Honeywell L8148 Aquastat sanity check
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Honeywell L8148 Aquastat sanity check
Got a new L8148 aquastat today for one that fried last week. Got it all wired up, flipped the switch, nothing. After confirming that I had a call for heat from at least 1 thermostat I jumpered the two T terminals on the board, still nothing. Question: that should force the boiler to fire correct? (cold boiler so high limit not an issue). Looking for a sanity check as I already RMAed the part as defective.
When I manually open the relay the burner and circulator fire right up no issues.
FWIW, 2 zones are hooked up with Taco zone control valves powered via a doorbell transformer hooked to the primary in. Nothing has changed in this part of the circuit but just thought I would mention it because it's super janky.
Anything else I should be checking before I rip out the new aquastat?
When I manually open the relay the burner and circulator fire right up no issues.
FWIW, 2 zones are hooked up with Taco zone control valves powered via a doorbell transformer hooked to the primary in. Nothing has changed in this part of the circuit but just thought I would mention it because it's super janky.
Anything else I should be checking before I rip out the new aquastat?
#2
If L1 and L2 had power on them..... at least the relay would close when the TT connections were shorted. Possibly a jumper was missing ? What model 8148 ?
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Correct, 120V coming In and and manually manipulating the relay fires the burner and runs the circulator. The relay does not close/open when jumpering the two T terminals.
Last edited by sniperpiper; 10-21-19 at 12:35 PM. Reason: Added a word
#5
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Aquastats provide contact closure to start burner. Obviously sandpiper issue is not the aquastat.
If sandpiper had a modern burner controller $64 with LCD display that shows status and history it would be a big help to understant what is going on here. https://s3.amazonaws.com/s3.supplyho...s/R7284Bro.pdf
Rather than paying $159 for old technology Honeywell L8184 sandpiper can save up to 20% annually on fuel costs with Tekmar aquastat/outdoor reset for $157 and save $2.00
https://www.supplyhouse.com/Tekmar-2...iler-4150000-p
The Tekmar 256 has LCD display and digital menus that enable system to be optimized. It requires one extra wire to keep power on at all times.
https://www.supplyhouse.com/Honeywel...tial-5477000-p
If sandpiper had a modern burner controller $64 with LCD display that shows status and history it would be a big help to understant what is going on here. https://s3.amazonaws.com/s3.supplyho...s/R7284Bro.pdf
Rather than paying $159 for old technology Honeywell L8184 sandpiper can save up to 20% annually on fuel costs with Tekmar aquastat/outdoor reset for $157 and save $2.00
https://www.supplyhouse.com/Tekmar-2...iler-4150000-p
The Tekmar 256 has LCD display and digital menus that enable system to be optimized. It requires one extra wire to keep power on at all times.
https://www.supplyhouse.com/Honeywel...tial-5477000-p
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Went back to the unit today and did some more debugging while I wait for UPS to get here.
Measured voltage across both T terminals and B2 and got 0V on both. I'm thinking it's a bad 24V transformer. I took the board out and check the solder on both T posts and have good continuity between posts and traces on the board so my only guess is the transformer is bad. We'll see when the new unit shows up....
Measured voltage across both T terminals and B2 and got 0V on both. I'm thinking it's a bad 24V transformer. I took the board out and check the solder on both T posts and have good continuity between posts and traces on the board so my only guess is the transformer is bad. We'll see when the new unit shows up....
#8
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If you've checked the continuity on both the primary and secondary xfmr windings, then the xfmr is good.
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I don't know how else to explain there not being 24V on either of the two T terminals or the fact that jumpering the two Ts doesn't suck the relay down when there is 120V on L1....
#10
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Measure the transformer voltages directly on the leads from it. If there is no bare spot to contact use pin thru insulation.
A bare transformer not connected to anything usually does not have continuity between primary and secondary. Reason xformers are used for isolation.
When power is on, T T terminals, when not connected together should read 18 - 24 VAC. Usually one side of xformer goes to one T. The other xformer to a 24 volt relay coil. The other side of relay coil goes to second T.
Next measure coil resistance, typically a few hundred or thousands of ohms.
A bare transformer not connected to anything usually does not have continuity between primary and secondary. Reason xformers are used for isolation.
When power is on, T T terminals, when not connected together should read 18 - 24 VAC. Usually one side of xformer goes to one T. The other xformer to a 24 volt relay coil. The other side of relay coil goes to second T.
Next measure coil resistance, typically a few hundred or thousands of ohms.
Last edited by doughess; 10-22-19 at 07:38 PM.