S86F MV control is dead
#1
03-15-09, 08:51 AM
S86F MV control is dead
I have a boiler with a VR8204H controlled by a S86F and an Aquastat L8184E.
The boiler has not been firing, and after a bit of debugging, it appears that the valve and aquastat work fine, but the S86F is only partially functional.
When there is a call for heat, the S86 starts sparking and opens the pilot valve, the pilot lights and after a few more sparks, it senses the flame and stops sparking. The circulator runs and the pilot stays lit, but the main burner never comes on. My investigation revealed that the S86 is never sending the 24v out the MV connection, so the main gas valve never opens. Further testing showed that if I do send 24v from the PV pins to the MV, it does indeed open, so the valve is working fine.
So, my questions....
1) Is the S86F in any way repairable? It did not look like it could be opened without breaking the case.
2) Where can I get a replacement S86F if they are still available, or what other units should I look at as a replacement? The S86F has no lockouts, main burner flame sensors or any other "safety features" so I can't imaging I would be losing much with a different model.
3) Since there are no safety features, is it OK to jumper the MV and PV leads so that both valves come on when there is a call for heat? As far as I can tell from the lit, when working properly the unit turns both valves on and off simultaneously. Actually I am guessing it is actually just a pass through for the 24v and that the aquastat is really controlling the 24v to the valves.
Thanks for your input!
The boiler has not been firing, and after a bit of debugging, it appears that the valve and aquastat work fine, but the S86F is only partially functional.
When there is a call for heat, the S86 starts sparking and opens the pilot valve, the pilot lights and after a few more sparks, it senses the flame and stops sparking. The circulator runs and the pilot stays lit, but the main burner never comes on. My investigation revealed that the S86 is never sending the 24v out the MV connection, so the main gas valve never opens. Further testing showed that if I do send 24v from the PV pins to the MV, it does indeed open, so the valve is working fine.
So, my questions....
1) Is the S86F in any way repairable? It did not look like it could be opened without breaking the case.
2) Where can I get a replacement S86F if they are still available, or what other units should I look at as a replacement? The S86F has no lockouts, main burner flame sensors or any other "safety features" so I can't imaging I would be losing much with a different model.
3) Since there are no safety features, is it OK to jumper the MV and PV leads so that both valves come on when there is a call for heat? As far as I can tell from the lit, when working properly the unit turns both valves on and off simultaneously. Actually I am guessing it is actually just a pass through for the 24v and that the aquastat is really controlling the 24v to the valves.
Thanks for your input!
#2
03-15-09, 04:26 PM
Is the S86F in any way repairable?
Where can I get a replacement S86F if they are still available
Install PDF 8610U
S8610U source
Since there are no safety features, is it OK to jumper the MV and PV leads
You gonna blow yerself up! There ARE safety features! The pilot must be proved before the main valve is allowed to open!
My advice is to call a tech... yer scarin' me...
#3
03-16-09, 10:58 AM
Originally Posted by NJ Trooper
There ARE safety features! The pilot must be proved before the main valve is allowed to open!
#5
03-16-09, 02:49 PM
1st NEVER jump a flame safeguard control the S86F xxxx controls are obsolete, they've been replaced with the S8610U controls. http://www.forwardthinking.honeywell...ll/69_1955.pdf
#6
03-16-09, 03:55 PM
The flame sensor is built in to the ignitor assembly. The control measures that 'flame rod' and determines whether or not there is a pilot flame established. The control will NOT open the main valve until pilot flame is proven.
Please, tell us you aren't going to try anything foolish.
Please, tell us you aren't going to try anything foolish.
#7
03-16-09, 05:54 PM
Originally Posted by NJ Trooper
What model boiler are you working with?
#8
03-16-09, 06:37 PM
Originally Posted by NJ Trooper
The flame sensor is built in to the ignitor assembly. The control measures that 'flame rod' and determines whether or not there is a pilot flame established. The control will NOT open the main valve until pilot flame is proven.
In fact, the ignitor assembly was replaced a few years back because it kept sparking the entire time the boiler was on, presumably due to the rod failing. The MV was definitely opening without flame being sensed at that point since it did provide heat despite the annoying clicking and other issues. At the time my plumber replaced the bladder tank and one of the zone control valves, so I imagine he did not think the S86 was faulty or he would have replaced it then.
Maybe it had already partially failed and he did not know but the documentation does not mention any delay on the MV opening.
Please, tell us you aren't going to try anything foolish.
I was thinking I could just remove the 8204 and let the gas flow 24/7 unrestricted. Then, the next time it gets cold I could get a new house. [this forum needs some explosion smileys]The boiler only heats a finished section of the basement, the rest of the house has forced air and a wood burning stove, so I am not exactly desperate to get it working ASAP. Hence the second part of question 2)
If I have to replace it with something newer anyway, are there additional features I should look for? I see the 8610 has an ignition trial time and a 5 minute lockout after failure. Still, I find it odd that the flame detection is on the pilot only. If the pilot lights but the main burner does not, I don't see anything to keep it from running gas full on until something makes it catch. Are there units with a main burner sensor that would be worth installing at this point? A flame sensing rod is pretty cheap to add if the controller can make use of it. I have CO and NG detectors in the basement and kitchen (gas stove), but I am not sure how helpful the loud beep immediately before the explosion would be.
#10
03-16-09, 09:38 PM
My 2 cents:: if the main valve opened without pilot being establish FIRST , than I could sell more boilers after they have blown up...It only seems as though they open at the same time.DO NOT WIRE THEM TOGETHER as stated earlier.Make sure flame rod is clean and all wiring is in good condition.
