Hotwater not circulating, no power from Aquastat ?


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Old 01-25-13, 08:44 AM
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Hotwater not circulating, no power from Aquastat ?

No water circulating, I have a 40yr. old boiler with a Honeywell Aquastat L80248 and also a Honeywell RA816A stack mount oil burner primary control wired in series with the aquastat. No power on the circulating pump wires, wired pump directly to get heat in house. I cleaned the points in the aquastat and noticed the stack mount control was tripped, after re-setting and re-hooked up the circ. pump everything worked but the stack control was making a buzzing noise, took cover off and flicked the relay and now working fine. Question can I disconnect the stack control and wire burner straight to aquastat ... why is that control even there, there's none on my brothers newer furnace, I'm thinking it was an extra safety back in the day with the older burners .. ? Do I need a new Aquastat ... or could it be the stack control ? .... thanks for any info.

PS: I guess I should have mentioned that the furnace has a newer type Riello Burner with the Cad Cell as mentioned by another member, this is why I'm thinking I can eliminate the stack control without it becoming a safety issue.
 

Last edited by rontoolman; 01-25-13 at 10:03 AM.
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Old 01-25-13, 09:38 AM
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Question can I disconnect the stack control and wire burner straight to aquastat ... why is that control even there, there's none on my brothers newer furnace, I'm thinking it was an extra safety back in the day with the older burners
NO! YOU ABSOLUTELY MUST NOT REMOVE OR BYPASS THAT CONTROL!

You, your family, and your property will be placed into harms way if you do so.

Older systems use the 'stack control' as a means of determining when the burner has actually LIT. It does this by sensing heat on a bi-metal strip. If no heat is sensed in a period of time after the burner has been called on to light, the stack control will time out and turn off the burner (and the oil spraying into the combustion chamber).

Newer systems do not use the stack switch any longer because they use instead a CAD CELL which is mounted inside the burner housing. A CAD CELL 'sees' the light of the flame and has no moving parts... it is MUCH more reliable.

If you remove your stack switch and the burner does not light immediately, the burner will continue to run and continue to spray fuel oil into the combustion chamber. This is VERY dangerous!
 
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Old 01-25-13, 09:43 AM
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noticed the stack mount control was tripped
This means one of two things:

1. Your burner did not light immediately for whatever reason. The control 'timed out' and shut the burner down.

2. The control is defective in some way.

ALWAYS when a safety control trips, PRESUME that it did so for a reason and determine WHY it tripped, WHY the burner did not light.

They DO on rare occasions trip on a 'nuisance' trip... which means for no good reason... but NEVER PRESUME or ASSUME that this is the case. It's dangerous to second guess a safety control.

The 'buzzing' is probably not a problem. Relays do that from time to time.

MONITOR your system. If the stack control trips again you should strongly consider having a tech look at the system and determine why your burner is not lighting reliably.
 
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Old 01-25-13, 09:54 AM
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Thanks Trooper, I guess I should have mentioned that this furnace is equipped with a newer riello burner with the cad cell as you mentioned. I'm just a little confused now as to what the problem is/was since cleaning the points or is it still a bad stack control or aquastat, what should I replace if anything ? ... thanks again.
 
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Old 01-25-13, 02:18 PM
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Ron, did you pay someone to install the Riello?

If so, they should have 'decommissioned' all the un-needed controls at that time.

I'm not going to suggest replacing anything until diagnostics are performed to find the problem. I don't believe in being a 'Tinkertician'.

So, first the problem needs to re-occur, and then troubleshot to find the problem.
 
 

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