L7224U Aquastat Question

HydroAirJoe

Thxs Chas. That language is more confusing than any legal document I ever read.

HydroAirJoe

Just had my defective L8124 Aquastat replaced with the L7224U. This is on a 3 zone Hydro-Air System with DHW coil (with Storage Tank), WM Boiler.

Set the Stat to 180 Hi 10 hi diff 160 Low 10 low diff.
Now if I read the instructions correctly (6 hourse latter)...
"setting the Low Limit less than the High Differential below the high limit is not allowed as improper circulator and zone control functions could result".

This is not a valid setting was the Aquastat suppose to allow me to do this? The way the instructions read, it was not suppose to. Also with the L8124 the variable diff for the low worked differently then the L7224U. With the L8124 If my low limit was set at 160 and my variable diff set at 20, assuing no call for heat, when the bolier temp droped down to 150, the burner would kick in and heat the water up to 170. With the L7224u under the same conditions and assuming a 10 degree low limit diff, when the temp drops to 150, it will turn the burner on until the temp climbs back to 160. There is no notion of a varibale differential working with the fixed diff.

Chas_2

Instructions

I can't answer your question. But I can say the instructions have at least two errors that I know of. Perhaps this is a third? Dunno, the way I read it is if you set the high limit to 180 and the differential to 10, thats 170, so your low limit must be less than that. The instructions have to be wrong I would say. The factory setting would be wrong if the instructions are right.

Chas_4

Yes, well after reading it again, it appears to be correct.

Fig. 7. Setpoints and differentials.
NOTE: Setting the Low Limit less than the High
Differential below the High Limit is not allowed as
improper circulator and Zone Control functions
could result.

What it is saying is that if the high limit is 180 and the differential is 20 degrees than you have to set the low limit to 160 or below.

Or, En Englais, setting the low limit to a temperature above the High limit minus the differential is not allowed. Same difference.