Burnham short cycle

ESpud

I have a Burnham 2 stage propane boiler manufactured in 1999. Model # 205PC-TEI5 serial # 64151145. I am the homeowner and have very limited access to technicians in our rural area. I hope to get some help from this group to address what I believe is a short cycling problem. About 6 months ago we noticed we had trouble with a lack of hot water when outside temps were around 70 degrees (no call for heat, so didn’t correlate). Tech came out and did troubleshooting. Did some cleaning of soot/debris. Determined a need for a Pressure Switch Controller. Part was not available. Hot water returned as before and no part was replaced. No other maintenance or troubleshooting performed. Fast forward to this week. Snow storms and lower temps with power outages. Power restored. Noticed a lack of hot water again and radiant floor heat not working. Pilot on. Furnace not firing when heat called for. Noticed a loose cover on Effikal Damper Control RVGP-KS-6BKF. Pressed on loose cover and furnace fired but short cycled. Removed cover and noticed that if orange connector on right side of controller, attached to computer board, was lightly pressed, then furnace fired and short cycled again. Runs for about 3-4 minutes if furnace is cold and then shuts down. Once damper rotates for about 30 seconds I can push on the connector and re-fire the furnace. Once furnace is warmed up, each firing lasts for about 1 minute after pressing on connector. Similar results from jumping yellow to orange posts on left end of computer board. When jumper was temporarily connected (yellow-orange) for several minutes, then furnace repeatedly cycled and fired producing much hot water in radiant floor and hot water at sink. I have calls into two technicians but have not received a call back (we had a major winter storm this week). Is this something I can address on my own? Thank you for any help or advice.

Jamie Hall

Maybe. From the description it may be the connector itself, or whatever the connector is attached (soldered) to on the computer board.

The first step then — the easiest — is to disconnect the connector and check that all the pins and sockets are secure and tight enough to make good contact, and that the wires connecting to the removable half of the connector are actually intact and connected. Then take a look at the computer board. You are looking for cracked or cold solder joints from the connector to the traces on the board. If you find any they need to be reflowed.

ESpud

This is the referenced orange connector (center of photo) on the damper control. I can make the furnace fire by gently pressing the side of the connector towards the metal plate.

ESpud

Thank you, Jamie Hall

I unplugged the furnace and removed the orange connector and looked at the green computer board. I did not see any cracks, burns, broken solder, etc. I reconnected the connector and plugged the furnace back to power. I initiated another firing sequence by pressing on the orange connector. This initiated short cycling where the furnace fired for approximately 30 seconds then stopped, fired for 30 seconds then stopped, and repeated for about 5 cycles and then stopped coming on and grew cold. During these cycles, when the furnace is about to stop, there is a click from the damper control/damper area, then the furnace stops and the damper begins to turn. The damper does not turn until closed but makes a full rotation and stops in the open position. Once the damper stops rotating then there is another click and the furnace re-fires. The duration of the non-fire segment is 30 seconds - exactly the duration of the damper turning. A couple of other details - the pressure gauge on the furnace reads about 24-25 psi consistently. The temp gauge is bottomed out at 60F when cold and rose to about 140F following the long period of cycling when jumper wire was in place. Also, the pressurized expansion tank has a small red cap on top of the large fitting on top of the tank. I have noticed 2-3 small drips of water (total) coming from this red cap area over the last 2 days and this area has mineral deposits from slow dripping over time.

Jamie Hall

You have two problems — at least.

The first is that damper motor and controller. I am still quite suspicious of a bad connection in that connector or possibly a broken wire in the kink just outside the connector — but it may be simpler to simply replace the whole assembly.

The other problem, however, is your expansion tank. There shouldn't be any water from that fitting — and I suspect that the tank is shot. This is not good.

ESpud

Here is a photo of the red cap above the expansion tank. Is there a good way to test the tank?

On another note, I pressed on a different component attached to the computer board and the furnace cycled on so I am now wondering if the orange connector is at fault at all - seems like any slight manipulation of the computer board has the same result of firing the furnace.

Jamie Hall

Ah. Different red cap, sorry. That's the outlet for the air eliminator, and it needs to be open — and probably will spit. I thought you meant the cap on the expansion tank's Schrader valve. Sorry…

ESpud

I am focusing on the Effikal Damper Control RVGP-KS-6BKF. Currently I have a jumper between the yellow and orange wires/posts on the computer board. The furnace is cycling on for 20 seconds and then off for 10 seconds, on for 20 seconds, off for 10 seconds, etc. The damper is rotating continuously during these cycles. This cycling is creating enough hot water for warm showers for the family. My brief research shows a replacement damper controller to be about $250, which I am happy to pay if I can find one, but want to be sure this is my problem. It looks like it could be easy enough for me to install. I know there are multiple connections and other safety controls related to the furnace firing. How can I isolate and test the damper control?

Jamie Hall

There is a switch on that damper which will allow you to lock it in the open position — or there should be. Try locking it open. If it's allowing the burner to fire in the open arc, the safety switch on the damper is unlikely to be the problem, and so long as the damper is held open the rest of the system should run just fine.

Personally, if that works I'd just leave it that way and forget about it. My own feeling on powered dampers of that sort is that they are more hassle than they are worth…

ESpud

Thank you, Jamie

Yes, there is a switch on the side of the control that allows “Hold damper open” or “automatic operation”. I have tried this on both settings. When it is in the hold open position, the furnace does not fire when called for heat. I cannot manipulate the computer board to make it fire when the damper is in the hold open position. As soon as I switch it back to the automatic operation, the damper rotates and the furnace fires - cycling off 20-30 seconds later and repeats.

Jamie Hall

Somewhere in there there should be a limit switch — a microswitch — activated by a cam or a linkage on the damper shaft. This switch should be in one position when the damper is closed, and should stay in that position as the damper shaft rotates. When the damper shaft reaches full open, the switch should change position, and when it does the damper motor should stop and the boiler should be able to fire. Is there such a beast? Can you find it? Did it lose adjustment?

ESpud

Perhaps. I was able to get a tech to come and check things. He did some testing and poking around. He agreed that it seemed to be the damper controller. He took my bypass of the damper controller to the next level. When I was doing the jumping, I was using a small wire to jump two tiny posts (1&3) on top of the computer board (little solder posts on the green side of the board - see 1st photo above - only I was on the left side of the board that cannot be seen in the photo). I believe this allowed the faulty components of the damper controller to remain in the circuit. The tech removed the 4-wire plastic plug (molex?) that went into the damper controller. He then jumped the labeled ports 1 and 3 in the plastic plug which fired the furnace. He completely took the damper controller out of the circuit - something I failed to do. The only problem I have, assuming the new damper controller solves all these issues, is that I must manually jump/fire the furnace each time I want it to fire. Once fired, the furnace satisfies whichever zones are calling for hot water and then shuts down until it is manually fired again. The part should arrive by late next week and hopefully that will resolve my issues. Thank you very much to those who have followed along / especially Jamie Hall for your suggestions and support.