Weil Mclain b 24 error

Zeezok

We installed a new Weil Mclain Ultra boiler about 18 months ago. Since then, we have been getting a b-24 error (incoming water temp higher than expected), but only in the winter. (At least I have only noticed it in the winter.) The manual calls for replacing the sensors. I have replace both sensors and am still getting the same error. The next step is to replace the control board. Before I spend another $300 on it, has anyone else had this problem? And what did you do to solve it?

Terry O

I have seen this with many customers....

and actually it happens frequently on my own boiler which is an early Series 1. The b 24 code is a soft lockout that occurs when the return water temp is greater than the supply temperature. An example of this which as I said, happens frequently in my own system... is with a domestic hot water call. First off let me say I have the water heater aquastat set higher than normal for higher temps and use a mix valve set at 120f to gain additional capacity from the heater. When the dwh aquastat calls for heat... water returning to the boiler from the dwh is often warmer than the boiler itself. This is read by the sensors and indicated by the b 24 code and thus a temporary soft lockout. After the brief lockout period, with the next cycle try, the boiler will fire because the temps have been "equalized". I wouldn't be overly concerned... in my own situation the boiler has been operating for years and I never noticed any negative result from it. When I first found the issue I was quite concerned and spoke with Weil Mclain rep (I work for a W/M distributor).... the factory confirmed this "glitch" in the control could happen as explained. I guess I would have to ask you... what "problem" is this causing you.... other than seeing the b 24 on occasion?

richard2

weil mclain

When this boiler is working hard I get a slamming when the zone valve closes! I've changed circulator pumps to slower speeds. Increased water pressure and decreased water pressures on the system but still experience the slamming of the zone valve . Any solutions out there?

eluv8

Slamming Zone Valves

Is the zone valve on the supply or the return? Are your pumps pumping away from the expansion tank? Which zone valve are you using? Is the CV rating adequate for the flow of the loop. You may consider switching to a thermal actuator. 

Zeezok

problem reply

The only problem we really have is during the winter. I don't even know that the error has happened unless it starts to get cold in the house. When the temp drops 3-4 degrees then we realize that something is wrong.



We never run out of hot water, even in our family of eight, or even over Christmas when we had 20 staying in our house. I have even set the HW tank temp lower than what the gauge says is "normal".



If this is a "normal" experience then I won't worry about it. My concern has been that it would happen when we are gone for an extended period and the house would cool down too much.