Differential Sensor Location - Hydronic System

[ChrisConley]

Hello All,

A long while ago I read an article on the placement of differential sensor in a hydronic system. Basically it boiled down to the rule of thumb standard to locate the DP sensor ~2/3 of the way into the hydronic system (how exactly you find that point in a real system was not addressed).

The article specifically addressed why we should never locate the DP sensor across the pump. Recently a European pump manufacturer has starting marketing a pump with an ECM motor that sensors DP in the system across them pump, no external DP sensors.

Finally to my question, does anyone have an article on DP sensor placement hidden on their harddrives? I'd also appreciate any comments/info anyone has on DP location in hydronic systems.

Thanks,

 

[texanman]

Hi,
I think the location of the sensor somewhat depends on the type of hydronic system balancing incorporated- Manual balncing or automatic flow limiting valves. Also depends on the building type-tall or short and wide (campus type). Also depends on system pumping design (one large system) or primary /secondary. I will look for any articles I can find and post it.

regards,

 

[marcoh]

2/3 is what I was taught and I try to locate the DP sensor 2/3 of the way between the first and last takeoffs (ie ignore the pipe length from the chiller plant to the first AHU). Some control valve literature also recommends locating the DP at the furtherest point in the system so the furtherest AHU's are not disadvantaged at part load.

Locating the DP sensor across the pumps seems illogical as the intent is to maintain a constant DP across the AHU's, how would a DP sensor across the pump accurately sense what is happening in the field?

 

[marcoh]

This might also be interesting, controlling system pressure without a pressure sensor.

http://mcliterature.danfoss.com/Web...html/010401/010401_02/02_010401_frameset.html

Never seen this installed but would be interested if anyone has any experience?