Burnham RSA85 boiler won't fire up not tankless


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Old 12-05-10, 05:24 PM
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Burnham RSA85 boiler won't fire up not tankless

Hello, my son has a RSA85 boiler for heating baseboard only. The controls are L8148A aquastat and R4184D1027 Primary control both are Honeywell. When the thermostat calls for heat the burner does not attemt to fire up.The contact in the aquastat pulled in but no attempt to start I checked the input to the aquastat for correct voltage and it was 120vac . I then checked the output and had no voltage, I checked at the red and white wire that feeds to the primary control. I'am not sure if I measured at the correct place. I opened the transformer and checked for 5k at each coil and had none . This is a 2 zone and from the aquastat I could see a green lightand a red light on trying to call for heat, lowering the thermostat below room temp shut off the red light. Is the 120VAC taken from the Aquastar and sent to the primary ? Getting cold in N.H need help soon.
Thanks,
Rickeyb
 
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Old 12-05-10, 06:50 PM
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from the aquastat I could see a green lightand a red light on trying to call for heat
You have red and green lights on the 8148 aquastat? Do you maybe mean on the 'zone control panel' ?

When there is a heat call, and the relay switch in the 8148A pull in, you should have 120 VAC on B1 and B2 in the aquastat. This voltage should go to the WHITE and BLACK wires on the 4184.

You've pushed the reset button on the 4184 ?
 

Last edited by NJT; 12-06-10 at 07:59 AM. Reason: dyslexia corrected
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Old 12-06-10, 05:03 AM
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Trooper I think you ment the 4184.....correct? There is no reset button on the L8148.
As Trooper stated there should be 120v on B1 & B2 on a call for heat.
 
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Old 12-06-10, 07:17 AM
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1. Yes the reset has been pushed with no results
2. yes I did mean the Taco zone control panel
I should have just edited this post, added another for your answer on B1 and B2
I have tried both thermostats and the relay in the aquastat will pick with either one.
thanks,
Rickey
 

Last edited by Rickeyb; 12-06-10 at 07:22 AM. Reason: more info
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Old 12-06-10, 07:21 AM
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I pulled the Aquastat product data sheet from the internet and Yes I did check the 120Vac at the B1 and B2 terminal, I had checked but was not able to confirm that I was at these terminals. I did not have 120vac at B1 and B2. i unplugged 1 wire and measured again and had 76vac.
Rickey
 
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Old 12-06-10, 08:03 AM
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If the relay in the 8148A aquastat has pulled in, and the boiler water is below the high limit setpoint temperature, then you should have 120 VAC at B1 and B2. The 76 V that you measured with the wire disconnected is not 'real'... with the wire loose like that, you are measuring a 'phantom' voltage... don't worry about that for now, just know that it is inconclusive of a problem.

What IS conclusive is that you have no voltage at B1 and B2 and this indicates a problem with the 8148A aquastat.
 
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Old 12-06-10, 12:07 PM
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OK, I'll pick up a new aquastat. do I remove the sensing bulb to replace the aquastat ? if I do should I recoat with conductive compound /
Thanks,
Rickey
 
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Old 12-06-10, 04:48 PM
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Yes, the sensing bulb should pull straight out of the 'well' after you loosen the clamp that holds the aquastat (and of course the wires) ... do yourself a favor and TAG THE WIRES so they go back where they were! (I know... it's a 'duhhhh' thing... but I'm just sayin').

Above all, when you reinsert the bulb, make sure it's all the way to the bottom of the well, and be very careful not to 'kink' the capillary tube. If you wanna use the heat paste, just put a 'blob' of it on the end of the bulb... like maybe 1/4 tsp or so.

Check out the L7224U before you purchase...

L7224U1002 - Honeywell L7224U1002 - 120 Vac Oil Electronic Aquastat
 
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Old 12-07-10, 03:32 AM
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one last question, do I have to drain the boiler before I pull the Well out?
Thank you
 
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Old 12-07-10, 10:37 AM
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hi Rickeyb –

I know very very little. But you don’t have to drain the boiler and you really don’t have to remove the well to put in a new Aquastat – thank goodness! (I’m sure Trooper or Grady or others will confirm that for you). Your old Aquastat 8148A has a sensing bulb that fits into a well and your new replacement will also have a sensing bulb. The new sensing bulb will fit in the same well. (I think that’s 100% certain, but the pro’s can correct that statement if it’s wrong.)

I put in the L7224U1002 as a replacement for the 8124A. The L7224U1002 sensing bulb looks something like the shape of the kind of capsule you swallow (something like that anyway, but longer) and it’s fastened to wires and those wires have a connector on the other end. The connector connects inside the Aquastat box. So in other words you have the Aquastat box and you have the sensing bulb on wires coming out the back of the box. Your job is to mount the new Aquastat box and make sure the sensing bulb is pushed all the way in the well and its wires aren’t kinked as Trooper says. Wasn’t too hard for me and I’m a klutz!

Then of course you have to connect the old wires (L1, L2, thermostat wires, etc.) up to the new Aquastat.
 
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Old 12-08-10, 03:55 AM
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Installed and working,
Thanks for your help
Rickey
 
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Old 12-08-10, 04:11 PM
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Great! Thanks for lettin' us know!
 
 

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