Ideal Icos HE24 Problem..Please help

Good Morning,

I have had a problem with my Heating system - the system is exactly 3 years old this month (December 2009).

In a nutshell...The heating controls...these are:

Danfoss TP5000 Hard wired inside house that controls the Central Heating set at 20C on at 4.30pm to off (15C) at 8.45pm. The flame on the panel re-ignites the boiler if the air temp falls in the house.

Danfoss FP 715 Si in the garage (next to boiler and tank) that only controls the hot water we use; set from 6am to 6.20am and 5.50pm to 6.20pm.

These are both wired into the fused spur powered Danfoss terminal box as is the boiler, pump, tank thermostat and the actuator valves.

This is my problem:

The Danfoss TP5000 ignites the boiler at 4.30pm and heats the house up nicely.

If the program is run through its entirety the flame disappears and the boiler keeps going....the temperature of the radiators keeps increasing and the house is like a sauna.

I have to switch the boiler off at the fused spur panel (as the pump sill keeps going if I turn the boiler off at its switch - Which is strange??) to get the heating off as the Danfoss TP5000 will not control the boiler at this point,

However I have had the panel tested and even swapped it with my next door neighbour (they have same system) there is no fault on mine and the same problem occurs with the perfectly working Danfoss TP5000 from next door.

The next thing I was advised on was the actuator 2 port valve on that controls the central heating. I have changed this with one I borrowed again from next door, this was a perfectly good Danfoss He24 2 port valve actuator.....again the same problem persists....I now have 2 Danfoss He24 valves...that presumably both work fine!!

Finally, the worst thing of it all, when I try to demonstrate the problem I have with the continuous running of the boiler even when the TP5000 has told the boiler to switch off is:

When I manually turn the TP5000 on to fire the boiler and central heating it does fine, I can leave it 10, 20, 30, 40 minutes then turn the thermostat to the non-flame off temperature e.g. 15C, 18C etc... The boiler turns off nicely...

I am now stuck on what is happening.....Is it the thermostats inside the boiler not operating properly or something I am totally missing???

The Central heating and Hot water work fine, it’s the boiler not shutting down when it is told to by the Danfoss TP5000 that is doing my nut in!!

Thanks for any support!!

Check motorised valves. These control the boiler NOT the programmer!!

Programmer controls the motorised valves.

Hi johnski15, is this installation a Warmfront job by any chance?

Tim

PS did you say Icos or Isar?

I assume you have a standard open vent Icos 24, not the system version from what you have posted.

The Icos does not have anything directly to do with the pump. This is controlled by the zone valves.

I do not feel that there is any problem with the boiler but it is actually an external control fault.

The only real way to find the component that is keeping the boiler firing is to use a multuimeter and trace the point that is wrongly giving the 240AC signal to bring on the boiler.

frost stat fitted ?

Thanks for the response everyone.....very quick.....

The boiler wasn't fitted by warm front. It's an Ideal ICOS HE24

I have swapped the Zone valve Danfoss HPA2 for one from my neighbour, I suppose this could be faulting also, as it has been used...But it wasn't as the time it was replaced...

Dave, Thanks very much for your advice, I have had an electrician come out and test the extrenal controls and found nothing wrong with them....

As initially posted: the Sparky spent 20 - 40 mins testing and the Danfoss TP5000 performed as it should, turning the boiler on and off when requested....Very frustrating!!

And when the program kicks in at 4.30pm tonight, I'll leave it for 20mins and go and knock the temp on the panel down to 15C which will stop the boiler....it's just when the timer is on for and hour or so, the thermostat detects the 20C temp, the flame disappears and the boiler runs and runs...the Rads are too hot to touch.....

If anyone can give me further advice or has come across this problem before I would much appreciate it!

Thanks in advance, John

It will be the motorised valve sticking endswitch. Or temp setting wrong on digistat, the boiler will only comeon with a C if asked to do so and the pump will be running too, both get power from motorised valves as said before.
But to test this when its on at boiler (but off at timer/roomstat) see if there is power in L2 on black five pin plug going into boiler.
There shouldnt be and if there is something externally is calling for heat

It will be the motorised valve sticking endswitch. Or temp setting wrong on digistat, the boiler will only comeon with a C if asked to do so and the pump will be running too, both get power from motorised valves as said before.
But to test this when its on at boiler (but off at timer/roomstat) see if there is power in L2 on black five pin plug going into boiler.
There shouldnt be and if there is something externally is calling for heat
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Thanks Shambolic:

So, just to clarify....You recon that by replacing the motorised valve (that being my Danfoss HPA2 Actuator) this correct the problem??

Or could the actual 2 Port brass valve (that is connected to the 28mm copper feed pipe) that the actuator attaches to be sticking, thus not allowing the Rads to switch off when the room thermostat tells it to?

Also, I'm sure that the temp on the Room stat cannot be set incorrectly as I have reset it, and used another one to verify that the TP5000 is not the culprit.

Thanks Again, John

Can the valve

Remove the HA2 head and see if you can turn the spindle with your fingers. It should be easy and smooth. Also check there is no water leaking from the spindle.

It could even be the ch body is stuck open and the HW actuator sticking on.

Your sparky should hopefully have tested the voltage on the orange wires from each actuator seperately, as it is these that supply the power to the boiler and pump.

Edit

Just re-read your post. I have had problems with the TP5000 sticking on in the past.

To all, Thanks again for all the help and info!!!

I am in the process of having the Spark come out and retest the 2 port valves....

I have left the heating running in the morning and this has indeed highlighted that the Room stat has turned off but the boiler has not....There is a code 'C' on the boiler....hence there is an electrical signal telling the boiler to run!!

I spoke to Ideal technical support the other day and they confirmed that the boiler is not in fault, as a different code appears on the boiler panel.

Another (strange) thing happened this morning though....My hotwater control panel (danfoss FP715 Si) is in the garage next to the boiler itself - and fires the hot water on at 6am to 6.20am.....However I noticed this morning the Rads came on (my Room stat was off).....Very strange..

Could this be a problem with the Hot water 2 port valve? And could this be the overall problem?

Thanks, John

If the rads are coming on when only the HW is selected it will be the CH valve that is stuck open.

is there an air/frost stat fitted in the garage, if so it may have been wired to open htg valve and fire boiler. If there is a frost stat you should idealy have a pipe stat fitted on common return, wired in seris with air/frost stat.

Thanks for all your help and advice....

Solved the problem in the end....

Changed the HPA2 2 port valve....no effect....

Then drained the heating system, changed the Brass Valve on the 28mm copper pipe, re-attached the new Danfoss HPA2 and refilled the system...

Rob's your Dad's Brother....The control system/Room Stat now turns the heating off and on as required!!!

Cheers, John