Ideal M30100 No HW no CH

[Kuzulvad]

My boiler switches on/off erratically. When HW tap runs, boiler sometimes switches on but cuts off right away. CH doesn't start at all.

I've changed the PCB, the display unit, the flame sensor (Slightly damaged). and the overheat control temperature sensor (Couldn't get recommended resistance reading)

The ignition electrode works OK and is in good condition .The boiler fires up nicely, but only for a couple seconds, after which I can hear a click in the gas valve area and an immediate shut down.

The reset button doesn't trigger anything when pressed. The HW indicator
(D) stays on, even when the CH room thermostat is triggered. with the pump running for a couple minutes before going back to neutral position (0). Then the cycle starts again, but not necessarily at regular intervals.

I checked the gas valve power supply (125volts),

the fan works OK

I checked the DWH thermistor resistance (11,000 Ohms reading, slightly above maximum recommended i.e. 10,300 ohms), checked the wiring but I didn't take it out to inspect it. should I have taken it out? Is there anything to "see" if the resistance is OK?

I checked the return temperature sensor (9,710 ohms, within range),

The diverter (Honeywell) seems to work as far as I can gather, but I'm not sure. The wiring is OK and the power supply as well, and when I switch the boiler on I can hear some clicks inside.


I'm running out of options and a nice hot bath would be nice! Has anyone got any suggestion? Have I omitted something obvious?

Hope to hear from one of you soon! Many thanks. Eric

 

[ollski]

What about the flow sensor....are you getting the correct readings from this?

 

[chrishutt]

If flames cut out after 2 seconds, I would suspect flame sensor (and lead). I know you've replaced this, but is it properly positioned with good electrical connections? Are flames spreading right across burner?

Otherwise what do Manufacturer's Instructions say (fault finding tables)?

 

[Kuzulvad]

Hi, Ollski and Chrishutt. thank you for your very fast replies!

The flow sensor gives correct reading.
Tomorrow I will certainly look at the positioning of the flame sensor and I will also check the flame spreading and electrical wiring continuity.

The interesting thing is that the display unit is supposed to give me an error code which then refer to the manufacturer fault finding tables.
But it does not happen. So as far as the display unit and PCB is concerned, it's all working OK! Could this point to:

- a problem in the PCB (But it's brand new and theand the fault was the same with the old one)

- a problem with the display unit (also brand new, and the fault was the same with the old one)

- a connection problem between one/several of the sensors and the PCB

- something else?

Once again, thanks for your ideas.

 

[ollski]

Has it had all the modified wiring?, there should be a big red sleeve around the ignition lead if it is the new one. Also have you got a leak on the hot water pipe?, this will cause the d indicator to stay on and prevent heating from firing. Could be that the diverter valve actuator is stuck in dhw preventing the preheat to work. Most of the stuff you have changed would be indicated by a fault code on the boiler.

 

[Kuzulvad]

Hi Ollski,

Thanks again for your reply.

When I switch the boiler on, the indicator goes from "S" to "D", and the diverter travels from a medium position to the CH position (As per the manual's drawing),the boiler fires, then switches off and then back to medium position, and sometimes back to the forward position (DHW as per manual drawing)

The diplay stays on D, doesn't go back to T or 0 (As if should)

I wonder if there is a problem with the diverter, or the signal from the PCB to the diverter or from the diverter to the PCB?...

I'm going to check the diverter's wiring now


since yesterday I cleaned the burner and exchanger, checked all resistances and wiring and it's all OK.

I'll get there, I'm sure...

Many thanks again for your support!


Eric

 

[BDL]

The diverter actuator is playing up.
You must have spent some serious pounds to get where you are now?

Take the actuator head off, remove molex plug and observe if this cures the fault.

A new diverter is available with teflon coated inside to resolve the sticking issues.

 

[Kuzulvad]

Hi BDL,

You're right, so far I spent about £100. I managed to find a spare PCB and dispaly unit from a plumber whose customer decided to get rid of his ideal boiler and replace it with "a proper one". I wonder why...

While it was on warranty, I had to call IDEAL engineers... 7 times, the PCB failed twice, the boiler was banging like mad, and it took 18months to get it to work! Brand new boiler!

The call out charge to fix it from IDEAL maintenance team was... £170.
So I'm still in the black! And I've learned a great deal in the process
and got to discover this very interesting WEb site, and talk to interesting people! You've got to be positive haven't you...

Thank you for pointing out the actuator problem.
I assume the molex plug you are talking about is the rubber ring at the top of the spring loaded thingy

If so, I'll do the test you suggested. If it doesn't work, Ill buy the teflon coated actuator you mentioned. Is it a Honeywell model?

