Aquastat probe temperature validation/adjustment


Old 02-14-16, 09:40 AM
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Aquastat probe temperature validation/adjustment

I just read a couple threads on this and wondering if any of the Aquastats have adjustable settings for reading? We have to verify calibrate probes and thermometers at work often but different equipment.

Any recommendations from supply house or other on a good screw in thermometer? I have the Webstone isolating flanges with drain on all 4 circulators so I can garden hose adapt and check all outputs to zones pretty easy. I can also put one easily at airvent next to output pipe.

Since I installed a new Beckett Aquasmart a couple years ago it has always read 10-20 degrees higher than my boiler gauge. The gauge reads real close to a clamped/insulated remote oven thermometer, the Intellicon HW+ sensor (now removed), and a Flir thermal camera as to what actual output to zones are.

Today was 1 degree outside and house taking a while to heat up. Aquasmart set at 180 high, 20 degree diff, no low limit. Boiler kept hitting high limit and then shut down working as normal. All other gauges and Flir showed 157 max temp to zones. I bumped high limit to 190 and now getting 170 to zones and turned heat manager off (at least for today).

I think part of my problem with no help from other plumbers, Peerless, Beckett is that since my aquastat is sitting in the large pot area where the tankless coil used to be (now blank plate) it of course catches heat a lot faster than what goes to zones and then shuts off. Once burner is off the water mixes with all of flow cools and then reads correctly matching what "everything else" says.

Based on the temperature readings a couple minutes after burner shuts off I think it reads correctly it's just that the large water area gets heated quicker causing shut down. Maybe I can move Aquastat sensor? I don't want to run hotter than needed or jeopardize safety. Maybe I'll just leave high limit higher with larger differential so I actually get 180 when needed. That might me a 200 degree setting on the Aquasmart.

The HW+ wasn't indicating much savings so disconnected and am now back to Beckett Aquasmart heat manager wired as Lawrosa gave me per manual so indirect water is on priority through Aquasmart and goes right to high limit. The short run times for heat still bug me but hot water is working fine so far. Not as cold for as long this year yet. I think a large part of the lack of savings is from the quick swings and where it reads on the peerless. The HW+ on multiple Weil Mclains at old house and friends shows good savings which matched actual oil savings over the years after install.

Thermometers between out and the one on my return pipe are showing a pretty consistent 5-10 delta T no matter what zones are on.
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Old 02-15-16, 11:45 AM
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Second question after reading with the Biasi unit with Hydrotherm reading 20-30 off.

Thoughts on switching the the electrowell and sensor to rear of Peerless WBV-04 and putting temp/pressure relief into plate where coil was. They are at the same height but looks like it would put Aquastat sensor right by output supply area.

I was looking at that on friends Weil McLain last night (while unthawing his frozen kitchen sink supply). The aquastat is right below the supply output to zones? He's also mechanical Aquastat with HW+ installed (temp matches boiler gauge)
Old 02-15-16, 03:15 PM
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The easiest, cheapest way to measure or verify temperate in aquastat probe wells is with a PID controller using a bead type thermocouple probe. Just slide the bead in the well alongside the aquastat bulb.

The PID/Probe displays degrees from -100 to +2000 F..

PID's are widely available on web, (ebay etc) with probes starting around $20. Just search for "PID Temperature Controller". Make sure it is both Fahrenheit and Celsius. Some are sold as a package with probe and solid state relay (SSR). Various types of probes are just a few dollars. Even 9" stainless steel ones for measuring stack temperature are less than $10.
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