frost stats?

[bob the plumber]

daft quaestion but one i would like to know...probably only put one frost stat in.

if a frost stat powers the boiler when it detects a tempreture of 3 degees or so on what then turns the boiler off, or does it just turn itself off when the boiler stat realises it has reached its max?

stupid question but handy to know

thanks

 

[gmac]

Whan temperature rises frost stat will turn boiler off, frost stat works same as room stat, senses air temperature
while the boiler is running it is controlled by it own thermostat the same as it functions normally

 

[GasmanxxxR1]

No, you should use a pipe stat on the return. This will shut the boiler off when a given temp is reached on the return pipe, usually about 25 degrees C

 

[gmac]

No, you should use a pipe stat on the return. This will shut the boiler off when a given temp is reached on the return pipe, usually about 25 degrees C

??????????? when your temperature of pipe is below set temp then it will automatically fire up boiler, even in middle of summer ?????????????

 

[SimonG]

GasmanxxxR1 is correct, was pulled on an OFTEC inspection and had to fit pipe stat to disable frost stat once return upto abot 25 - 30C.

 

[gmac]

GasmanxxxR1 is correct, was pulled on an OFTEC inspection and had to fit pipe stat to disable frost stat once return upto abot 25 - 30C.

so you still using frost stat with the addition of a pipe stat and run electrical supply through pipe stat pipe stat first then to make a circuit to frost stat which in turn will fire boiler if required ???

That does actually make sense

 

[SimonG]

Yep, so you need return below 25 - 30C and air temp low enough to kick in frost stat. I was told it's down to the low temperatures of condensing boilers not heating the air enough to kick out the frost stat, all part of energy conservation.

 

[bob the plumber]

im glad you have mentioned a pipe stat cause my way of thinking was, if the frost stat kicks in because the boiler is in a garage at near zero tempreture then what actually turns the frost stat off as it will not detect the increase of heat off maybe a small run of already insulated pipe work.

thanks

 

[Ian10261]

Another way of looking at it is...once the frost stat has kicked in then its not going to knock off until the air temperature rises again which could be days if last winter is owt to go by, so summat needs to knock the boiler off when the pipework warms up. enter the pipe stat which will break on rise and kill the boiler until the pipework temp drops below the preset at which point the boiler will fire unless the air temp has risen in the mean time and then nowt happens....job done. The local Chapel near me thought they'd had all their oil nicked last winter, turned out htey only had a frost stat and no pipe stat so the boiler just kept going til it emptied the tank and then everything froze up anyway!!

 

[dontknowitall]

Is there a wiring diagram of this somewhere? I understand the principle but can't visualise the brown and blue things ...

 

[Ian10261]

I always buy Honeywell and the wiring diagram for the two should be included with the frost stat.

 

[tamz]

If just to protect the boiler AND if it has a bypass, wire it to the boiler switch live.
To put a bit heat around the house wire it to the brown of the heating motorised valve (or the white of a mid pos).

As both stats break on rise, in normal operating conditions although the pipe stat will make, no power is supplied as the frost stat is still at break.

 

[dontknowitall]

Brilliant! Many thanks, Tamz!!

 

[bob the plumber]

i want to know why there is never mention of this in your installation instructions?? they never mention a pipe stat, but i understand now why it would require one :$

 

[tamz]

Lots of things are never mentioned in the installl instructions

 

[stevetheplumber]

basicly its a simple circuit, from permenant live to the same terminal that calls for heat normally ,which is through two switches which in this case are the stats
for those that struggle with wiring think of it as a heating circuit where live is the flow and neutral is return and switches are valves