boiler pump keeps turning off then back on

[snadge]

we noticed tonight that the boiler pumps seems to turning off & on randomly every 5-15 seconds or so after turning the heating off and does it a bit when on too...?

i know the pump is supposed to stay on for 5-6 minutes after turning heating off but seems a bit erratic tonight - last night i had to drain the system and filled it back up again and bled it too - worked great last night...

the boiler is an Ideal ISAR HE30

are these random and sometimes lengthy pump 'actions' meant to happen? - just as typing this it seems to have settled back to one long pump , i turned heating off about 10-15 minutes ago

status is 'd'

 

[petit_pablo]

D is hw demand. Likely to be the preheat running and not satifying.

Turn boiler off. Let the CH cool down then turn boiler on wih CH off. Run hot tap and see if the heating pipes start to warm up. If it does the diverter is stuck. If it doesnt, then does the burner cycle on and off every 30 seconds or so? if yes, suggests a restricted plate heat exchanger.

 

[snadge]

D is hw demand. Likely to be the preheat running and not satifying.

Turn boiler off. Let the CH cool down then turn boiler on wih CH off. Run hot tap and see if the heating pipes start to warm up. If it does the diverter is stuck. If it doesnt, then does the burner cycle on and off every 30 seconds or so? if yes, suggests a restricted plate heat exchanger.

ahhh right... well, weve been having problems with hot water ive noticed past week that the hot water is just warm and had to run taps slow for about 10-15 seconds before it would heat up... does this help?

I think u are right about the preheat for water not satisfying - the burner wasnt coming on and off much but had been - not every 30 secs - seemed quite random but burner defo come on once or twice during the pump moments when CH was off...

i will try what you said

thanks very much

 

[petit_pablo]

if the diverter is stuck then this would explain the slow heat up of HW.

Give the test a try and post back.

 

[snadge]

hey Pablo - turned back on after CH cooled down and its OK... its not doing anything

BUT, just before i went into toilet and hot water tap was still on but only VERY slight dribbling to almost dripping - the tap was warm... I think this may have caused it too....

thanks

 

[petit_pablo]

Dribbling hot tap will cause random preheat fire up.