L8148A Doesn't Break When Setpoint Is Reached

Did you try checking the bulb? Better yet, why a mechanical aquastat?

Are you sure you pushed the sensor all the way into the well?

A agree with @HydronicMike and @Steamhead with the reason for a new out of the box L8148A?!?!?🤷‍♂️

You can save $100.00 and end up with a better control

Why? That 3150 does everything the L8148 does and it has all the same wire terminals. If you want ODR and you want to turn this into a make work project then you also need the matching well adaptor for the LWCO feature. Even so, the 3250+ is still a lower cost if you install it just to replace the L8148A wire for wire, and not use any other feature.

The aquastat with the reverse using the two knobs like the L8124 will fail not reaching temp along with the L4006a, L4081 .. The model used in the L8148 and the L4080 fail with a over ride…..

There is some kind of factory adjustment below the wheel if dare to adventure ..

That, of course, will change as fuel prices rise. And they will rise. But even if it's not dramatic, if one has to replace the control anyway, it makes sense to upgrade.

Here's where I did exactly that in my own house:

OK, is this a side-outlet boiler with a tee installed just outside the boiler, the supply line to the system piped into the bull of the tee, and the control well in the other end of the run?

You can't fix stupid.

If you don't know why that aquastat location is against code and common sense, PM me and I will tell you why!

The AquaSmart and HydroStat can use extension cables too. Just have to order them.

Yeah that not going to work . :)

Looks like 3/4" run , instead of the tee replace it with a 1" cross . It will put the sensor in the stream ..

@109A_5 I KNOW … RIGHT!!! I have been picking at my computer's screen for the past half hour trying to get rid of that stuff.

Gosh I feel So Blond.

🤦‍♀️

Hi everyone, thanks for your advice! I'm the homeowner and rewired the boiler with a Hydrostat 3250+

Alan and I re-commissioning the system today. Can you double check our assumptions on how to program the unit?

Here's what I pulled from Gemini.

1. Core Temperature Settings (Dials)

• Low Limit: Set to "OFF".
  • Reasoning: Since the BDP XEB-3 is a gas boiler without a tankless coil for domestic hot water, it should operate as a "cold start" boiler. Setting the Low Limit to "OFF" prevents the boiler from firing unnecessarily when there is no call for heat, which significantly saves fuel.
• High Limit: Set to 180F.
  • Reasoning: While radiant floors require low temperatures (often 90F–120F), the cast iron boiler requires a high internal temperature to prevent condensation. The High Limit acts as a safety ceiling; the "Economy" feature will manage the actual lower target temperatures for the floors.
• Economy Dial: Set to "1" (or the number of your heating zones).
  • Reasoning: This activates Thermal Targeting. The control will analyze thermostat activity and automatically lower the boiler's target temperature during milder weather to match the lower heat demand of a radiant system, maximizing efficiency.

2. Programming Optional Features (The "Pro" Menu)

• Feature 5: Circulator Hold Off (Enhanced Condensing Protection) — Set to "ON".
  • Reasoning: This is the most critical setting for a radiant system. Radiant floors return very cold water to the boiler, which can cause acidic condensation that rots cast iron. When ON, the control will hold the circulator off until the boiler reaches 125F, ensuring the heat exchanger is hot enough to prevent damage before the cold radiant water starts circulating.
• Feature 1: Thermal Pre-Purge — Set to "ON".
  • Reasoning: This feature maximizes efficiency by using latent heat left in the boiler from a previous cycle before turning on the burner. In a high-mass radiant system, there is often significant residual heat that can satisfy a small call for heat without burning any gas.
• Feature 8: Well Type — Set to "b" (Standard Immersion Well).
  • Reasoning: Unless you specifically installed a Hydrolevel "Electro-Well," your boiler uses a standard copper well. Setting this to "b" prevents false "Low Water" alarms caused by lack of metal-to-metal continuity in older wells.
• Feature 4: Circulator Options — Set to "A" (TT Call Only).
  • Reasoning: For most single-zone radiant setups, you want the pump to turn on only when the thermostat (T-T) calls for heat.

3. Final Verification

• Thermal Stacking: After the burner shuts off, you may see the temperature rise above your set limit. This is normal "thermal stacking" as the cast iron continues to release heat into the water.
• Purge Indicator: If the display reads "Pur", do not be alarmed; the control is simply performing the Thermal Pre-Purge to save fuel.
• Sensor Depth: Ensure the sensor is inserted ALL THE WAY into the well. If it is not fully seated, the control cannot accurately protect the boiler or your radiant floors.