Meh, boiler firing, heating water briefly, then turning off?

Scam · 22 Oct 2022 at 09:22

Any ideas before we need to get someone out? It’s an Intergas Combi Compact Eco RF 30.

When you run hot water it fires, actually goes through the cycle of Ignite, Heat, Ventilate according to the display, then just turns off again :confused:

So you get a bit of hot water (comes up to temp) and then no more. Pressure is saying it’s 1.5 which is fine. No error codes either.

Any ideas before I need to get an adult out?

Nemiyen · 22 Oct 2022 at 09:43

No error codes is a weird one. My old boiler did something very similar but errored with no flame detected. I think a sensor somewhere got replaced. The boiler broke down later on and it turned out to be the main board that got replaced. Very similar symptoms as well but the second time you could just hear a relay clicking and 9 times out of 10 it wouldn't fire up. That was a chateau mordaux boiler or however it is spelt!

Mercenary Keyboard Warrior · 22 Oct 2022 at 10:01

Same issue for me (was heating but some process) was due to stuck diverter valve

Does it heat the rads properly?

Scam · 22 Oct 2022 at 10:23

Mercenary Keyboard Warrior said:
Does it heat the rads properly?

It did about a week ago (when we succumbed to the cold patch)! It was weird because yesterday my other half had a shower no problem. I went in about 10mins after her and the water just slowly got colder and colder. The only thing j can think of that changed was a builder went on the roof above and turned the outlet pipe around, we put it back though. Clutching at straws there I think.

She’s trying a shower now so I’ll try the heating in a sec.

Very annoying if it’s anything serious; it’s getting moved (and presumably serviced) in a few months when our new kitchen goes in!

Thanks for the ideas anyway, will do some googling.

Nemiyen · 22 Oct 2022 at 11:09

You may even have home emergency cover. Some people buy the bronze or silver home insurance without realising and that may include things like boiler breakdowns. If you're 100 percent sure you don't have it then fair enough but when my old boiler broke it was always fixed for free with my house insurance!

We now have a Worcester Bosch boiler that's been fantastic. But then I'd hope it would be when it's brand new!

Edit: if you're not getting any errors then my guess it's something to do with SOP that's failing. The diverter valve is a good call so see if it heats the rads and not the taps. Or while it is heating the rads, do you get slightly warm water from the taps?

Also, the sensor that detects you're running the water may have failed. I'm not a plumber so my answers are here to help others chime in

but whatever flow sensor or detection the boiler uses to know you're running water so it heats up could be failing. The boiler thinks you've turned the tap off and so has no errors because it is normal. I'd expect there to be 2 flow sensors or more but they could be from one control board so then I'd go looking at that to see if it's failed.

Scam · 22 Oct 2022 at 11:10

Yeah so putting the CH on is fine. Heats the rads and gave me a nice hot shower much to my girlfriends annoyance

What could that mean then? :confused:

Mercenary Keyboard Warrior · 22 Oct 2022 at 11:12

its almost certainly diverter valve if the heating works fine but water doesnt
Boiler is switching off because it cant move the hot water on

Darey · 22 Oct 2022 at 11:23

Had something similar and was the flow sensor, heating was fine but the hot water would stop after 10 seconds or thereabouts.

Scam · 22 Oct 2022 at 12:09

Mercenary Keyboard Warrior said:
its almost certainly diverter valve if the heating works fine but water doesnt
Boiler is switching off because it cant move the hot water on

Even though hot water is fine when the CH is on? I presume this is not something I can fix?

Darey said:
Had something similar and was the flow sensor, heating was fine but the hot water would stop after 10 seconds or thereabouts.

Thanks. Again, not something I should be trying to fix?

Mercenary Keyboard Warrior · 22 Oct 2022 at 12:28

Scam said:
Even though hot water is fine when the CH is on? I presume this is not something I can fix?

Thanks. Again, not something I should be trying to fix?

If its diverter it really depends on how handy you are.
Its a simple two wire thing if it needs replacing, first thing is to find where it is, it might free up with a gentle tap
Your going to need to do a bit of googling/youtubing to see what they look like so you can go and find yours then try some gentle taps and try to get it to fire up a few times.

If that doesnt work then its a replace job or a sensor issue as pointed out can show as the same. They aren't expensive, like £20 or so and loads of places like screwfix stock the common ones

Barry Smalley · 22 Oct 2022 at 12:41

Had a similar thing on our Intergas boiler earlier this year which turned out to be a blocked CH pressure sensor. I replaced it and it's been fine since. Our CH hardly runs as we are well insulated, but boiler was shutting down particularly when using the shower and on full load.
To diagnose it, unplug the wiring from the CH pressure sensor and install a manual gauge to check the pressure and see what's happening. I wouldn't trust the fitted pressure gauge if its a few years old - they are prone to failure.