[Hai-users] Temp sensors accuracy again.
Ken Schumm
kwschumm at qsolv.com
Sun Jan 15 09:04:58 CST 2006
I don't think anyone is talking about maintaining a temperature setpoint within a degree or two, although I did have one job that required maintaining temperature within 1/2 degree and humidity within 5%. Couldn't do that with HAI or normal HVAC equipment though.
At issue is only the ability of the sensors to give an accurate view of current conditions.
----- Original Message -----
From: Jim Willeke
Cc: hai-users at tssi.com
Sent: Sunday, January 15, 2006 1:35 AM
Subject: Re: [Hai-users] Temp sensors accuracy again.
I have never seen a single room, let alone a house or a movie theater, that the HVAC could maintain 1-2 degree temperature through out the room.
And likewise, changes of 10-15% in humidity throughout a home would be normal. (Basements vs top floors and kitchens/bathrooms vs bedrooms)
Anyone talking of having all thermostats within 1-2 degree readings throughout a home (or building) has a inaccurate view of reality.
Most "normal" thermostats accept a 5 degree differential for from for on/off conditions.
Differences of comfort is largely related to activity. So differing conditions in the Bedroom vs the workout room should be expected. The ASHRAE Standard 55-1992, "Thermal Environmental Conditions for Human Occupancy is the standard used by the HVAC industry for decisions on temperature and humidity. (See this calculator http://www.automationcollege.com/myfacilities/tools/ComfortCalculator.asp)
Generally, Human comfort is very subjective and depends on:
Air factors
Dry bulb temperature
Relative humidity
Environmental factors
Air movement
Mean Radiant temperature
Personal factors
Activity (metabolic rate)
Clothing
-jim
Brad wrote:
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Well in my case, similar to what others have already said, when you have temp & humidity sensors each reading all over the map, it makes the customer question my credibility and HAI's credibility. Its all installed as a system, not they question the entire "expensive" systems reliability.
This latest install was in a movie theatre. 1 or 2 degrees off can make the difference between customer complaints and not.
We are talking about folks that are setting inactive for 2-3 hours at a time. They notice the difference. Especially the female persuasion. They are much more sensitive to temp swings. Then of course you get into the humidity. We all know how humidity affects the comfort "feel".
I of yet have not had the chance to put instruments in place long term to track the inaccuracies, but I will this week.
As an installer, when I install products I expect them to work as they are "perceived" that they should. The customer has the right to expect this as well. HAI has excellent products for the most part, but by far the temp/humidity sensors and Web-link are sore points in their product lineup. When I install a system, it is not fair to the customer for me to have to figure in labor cost for "futzing with it time" to get things to work as they should.
I'm the anal retentive type, and I have this odd trait that I expect things I purchase to work as advertised. Not sorta maybe kinda work as advertised.
If you bought a clock and it lost 3 minutes per day, everyday I don't think you would keep it very long.
I for one will stop recommending HAI's temp/humidity sensors to anyone until they can get the issues cured. It's not rocket science.
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From: hai-users-bounces at tssi.com [mailto:hai-users-bounces at tssi.com] On Behalf Of Brett Griffin
Sent: Saturday, January 14, 2006 12:46 AM
To: 'Ken Schumm'
Cc: hai-users at tssi.com
Subject: RE: [Hai-users] Temp sensors accuracy again.
Ok, so I have read this conversation many times over the years, and have heard different explanations. I have some questions, please take a moment to read and don't get annoyed that I take a defensive stance, I am really trying to create a good dialogue, and maybe HAI will read this and make adjustments.
My few questions, What is everyone doing with these temperature sensors that you need .1% accuracy? You cannot program the HAI system to respond to decimal levels. So your programs have a 1 degree accuracy, and realistically thinking a 2 degree accuracy since you cannot and should not write a two direction program with the temps setting closer than 2 degrees.
I have an OP2, and I had about 4 temp and humidity sensors hooked up to the system prior to my move to my new residence. I used them for outside temp, and curious things like the temp inside my controller, my basement, and my second floor. I could care less if the temp outside was 14 degrees or 18 degrees, regardless I had to dress warm.
