Central Heating will not turn off

[lpickrell]

Recently moved house and have been unable to turn off the heating.

The heating system includes two centaurstats, a horstmann channelplus h27 programmer that all seem to feed into a Honeywell 42005748-001 Wiring Centre along with the pump, hot water cylinder stat and a Danfoss 2 port spring return zone valve. The valve is located from the output of the hot water cylinder (I guess the heating coil?) and then the pump which I assume pumps the hot water round the heating pipes.

I've tried turning off all the stats and the programmer but the heating remains piping hot. Should the honeywell wiring center be controlling the 2 port valve and close the heating off if none of the stats are demanding more heat? It looks like they previously had more zone valves as there are 3 redundant zone valves further down that have no head or wiring.

The plumbers I've had around so far don't seem to want to try and work out why it's happening as they see the redundant zone valves and say that's my problem but surely the zone valve that's wired to the honeywell wiring centre (wired as an S-plan) should still control the heating?

I'm not sure how these wiring centres are suppose to work but assume it's either this creating the problem? or the zone valve is not closing off? I've taken the head off the valve body and I don't see any movement when turning the heating off at the clock, but also if I manually turn the valve it still stays hot.

Any ideas would be much appreciated.

Thanks.

 

[JLMGas]

Could be the microswitch is jammed in the on position in the CH motorized valve, turning off prog etc will have no effect, the only way you can get the boiler to stop firing is turning off the spur unit.

If you are confident with electrics, switch off the spur unit, open the wring center and locate the orange cable coming from the valvehead, if the 2 motorized valves are active there will be 2 orange cables.

With a volt tester turn on the spur unit and with the programmer all off test the orange cable/s to see if its live.

If it is yout microswitch is jammed on.

Again (don't mess with electrics) turn of the power and if there are indeed 2 cables seperate them then you can test what one is live with your zolt tester. (with the power back on- again be careful)

If the orange is "live" at one of the oranges that microswitch is stuck in on position and you need a new zone vavle head.

 

[Agile]

It seems to me that the apparent complexity of your system will require a competent heating engineer to attend and advise.

Obviously with neither heating nor hot water calling for heat the unidentified boiler and ( perhaps later ) the pump should turn off.

If you have only had "plumbers" then its unlikely that they will be able to understand your system.

Of course in saying that I am asuming you are prepared to pay someone and that you did not just call them for free advice!

Tony

 

[lpickrell]

Thanks JLMGas, I will try that.

Agile, you assume correctly, I'm happy to pay someone who can resolve the issues I've been having but so far I've been unable to find someone who seems to have the design or electrical knowledge to investigate why the system was designed as it was and which component if failing.

Boiler is a Potterton Kingfisher 2 RS100.

Thanks.

 

[Axel]

At least it is winter.

I am in NW10 and might be able to fix on a no fix no fee basis. Your setup looks similar to my own, so it should be possible to identify the problem by systematically checking it.

[email protected]

 

[lpickrell]

Yep, no complaints there ... bar the gas bill

 

[Axel]

I am in NW10 and might be able to fix on a no fix no fee basis. Your setup looks similar to my own, so it should be possible to identify the problem by systematically checking it.

[email protected]

 

[heatingman]

could be a number of issues, from the very simple to system design. Any half decent heating engineer should be able to identify problem within 1/2 hour tops.

 

[tamz]

Sticking microswitch

 

[matt1e]

hi pickrell firstly your problem may be down to a frost stat kicking in,its been cold lately!!! but to answer some of your questions

The valve is located from the output of the hot water cylinder (I guess the heating coil?) and then the pump which I assume pumps the hot water round the heating pipes.

Should the honeywell wiring center be controlling the 2 port valve and close the heating off if none of the stats are demanding more heat?

not if the first pargraph is correct
(the hot water output is at the very top of the cylinder, i take it the valve is not connected here! and you do mean the output of the coil)

It looks like they previously had more zone valves as there are 3 redundant zone valves further down that have no head or wiring.

when you say you have two centaurstats do you mean these? if so they are probably supposed to be controlling some of the said zone valves

It seems to me that the apparent complexity of your system will require a competent heating engineer to attend and advise.

Tony

tony sums it up here! why are there 3 redundant valves? I take it they are 2ports and control different zones?? where are they physically connected to? it sounds as though the whole system has now been modified(degraded) you most likely need someone onsite to advise (this should not be a lengthy or difficult diagnosis to a competent engineer with easy access to the valves and wiring centre)

surely the zone valve that's wired to the honeywell wiring centre (wired as an S-plan) should still control the heating?
.

it isn't an s-plan with only 1 zone valve and no it will not be controlling the "heating"
from what you have written i think that it may have indeed originally been s-plan and yes the valves would (or should) have been controlling the boiler but since the the other valves have been made redundant then I think that your system may now have been converted to "c-plan" in which case the two port valve may be stuck open and keeping the boiler firing via its microswitch(if wired conventionally) but it shouldnt be keeping the heating on (though the upstairs rads may get hot via gravity)

with the programmer set to CH and HW off and stats turned down is the pump running?

matt

 

[lpickrell]

Thanks Matt.

Yes, the valve is on the output of the coil.

Yep, those are the centaurstats one upstairs and one downstairs, they're all wired into the wiring centre.

The 3 redundant zone valves are connected as follows:

Untitled

• lpickrell
• 18 Jan 2010
• 1

What's the purpose of the single zone valve if it's not there to control the heating?

Yes, the pump is still running when the stats, ch and hw are off.

Thanks again,

Lee

 

[Agile]

You keep calling the zone valves redundant.

If they are indeed still connected to heating circuits then they are not redundant but have simply had the heads removed.

Have the heads been actually removed or are they still hanging on their wires?

Regardless you still need a competent heating engineer to advise you.

Tony

 

[lpickrell]

Hi Tony,

The heads have been removed, no sign of them or any wires.

Just the valve bodies left on the pipework.

Thanks,

Lee

 

[Agile]

I can imagine the senario!

A valve or two fails ! The owner is faced with a charge of perhaps £220 to replace them.

So he opts to pay £100 to have the heads removed and to leave the system not fully controlled.

I encounter this all the time. The owner, particularly landlords, just want it got working again at the lowest cost.

Tony

 

[lpickrell]

Yep, you're probably spot on there.

We're planning a loft conversion at which point I'll replace the existing system so long term we can start from the beginning, but right now I'll simply be happy if I can get the programmer/clock correctly turning the heating off and on.

Cheers,

Lee