How to reset Honeywell L7224U


Old 08-15-19, 12:16 PM
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How to reset Honeywell L7224U

My peerless is running as cold start. It is not turning on for the tankless coil. But it run fine for the heating call.

High Limit set to 190
Low Limit set to 160
LDF set to 15

I tried to follow the cold start instructions from the manual but no success.

If I got LL set up, using down button, limit goes down to 110 but don't see an option to turn ON the boiler on low limit.

any idea please?
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Old 08-16-19, 10:27 AM
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I have the L7224U but maybe not the same rev number as yours. But on mine UNLESS the LL display says OFF, the Low Limit (LL) is active. (You have to explicitly set the LL to OFF if you donít want the LL to be used (i.e., if you want a cold start operation) and it sounds like you havenít turned the LL OFF by accident.)

If your LL=160 then your Low Limit should be active and kick on when the boiler water temp drops 10 degrees below the Low Limit. In your case that would be at 150 degrees (i.e., 160-10).

I would turn ON your heat and let the boiler water heat up to 160 or some number close at least that high, and then turn OFF your heat and watch the boiler water drop below 150 and see what happens. If the burner does not kick ON when the water temp drops to 150 then there is a good chance your L7224 is bad.

You could check the output terminals B1-B2 on the L7224 with a volt meter and you should be getting voltage when the water temp drops down to 150.

(Above assuming your LL is set to 160)

Here is what my manual says about setting the Low Limit:

To use the L7224U in a cold start boiler application, disable the Low Limit function by pressing the UP arrow button, DOWN arrow button and I button simultaneously for three seconds. Then push the I button until LL_ is displayed. Then press the down arrow button until OFF is displayed.

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