Hydrostat 3250+ Failure

This past weekend my brother called me to let me know he was evacuating his house because his EFM was blowing steam into the basement and all of the pipes in the house were rattling. He had already killed the power, so I had him turn on some hot water taps to pull some heat out of the boiler while I was driving over there. Once I was on the scene it did not take long to figure out what went wrong. When I flipped the power on I got the death screen on the Hydrostat control - which is all of the LEDS flashing on top of the control, and the screen flashes "888". I did not see any physical damage on the circuit board, but there was constant power across B1 and B2 when there should not be any. I made sure the timer was not malfunctioning, checked all the wiring, and that all checked out fine - so the Hydrostat went in the trash can and I rigged up a Honeywell L4006A to keep the house warm until I could get new parts. Thankfully the relief valve did not leak once the boiler was refilled, and there was no damage to any of the pex tubing in the system. Yesterday I installed a new Honeywell L8124A, and also added a high limit aquastat to the pipe coming out of the top of the boiler for redundancy. Everything is running good.

I am not sure what the problem is with the Hydrostat controls, but this is the third one that has failed in our family. The other two did not overheat the boiler, they just quit working. I know there is another forum member that had an overheating problem with their Hydrostat controlled Keystoker, and two that have had the circulator contacts stick inside the control so the circulator would not shut off. The features of the 3250+ are great (a lot easier to wire up than the L124A), but for some reason they just are not reliable in a stoker boiler application. I know these controls are widely used on oil boilers and I don't hear about any issues with those, so I am not sure what the story is.

Going forward I am only going to install Honeywell aquastats, and every one will have a second high limit control for redundancy. I will also keep that L4006A on the shelf for backup.

I like your last two sentences,
and one i pretty much adhere to especially in critical life safety controls. they have a long established history.

Sure is a case for regrets...of the 'now obvious'.

Nothing beats the good old Honeywell controls

McGiever wrote: ↑

Fri. Feb. 19, 2021 10:13 am

Sure is a case for regrets...of the 'now obvious'.

For sure. Following the manual in this case was not enough. A dump zone would not have helped either...the EFM running non stop on 5 teeth makes more heat than the entire house can use.

Wow. Fortunate he was home at the time and you were available to patch the system until a reliable replacement was found.

I had been considering that unit as my aquastat is aging and the dials aren't quite accurate.

Now ruling out the 3250.

Glad all is well and thanks for sharing your experience.

High limit should be manual reset

Thanks for the post. I see the 3250 on more boilers because it has the LWCO function.

David

franpipeman wrote: ↑

Fri. Feb. 19, 2021 12:11 pm

High limit should be manual reset

Yes, and it should be mounted in a well. I had a few hours to get this done on a hot boiler, so we strapped a 6006 on a pipe.

We have some piping modifications to do before next season, so I may add a well to the boiler and manual reset control.

Thanks.

Roger understood on emergency repair nothing like a manual reset to draw attention to itself

franpipeman wrote: ↑

Fri. Feb. 19, 2021 2:15 pm

Roger understood on emergency repair nothing like a manual reset to draw attention to itself

That is a good point - the way I have it setup now, the L8124A could fail and the L6006 would keep the boiler from going over 200F. Better than a basement full of steam, but it might take someone a while to notice. A manual reset would get noticed much quicker.

You know, I remember reading about these units failing back in 2016-2017, but I thought they had worked it out. Most had just stopped working, they weren’t causing runaways. When my Keystoker came with one from the factory, I figured that I’d run it until it failed and then replace.

I now know what my first boiler upgrade of 2021 is going to be...

This might be over kill but the Tekmar 403 is a really nice control.

https://www.watts.com/products/hvac-hot-water-sol ... ls/403/403

I was considering a Tekmar control, but after this issue with "modern electronics" I am thinking my L4006A will stay put. I know Tekmar makes great products, I just like the idea of keeping things simple.

The hydrostat controls are home owner quality. A tekmar is commercial grade. You pay for what you get.