Replacing Honeywell L8148E aquastat relay with L8148J1009

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Old 10-03-14, 08:53 AM
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Replacing Honeywell L8148E aquastat relay with L8148J1009

I am replacing an aquastat relay because my boiler would not fire, also there was no voltage at TV and T. On the new L8148J1009 it came with an additional jumper that goes from Z to TP. The manufacturer already has a jumper from W to Z. I tried the boiler with the jumper (Z to TP) but it did not fire. Now I'm questioning if I did the right thing. When I turn on power and call for heat via thermostat the damper does open and the circulator pumps are running, but boiler does not fire. I measured the voltage with power on and thermostat calling for heat, here is what I found. TV (black wire) = .9; W (with jumper)= 1.7; T (white wire)= .9; B1 (Blue wire) =1.7; B2 not used; B3 (purple wires) = .9; C1 (black wire) = 116.5; C2 (white wire) =0; L1 (black wire) =116.5 L2 (white wire) =0. I used a digital multimeter set to 200 AC. What can I try next?
 
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Old 10-03-14, 10:04 AM
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What's the make and model of the boiler?

and if you can determine, the model number of the gas valve itself.
 
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Old 10-03-14, 11:16 AM
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Slant/Fin Sentry Gas Fired Model S-120P; Gas Valve Honeywell VR8200A2421 24 volt; Taco Low water cutoff LNA 1203S-1 (green light is on); Slant/Fin Damper part # 412706040 24volt; 4 zone switching relay Taco SR 504 (only 2 zones are being used; and what looks like a temperature overload protector 330543 (on the back plenum with pink or red wires to it). That's the whole setup
 
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Old 10-03-14, 11:53 AM
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For a 24 VAC gas valve which you have, the TP-Z jumper SHOULD be installed, along with the Z-W jumper.

B1 (Blue wire) =1.7; B2 not used; B3 (purple wires) = .9
From where to where did you measure the voltages on B1 and B3 ?

When the thermostat is calling for heat, you should see 24 VAC (nominal) BETWEEN B1 and B3

The wires from B1 and B3 should ultimately land at the TH and TR terminals of the gas valve where you should see 24 VAC also.

Between the aquastat and the gas valve, wired in series, are 'safety switches'... There is a "Rollout Switch" which is located down by the burner, and the one on the atmospheric hood is called the "Blocked Vent Switch".

How is the damper wired in? It's also got a safety switch that will prevent firing if damper doesn't open... damper IS opening but it's possible that safety switch isn't making contact.


First check to see if you get voltage and B1 and B3, then at the TH and TR. If you have it at the aquastat and not at the gas valve, then one of the safety switches is preventing the burner firing...
 
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Old 10-03-14, 12:17 PM
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I read B! & B3 to ground but when I measured between B1 and B# I got 23.6V. When I measured between TH and TR I got 0.0. So its either the safety switch on the burner or the damper safety switch is not making contact, correct? Should I have measured TH and TR to ground? I don't see any safety switch on burner. The damper has a 4 wire terminal block which I marked although it only goes on 1 way.
 
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Old 10-03-14, 01:08 PM
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Yea I found the safety switch for the burner, jumpered it and voila I have fire. Now to order the safety switch. Thank You So Much NJ Trooper!!!!
 
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Old 10-03-14, 01:31 PM
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Which safety switch Bob?

If it was the 'rollout switch' down by the burner, it may have tripped for a reason. These are typically 'non-resettable' thermal fuses.

Be sure that your boiler is not 'plugged' with debris in the flue passes and this is causing the 'rollout' condition to trip the safety.

They DO OCCASIONALLY trip from 'old age'... just like me.

But just to be on the safe side, start by assuming that it tripped because of a legitimate reason and do the required inspections to be safe.
 
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Old 10-04-14, 03:47 PM
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It tripped because I adjusted the flame too high when I was adjusting the flames on the burners. I have ordered a new roll out switch and did all inspections you suggested, I appreciate your concern. Thank You again.
 
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Old 10-05-14, 08:29 AM
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Hi Bob, what do you mean by " ... adjusting the flames ... " ?

The only adjustment that should be performed on the gas valve is by means of adjusting the gas pressure, and this is done with an instrument called a ' Manometer ', NOT by eye looking at the flames.
 
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