Probe on low level, a nuisance to steam boiler

Christian Egli

This low water level sensor, electric ohm type, causes a lot of nuisance alarms. It controls the low water level. There is a float type sensor that keeps the normal operating water level.

The float sensor never fails to do its job, but the electric sensor often panics and shuts things down.

The water line is very stable with no bouncing. The steaming space is very large with little chance of surging. The boiler is slightly over sized.

The make-up water comes from the city, it's delicious and not hard. It then goes through a water softener, then chemicals are added to it automatically trough the feed line and then the feed tank is preheated so that water going into the boiler is even de-aerated a bit.

Could this be a case where the water is so soft and squeaky clean it does not even conduct an electric current? And when the probe senses no current, it thinks there is no water. Is this the way those sensors work?

Is there a difference between probe sensors meant for hot water and those meant for steam boilers?

Unknown

What brand LWCO are you referring to ?

I've seen a new type of cutoff that automatically shuts the boiler down every few minutes , I think to calm down any surging issues . It was installed on a packaged Peerless steam gas boiler . On larger boilers we use a probe and float LWCO , haven't had any nuisance issues yet .

But it can be like you said - the water might just be to damn clean for the probe to sense .

will smith_2

Just out of curiosity, what's the voltage of the probe type that's giving you problems?

Christian Egli

McDonnell-Miller

McDonnell-Miller PCH, manual reset, one RS probe.

Obviously, an automatic reset would solve the nuisance, but that't treating the symptoms not the sickness.

The new controls LPC-2000 have a time-delay feature that only trips if the low level is recorded for at least a while.

Is changing brand better than just changing the model?