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Our CH hasn't come on again this morning, despite it being a balmy 4°
Boiler tripped over, it usually does this due to a frozen condensate pipe but this morning it's due to lack of pressure, trace it back and the ch pump hasn't kicked in.
Switching the little metal switch over has no effect, perform the universal reset and bingo starts up, boiler fires up and all is good with the world, this is the second time it's done this in the last few months, last time following a power cut admittedly.
Is there anything obvious to check before I get someone in only to be told its the batteries in the thermostat or I just need to press reset on the shatner's bassoon?
(should probably mention it's a cylinder with header tank in the loft, will go check that in a bit but it was fine last time I was up there a couple of weeks ago)
Common fault at this time of year. Hit pump with hammer to free it up. Bearings are siezed.
Hit it with a hammer you say? I know just the "maintenance person" for that!
Maybe
But might be a tiny leak somewhere.
Is it new ? New systems like 10psi minimum or more depending on make / model.
Is there a pressure gauge , what does that read?
Alot of combi boiler run the pump for a few seconds as part of the cool down cycle to stop calcification
Might be wonky time clock if it's mechanical
System boiler needs the correct position on a diverter valve, thats a hard go / no go on some ch installs.
Air pressure switch sensor unit is another.
Std start up would be
Timer or manual switch on .
3way valve where it should be
Fan on . Purge cycle for a few seconds. Which also triggers a go / no go from the APS.
Then gas train pressure in value.
Gas on , ignition
Whommmph fire in the hole.
Closely followed by flame detection , ionisation , magic eye check to ensure burn.
Well it's fell straight back over the first time but having powered off and on again it's currently running and running fine... I've given the pump a bit of gentle persuasion just incase.
Mrs brain woke from covid coma long enough to wonder what I'm up to and when I explained she mentioned the power did go off for a minute or so yesterday.
Boiler itself is running fine so don't think it's anything there. Once the pump kicks in, by the time I'm down stairs to check the boiler the fault code has cleared and it's firing.
If the pump goes off everything stops in short order - I know next to nothing about these things but it *feels* like it's a sequence thing if the boiler over runs the pump -
eg when the power goes off, there's insufficient pressure in the system, the boiler errors. When everything powers back up if the boiler tries to fire before the pump primes the system, no pressure, error, pump then doesn't pump because there's no demand from the boiler.
It feels like I need to put some sort of a delay on the heating and ch controller (or the boiler) so that the pump gets chance to prime first at power on.
We'll see how we go...
(to really rub it in the chimney was freezing so getting the burner lit was a pita too!)
Ok
But the pump does not prime the system. It's a closed loop. It's always ( or should be under pressure ) . Need more information. Is it system ...hot water tank in cupboard...or combi ...box on wall.?
Might be airlock , but you will hear gurgling and most system will have an air separator somewhere
Cylinder in bedroom, boiler in garage, twin tanks in the loft - one small ch header, one water header.
I assume the ch header serves as the expansion tank as there's no obvious vessel anywhere else. Will check later that there's some volume in that.
Diverter valve beside cylinder which I guess switches the feed from the boiler over from the coil in the cylinder to the ch loop. (silvery metal thing with manual and auto positions).
Large red grundfoss ch pump, everything is fine when this is cycling and the heating is on, it is also fine when this isn't cycling and the hw is on* or everything is off.
The issue only seems to arise when the ch is "on" but the ch pump isn't driving. At that point I get a pressure error on the boiler and this seems only to have happened when the power has gone.
That's a broadly new problem though - the power goes off a few times a year without fail and it's always fired back up just fine in the past.
*I presume the tank is at temp at this point as I believe it will also run to deliver hot water to the coil.
Large red grundfoss ch pump, everything is fine when this is cycling and the heating is on, it is also fine when this isn’t cycling and the hw is on or everything is off.
The pump should be on whenever the boiler is on regardless of what loop it is heating. If you're that way inclined I'd check whether the pump is 100%, you could take the thermostat off the wall and connect the live in/live out wires together to force a start on the boiler. Another would be a check in the wiring centre to see if there any loose connections but I'd only recommend this if you are certain you know what each wire is.
Obviously do this with the electricity off...