is my aquastat bad


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Old 01-26-11, 11:12 AM
J
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is my aquastat bad

My Teledyne Laars JVH100 has a limit switch part #E0098700 which is also stamped 4080D1051 on the aquastat. I am assuming this is a Honeywell part that is only available through Laars. Anyway, my question is whether a 40+ degree range between on and off is correct? The boiler shuts off at 190 but does not turn back on until it drops to 140-150. Seems like it used to turn on regularly at 160. I do not have the spec sheet for this specific limit switch that came with the boiler. However, the info on the Honeywell site for the basic L4080D says the differential is approximately 15 degrees and some are available with 8 degree differential. So I am assuming mine is bad.

Is there another model aquastat that has an adjustable turn on temp that will fit this boiler? I am not interested in the fancy digital ones just one that will allow an adjustable differential. Or, am I best to just replace with same?
 
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Old 01-26-11, 02:35 PM
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Here is the aquastat Honeywell lists as the replacement for the
L4080D1051. Product
 
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Old 01-27-11, 09:02 AM
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Thanks Grady Trying to heat the indirect to 150 when the boiler is not firing until it drops sometimes below 130 is counterproductive.
 
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Old 01-27-11, 07:40 PM
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I can certainly see where that could be a problem. I presume you are going to get a new aquastat? Let me know how things go.
 
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Old 02-10-11, 08:56 AM
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changing out the aquastat

I've received the new aquastat. It looks like a pretty straightforward install swap out. This one includes the immersion well for the boiler. Other than needing to cool and drain the boiler to swap the new well with the old one, are there any things I should know before starting?

Thanks
 
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Old 02-10-11, 09:08 AM
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You may not need to change the well... chances are very good that the new a'stat will fit on the old well with no problem at all.

Other than that it should be a straight swap.
 
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Old 02-10-11, 02:00 PM
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Once you remove the old aquastat compare the sensing bulb size to that on the new control. If they are the same diameter, no well change is likely needed. I do suggest cleaning the inside of the old well with a brush made for cleaning copper pipe fittings. If I remember correctly you will need one for 3/8" or a well worn 1/2".
 
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Old 02-14-11, 07:44 AM
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It was a pretty easy swap. The sensing bulbs were the same so no need to change out the well. Hardest part was the actual mounting of the aquastat as it is a larger unit. Drilled a couple of new mounting holes and done in only a few minutes. All seems to be good...

Thanks again Grady and NJ Trooper for the good advice. Hopefully, my boiler will be good to go for a while now. House did heat better during the last below zero spell.
 
 

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