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Ashereng, I see from other posts that you have the "FAQ" included in your regular signature. My bad for thinking it was specific. Please accept my apology for thinking otherwise. Mea culpa.

Have you familiarized yourself with smiley faces that are blinking? That is described in detail in item #9 in the FAQ's you helpfully cite. On the other hand, I spent a large portion of my career replacing antiquated, pneumatic controls with DDC components. Replacing instead of repair became...

Throw it away and get something digital. ;-)

Two units is the Cadillac option. Better in almost every instance, but technically, not necessary. In fact, it is one of the ways I judge builder quality in house shopping. With commercial/industrial applications, you can get into significant building airflow problems if a definite...

No one ever said an expansion tank wasn't needed - only that it's not the tail wagging the dog with respect to the position of the pump in the circuit. I'm sorry, but the whole point of pumping a utility medium is to serve a device - pump+device. The rest are just "nice-to-have" accessories...

High rise buildings sometimes change the advantages of "pushing" through the chiller. In those cases, the return head is of sufficient pressure that NPSH is not a concern, but pressure drop through the chiller, when you already have a huge head to make up, is disadvantageous. If you are...

I agree with imok2's suggestion completely. Good advice.

P.S. I admit that an air separator is probably a good idea for a hot water circuit, perhaps even mandatory. It is not needed at all for chilled water. Here's the original question: Again, any discussion of an air separator is just "clouding" the issue (sorry for the pun). It is not...

TBP, * sigh * No one disagreed that positioning is important. Please let me state it again, more clearly: A. The question was how to position the pump relative to a water chiller in chilled water circuits vs. positioning the pump in water heater circuits. B. Stanlsimon stated "It has to do...

??? TBP, Perhaps I've misinterpreted, but no one was talking about air separator location, anyway. Stanlsimon interjected that as a reason for pump location relative to a water heater vs. a chiller. (Refer to original question for this thread.) I merely stated that air separators have nothing...

P.S. Air separators have little to do with the issue, since many systems function quite well without them. If you use them, the description above is valid for correct placement, but their actual requirement is often a debated topic.

Pressure is the point, but for slightly different reasons than stated. If you are referring to a water heater, then you have a storage tank. If the storage tank is not at the highest pump head of the system, then you've wasted your pump energy by pumping into the tank - not into the system...

Well, that is the problem isn't it? Sorry, I have no answer to lawyers and judges who think they know Engineering - except to vote (assuming you can) for the politicians that will change them.

A purge device is a proven - and actually necessary - piece of equipment on most low-pressure chillers (R-11, R-123). They are not really useful on high-pressure machines (R-134a). The refrigerant contamination most often occurs on the negative pressure side of a low-pressure centrifugal -...

Tell the Mayor he will need to budget for more Cold Fusion generators.

Typical. Architects step-in wherever they please, and Engineers are normally left to clean up the mess. This confirms that the arrogance does not stop at a country's borders. ;-) ;-) Without naming, I can tell you of a place that refuses to hire Structural Engineers - because it would mean...

walkes, You surely know better than that, especially if you've ever connected a Type B2 BSC to ductwork that serves fume hoods. ;-)

I'm not sure a purge unit addresses the same issue. I believe the problem described was a failure of oil return - due to lower pressures with low loads. It's an oil level safety that trips in the sump, not a refrigerant contaminant issue. It occurs in a matter of a week or two, or even just a...

This all assumes warm air heating. There is another approach. Gas-fired radiant tube heating can be a better choice in large aircraft hangars and warehouses. In effect, the radiant heating is irradiating the slab and surrounding surfaces. They become the heat source rather than a point of...

CinciMace: Yes, it is too bad that labor issues can "infect" what would otherwise be a simple life-cycle cost judgment. If the existing unionized work force is in a central plant, then the unitary approach might allow an outsourcing to a cheaper maintenance contractor. If the existing...