Need a Plumbers advice...

Matt-Page

Matt-Page

Matt-Page

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23 Nov 2004
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Hi,

I've had a problem with my boiler for quite a while but not had the money to fix it.

Initially, I noticed the hot water wasn't coming out very hot when I turned it on full blast. I used to turn my shower on (via bath taps) hot water on full, and then a bit of cold to cool it down. I then noticed the temperature dropping so I just had the hot water tap on.

Then the issue developed further a week or so later, the water came out less and less hot, so I had to turn the hot water tap down to reduce the speed of the flow. This made it a bit warmer.

Again, it got worse a week or two later, it would then output hot water for 10-20 seconds, and then go cold, and repeat.

Now the boiler wont work at all for hot water or central heating. The front boiler panel was showing error H 3.

With a new job and more urgency I decided to get a plumber out. He messed me around countless times by not showing or not calling. Looking in the manual the faulty part was a DHW Thermistor. I replaced this but the fault is still there. I disconnected the boiler from the mains for a while but this made no difference. The boiler also doesn't respond to the Reset button. It just stays flashing H 3

The manual suggests the fault could be the main PCB. Research shows these are eye watering expensive!

A quick Google shows there is a decent person that refurbs PCB's : http://www.ebay.co.uk/itm/IDEAL-ICO..._Air&hash=item53ebc1725b&_uhb=1#ht_1465wt_952

Am I going down the correct route in replacing this? Do my symptoms point towards a faulty PCB?

My boiler is an Ideal HE35

Any advice from plumbers would be welcome.

Thanks.
 
it sounds to me like a blocked heat exchanger/secondary heat exchanger. or a blockage in the boilers pipework somewhere. but you could end up replacing parts until you hit the right one which will be very expensive in the end. i/you/we could keep guessing but the boiler really needs to be stripped down and examined to find the faulty part
 
i am a gas safe engineer. your problem is unlikely to be the hot water heat exchanger as this would take a long time to scale up and stop giving you hot water. This may be a contributing factor though.

I'm pretty certain it's the diverter valve that's failed but without a proper diagnosis from a qualified engineer this is purely speculation. It could be the pcb as ideal make them out of chocolate.

where are you based?
 
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I had a very similar problem with my boiler which is fairly old, cos £100 inc part for a heating engineer to do it - turned out it was the diverter valve.

for reference our tap water was cold but the central heating was fine, we'd get a few seconds of nice warm water then it'd go cold, as time went on this got gradually worse until there was no warm water at all from the tap - but again the heating was fine.
 
the diverter valve in this boiler comes in 2 parts. if it is the diverter that's at fault then expect a bill between £160-220 plus vat depending on which part has failed. it's likely to be the head which is the more expensive part.
 
justalex81 said:
i am a gas safe engineer. your problem is unlikely to be the hot water heat exchanger as this would take a long time to scale up and stop giving you hot water. This may be a contributing factor though.

I'm pretty certain it's the diverter valve that's failed but without a proper diagnosis from a qualified engineer this is purely speculation. It could be the pcb as ideal make them out of chocolate.

where are you based?
Click to expand...

I'm near Somerset.

Halfmad said:
I had a very similar problem with my boiler which is fairly old, cos £100 inc part for a heating engineer to do it - turned out it was the diverter valve.

for reference our tap water was cold but the central heating was fine, we'd get a few seconds of nice warm water then it'd go cold, as time went on this got gradually worse until there was no warm water at all from the tap - but again the heating was fine.
Click to expand...

Sounds very similar! And this was the initial problem, except last week it stopped working all together. Nothing works now, it just flashes H 3. I've tried the new sensor as above, but it didn't do anything. Removing power from the boiler made no difference either. Holding down Reset has no response.

I guess I'm going to have to replace the PCB to get the boiler past this fault and then go from there. A replacement PCB from Ideal, etc Is going to be around £200 I'm sure. A refurb one from an eBay seller with good feedback may well be an option...
 
I doubt very much its the diverter valve or the motorised head driving it.
If the motor had failed, the valve would be stuck in either DHW mode or CH mode...Either way the display would not give an error..

If the hydrualic cartridge had failed in the diverter valve, then again you wouldnt get an error, you would find that the heat generated for DHW would go into the CH, I doubt that the cartridge has collapsed to cause a blockage...Either way that would result in a different error code.

Doesnt point to a blocked plate to plate heat exchanger either as that results in the overheating of the primary circuit...different error code.

So, looking at a H3 fault, its pointing to the DHW thermister, but you say that has been swapped..So that leaves the wiring loom (unlikely) or the PCB ( highly likely)

These boilers use an unconventional method to detect DHW flow (hot tap running) Instead of using a hydraulic valve or flow turbine/switch, they detect flow by temperature change, temp sensor plugged into the plate2plate that only shuts the boiler off once its hot. Run a tap, cold water cools it down and the boiler fires, close tap, boiler keeps running until sensor reaches temp...Job done, its sort of like a mini preheat in the plate2plate!

