L8148A Doesn't Break When Setpoint Is Reached
Brand new aquastat relay. Setpoint is 150F and water temperature continues to climb past 200F.
I've seen these stuck open, not closed.
Two btu per sq ft for degree difference for a slab
Comments
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Did you try checking the bulb? Better yet, why a mechanical aquastat?
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Hi, Are there contactor points you can get to? Any chance they got fused together? I still have a point file in my tools somewhere if you need it 🤠
Yours, Larry
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Are you sure you pushed the sensor all the way into the well?
All Steamed Up, Inc.
Towson, MD, USA
Steam, Vapor & Hot-Water Heating Specialists
Oil & Gas Burner Service
Consulting
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We've been coming across quite a few parts that are bad right out of the box. But a limit that won't open is inexcusable. Thats why you don't replace and run. CYA. Disaster averted.
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Yes, I pulled the sensor out and pushed it in again and it's in contact with the flow.
8.33 lbs./gal. x 60 min./hr. x 20°ΔT = 10,000 BTU's/hour
Two btu per sq ft for degree difference for a slab0 -
Had to ask. Looks like that's an oil-fired unit, right?
If so, I would recommend replacing that with either a Beckett AquaSmart 7610A or a Hydrolevel HydroStat 3250+. Either would be a vast improvement due to energy-saving features. They are both designed to mount on standard aquastat wells. And if you replace the well also, you can add low-water cutoff functionality.
If this is a single-zone job, I prefer the AquaSmart because it has a circulator-off delay option that would move heat out of the boiler for a few minutes after the burner shuts down. If it's 2 zones or more, either is fine.
On the AquaSmart, if you don't replace the well, use the temp-only sensor; if you do, use the 2-in-1 sensor.
All Steamed Up, Inc.
Towson, MD, USA
Steam, Vapor & Hot-Water Heating Specialists
Oil & Gas Burner Service
Consulting
2 -
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
Edward Young Retired
After you make that expensive repair and you still have the same problem, What will you check next?
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Wrong comparison- you need to use the 3250+ HydroStat, not the 3150.
All Steamed Up, Inc.
Towson, MD, USA
Steam, Vapor & Hot-Water Heating Specialists
Oil & Gas Burner Service
Consulting0 -
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.
Edward Young Retired
After you make that expensive repair and you still have the same problem, What will you check next?
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The only time I've seen the L8148A over shoot was when the circ wasnt working properly or a flow control was jammed up.
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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 was an error rendering this rich post.
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it's not just ODR. The AquaSmart and HydroStat both have non-ODR economizing features. Why not take advantage of this?
All Steamed Up, Inc.
Towson, MD, USA
Steam, Vapor & Hot-Water Heating Specialists
Oil & Gas Burner Service
Consulting0 -
There is some kind of factory adjustment below the wheel if dare to adventure ..
There was an error rendering this rich post.
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Because the savings comparison is not a dramatic. !
Edward Young Retired
After you make that expensive repair and you still have the same problem, What will you check next?
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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:
All Steamed Up, Inc.
Towson, MD, USA
Steam, Vapor & Hot-Water Heating Specialists
Oil & Gas Burner Service
Consulting1 -
More information: This is a gas-fired boiler. We have no oil out here, other than offshore.
The owner had a heat pump water heater installed next to the boiler and the installer - not me - moved the aquastat relay to a better location for service.
I don’t particularly like how it was done, but I checked the well and it extends all the way down into the tee.
8.33 lbs./gal. x 60 min./hr. x 20°ΔT = 10,000 BTU's/hour
Two btu per sq ft for degree difference for a slab
1 -
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?
All Steamed Up, Inc.
Towson, MD, USA
Steam, Vapor & Hot-Water Heating Specialists
Oil & Gas Burner Service
Consulting0 -
Exactly.
8.33 lbs./gal. x 60 min./hr. x 20°ΔT = 10,000 BTU's/hour
Two btu per sq ft for degree difference for a slab0 -
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!
Edward Young Retired
After you make that expensive repair and you still have the same problem, What will you check next?
0 -
How deep does the well protrude into the tee?
All Steamed Up, Inc.
