Aquastat not sending power to circulating pump

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Old 02-21-21, 06:32 AM
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Aquastat not sending power to circulating pump

Hello,

I noticed today that my baseboard was not heating up even though the boiler is running and the zone is opened. I figured out that the circulating pump was not running. I have an Aquastat relay L8148A. I tested at C1 and C2 and no power. I tested the pump manually to an outlet and it runs fine. Here's the weird part. When the pump is disconnected at the relay I do get 118 volts at C1 and C2. But when I connect the pump back to the relay I get no power.
 
  #2  
Old 02-21-21, 09:02 AM
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p,
Try jumping TT on your control and see if your clapper opens and if your pump comes on or if you get power to C1 & C2. If the pump works independently it could be a bad solder connection in the control. Those aquastats are known for that they start to work inconsistant unless you have loose wiring in the pump itself.

With given info it's just a guess.
 
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Old 02-21-21, 09:39 AM
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Try jumper on B1 to C1 the circulator should start. If it does start relay in L8184A is bad.

With modern, high sensitivity meter 118 volts measured between C1 and C2 may indicate bad relay contacts.

To see when powerd up and trouble shooting easier, wire 120 volt pilot light to circulator motor .
 
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Old 02-21-21, 09:41 AM
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Spott,
I disconnected the board and took a picture of the back before I read you reply. It doesn't look like any bad solders. When you mean "clapper" I assume you mean the magnetic thing. That does activate when heat is called. Here's a picture of the back. I could not take the thermocouple out as it's stuck and don't want to break it.

 
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Old 02-21-21, 10:00 AM
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Try jumper on B1 to C1 the circulator should start. If starts then relay 'clapper" in L8148A is bad.

With modern, high sensitivity meter 118 volts measured between C1 and C2 may indicate bad relay contacts . When circulator motor connected resistance of those contacts limits current and motor does not start.

Wire 120 volt pilot light to circulator motor to see powerd on. Makes systen diagnostics easier.

Honeywell L8148A is old technology product. For same price replace it with Tekmar out-door-reset/ aquastat than may save up 20% on fuel costs. Also is more reliable, accurate with numerous benefits and features. Just remove L8148A sensor and use L8148A for 24 Volts to power Tekmar.

$169 https:/www.supplyhouse.com/Tekmar-256-Boiler-Control-One-Stage-Boiler-4150000-p

$167 https://www.supplyhouse.com/Resideo-...F-differential
 
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Last edited by doughess; 02-21-21 at 11:24 AM.
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Old 02-21-21, 10:29 AM
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Doughess,

I put a test light on the circulator motor and jumped B1 to C1 and the motor came on. I guess I need a new L8148A. Can I leave it jumped until I get a new board? I've been powering the circulator motor from an outlet and left it always running with one zone constantly opened.
 
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Old 02-21-21, 11:27 AM
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p,
No problem B1 - C1. When burner comes on pump will come on. The thing is that if the burner shuts off on limit so will the pump and the stat might not be satisfied.

Do you only have 1 zone. My guess is no tankless because that is only a high limit aquastat. If you have more than 1 zone you can manually open your flocheck valve and whenever any other zone calls it will heat that zone also. The drawback to that is it might get a little warm from the other zones calling for heat.

Hope this helps a little. Just my thoughts.
 
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Old 02-21-21, 11:43 AM
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p,
No problem B1 - C1. When burner comes on pump will come on. The thing is that if the burner shuts off on limit so will the pump and the stat might not be satisfied.

Do you only have 1 zone. My guess is no tankless because that is only a high limit aquastat. If you have more than 1 zone you can manually open your flocheck valve and whenever any other zone calls it will heat that zone also. The drawback to that is it might get a little warm from the other zones calling for heat.

Hope this helps a little. Just my thoughts.
 
