Outdoor Wood Furnace Info

All-Purpose OWF Discussions => Electronics => Topic started by: Bluegrass Wood Burner on January 08, 2018, 06:57:07 AM

Title: Maverick probe reading driving me crazy
Post by: Bluegrass Wood Burner on January 08, 2018, 06:57:07 AM
Can you guys give me a heads up on how you get the probes to give accurate readings on my supply line just before it goes into my heat exchangers. Sometimes off as much as 20-25 degrees. I have it zip tied on the plastic pex with the tip on the brass fitting. I also have a short piece of pipe insulation zipp tied over the whole probe. Not working for me at all.
Title: Re: Maverick probe reading driving me crazy
Post by: smithbr on January 08, 2018, 07:32:38 AM

In electronics, when you want good heat transfer from a semiconductor to a metal heat sink, you need two smooth, clean faces bolted to one another, usually with "heatsink compound" or "heatsink grease" applied to the surfaces before you bolt them together.  Barring that, even with two visibly smooth plates, you're looking at trying to make contact between two bandsaw blades placed business-edge to business-edge; I've seen the microscope pictures to verify this.

So to improve your heat transfer, grease the interface, then wrap the whole thing.  Keep in mind that your probe itself will conduct heat away from the contact point, so you'll need to insulate 3 or more inches of the probe as well.

Finally, keep in mind that the actual sensing point on the probe tip often is offset from the point, so you might get a better reading just rotating the probe.  I've done this with 1/8" type K thermocouples.

The best way to get good readings is immersion of a long portion of the probe, but that only works in some circumstances.
Title: Re: Maverick probe reading driving me crazy
Post by: E Yoder on January 08, 2018, 01:48:27 PM
I've used foil tape to help transfer heat, several wraps. Then insulate thoroughly. Usually within 5℉.
Title: Re: Maverick probe reading driving me crazy
Post by: artbaldoni on January 08, 2018, 04:41:51 PM
I just do the adjustment in my head. Reading + 20 is close enough for me.
Title: Re: Maverick probe reading driving me crazy
Post by: tinfoilhat2020 on January 08, 2018, 11:27:56 PM
wrap foil tape around the pipe. then put sensor on the foil tape and tape down with a few wraps of foil tape. then place a small piece of pipe insulation over that area and zip or tape it down nice and tight. That should get you within a few degrees if not dead on. If you have any piece of copper on your supply or return run, just tape the sensor right to the copper with foil tape. I use two of these sensors (both mounted to copper), on in the house and one in the barn and they are dead on.
Title: Re: Maverick probe reading driving me crazy
Post by: Bluegrass Wood Burner on January 09, 2018, 03:13:36 PM
I have never bought foil tape before. Is it like the HVAC guys use on duct work? Where is the best place to buy it.
Title: Re: Maverick probe reading driving me crazy
Post by: E Yoder on January 09, 2018, 03:33:51 PM
If you just need a small roll Lowe's or HD would have it. I get it through Supplyhouse.com. silver metal tape like you use on ducts.
Title: Re: Maverick probe reading driving me crazy
Post by: Bluegrass Wood Burner on January 12, 2018, 10:34:51 AM
I finally got my temperature monitor all set up and am very please at this point. I bought a roll of foil tape from Rural King and put foil tape on pex and copper fitting and then put foil tape on the probe about 4 inches up. I then place the foil covered probe on the pex wit the tip being on the brass copper pex fitting. I wrapped this continuously with the foil tape as tight as I could get it. Then I placed a piece of foam insulation the size of the whole probe over the probe and wrapped it tight in the foil insulation. My reading is 3 degree off boiler temp. The brand I have is not Maverick, unless this unit is made by Maverick. The brand I have is Ivation , it seems to be doing a great job. I have my MAX high set for 195 and my low minimum set for 160. Anxious to see how it performs next couple days. Hoping it saves me some trips out to the boiler. When temp starts dropping I Know it needs wood. When its steady or gradually climbing I know its cycling with plenty of wood.
A thumbs up to this simple device. :thumbup: 
Title: Re: Maverick probe reading still driving me crazy
Post by: Bluegrass Wood Burner on January 16, 2018, 04:36:30 PM
Forget everything I said on last post. The thing has been everything but accurate. I have a split system and the 2 exchangers are side by side. I ran a probe to each of th two inlets on each side and foil taped zipped tied, pack tight. When I first turn the monitor and transmitter on they came right up to temps of 178 with boiler sitting on 180. After about 30 minutes to an hour the temps started falling on the monitor. The temp fell to 161 and I thought maybe the boiler dropped that much. I went out there to check and it was sitting right on 180. Both probes were sending the same temp so I can't blame it on the contact and accuracy with the pex. It has to be the unit. So next day I turned it back on and it did the same thing. It went up to 178 or so for an hour or two and then started dropping. Both probes are reading exactly the sme temp. What could cause my temps to fall 20 degrees for no reason at all? I'm about ready to remove and forget the crazy thing. It was a Christmas gift or I probably would have already. Anyone else experience this?
Title: Re: Maverick probe reading driving me crazy
Post by: shepherd boy on January 16, 2018, 06:05:15 PM
 What's going on inside the boiler? If the temp drops after it runs for a while, with the boiler temp the same, I would suspect your lack of circulation within the boiler. Your water is flowing from the return to the supply without being heated.
Title: Re: Maverick probe reading driving me crazy
Post by: tinfoilhat2020 on January 16, 2018, 06:45:26 PM
you can use some boiling water to test the accuracy of the sensor...but I would agree with shepards theory....the mixing within the boiler seems to be suspect
Title: Re: Maverick probe reading driving me crazy
Post by: Bluegrass Wood Burner on January 16, 2018, 08:14:16 PM
How do most people hook theirs up. There are 4 ports, 2 at top 2 at bottom. Do you all recommend return coming in at the bottom and supply going out at top?