Chilled systems

Glen

I have a client that aside from a couple of VSB 89 boilers in the basement - also has a large chilled system for ice making, dehumidification etc. Recently - due to a break in the piping - lost most of their glycol. The system did have a lwco - which did not alarm. This was not an inexpensive problem. So the question(s) is - what Canadian codes come into play re low water situations, and do these codes specify number and location of these safety devices? Do the same principles apply as boiler systems of this size? What would be better - to monitor pressure or fluid level?

Brad White_9

Not sure about Canadian Codes, per se

but would ask, was the LWCO wired to alarm and fail to do so, or was it just not wired to alarm?

As a matter of good practice, we design-in a flow switch to the water make-up line (if there is one hard-piped) and to the make-up pump if glycol from a reservoir. Alternately we specify a pulse meter reporting to the DDC system. Either way, any flow when there should be none is alarmed.


This is probably not what you wanted to hear but just an inexpensive way to do what you needed.

So in answer to your question, I think flow and pressure is far more pro-active than fluid level, especially if your sensor is not at the very top.


To me, use of a LWCO is to shut down the combustion circuit in a steam or HW system and probably alarm it; location would be above the safe service waterline of the boiler.

In a chilled system (noting that yours is combined) it serves no direct function aside from preventing freezing the bundle. The flow or DP switch is the protection for that side of things.

Sorry about the mess... truly I am.

Glen

thanks

This is a closed system so your first thought is a no go. LWCO is wired hard to DDC - and that company is telling the client the alarm was turned off - but that can't happen on the local DDC controllers (??). Existing lwco is not at the highest point. But your idea of monitoring pressure may fit nicely here. A low pressure switch - wired to The DDC - with outputs to a cell phone for immediate response would work. thanks.