Towson, MD, USA
Steam, Vapor & Hot-Water Heating Specialists
Oil & Gas Burner Service
Consulting0 -
Two come to mind:
- Too far away from the heat source
- Should be horizontal
8.33 lbs./gal. x 60 min./hr. x 20°ΔT = 10,000 BTU's/hour
Two btu per sq ft for degree difference for a slab0 -
That control works in the current orientation position, but not in the current temperature location. I have installed that contol on a buderus boiler in that orientation.
There is a control that will work for you. Resideo L7224U 1002 with this long wire temperature probe Resideo 50001464-005 probe to be placed back in the original well adaptor on the supply tee fitting. I hope the water heater installed left it there!
Edward Young Retired
After you make that expensive repair and you still have the same problem, What will you check next?
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Totally brilliant! Thank you!
The existing aquastat relay has an adjustable operating limit starting at 150F; too hot for radiant, but appropriate for boiler protection. The one you suggest starts at 110F and a thermal bypass can be added.
8.33 lbs./gal. x 60 min./hr. x 20°ΔT = 10,000 BTU's/hour
Two btu per sq ft for degree difference for a slab0 -
It should be in the boiler. The sensing bulb isn't in the flow. And instead of getting the correct control, they powered a transformer with B1,B2 for the burner circuit. Are those Shark Bite ball valves?
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The AquaSmart and HydroStat can use extension cables too. Just have to order them.
All Steamed Up, Inc.
Towson, MD, USA
Steam, Vapor & Hot-Water Heating Specialists
Oil & Gas Burner Service
Consulting
1 -
Good call. The schematic shows the external transformer and it looks like the pressure switch controls the burner. Seems odd, but creative.
8.33 lbs./gal. x 60 min./hr. x 20°ΔT = 10,000 BTU's/hour
Two btu per sq ft for degree difference for a slab0 -
Yeah that not going to work . :)
There was an error rendering this rich post.
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Wow this is an oil burner control that is used to power a 120 VAC burner control. The manufacturer has installed a second 120 to 24 VAC transformer on B1 a nd B2 to power the 24 V gas controls. I suggested that to someone before and was told here by a "Wallie" that it is not an accepted practice. I should not have left that as a perminent fix for a customer.
I guess the manufacture of your boiler didn't get that memo!
Using a L8124 or s L8148 to operate a 24 VAC gas system ?!? there is already a control set up for that. TheHydrolevel 3200 Plushas a 24 V. burner circuitDiagram to follow. Order the 48" probe cable for the Hydrostat 3200Oops. that was wrong… don't order the 3200 plus
you need the 120 V burner circuit to power the inducer fan motor. I realized that when I went to draw the wiring diagram. The Resideo L7224U 1002 is the correct control for your setup.
Edward Young Retired
After you make that expensive repair and you still have the same problem, What will you check next?
1 -
Thanks @Steamhead and @HydronicMike for this suggestion, but these controls aren’t familiar to me and I don’t know if they have all the required terminals that the Residio has. Which models do you suggest?
8.33 lbs./gal. x 60 min./hr. x 20°ΔT = 10,000 BTU's/hour
Two btu per sq ft for degree difference for a slab0 -
They do. Check out the manuals- the AquaSmart 7610B is here. That's the usual control for a gas boiler- but if you need the 120V version, get the 7610A:
Extension cable and mounting kit, 48":
and the HydroStat 3200+ is here. That's the usual control for a gas boiler- but if you need the 120V version, get the 3250+:
Extension cable and mounting kit- you'd want the 48-102 which has a 48" cable:
Any questions, you know where to find us.
All Steamed Up, Inc.
Towson, MD, USA
Steam, Vapor & Hot-Water Heating Specialists
Oil & Gas Burner Service
Consulting2 -
Looks like 3/4" run , instead of the tee replace it with a 1" cross . It will put the sensor in the stream ..
There was an error rendering this rich post.
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The solder splash on the wiring diagram is a nice touch too.
National - U.S. Gas Boiler 45+ Years Old
Steam 300 SQ. FT. - EDR 347
One Pipe System
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@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.
🤦♀️
Edward Young Retired
After you make that expensive repair and you still have the same problem, What will you check next?
1 -
Putting a control on a tee is questionable. Should be in the boiler.
1
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