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Honeywell L4006A2114 Issue

I have a Crown MS40 I installed almost 3 years ago. Lately I noticed the water was hotter than in the past. I checked it and it reads 140° which I consider too high. So I backed the stat down 20° and read the stat again after two days, now it is at 135°. I am thinking the stat has gone bad and I need to replace it.

My question is 1) Should I use the same Honeywell L4006A2114? 2) Is there any other brand that is more reliable? 3) Is well grease required?



  • Abracadabra
    Abracadabra Member Posts: 1,948
    honeywell L4006 is fine. I always use the thermal compound in the well. Makes for a more accurate reading. A new L4006 will come with a packet of it.
  • Condoman
    Condoman Member Posts: 91
    I needed to update this post so everyone can have a good laugh at days end.

    I ordered the replacement stat from Zoro and it arrived yesterday. Wanting to get this back in the safe temperature zone I replaced it immediately.

    First I checked the temp with a digital stick thermometer and it was 160.

    Next I replaced the stat. I did not use well grease as none came with the package. The package was marked Crown with sub marking for the Honeywell part number. I assumed if they wanted well grease they would have included some. I used a small amount of silicone lubricant after reading the thread about well grease.

    A few hours later I check the temp and it was 165. I thought, OK, maybe I have a full tank of 165 and it will take some time to cool to the 125 I set the stat at.

    This morning I took a shower and it was the hottest I had ever seen. I had to add much more cold based on the position of the single control valve. I concluded all was fine but I was going to verify the new stat was working OK.

    I pulled the stat out of the well and watched the ZVC404 to see when the call LED came on as the bulb move closer to room temp. It operated as expected. I put the stat back in the well and went about my daily chores.

    Around 4:00 PM EST I checked the temp again. Still at 165 with two showers and a dishwasher run. Something else is going on here.

    Now it's time to chuckle. On September 2nd the service company I use performed the annual cleaning. At that time they must have been impatient for the zone valve to cycle and manually operated it. From that day till the heat need to be used the call for DHW worked fine. Once the home stat took over both the heat & DHW zones were on and the DHW call never needed to be used.

    I have set the DHW# zone back to normal and will start to monitor the temp again. At least I have a spare stat if I need one.