Frost Stat/Pipe Stat Locations..Opinions Please

[scatmanjohn]

Yes that old chestnut.

Went to a job today, boiler overheating.

Boiler: Glowworm 30 Hxi in very cold garage
System: Fully pumped s plan / auto bypass valve fitted about 2 metres from boiler.

Now what had happened was that during the night with no demand from HW or CH (therefore both ZV closed) the frost stat had kicked in, fired up the boiler. However the auto bypass was stuck which meant the water had nowhere to go resulting in boiler overheating.

If the bypass had been working ok then it would not have overheated and no one would be any the wiser.

It got me thinking if it was good practice to have the frost stat wired up so that it just fires up the boiler and pump (on a s plan) resulting in the hot water just going round the bypass (4 metres of pipe).There was a pipe stat fit on the return within 6" of the boiler.

Would it not be better to wire up the frost stat to the ZV switched lives so that the whole system is protected should it get cold.

In this garage there was about 10 meteres of pipework that could well have frozen.

Any thoughts.

 

[cozzmic]

Yes your right connect the frost stat output through a pipe stat then onto the brown wire if it's a S plan on the ch mv. When the pipe stat trips out at 35-45 celcius it will break the circuit shut the valve and turn your heating off. REMEMBER turn off the power and pull the fuse if your doing it yourself