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canuck the pro
canuck the pro, Handyman
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Experience:  Plumber and Handyman
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I have an Ideal boiler. Not 100% certain on the type but think

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I have an Ideal boiler. Not 100% certain on the type but think it is a Ideal C32 Combi (instructions cover a number of different boilers) which I would like to know a little bit more about normal operating behavior.
So cold, the pressure gauge sits at about 1.5 BAR. When I make a call for DHW pressure slowly raises to about 2 BAR and the water heats up nicely. But once the temperature gauge hits around 70 degress the indicator light on the front of the boiler flashes rapidly and the burner turns off. The indicator light goes back to normal (flashing once every second), the temperature drops to about 60 degress and the burner kicks back in again. This process then repeats itself.
Is this normal behaviour in that the boiler is heating and then, rather than reducing the burner to maintain temperature, it switches off and then 're-heats' to 'maintain' the temparature? I understand it may be normal, but the water temperature (when in the shower for instance) goes from really hot to really quite cool whilst it is going through the cycle. If this is normal I assume that the temperature of the water when the burner is off will be completely dependant on the temperature of the external water supply - is that correct? So on cold mornings while the burner is not lit, the water coming out of the shower may be colder than on a warmer morning.
It just seems like the switching on and off of the burner is 'new' (we have been in the house for two years) but I am just wondering if it is just because I have never had cause to notice before.

Hi, my name is ***** ***** I have been in the home improvement and repair field for 20 years. I will be glad to help you today. You should be getting steady hot water and I may have more questions before the answers start coming. The first question will help us determine what the fault code is. Will you tell me which lights are blinking and how many times it blinks and also the colour of the lights that are illuminated and when? For example LED 1 solid green and LED 3 indicates DHW demand and no error. If will tell me what the lights are doing during DHW demand and CH demand and also when no demand and any other conditions that you may discover.

JACUSTOMER-x55nixvs- : There is only 1 indicator light the flashes green once a second all of the time regardless of action (dhw, Central heating or not in use).
JACUSTOMER-x55nixvs- : when the temperate hits about 70 it flashes rapidly green about 4 times a second, the burner stops. The light then goes back to flashing 1 second as the temperate gauge falls. At about 60 degrees the burner kicks back in with the indicator light still flashing once per second

There is only one LED?


Not 3?


If there are 3 lights then I would like to know which light is flashing and if there is only one light will you look on the rating panel for the model number?

JACUSTOMER-x55nixvs- : The boiler is a Mini C28 not C32 and has an appliance ON lamp and a Lock Out Signal lamp

There is not a burner status LED, Lockout LED and mode LED? Which light is flashing?

JACUSTOMER-x55nixvs- : appliance on lamp (blinks every second under normal operation)
JACUSTOMER-x55nixvs- : Lockout signal lamp I have never seen on
JACUSTOMER-x55nixvs- : No third lamp
JACUSTOMER-x55nixvs- : So two lamps

Do you have a multmeter? There is likely a faulty thermistor. The resistance should be 10k ohms.


The reading is approximate depending on temperature. Should be about 10k at 25C.


If you do get a reading near that then replace the thermistor and test voltage across the thermistor and that reading should be about 3.75V

JACUSTOMER-x55nixvs- : I will need to get a multimeter.
JACUSTOMER-x55nixvs- : But are you saying that the burner should not be cutting out when dhw?

No, you should be getting continuous hot water. Almost certainly the thermistor but that will be determined at your convenience. Take your time. I am online often so just post your findings when you are able.


Basically it is either the thermistor, PCB or wire harness.....the most likely being the thermistor.


I haven't heard from you. Was the information I provided helpful?

JACUSTOMER-x55nixvs- :

The message you sent on 7th January has only just appeared in my inbox. I have not had the chance to check...what I was more concerned about was the operation (as in whether it should be heating / cooling as it is).

Am in rented accomodation so have brought it to landlords attention.

canuck the pro and other HVAC Specialists are ready to help you
I see. Well, I am glad I was able to help although it sounds like it would have been just as fast for me to regular mail the message! Sorry it took so long to get there.