GSHP/thermal store Instrumentation

[StBarnabas]

List
I will be installing a new thermal store (1000L) in my GSHP system in about two weeks time and would welcome suggestions re instrumentation. Would like to be able to work out the total heat generated, electrical power in and also COP obviously. The system is high flow rate - low temperature differential. I have a few flow meteres as suggested by KenB http://www.seeedstudio.com/depot/water-flow-sensor-p-635.html?cPath=6 but the 28mm pipe would be throttled right down first to 15mm and then about 11mm through the sensor. Is that likely to cause a problem? Does anyone have other suggestions?

Sean

[dhaslam]

The way I propose to measure flow rate  for  my system is with a  bucket, just time how long it takes to fill it at different pump speeds.   It would give a small error in that the circuit wouldn't be closed  but  it should still be accurate enough.

[Baz]

If you are worried about flow rate, and it would be a problem in a gravity circuit, you could put in a parallel bypass with a valve and calibrate it, before install, so only half the flow goes through the sensor.

[StBarnabas]

DH
an interesting idea. If the flow rate is constant then I just need a pump sensor. Anyone had any 1-wire pump sensing thoughts recently?
Baz

Bypass is also a good idea. How confident would you be if the water temperature changed?

Sean

[Baz]

Good point, it does change a lot. http://en.wikipedia.org/wiki/File:Dynamic_Viscosity_of_Water.png
Perhaps you could heat up, close valve, make reading, open valve until flow halved.

[KenB]

Sean,

It might be worthwhile investing in a proper heat meter - like this one from Sontex.

http://www.dmsltd.com/SONTEX/Supercal_539_Compact_Heat_Meter

Whilst DIY systems are interesting to tinker with, you would be guaranteed accuracy with a commercial product such as this, and it would not compromise your plumbing bores.

It has an open-collector pulse output - so easy to read with any pulse counting micro.  The LCD display means that you always have a visual tally of heat measured since it was installed.



Ken

[Iain]

Hi Sean
If they are cheap enough put 2 or 3 in paralell, it will half/third the restriction, put the output in paralell as well to add the pulses.
Iain