Honeywell Outdoor Reset/Aquastat Installation issue

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Old 04-18-12, 09:20 PM
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Honeywell Outdoor Reset/Aquastat Installation issue

I am attempting to add outdoor temperature reset to an oil-fired Buderus G115 boiler controlled by a Honeywell L7248C aquastat, using the Honeywell Outdoor Reset Module. It seems like a straightforward installation and setup, but I am encountering a problem. The parameters for the Outdoor Reset are supposed to appear and be set on the L7248 display in its adjustment mode, but they do not appear, so there is no way to set the minimum and maximum outdoor temperature parameters or the minimum boiler temperature, or to view these or the default parameters in the aquastat's display mode. All appears to be wired correctly, and I can observe qreen lights flashing on the Outdoor Reset Module's circuit board, so it appears that there is some communication going on between it and the aquastat. Dialing up the thermostat to call for heat on a 50 degree day resulted in the boiler running to its 180 degree maximum, which certainly suggests that the reset is not functioning as I expect that it would-I thought the boiler maximum would have been adjusted downward by the reset function, based on the default settings the reset unit is supposed to have.

Prior to the Outdoor Module installation, the following were visible in the "display" mode:

Boiler Temp
Boiler Maximum
tt (thermostat status) on or off
tte (Enviracom thermostat) on or off

In the "adjustment" mode, the following were adjustable:
Boiler Maximum
Celsius or Fahrenheit

After the installation of the Outdoor Module, there was no change in the available display or adjustment items. Based on the manuals for the aquastat and outdoor module, I expected a wider array of display items to be available. This and the above problems in getting the outdoor reset to operate lead me to suspect that something may be amiss with the aquastat itself, but that is just a guess.

Any thoughts on resolving or further diagnosing these issues would be very helpful.

Thanks,

George
 
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Old 04-21-12, 09:29 AM
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Hi George, I'm not 100% certain of this... maybe 99.8... but...

The add-on ODR for the 7224/7248 aquastats was not released until long after the a'stats were in production, several years at least, maybe more than five even.

I do know that the older instruction manuals for those a'stats contain no reference to any of the 'add-on' features that now exist on the current production builds.

My belief is that the firmware in the older a'stats does not support the add-on ODR module and I am quite sure there is no way to 'flash' a new firmware into the older a'stats.
 

Last edited by NJT; 04-21-12 at 10:02 AM.
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Old 04-21-12, 09:32 AM
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Trooper,

I think there are attributes for just the aquastat that aren't showing up as well.
 
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Old 04-21-12, 10:04 AM
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Yeah, there were more changes than just the add-on stuff... some didn't have an adjustment for the HIGH DIFF ... there are all kinds of OEM models out there as well that may have 'customized' firmware.

George, how old is the boiler?
 
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Old 04-23-12, 08:07 AM
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Hi,

The boiler was installed in January 2007.

The thought that this aquastat pre-dates the ODR/Enviracom features has occurred to me, based on what I have read in older posts on this site. However, there is a label on the inside of the cover for the aquastat which refers to the Enviracom features and shows a wiring schematic for the connection of an Enviracom device. Not that this is conclusive of course, but it is a hint. It does seem, with the inability to access things like the boiler differential, etc. that something else is going on. I wondered if there was some further lockout (beyond requiring that the three buttons are simultaneously held down to access the menu) that a technician might apply to prevent homeowner fiddling with the controls, but there isn't anything in the literature about that. But maybe it is just that this aquastat is too old or too basic and can't handle the outdoor reset.

Assuming that the aquastat cannot function with the outdoor reset, then I guess the next logical option is replace the aquastat-they run about $125 or so for a L7224 and it should be straightforward to replace since all the connections are the same as for the current unit. Is that the right way to go? Can the L7224, which has a low limit, be used with a "cold start" boiler? Reading the manual, it isn't clear whether the low limit controller can be turned off.

Thanks for the input so far-much appreciated!

George
 
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Old 05-09-12, 09:09 AM
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Hi NJ Trooper,

I am curious if you have any feedback on the idea of replacing the aquastat with a newer model that can handle the outdoor reset? I hate to go into "parts replacement" mode with something that is otherwise operating, but it doesn't appear that there is another way to get the outdoor reset to function. Any thoughts would we helpful.

Much appreciated,

George
 
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Old 05-09-12, 03:57 PM
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Hi George, sometimes I think I've replied to a message and now I see that I didn't to your last... maybe I forget to hit the 'submit' button? sorry 'bout dat!

Can the L7224, which has a low limit, be used with a "cold start" boiler? Reading the manual, it isn't clear whether the low limit controller can be turned off.
Yes. The LL can be turned 'off'.

Use the latest version of the L7224U1002 . The newest ones also have an added "Pre-purge" feature which will delay burner firing if there is usable heat still standing in the boiler. (this make it compliant with the latest DOE requirements)

Patriot-Supply.com

This looks like the latest PDF:

http://customer.honeywell.com/techli...69-1720EFS.pdf

Make sure that the retailer assures you that he isn't selling you one that's been on the shelf for a year or three... and that you will be bringing it back if you find differently (and get the OK to do so in writing!)
 
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Old 05-12-12, 09:56 AM
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Thanks! That's very helpful. The version of the manual you linked is more recent than the one I had been able to find. Thanks also for the cautionary words regarding obtaining a recent production aquastat as well.

Much appreciated,

George
 
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