Smart boiler slow response radiators and hot water

[notmyforte]

This is a DIY find the problem rather than a DIY do the job post.

The central heating is not on and the boiler may have been cold for some hours. I run the kitchen hot tap (to do some washing up) and the boiler does not fire. Fill a kettle several times (and save water for other uses), and still the boiler does not fire. I go into the lounge and turn the radio thermometer up from below the ambient temperature to maximum (35°C) – still the boiler doesn't fire. Sit for a few minutes – still nothing. I go back into the kitchen fill the electric kettle and switch it on – it's getting hot, and suddenly the boiler fires.

This is the last time – I've had to wait before. There are no faults shown, it just sits there doing nothing.

It's an Intergas Xclusive 24, 5 years old.

The Intergas engineer came this morning to do the annual service. He's not had the problem before with both radiators and hot water not causing the boiler to fire. It's not a design fault, the PCB not too likely ... the Internet connection? He's supposed to be coming back with a new hose component, it would be good to e able to tell him where the fault might be.

Anyone know of this problem?

 

[Madrab]

The 2 issue would normally be independent of each other as they use different actions to fire up the boiler -

1) HW - you turn on the hot tap - the boiler flow switch senses the HW demand and tells the PCB to fire up the boiler to heat the cold water
2) CH - your turn up the thermostat - that sends a signal to the receiver that sends a live to the boiler PCB to switch it on in CH mode

The only fundamental common element is the PCB, so why not the PCB. Easy enough to test though. If it's getting a signal from the flow switch or a live from the receiver and still not firing up, then it really has to be the PCB but leave that to the engineer - @ 5 yrs then it should still be under warranty?

 

[notmyforte]

Thanks for the reply.

The boiler has always seemed slow to me as an electronic device, and it taking tens of seconds, a minute perhaps, to respond has been very much the case.

At the moment, I have the idea it happens more when it is starting from cold, but I shall have to correlate events to make sure that is the case.

It also has the habit with the CH of not stopping the burner if I turn it on and then decide I don't need it. Not for terribly long, but long enough to get the radiators hot. Odd, I mean, I can understand the pump continuing to dissipate the heat, but why keep the burner going?

What is the delay process in the circuitry and programming? How much control does the Internet gateway and remote Internet connection have? I think I might try turning off the gateway if the problem becomes more serious and persistent, and see if that makes any difference.

At the moment, it is not too bothersome, but come next winter and the CH leaves me sitting in the cold for half-an-hour deciding to come on ....

 

[Madrab]

If it's simply a delay with the CH coming on then that would more likely to be the receiver, the boiler should fire in less than a min once it receives a call for heat from the receiver. The HW is different though and the boiler should fire straight away when there is a demand for HW.

If it's not doing that then there may be an issue somewhere and that needs to be diagnosed, the IG engineer should be able to do that without too much issue if it's the boiler at fault.

 

[notmyforte]

When the IG engineer came to replace a hose (which he didn't have) and do the annual service (which his call-out wasn't listed as), he said about a little propeller might be getting stuck for the HW, and about radiator valves and thermostat/boiler communication for the CH.

But it is with both the HW and the CH. Presumably, in both cases, there's something on the circuit board that has to send the final signal to fire the burner. Now, my computer monitor has an EEPROM that checks various things before it allows the main circuitry to come on, taking a couple of seconds. This "unprograms" itself every 2 to 3 years, and the monitor will not come on at all until it is reprogrammed. So, EEPROMs on the PCB? Something's gone high resistance and something is taking time to charge, while warmth solves the problem? I don't know.

Also, the gateway is no light piece of electronics. St the thermostat to "ho" rather than "bo" and the radiators don't get hotter than about 45°C.

When IG admin called with the appointment for the engineer to actually come with the hose, I said that the delay problem may have to go to their design engineers, or an engineer in that circle. I was put through to the technical support team, but they hadn't had the problem before.

So, anyway, Intergas has the problem as a "pending issue".

I suspect the maintenance engineer could swap the PCB if that's what they decide to do.

 

[notmyforte]

I'm now wondering about the ignition. Some part associated with it was replaced last year, I now seem to remember. I think it showed a "no ignition" fault then.

What if the gas inlet valve were to be sticking? (In the 60s they were just a conical point and a cone-shaped receptor, the pointed element being raised electromagnetically by a coil, I don't know if that's been improved on.) I had a new gas meter fitted about a month ago. Will it even attempt to fire if there's no gas? Will it keep checking for a gas supply until there is one?