surface mount dew point sensor

NRT_Rob

anyone know of a dew point sensor with a remote probe that could be surface mounted on, say, a ceiling face?

Mark Eatherton

Any sensor will do....

The sensor is not looking for dew, it is looking for a surface temperature, and before it can calculate dew point, it needs to know the relative humidity.



I think Danfoss and Uponor both have dew point calculator/controls.



You can control the dew point via one of two ways. Either control the relative humidity (tough to do in certain climates), or control the surface temperature (easier to do in some cases than others) by raising the surface temperature above the dew point.



Historically, raising the dew point has been more effective, but may require you to introduce heat into the panel during what would normally be considered a cooling season.



In a totally controlled environment (no open windows or OSA ventilation allowed during certain periods) dehumidification can be done, allowing for a cooler surface temperature and eliminating the need for latent energy removal for the most part. However, attempting to carry the total load (sensible and latent) with radiant cooling has a tendency to create a cool muggy condition, which is probably not an acceptable condition for most human beans.



Geoff McDonell is probably much more familiar with the state of the art controls, because he has actually applied radiant cooling in numerous scenarios.



HTH



ME

NRT_Rob

we have the control figured out

but I need a failsafe in case, say, someone opens a window, or we have a pump failure, or whatever could occur that might bring us into a condensation situation. I thought dew point sensing the surface of the panel would be the most direct way to do this.



I can get monitoring equipment with temp and humidity sensing, but they don't run relays. I can see a dew point sensor from Teleaire, but it doesn't have a surface mount probe, it just senses air temp (so I don't really know what people use it for... do they often cause rain in their own spaces?). Honeywell has one, but it has a weird proprietary output that requires you to use their own control setup.. annoying.

don_9

Fail safe

Not going to happen without constant monitoring.What will you do if they have 50 people over all exhausting high level of co2?What if all these people smoke and the host does not allow smoking in the home..so the door is constantly being open.Only thru constant montoring of the air thru your/there computer will you stand a chance.When it comes to mother nature/people nothing is fail safe.

Look alittle harder at telaire products you can connect it thru a computer and i believe you can set it up to alarm you, if and when you reach the danger zone or if a fronts moved thru dropping lots of rains.

Sounds like another great project and i envy you guys that get a chance to work with all todays technology.

NRT_Rob

yes

that's why a controller is needed, to monitor continuously. problem is, I can't monitor directly what I want to monitor... the surface temp of the ceiling, vs the dew point of the air. the Teleaire unit only appears to measure the air itself and I am not confident that whatever it is reading on a wall will be relevant to the actively chilled floor or ceiling I'll be working with. Ideally it would have a remote temperature probe I could put on the ceiling, and it would trip if the ceiling were going to cross the dew point.



If I can solve that trick, the control strategy is complete and pretty much dummy proof. Or if I can approximate it another way...

Mark Eatherton

Moisture sensor...

Rob, I think you are looking for a moisture sensor. And unfortunately, the current offering of moisture sensors are not small nor compact.http://sens2binternational.com/comm/product_info.php?cPath=557&products_id=3497&language=en&osCsid=g0umgql8e3g7j6qrb88vaptfs6



They are out there tho...







Heres a link to a dew point calculator.



http://www.omega.com/temperature/Z/pdf/z102.pdf







ME

NRT_Rob

holy cow mark

that looks perfect. thank you so much!!



I definitely owe you one for that. Cash in anytime. I think that's the last piece of our puzzle and it really looks like it is exactly what I was looking for. Thanks again!

Mark Eatherton

No problem my friend...

We're here to help each other.



That is what this place is all about.



ME