weil-mclain ultra 80

siteman

I have a weil-mclain ultra 80 boiler and I recently had a servicing dealer from my area install a new dhw tank,I am now getting a 6.25 code and the system is not heating but you can hear the pumps running...Can anyone give me an idea what it may be ..Thanks  mike

Tim McElwain

How old is

the boiler. The early Ultras had a Honeywell Control. The new ones have an United Technology control. To determine the code we need the age.

siteman

weil;mclain ultra 80 series 2

The boiler is 5 years old and sometimes I need to reset it a few times for it to stay on. thanks

Ross_7

b 25 error code

Hello,



I think you mean a b 25 error code. This indicates "High Limit"operation. First of all make sure the system isn't air locked somehow. This would be my first guess. Does the DHW tank have a dedicated pump? Is the DHW indirect piped correctly.  Does the pump have the correct voltage? Try these first, and good luck!

Ross

siteman

ultra 80

Ross,

      It could be a b instead of a 6 I will have to look better when it happens again.

    The DHW does have its own pump which seems to be working correctly although I will check the voltage as well as try to determine if it may in fact be air locked,I have owned this house for 18 months now and have found this system to be very unreliable,I am hoping to get this resolved soon tks

Jean-David Beyer

Hot water tank.

Is your hot water tank an indirect hot water heater? If it is a W-M indirect hot water heater, there is a vent at the top, like a Taco Hi-Vent to let the air out of the outer tank. The cap on the Hi-Vent schould be screwed all the way down and then opend one full turn. The boiler supply should go into the bottom and return to the boiler from the top. For small tanks, such as you might use with an Ultra 80, a Taco 007 with either an IFC or a Flow Check valve, is normally used. An equivalent circulator from another vendor would probably work as well. Anyway, this vent should keep that part of the system from becoming air bound. Your expansion tank should be a diaphragm type to fully protect the indirect.



When the indirect is running, the other pumps should shut off if the system is piped according to W-M's directions; usually with the indirect across the supply and return of the boiler. There is one configuration where you would want to run the boiler circulator at the same time.



P.S.: I am not a professional, but I have an Ultra 3 and a W-M 30-some gallon indirect.

I have found my 80,000 BTU/Hr Ultra 3 to be reliable, so I hope you get your system straightened out.

Tim McElwain

Ultra b-25

indicates that there may be a problem with the domestic hot water differential.



This is the temperature the boiler water must rise above setpoint temperature to turn the boiler off. (As outlet temperature increases, the control module reduces boiler input.If the temperature continues to rise with the boiler at minimum input, the boiler will shut down when the temperature reaches setpoint plus the parameter 23)





The b-25 can indicate that the flow rate is to low.



I would suggest you have a professional who knows this boiler come and check its operation.

EricAune

Where are you located?

Maybe someone on this site is near you and could help you with your problem.  It sounds like an issue with the indirect piping and circulator sizing.  The DHW circ must be able to overcome the head loss of the indirect heat exchanger (which is likely higher than the head of the boiler exchanger).  Its likely that the flow through the indirect piping is too low due to a high head loss and the improper circulator.  Piping configuration may also be suspect, your best bet is to have a different local service man out (unless you have confidence the latest installer can fix it) or contact Weil-McLain for a local rep to take a look.

Jean-David Beyer

domestic hot water

With my Ultra 3 and W-M indirect, the aquastat in the water heater is just on-off. I have it set around 125F. My boiler is set to supply 170F (default is 190F) water to the outer tank to heat the domestic in the inner tank. It recovers quite quickly; typically under 10 minutes. I can watch the supply and return temperatures. Assuming the boiler was not doing anything when the call from the indirect came, it starts heating up and the temperature drop is around 20F or so because it takes a few minutes to get the boiler temperature up to 170F and while it is doing that, the indirect is taking heat out and warming up. By then, the indirect has recovered a lot, but not enough to shut off the boiler. When the boiler gets very near 170F, it notices the supply temperature is near the set point of 170F and gradually reduces the firing rate. When it gets to 170F, it lowers it a bit more, and if it ever got to 175F , it would shut down the firing until the temperature gets down to 165 and starts firinig again. The area of the implicit heat exchanger in this indirect is so large that it can take the heat about as fast as the boiler can supply it. Only if the hot water aquastat is set close to the boiler supply temperature would the boiler cycle while recovering the indirect.



If you set the boiler supply temperature at least 30F higher than the domestic water temperature, I would imagine that the boiler would not cycle off. Mine is about 50F higher. If it is not enough higher, the recovery rate would be too low even if the boiler did not shut off.