Not I understand that there are some more critical things like humidors and wine cellars, but even the accuracy is not going to make a overall difference.
The point of the temperature sensor being next to the thermostat, I can understand the frustration that they are off by a couple of degrees. However taking the safe assumption that the error likely tracks over the temperature range (i.e. your home temps swing about 25 degrees for extremes) why not just adjust the thermostats to match the temp sensor.
The same being true for humidity. What are you guys doing that requires such high accuracy in your home? The application I have run are like turning the bathroom fan on while taking a shower. The humidity will climb close to 100% so I write rules that if it exceeds 70% turn the fan on. If you have an air conditioned home, your humidity levels will swing between 30-45% Much beyond those levels you got problems like static electricity build up and mold. Again I don't see an application that requires such high accuracy.
Now I understand the concerns of what's expected and what's reflected are not the same thing and that is a legitimate complaint.
Now to my next question, I am done Ranting, now I am pondering...
If you could buy a $20 radio shack sensor and make it work with the HAI system, would you buy them over the $80 temp sensor? What if the accuracy was +/- 2 degrees. Would you buy one for general use like I do, and buy the higher accuracy ones for humidors and wine cellars, where the accuracy was more critical?
Just trying to get insight to your concerns, and by now means do I intend to derate your complaints.
Brett Griffin
Architechtronics
www.architechtronics.com
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From: Brad [mailto:looney2ns at sigecom.net]
Sent: Friday, January 13, 2006 5:46 PM
To: 'Ken Schumm'
Cc: hai-users at tssi.com
Subject: RE: [Hai-users] Temp sensors accuracy again.
Thanks for the replies Ken. Your explanation makes lots of sense. Hadn't thought of the wire length issue.
I'm comparing the readings to a $300 Kestrel 4100 Pocket HVAC tool.
Its temp specs are +/- 1.8 degrees.
Humidity specs are +/- 3%
I also have 3 of the Radio Shack gauges, and those and the Kestrel agrees with each other within a few tenths of each other on temp and Humidity.
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From: hai-users-bounces at tssi.com [mailto:hai-users-bounces at tssi.com] On Behalf Of Ken Schumm
Sent: Friday, January 13, 2006 4:59 PM
To: Brad
Cc: hai-users at tssi.com
Subject: Re: [Hai-users] Temp sensors accuracy again.
Just curious, if your humidity readings are off what are you comparing them to? I believe the Radio Shack humidity sensor is accurate to +/- 5 %. If the HAI is also +/- 5% the difference between the two could be 10% and they'd be within specs.
----- Original Message -----
From: Brad
To: 'Wenzel, Guy'
Cc: hai-users at tssi.com
Sent: Friday, January 13, 2006 2:00 PM
Subject: RE: [Hai-users] Temp sensors accuracy again.
In my case, the thermostats readings are very accurate; it is the Temp.Humid sensor's that are off.
The new temp/humid sensors can not be calibrated. The Thermostats can be if needed.
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From: Wenzel, Guy [mailto:Guy.Wenzel at capella.edu]
Sent: Friday, January 13, 2006 12:40 PM
To: Brad
Cc: hai-users at tssi.com
Subject: RE: [Hai-users] Temp sensors accuracy again.
I have a similar setup with an Omnistat and a Temp sensor in the hallway near the same room and see the same 3 - 5 degree difference. I have not cheeked to see which is more correct. Does anyone else know if it can be adjusted or just the thermostat?
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From: hai-users-bounces at tssi.com [mailto:hai-users-bounces at tssi.com] On Behalf Of Brad
Sent: Friday, January 13, 2006 12:19 PM
To: hai-users at tssi.com
Subject: [Hai-users] Temp sensors accuracy again.
Just installed 3 HAI temp/humidity sensors. Also installed 3 HAI OmniStats with remote temp sensors. The Thermostat remote sensors and the Temp/Humidity sensors are mounted on inside walls within 6 inches of each other, each set in a different room. Temp/Humidity sensors show temps being 3-5 degrees higher than the thermostats show.
Apparently HAI STILL has not resolved the issue of the Temp/Humid sensor's being inaccurate.
The Humidity is reading low on them as well. Very frustrating.
Anyone else seeing this?
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