Weil Mclain Ultra series 3 gas boiler--lockout problem


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Old 10-17-09, 08:57 AM
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Weil Mclain Ultra series 3 gas boiler--lockout problem

Last spring we installed a Weil Mclain Ultra series 3 high efficiency gas boiler. This was in addition to an existing oil fired boiler we have in the building; wanted both oil and gas fuels. There were a lot of start up problems with the new boiler that were resolved by a factory rep who installed a new control board. Things ran well during the summer months using the boiler for domestic hot water.

This fall, we cannot keep the Ultra running while combining uses for both DHW plus heating 3 apartments; it locks out with a TEMPERATURE SENSOR fault. Plan to get help soon from Weil Mclain but maybe others here in the forum can provide guidance.

Because the system worked well during the warm months when it was only needed for DHW, there must be something in the heating load causing our problems. The building is plumbed for 3 zones with 3/4" copper to finned baseboards. Each zone is controlled with Taco zone valve. We have one master circulator that circulates water through the zones including the DHW tank when the specific zone valve opens on demand.

We are using a Taco 007 circulator for circulating the boiler's water through the zones.

I have tried numerous boiler resets but it will not stay on with the a basboard heating load. The fault as I mentioned is TEMPERATURE SENSOR. Now I did notice that this fault condition will occur when there is a 10 degree difference between sensors on either the heat exchanger outlet or the flues.

I am guessing the problem is going to have something to do with the main circulator being too small allowing a larger temperature difference between the heat exchanger input and output sensors. But I am guessing.

There must be thousands of similar boilers now in use so my problme must have occurred many times before in similar applications. Any thoughts on what could be causing this fault? At the time, we cannot use this boiler and have resorted back to using the oil system.

Thanks--

Foggy
 
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Old 10-17-09, 09:28 AM
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The only way I think we can help is if we can see the setup...

so, as usual, I'm gonna ask for pictures... take MANY, of EVERYTHING. Take some from a distance so we can see how it's all connected together.

free account / Image hosting, free photo sharing & video sharing at Photobucket / upload pics there / place link here so we can view the album.
 
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Old 10-17-09, 09:36 AM
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Originally Posted by NJ Trooper View Post
The only way I think we can help is if we can see the setup...

so, as usual, I'm gonna ask for pictures... take MANY, of EVERYTHING. Take some from a distance so we can see how it's all connected together.

free account / Image hosting, free photo sharing & video sharing at Photobucket / upload pics there / place link here so we can view the album.
Thanks Trooper!

Will not be able to provide photos untill next week sometime.

Foggy
 
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Old 10-17-09, 09:41 AM
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In the meantime, double check and make sure that the sensor wiring is not reversed... I seem to recall this being the case at least once in the past.
 
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Old 10-17-09, 10:11 AM
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First verify that the sensors are the specified distance from the boiler.

Then try changing the pre- and/or post-purge time to something like 75-90 seconds.
 
 

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