from the wiring centre and there will be two grey wires from the 2 valves and two orange wires from the valves going into 2 terminals remove these 4 wires and see which grey and orange has continuity the one that does is the faulty valve that you need to replace the actuator head on, you said that you never had a problem with the HW valve but unless you done this test then you wouldnt really know

 

[MrFeathersMcGraw]

Ian

Forgive me for being dumb and pestering you....
If it's only ever the central heating that causes this, and only on messing with the actuator at the top (for the heating) does it stop, do I still need to check the other actuator??

Also, the actuator connects to another wire using a square connector - if I replace this actuator with another brand is it just a case of joining the wires using a junction block instead. After looking at a replacement, they just come with 4 wires rather than a connector.

Really do appreciate your help mate.

Craig