Would anyone know if an external frost stat connected to a Junior 28i should cause both the burner to ignite and run the pump ? On my installation it seems to run just the pump . I would have thought the burner would fire up as well .
Worcester Greenstar 28i junior and Frost stat
- Thread starter Rick01
- Start date
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, I have a feeling the junior has a feature where it spins the pump up every now and again just to keep things ticking over.Thanks for the reply ollski . This was a new boiler installation connected to an existing external frost stat , which happened to be faulty (short circuit). This has been replaced and has not yet called for heat . The 28i has an internal frost stat which will spin up when required . I was just surprised that with an external call for heat , allbeit a false one , the burner did not fire up
K
keego
It sounds like your external frost stat may be wired up wrong, get the wiring diagram out & check.
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Fortunately there are only two connections in the boiler for the ext stat .The stat is wired as a simple switch (open or closed ) so I'd like to think this ruled out wiring as the culprit . Do modern combi boilers just use the pump to prevent freezing if called for by an external stat ? Presumably if an internal frost stat calls for heat it will fire up the burner and the pump , or does it ?
The point others are alooodin to about pipe temperatures is separate but important. If say the boiler is at outside temperature, your pipe stat may bring it on if the ambient is below say 5C. About right because wind chill could freeze the pipes. But you don't want the heating on all night, so add a pipe thermostat, on the Return, set to say 15C. That way everything's well above freezing but nothing feels too warm.
Question is, does the Junior's frost stat connection do this automatically - it appears that it does.
Question is, does the Junior's frost stat connection do this automatically - it appears that it does.
Many modern boilers have a seperate external frost stat connection as well as an internal frost stat device.
That is provided so that if the boiler is mounted in the house but part of the heating system is remote such as an annex or granny flat then a frost stat can be fitted in the area vulnerable to freezing.
IF that was provided then it would explain why the pump is running when the frost stat is activated.
Unfortunately my Worcester boiler CD only shows vague specifications for the Junior so I am unable to see if the junion does have that facility.
Tony Glazier
That is provided so that if the boiler is mounted in the house but part of the heating system is remote such as an annex or granny flat then a frost stat can be fitted in the area vulnerable to freezing.
IF that was provided then it would explain why the pump is running when the frost stat is activated.
Unfortunately my Worcester boiler CD only shows vague specifications for the Junior so I am unable to see if the junion does have that facility.
Tony Glazier
The 28i falls into that catagory - connections for a 3 wire room stat and a 2 wire connection for an external frost stat .The book of words does not go into the details of ext frost stat operation and an initial e-mail to Worcester B implied that the burner should light , but it was a less than convincing reply
If the facility is provided then it will function as I have described above!
Unfortunately the calibre of person employed to deal with tech enqueries is not the status of designer who understands the inner workings of the boiler.
Thats because 99% of calls are very basic and can be answered by reading from the installation manual. Potty say "no experience necessary" in their adverts for staff to answer tech helplines.
Tony Glazier
Unfortunately the calibre of person employed to deal with tech enqueries is not the status of designer who understands the inner workings of the boiler.
Thats because 99% of calls are very basic and can be answered by reading from the installation manual. Potty say "no experience necessary" in their adverts for staff to answer tech helplines.
Tony Glazier
Yes, Agile is correct:
Internal autofrost demand --> Run pump four minutes if below 5 --> commence heating mode.
Between 5 to 9 wait in off state for 30 minutes, then try again.
Above 9 --> return to normal off.
Taken from flow diagram in manual.
Internal autofrost demand --> Run pump four minutes if below 5 --> commence heating mode.
Between 5 to 9 wait in off state for 30 minutes, then try again.
Above 9 --> return to normal off.
Taken from flow diagram in manual.
Qoute from the installation instructions
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