Which one should I believe? (Herpstat vs. Temp Gun)

[jason221]

I recently received a Herpstat and decided to test it out on a spare sheet of Flexwatt.

Here's the problem:


Untitled by jason.granger, on Flickr

The tempgun is 4-6 degrees off of what the thermostat is set to! Before you ask how I'm measuring the temps, here's how it's set up:


Untitled by jason.granger, on Flickr

As you can see, I'm measuring the temperature of the Flexwatt directly since it's not attached to a cage. Any ideas what's going on here? Is that tempgun just inaccurate?

[saber2th]

OK, heres my thoughts on what I see. The probe is taped to the Flexwatt, but only a portion of the probe is actually making contact with the Flexwatt. The rest is being exposed to room temp air and the heat coming off the flexwatt. So the Herpstat is heating it up more to get the right temp. Take a piece of aluminium tape and cover the whole probe, that way the heat will be trapped all around the probe and you should get a closer reading.
Just my thoughts, correct me if I'm way off base here!

[AMBiEN22]

Bump I'd like to hear if anyone knows the solution too. IMO i feel that maybe its the herp stat as the probe is spherical. Thus leading to inaccurate readings as the ambient air cools the probe as its being heated by your flex what. This is just the chemistry major of me speaking, strike a hypothesis! But you could try to maybe put the flexx watt were you are going to use it keep it there let it heat and re-take the readings. Meaning don't move anything from were your actually going to use it and shoot the temps.

If they are still different you got me.

If you want fast results do a simple test. I am not sure if the herp stat probe is waterproof but grab a cup of warm water... shove the probe in... then shoot the water with the gun. see what you get!

But i feel its kind of hard to answer your question as its hard to pass the blame to either product.

[AMBiEN22]

OK, heres my thoughts on what I see. The probe is taped to the Flexwatt, but only a portion of the probe is actually making contact with the Flexwatt. The rest is being exposed to room temp air and the heat coming off the flexwatt. So the Herpstat is heating it up more to get the right temp. Take a piece of aluminium tape and cover the whole probe, that way the heat will be trapped all around the probe and you should get a closer reading.
Just my thoughts, correct me if I'm way off base here!

My thoughts exactly your a faster typer then me =P!

[saber2th]

Or just try putting the probe under the Flexwatt.

[Ladybugzcrunch]

Is your temp gun consistent? If you zap the tape 10 times in different spots will it read the same temp or very close? I bought a infrared thermometer last week that is crap. It reads different everytime. My herpstat has always been spot on. But my probe is covered in foil tape too. I agree with the others, try covering the probe with foil tape but also try taking the average of your readings from the temp gun. If the range of the readings is kinda great, you may have a problem there. Herpstat is accepted as a great product - great choice!

[kitedemon]

Ir reflects and flexwatt is shiny this will lead to false readings. Most ir guns are calibrated to be looking at something roughly the colour and reflectance of a brown paper bag everything else is off somewhat. The allowable deviation of this ir gun is about 2ºF up or down (the PE1 is the best sub 200$ gun I have found at 1.5º +/-) So 5 degrees off is not a big surprise. The deviation on the herpstat probe is very low .3 I believe. IR guns are really not very accurate under the correct circumstances they can be ok. but that is it. Get a GOOD thermometer (mercury lab grade or platinum probe traceable digital but sit down when you look for a good (.5º accuracy digital one it will scare you. some LC ones are also very good and are cheap. Just check the packages on the shelf if ten or more read the same you can expect a .5 degree accuracy. To test this for your self flip the flexwatt over for an hour or so so the herpstat probe is on the carpet away from drafts and them quickly move it and check the carpet it should be with in 2 degrees. Don't take my word for it CHECK the SPECs and email Dion at spyder Robotics he will tell you the same thing.
Alex

[jason221]

OK, heres my thoughts on what I see. The probe is taped to the Flexwatt, but only a portion of the probe is actually making contact with the Flexwatt. The rest is being exposed to room temp air and the heat coming off the flexwatt. So the Herpstat is heating it up more to get the right temp. Take a piece of aluminium tape and cover the whole probe, that way the heat will be trapped all around the probe and you should get a closer reading.
Just my thoughts, correct me if I'm way off base here!

I was told specifically not to use foil tape by the owner of the Herpstat site. He said to use clear packaging tape, which I didn't have, so I just used Scotch tape.

Is your temp gun consistent? If you zap the tape 10 times in different spots will it read the same temp or very close? I bought a infrared thermometer last week that is crap. It reads different everytime. My herpstat has always been spot on. But my probe is covered in foil tape too. I agree with the others, try covering the probe with foil tape but also try taking the average of your readings from the temp gun. If the range of the readings is kinda great, you may have a problem there. Herpstat is accepted as a great product - great choice!

It is fairly consistent, depending on what I'm aiming at. If I aim it at my wall, it is within a one degree margin every time. Flexwatt, more like a two to three degree margin.

Ir reflects and flexwatt is shiny this will lead to false readings. Most ir guns are calibrated to be looking at something roughly the colour and reflectance of a brown paper bag everything else is off somewhat. The allowable deviation of this ir gun is about 2ºF up or down (the PE1 is the best sub 200$ gun I have found at 1.5º +/-) So 5 degrees off is not a big surprise. The deviation on the herpstat probe is very low .3 I believe. IR guns are really not very accurate under the correct circumstances they can be ok. but that is it. Get a GOOD thermometer (mercury lab grade or platinum probe traceable digital but sit down when you look for a good (.5º accuracy digital one it will scare you. some LC ones are also very good and are cheap. Just check the packages on the shelf if ten or more read the same you can expect a .5 degree accuracy. To test this for your self flip the flexwatt over for an hour or so so the herpstat probe is on the carpet away from drafts and them quickly move it and check the carpet it should be with in 2 degrees. Don't take my word for it CHECK the SPECs and email Dion at spyder Robotics he will tell you the same thing.
Alex

I've heard of temp guns reflecting off metal and giving inaccurate readings. Interesting.

[seeya205]

You can't go by what the thermostat is set at. Sometimes you have to put them a couple degrees up or down from what you actually want. The important thing is to have the floor of the enclosure the temp you want. Measure this with a digital thermometer and see how close it is to your gun. My gun is only 1 degree difference from both my thermometers!

[Valentine Pirate]

I'd be partial to the temp gun. They're incredibly accurate, and they will change from area to area depending on how far away you are and such. I've heard of themostats being off much more often than I am comfortable with, so just set the thermostat to whatever gives the correct reading for the temp gun