Thank you BDL and all the previous people who reply. I'll report back the results for unfortunate Ideal boiler owners like me. My wife is moving back to her mum tomorrow. She hasn't invited me yet. I wonder why... Mind you her boiler is a glowwarm. The business, she says...

Cheers.Eric

 

[Agile]

You keep on saying that you are getting a "D" on the display. If this indicates a hot water demand then thats what the boiler thinks is happening. Either the flow sensor is faulty or there really is a demand.

The best way to check if there IS a demand is to turn off the cold water in to the boiler. Alternatively switch it off for 30 minutes then on and see if the HW out pipe gets hot a few feet away from the boiler.

When its correctly differentiating between an HW or CH demand you can see if the diverter is going to the right position for each requirement.

I once went to a combi with a no CH fault. I quickly decided there was a real demand for hot water. The owner had not considered the relevance of the dampness in the hall for which some of the floor boards were already being lifted!

Tony Glazier

 

[Kuzulvad]

Hi Tony,

Thanks for your reply. I will follow your suggestion to cut the water off
to make sure that there is no demand, and start the boiler again.

I'm also wondering about the DHW sensor. Is this the sensor you are talking about?. As mentioned previously, I measured the resistance which was as per the manual's requirement.
Could it be that it's damaged anyway...

By the way, how does the boiler get triggered to start when you open the hot water tap? Is it the DHW sensor's job to detect the flow? If it's the case, may be the boiler starts because the sensor is damaged and keep sending the signal"flow on"

does that make sense

Many thanks for all your help.

Eric

P.S: a liitle quote from James Dyson (The vacuum cleaners man) which I quite like.

"Enjoy failure and learn from it. You never learn from success"

 

[Agile]

""By the way, how does the boiler get triggered to start when you open the hot water tap? Is it the DHW sensor's job to detect the flow? If it's the case, may be the boiler starts because the sensor is damaged and keep sending the signal"flow on" ""

Thats what I am wondering based on your postings.

Either there IS a demand for HW OR the boiler THINKS there is a demand!

However this on its own would not ecplain why the boiler is not giving HW when you turn on a tap!

The trouble is when you rush into changing bits you run the risk of adding new faults. Particularly so when you buy cheap second hand bits from other people! Its much better to use logic to work out whats wrong!

Tony Glazier

 

[Kuzulvad]

Hi Tony,

Point taken about second hand bits. In fact it turned out the second hand PCB and dispaly panels didn't solve anything. And I get exactly the same fault whether I use the new or old ones... Which means I've got a couple spares, just in case... or they both have identical faults.Not likely.

So, if we follow logically, the DHW may be at fault for triggering the boiler to start without demand (Providing no leaks in the system). But there may be another fault (as well or instead) for the boiler not keeping on when it's fired.

So what triggers the boiler to stop?

1. the DHW sensing no flow, but it may be faulty and stuck on "on"
2. The flame sensor? Brand new, tested for resistance, position and wiring checked and burner cleaned
3. the electrode? but the sparks are generated successfully at start up
4. the gas valve? Not sure about that one. Gas is supplied at start up when ignition happens.what may triggers it to stop supply?
5. Flue sensor? Not sure about its role. is it to do with condensation?
6. the valve. how can it trigger the boiler to stop?

Any other thoughts anyone? I'm going to bed. Eric

 

[ollski]

well lets presume that the basics are ok and that you have cleaned out and emptied the condensate trap and that the fan and venturi are clean and that the gas working pressure is ok. Also checked all wiring and connections as these are notoriously troublesome on the isar.
I think my first point of call would be the dhw thermistor, this operates as the flow switch by sensing a demand by a change in temperature so try removing it and checking the resistances at different temperatures...just out of interest is the preheat working with a t on the display?

 

[Kuzulvad]

Hi Ollski,

Thanks for your reply.


When switched on, the display goes straight from "S" to "D", no "T" displayed at all at any point, ignition proceeds,gas flows OK, then after a few seconds gas gets cuts off, the "D" sign stays on, and does not go back to "0".

According to the manual, "with no call for CH or DHW the boiler should fire for a short period to preheat the DHW plate heat exchanger, the display should read "T" "*" returning to "0" when burner switches off"
This does not happen. Does this point to the DHW sensor


Thanks for pointing out the other checks. I will get the DHW sensor out and will test at different temps, as indicated in the manual. I will also thoroughly check all the wiring again for continuity.

Many thanks for your help

Eric

 

[Agile]

You are continuing to confuse the functions of the DHW flow switch and the DHW temperature sensor!

You dont seem to have done the check of the DHW flow either as i described!

Tony Glazier.