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Nov 14, 2021
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Hi all,

Recently our house central heating always turned on in the morning (and in the evening of course), but this morning, Saturday, we got up late without turning it on yet, about 9:20ish I heard the pump was making noise! About 9:29ish the noise stopped.---This is to say, boiler not turned on, zone valve not opened, just pump made noise.
Then on 10:23 pump started to make noise again, on 10:29 it stopped---the outside temperature was 2C;

So I began to monitor it to see why:
On 10:56am pump made noise again, then 10:57 just 1min it stopped;
on 11:20am pump made noise again, 11:27 it stopped;
on 11;56am again started noise, some minutes later it stopped;
on 12:19pm pump started making noise, 12:28 stopped---the temperature was 6C.

As you see, there was 6 times the pump made noise for some minutes, then stopped. (I didn't want to see this happen again, so I turned on CH to stop it)

Then I did some research for my boiler which is worcester/greenstar-30i, I see below:

"
▶If the temperature within the appliance falls below 8°C the pump will run to circulate water and prevent the system freezing.
– If the temperature does not rise to 9°C within 30 minutes of the pump operating, the appliance will fire up.
▶ If the temperature within the appliance falls below 5°C the appliance will fire immediately, bringing the appliance temperature
up to 12°C to avoid the possibility of the appliance freezing.
▶ This process will be repeated until such time that the appliance temperature does not drop below 8°C.
"

So I assume the above tracking records were because pump was circulating water? Could anyone confirm this is the case?
Has anyone experienced this pump making noise? And repeated for quite some times ?

Also, for these two points:
"If the temperature does not rise to 9°C within 30 minutes of the pump operating, the appliance will fire up" and
"If the temperature within the appliance falls below 5°C the appliance will fire immediately,"

===what does here fire up mean? It means: zone valve opened and boiler either HW or CH started to operate?

If yes, then it means even if the timer not on, the boiler CH or HW will be on with zone valve opened because of appliance needs to fire up to prevent the system freezing?

Thanks for all your advice!
 
Sounds right frost protection and yes fire up / heat
thank you for your reply!
one query is: as my records show, about 11:56am-12:19noon, the outside temperature was 4-6C already, my boiler is inside garage, so the garage should be more than 8C, why during 11:56am and 12:19pm the pump still started to circulate?
 

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