Concept 21 Boiler

rob

Looking for info on a service experience with a Slant Fin Concept 21 gas boiler with a DHW capability (W/M Plus Gold 60) Model CB-180. The expansion tank failed/ruptured over the weekend, a #15 (??!!). The on-call tech was reassigned after he replaced the tank but could not interpret the fault code(s). This morning I was assigned the task. I found a Code 3 indicating a pressure switch fault. I turned off the boiler and checked the p/s for continuity per my manual. The switch was open per manual. After reconnection I retried the boiler. Code #3 no igntion. I noticed the sensing tubes were all water bound- 2 p/s tubes (differential) and the gas control sense port. I drained the tubes and retried the boiler. Green,then amber LED, boiler on line. OK. I decided to check the vent terminal, found an old surf board leaning against the termination/intake. I think the condensation was actually caused by exhaust gas recirculation. I do not see how the x-tank failure can be related. I also recommended to my supervisor that any gas control that was wet or could have been wet (since I did not see the original x-tank failure) should be replaced. Any thoughts/comments. Thank-you for your assistance.

jim sokolovic

Concept 21 Boiler

Rob,
Very nice work in recognizing these field related problems and making the correct fixes and recommendations!
The #15 expansion tank that failed seems very undersized for most 180,000 BTUH input capacity systems - did you replace it with a larger (#30 or #60) unit, and did the boiler water pressure hold O.K. after heating the water? We agree that this probably had no relation to the water found in the pressure switch/gas valve clear tubing - was the water buildup enough to fill the tubing, or just droplets? There is a possibility of exhaust gas recirculation condensing in the chamber below the burner, and then forcing its way into the tubing from the positive pressure of the combustion blower - we assume that you advised the homeowner not to allow any items to block the terminal in the future!
We strongly agree with your proposal to change the gas valve. Since you found water in the the reference tubing that leads to the gas valve, it could have gotten into the valve itself. This tubing transmits the air pressure signal from the blower, to insure the correct air/fuel ratio for safe combustion. When you change the valve, be sure to use the same model and calibrate it as per our Concept Instruction Manual CB-40.
If you need any further assistance, please contact our Technical Service Dept at: (800) 873-4346.

rob

CB 18

Thank you very much for your assistance and for providing me with a contact number and access to your technical staff.
Unfortunately, this boiler went down again Monday morning.
Code 2- no ignition. I reset the power and observed the operation. The ignition sequence proceeded per manual but would not sustain ignition. The exhaust pipe got very warm and it sounded like the main flame was on for about 3-5 seconds. I checked the microamp signal per the manual.
The signal read from 1 or 2 and then up to almost 8 microamps before the gas control dropped out. It seemed like the IFC woild not recognize the microamp signal.
Since the IFC was wet due to the Xtank rupture, I recommended to my supervisor that we get the IFC and PS ASAP. I do not know if we ordered the gas control, but I am going to print this e-communication and let my supervisor take the necessary steps. Thank-you again.
PS I may be calling you from the boiler room as this is my first CB. I may need a more experienced pair of eyes and ears to walk me through this and "hold my hand". Something like the old adage, (to paraphrase) give a man a fish and you have given him dinner, TEACH a man how to fish and you have fed for him life. Best regards.

jim sokolovic

Need to discuss the details...

Rob, Sorry to hear you are still having problems with the Concept boiler. Perhaps it would be best for you to call John Schrank, our Director of Technical Services, at the phone number that I provided yesterday, as soon as possible. This way, we can determine exactly which parts got wet from the expansion tank (did the shell actually rupture, or just the diaphram - causing the relief valve to blow off?). If you call from the jobsite, it would be good if you have a differential pressure gage (0-1.0" range) with you to help us "fish out" the problem.

rob

Details

> Rob, Sorry to hear you are still having problems

> with the Concept boiler. Perhaps it would be best

> for you to call John Schrank, our Director of

> Technical Services, at the phone number that I

> provided yesterday, as soon as possible. This

> way, we can determine exactly which parts got wet

> from the expansion tank (did the shell actually

> rupture, or just the diaphram - causing the

> relief valve to blow off?). If you call from the

> jobsite, it would be good if you have a

> differential pressure gage (0-1.0" range) with

> you to help us "fish out" the problem.

rob

Details

Assigned to this task this morning. Supervisor had ordered replacement parts for repair. I replaced the boiler control module (new UTec model with revised flame sense wiring), pressure switch, hot surface ignitor and flame sense probe. Supervisor decided to order the new gas control after I reviewed our e-conversation. Gas control will be replaced when we receive it. I followed all the enclosed service instructions to the letter. Check boiler input rate with a magnehelic guage set up for reading differential pressures per manual. Set air adjustment for .60" which is about 10% derate compared to .85 (overfired- by others) and checked and set the gas control differential for zero 0" differential. I think this is the correct method per manual. The directions sent with the parts were very helpful and ensured that I did the job properly. Boiler is up and is running fine. I will know for sure in a couple days. Thanks again for your interest and assistance. Its nice to know that I can reach a helpful staff if I need help with your products. Best regards.

jim sokolovic

Good news! but....

Rob, Glad to hear the Concept boiler is running good now. The United Technology control you installed has proven to be very reliable for us, and is being used on all production boilers (for a few years now). The boiler is input range rated, allowing for you to set the input higher (by up to 15%), or lower (by down to 25%), via adjusting the combustion blower air shutter and correlating differential pressure. We were still interested in what parts were soaked with water, and exactly how, if you know. We hate to see so many parts changed, if not necessary. Changing the gas valve still sounds like the right thing to do, assuming there was a significant amount of water in the clear tubing going to it. Thank you for following our instructions so thoroughly, and your confirmation that they were adequate.

rob

Still running,

and providing DHW to the best of my knowledge. The whole problem was caused by a rupture in the #15 expansion tank installed (by others) located directly above the boiler.
The seam split and according to the owner it looked like rain shower down there all over the boiler. Due to air louvers on the top jacket I venture to say most components were probably wet. As I mentioned before I was not the on-call tech so all of my info is second hand. Most likely it was just pure coincidence that both problems occured simultaneously. The water bound sense tubes were full of liquid probably caused by recirculation of flue gas, due to blocked vent terminal. Some parts such as HSI and FSR were never at risk, but I feel my supervisor wanted to make sure that the job is done properly the first time and that our client and his family's best interests and safety are first and foremost. I agree. I get one chance to make a good first impression. Thanks again for your help and concern. Best regards.