Can Taco VT2218 Circ Supply-Return Temp Probes Be Taped To Pipes?

D107

Due to swapping of VR 1816 and VT2218 circs, finding a well to insert the probe wires on the return is problematic without taking apart piping and putting in a well. Can the return wires just be taped onto the black pipe and give a relatively accurate reading? (We're hoping the run the circ in ∆T mode for the DHW.)

pecmsg

Works well. Just make sure to insulate it!

D107

I probably have to assume the reading from wires will be a few degrees colder than what direct contact with the water would be.

STEAM DOCTOR

> @D107 said:
> I probably have to assume the reading from wires will be a few degrees colder than what direct contact with the water would be.

Doesn't really matter if you are measuring delta T and not actual T. Kicker is to eliminate variables. Make sure that supply and return piping are same material. Supply might be closer to flue, throwing things off.Thats part of why insulation is so important.

D107

@STEAM DOCTOR Thanks, but if the return probe has to be taped onto the pipe, I should probably tape the supply probe as well to keep the relative ∆T more accurate? And yes we eventually want to insulate all the near boiler black pipe, but at least for this project, for now insulate at least a foot either side of the probe.(?)

Zman

I like zip ties, then foil tape. then insulation. It seems like if you just use tape it eventually breaks down and the sensor falls off.

STEAM DOCTOR

> @D107 said:
> @STEAM DOCTOR Thanks, but if the return probe has to be taped onto the pipe, I should probably tape the supply probe as well to keep the relative ∆T more accurate? And yes we eventually want to insulate all the near boiler black pipe, but at least for this project, for now insulate at least a foot either side of the probe.(?)

Current. Both supply and return should be zip tied. Foot either side is fine. Obviously, sensor itself should be insulated. Do you have same piping material on supply and return?

D107

@STEAM DOCTOR Yes, 1.25" Steel pipe. The blue wire that came with the VT2218 probably not long enough but similar gauge insulated copper wire should be ok right? (Captions were written before I realized one could just attach probe to pipe without a well.)
Given photos below, appears that DHW return or common return would be fine.

hot_rod

A hose clamp give you a nice tight connection also, then some pipe insulation.

D107

Thanks @hot_rod I guess the nose clamp (or band clamp?) would be superior to zip ties re: conduction. Someone recommended I also apply thermal conductive compound to the contact area.

hot_rod

D107 said:

Thanks @hot_rod I guess the nose clamp (or band clamp?) would be superior to zip ties re: conduction. Someone recommended I also apply thermal conductive compound to the contact area.

Yeah, zip ties after time tend to loosen and harden, especially on hot pipes. The SS hose clamps give a nice tight, permanent "hold". Don't over tighten and crush the sensor, just enough to hold in place.
A piece of pipe insulation over the clamp, cut a notch in the bottom of the insulation to accommodate the clamp screw, if you want pretty