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Old 02-21-21, 11:44 AM
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spott,

I have five zones, 4 for baseboard heat and 1 for an indirect water heater. I will jump B1 -C1 for now until I get a new Aquastat. Is there a better relay I can buy to replace this one? The system was built in 1995 and the first crapped out about 5 years ago. Not bad for twenty years, but 5 years on the second?
 
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Old 02-21-21, 11:48 AM
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For same price replace L8184A with Tekmar 256 and save up to 20% on fuel costs. A side benefit of ODR/A's is more comfortible home. Heating element water temperatue varies according to outside temperature.

A Honeywell out door reset aquastat setup costs $450+

Honeywell for the past 30 years has been milking the old products and not investintg in new technoloy.

Honeywell no longer makes thermostats, just licenses name to other companywhose units have many issues. DH just returned two of their new programable Wi-Fi thermostats.
 
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Old 02-21-21, 12:34 PM
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Now I'm really confused. Please excuse the ignorance as I'm a newbie to all this. I searched the Tekmar but i am not sure how would I install this in place of the L8148A.
 
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Old 02-21-21, 03:06 PM
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P,-

Iím no expert but I think the Tekmar does not replace the 8148. The Tekmar measures outdoor temps along with boiler water temp (I think you strap a water temp sensor somewhere on your pipes, pretty sure), and it also gets input from the thermostat (heat call), and from all that decides when/if to turn on the boiler. (I think that it would send the T-T signal to your 8148 when it wants the boiler to come on).

I donít think the Tekmar would have any kind of safety limit like the High Limit provided by the 8148.

I donít see how itís a replacement for the 8148, but maybe it is. I guess ďDĒ and the other boiler guys here will clarify things.


 
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Old 02-21-21, 03:25 PM
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p,
You are not confused or wrong. As Z pointed out it does not take the place of your aquastat. This has been an age old discussion that I have just given up on with the poster. We just have different opinions on the subject. The purpose of the Tekmar is to ajust the water temp according to the outdoor temp for possible fuel savings and not to be used as a high limit. You still need your aquastat but I'm sure there will be disagreements.

Do your research before diving into one of these Tekmars.

 
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Old 02-21-21, 06:06 PM
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Tekmar 256 is used for high safety limit. It is aquastat with both low and high limit settings, in 1 degree increments. High and low have separate delt-T options.

Thermostats sensing room heat on hydronic systems issue "call for heat" to start circulator. Aqustats sensing boiler water temperature issue "call for heat" to start boiler/burner.

The original aqustats were only a two terminal temperature activated switch wired to start burner. Different meaings of "aqustat" causes frequent issues on DIY.com

Honeywell L8148A has several functions beside simply being an aqustat. Diagram show terminals for those functions:
https://s3.amazonaws.com/s3.supplyho..._PROD_FILE.pdf

Tekmar also has out-door-reset to lower fuel costs make for more comfortible home. Put simply modern aquastat with ODR have major benefits over old. Price of old and new is similar but cost savings are major, tangible benefit.not available on old technology Honeywells.

When DH has to replace defective part, look for something that will also improve system performance, reliability and reduce costs.
 

Last edited by doughess; 02-21-21 at 08:43 PM.
  #15  
Old 02-22-21, 11:42 AM
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D,-

If the Tekmar replaces the 8148, how do you handle the circulator? Seems like you would need something else like the 8148.
 
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Old 02-22-21, 01:06 PM
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The L8148A is not replaced. Only the boiler temperatue/aqustat function on wires to L8148A terminals B1 and B2 are rerouted to Tekmar contacts.

L8148A other functions remain with connections to terminals T & T room thermostat and C1 & C2 circulator

Tekmar leads for 24 volts are connected to L8148A terminals Z and Tv.

The small Tekmar sensor can ge slipped in boiler well behind L8148A bulb. Alternatively bulb can be removed and Tekmar sensor replace it in well.
 

Last edited by doughess; 02-22-21 at 03:28 PM.
 

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