Combi Boiler issue

C

Charley

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The Combi Boiler is Ideal Logic. Hot Water is fine but Central Heating is not working. Pressure gauge seems consistent around 1.5 bar.

There was a radiator leak and the plumber put a sealant in to try to fix the problem.

Central Heating was partially working on timer (in the mornings) but now not working at all on Timer/Boost.

There doesn't seem to be any air in system if we bleed the radiators.

Would anyone have any ideas on anything else we could try to fix the problem?
 
1 to 1.5 bar is fine while cold. When you say not working, can you describe that? Does anything happen, like does the boiler fire initially, is the circulation pump running?

If the boiler fires but the pump doesn't run, it may be jammed, most pumps have a little cover you can remove to rotate them manually (do that while the system is off). A jammed pump could be a little piece of debris or a sign the pump is on the way out.
 
Leo said:
When you say not working, can you describe that? Does anything happen, like does the boiler fire initially, is the circulation pump running?
Click to expand...
When we turn on Hot Water tap, the burner symbol on the display lights up and the status on the display goes from 0 to 'd'

But when we set the digital timer switch to control the central heating, it does not work consistently.... i.e. the boiler doesn't fire up, burner light on the display remains off and Status stays at 0. Pressure seemed to be maintained around 1.5 bar though.

It doesn't seem to matter whether it's a programmed into the timer or whether we use the Boost function. The boiler won't fire up for the central heating but works fine for the hot taps.

However, at intermittent times the Central Heating will function.......e.g. if we hit Boost the boiler will remain silent for some time (as above) and then all of a sudden fire up and kick into action someway through the 60 mins. For a while there, the CH had been activating the boiler for timed periods in the morning, but then wouldn't activate for timed periods in the evenings, but lately has been not activating either.

So it's hard to figure out why the boiler doesn't kick in the majority of the time for the CH and then occasionally will function normally, when the Hot Water function remains fine.
 
What stats are in place? Can you check they work by isolating and ensuring the loop opens and closes as you adjust the target temperature?

The '0' to 'D thing just means it has switched from standby (o) to 'On Demand' (D) heating. Staying as O means the boiler isn't getting the command to fire. There's a chance that the timer itself is the issue. Is that hard-wired or a wireless one?
 
Leo said:
What stats are in place? Can you check they work by isolating and ensuring the loop opens and closes as you adjust the target temperature?
Click to expand...
Not entirely sure what you mean but I'm guessing it's something to do with the blue & black levers on the pipes underneath, which we have opened & closed so they have brought up the pressure when needed. Can you explain how to isolate them? and what you mean by What stats are in place? thanks
 
No, stat is an abbreviation of thermostat. Each zone in a central heating system typically has a thermostat. For a timed heating cycle, the boiler will only fire up if the ambient temperature around the thermostat is below the target temperature.
 
Yep, Leo's suggestion re the circulating pump seems the most likely cause. Hot water will still heat by convection but central heating needs pump for circulation (some upstairs rads might still heat slightly by convection). Locate your circulating pump, screw off the brass screw (bout the size of 5c coin) off the front and insert a small screwdriver in to the notch on the pump spindle to turn and loosen it up. If this doesn't work, then your pump likely needs replacing (Pumps have an average lifespan of 10-15 years though some last much longer). Contact a plumber for diagnosis.
 
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