If you get a recon PCB, I doubt you would be able to get any warranty unless you were a registered fitter, and you would need the configuration leaflet with the PCB, as it has to be set up correctly for your boiler, as you can see that PCB assy covers lots of models...You have to set it up, so it knows what your boiler is.

Have fun
Mick (boiler fixer uperer of many years)
 
Hi all,

Many thanks for all the replies. I have tidy received my replacement PCB. I had to set the jumpers on it to match my boiler (Ideal H35). Plugged everything back in and turned it on. Unfortunately the same H3 error code is flashing up.

Can anyone point me in the direction where to go next? The manual for the boiler stops after replacing the DHW sensor and the PCB.

Appreciate your help.
 
Use a multimeter, check the dhw thermistor resistance, connectors and wiring loom.

Mick

Edit: If that fails to reveal the fault, and your sure the pcb is precisely set as needed for your boiler model, then there is always the possibility that the dhw sensor/thermistor is faulty.
 
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Hi,

I called the Ideal technical helpline and they said there are only 3 possible faults.

1) DHW Thermistor
2) PCB
3) Wiring

OR possibly the front control switch panel. They said if I was a proper plumber they could take me through the voltage/resistance readings to diagnose the problem properly.

The option they gave me is a flat rate of £245 for the repair. Even if the part costs a couple of quid, this is what I will pay. TBH I can't afford the £245 at all.

She said there are other documentation out there other than what I have (user guide) that will give more information. Does anyone else have this?

Any more advise would be great, thanks.
 
FlyingFish said:
I doubt very much its the diverter valve or the motorised head driving it.
If the motor had failed, the valve would be stuck in either DHW mode or CH mode...Either way the display would not give an error..

If the hydrualic cartridge had failed in the diverter valve, then again you wouldnt get an error, you would find that the heat generated for DHW would go into the CH, I doubt that the cartridge has collapsed to cause a blockage...Either way that would result in a different error code.

Doesnt point to a blocked plate to plate heat exchanger either as that results in the overheating of the primary circuit...different error code.

So, looking at a H3 fault, its pointing to the DHW thermister, but you say that has been swapped..So that leaves the wiring loom (unlikely) or the PCB ( highly likely)

These boilers use an unconventional method to detect DHW flow (hot tap running) Instead of using a hydraulic valve or flow turbine/switch, they detect flow by temperature change, temp sensor plugged into the plate2plate that only shuts the boiler off once its hot. Run a tap, cold water cools it down and the boiler fires, close tap, boiler keeps running until sensor reaches temp...Job done, its sort of like a mini preheat in the plate2plate!

If you get a recon PCB, I doubt you would be able to get any warranty unless you were a registered fitter, and you would need the configuration leaflet with the PCB, as it has to be set up correctly for your boiler, as you can see that PCB assy covers lots of models...You have to set it up, so it knows what your boiler is.

Have fun
Mick (boiler fixer uperer of many years)
Click to expand...

All the above sounds good to me too.

OP, you need to get someone qualified. Throwing more and more parts at it is not going to help if it's something not even covered in the manual.

There are other companies who will also charge less than £245 for a flat rate repair. If you can't afford it then how long can you "afford" not to have heating or hot water?
 
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St0rmer66 said:
All the above sounds good to me too.

OP, you need to get someone qualified. Throwing more and more parts at it is not going to help if it's something not even covered in the manual.

There are other companies who will also charge less than £245 for a flat rate repair. If you can't afford it then how long can you "afford" not to have heating or hot water?
Click to expand...

To be honest, it will take me a couple of months (maybe 3) to save that up, so until then.

Fuzz said:
He could spend £20 on a bigger kettle :D
Click to expand...

Haha thanks :p

OK, well I have done some more investigation tonight.

I have stripped down the PCB, and checked there is continuity between the 2 pins the DHW thermistor connect onto. I also checked all of the other pins on that plu and they seemed fine. There is also no 'burn' marks or cracked solder I can see.

Now, im taking it from the plumber I had out to do the work that he DID replace the DHW thermistor, although that could be wrong :)

I have checked the resistance on the thermistor. The book says:

At 25 degrees C expect 9,700 - 10,300 Ohms
At 60 degrees C expect 2,400 - 2,600 Ohms
At 85 degrees C expect 1,000 - 1,100 Ohms

Now I haven't removed the sensor yet, so it is probably sitting in standard tap temperature water (7-10 degrees C) and it is reading 96.0 on my Voltmeter. Is that 9,600 Ohms?

I called the Idea technical line in the manual and they said the flashing H 3 error is always the Thermistor, the wiring or the PCB. Perhaps the PCB I have received is duff?
 
Unplug the sensor, nearest to the part itself, normally a small plug.
Set your multimeter to read resistance, Ohms. Ω
And then use the multimeter probes to check the resistance of the sensor. Make sure you have made a nice firm contact.

If it reads the correct values, then connect it back to the loom and then check the reistance again at the other end of the loom with it unplugged from the pcb assy. It should read the same to indicate there is no fault with the loom.

Mick
 
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