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HONEYWELL L7224U ELECTRONIC AQUASTAT Ron in NY 11-17-2006
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Posted by Ron in NY on November 17, 2006, 8:13 pm
Hi all,

Has anyone used the Honeywell L7224U electronic aquastat on an oil fired
boiler yet ??? In the past 6 years, I have had to replace 3 L8148A control
boxes. The circulator relays keep going bad. It is not the relay contacts, but
rather the relay coil fails to hold the relay in the energized position after
the box heats up, and then it starts to chatter. I replace the box, and then
it's good for another year or two. It's working OK now, but just in case it
fails again, I got an electronic box--the L7224U.

This box has both high & selectable low limit controls--low limit can be turned
on or off. Everything is microprocessor controlled, and there is a digital
display. All functions are electronically adjustable via 2 buttons. Are these
boxes any more reliable than their predecessors ??? If there is a power
interruption, does the box lose all of its' settings and have to be reprogrammed
again ??? I see what appears to be 3 miniature relays on the circuit board. Are
these more reliable than the old style larger ones ??? This box comes with a
temperature probe for the boiler well that has a cable and a sensor at the end
of the cable. It comes with heat transfer compound--how much do you use ???


RON
========================================================
Remove the ZZZ from my E-mail address to send me E-mail.

Posted by RBM on November 17, 2006, 8:23 pm
I just saw one of those. It came with a Buderus boiler as part of the
package, but we were installing the "logamatic" control instead. My personal
opinion: Go with the more conventional mechanical box, at least at this
point, you don't want to be the Guinea Pig. In your situation, since its
only the circulator relay that isn't working, I'd leave the existing
aquastat relay in place and get a Honeywell R845 relay to control the
circulator and if you need it to also start a "cold start" boiler, (if you
aquastat relay doesn't have a low temp cut in) it has auxiliary contacts for
that purpose



> Hi all,
>
> Has anyone used the Honeywell L7224U electronic aquastat on an oil
> fired
> boiler yet ??? In the past 6 years, I have had to replace 3 L8148A
> control
> boxes. The circulator relays keep going bad. It is not the relay contacts,
> but
> rather the relay coil fails to hold the relay in the energized position
> after
> the box heats up, and then it starts to chatter. I replace the box, and
> then
> it's good for another year or two. It's working OK now, but just in case
> it
> fails again, I got an electronic box--the L7224U.
>
> This box has both high & selectable low limit controls--low limit can be
> turned
> on or off. Everything is microprocessor controlled, and there is a digital
> display. All functions are electronically adjustable via 2 buttons. Are
> these
> boxes any more reliable than their predecessors ??? If there is a power
> interruption, does the box lose all of its' settings and have to be
> reprogrammed
> again ??? I see what appears to be 3 miniature relays on the circuit
> board. Are
> these more reliable than the old style larger ones ??? This box comes
> with a
> temperature probe for the boiler well that has a cable and a sensor at the
> end
> of the cable. It comes with heat transfer compound--how much do you use
> ???
>
>
> RON
> ========================================================
> Remove the ZZZ from my E-mail address to send me E-mail.



Posted by =?iso-8859-15?Q?Tekkie=AE?= on November 18, 2006, 8:38 pm
Ron in NY posted for all of us...

> Hi all,
>
> Has anyone used the Honeywell L7224U electronic aquastat on an oil fired
> boiler yet ??? In the past 6 years, I have had to replace 3 L8148A control
> boxes. The circulator relays keep going bad. It is not the relay contacts, but
> rather the relay coil fails to hold the relay in the energized position after
> the box heats up, and then it starts to chatter. I replace the box, and then
> it's good for another year or two. It's working OK now, but just in case it
> fails again, I got an electronic box--the L7224U.
>
> This box has both high & selectable low limit controls--low limit can be turned
> on or off. Everything is microprocessor controlled, and there is a digital
> display. All functions are electronically adjustable via 2 buttons. Are these
> boxes any more reliable than their predecessors ??? If there is a power
> interruption, does the box lose all of its' settings and have to be
reprogrammed
> again ??? I see what appears to be 3 miniature relays on the circuit board.
Are
> these more reliable than the old style larger ones ??? This box comes with a
> temperature probe for the boiler well that has a cable and a sensor at the end
> of the cable. It comes with heat transfer compound--how much do you use ???
>
>
> RON
> ========================================================
> Remove the ZZZ from my E-mail address to send me E-mail.
>
I'm not in the business but would the relay be failing because the circulator
is drawing too much?
--
Tekkie Don't bother to thank me, I do this as a public service.

Posted by on November 20, 2006, 10:37 am

Ron in NY wrote:
> Hi all,
>
> Has anyone used the Honeywell L7224U electronic aquastat on an oil fired
> boiler yet ??? In the past 6 years, I have had to replace 3 L8148A control
> boxes. The circulator relays keep going bad. It is not the relay contacts, but
> rather the relay coil fails to hold the relay in the energized position after
> the box heats up, and then it starts to chatter. I replace the box, and then
> it's good for another year or two. It's working OK now, but just in case it
> fails again, I got an electronic box--the L7224U.
>
> This box has both high & selectable low limit controls--low limit can be turned
> on or off. Everything is microprocessor controlled, and there is a digital
> display. All functions are electronically adjustable via 2 buttons. Are these
> boxes any more reliable than their predecessors ??? If there is a power
> interruption, does the box lose all of its' settings and have to be
reprogrammed
> again ??? I see what appears to be 3 miniature relays on the circuit board.
Are
> these more reliable than the old style larger ones ??? This box comes with a
> temperature probe for the boiler well that has a cable and a sensor at the end
> of the cable. It comes with heat transfer compound--how much do you use ???
>
>
> RON
> ========================================================
> Remove the ZZZ from my E-mail address to send me E-mail.

The L8148A is prone to bad solder joints where the relay solders to the
board.
They used a small flexible pin in a big hole, solder rings are on both
sides but they didn't use a plated through-hole.
Cheap, cheap, cheap.
Repairable if you want to take the time to pull the board from the box
and have at it with a soldering iron.

Dave


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