Baxi Luna HT380: DHW but no heat


Old 03-07-17, 09:58 AM
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Baxi Luna HT380: DHW but no heat

I woke up Sat to a cold house. The HT380 showed DHW light on all the time. I had good DHW, but no heat. I figured it must be the Hall Effect switch and unplugged it. Then I got heat and only DHW when re-plugged in. I replaced switch yesterday, but DHW is intermittent. Anything else I should do to make it work properly?
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Old 03-07-17, 01:58 PM
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Those boilers are tricky to work on. There is very little technical info published on them.

I would expect you to be getting a trouble code with your problem and certainly a code when the sensor is disconnected.
Old 03-07-17, 02:38 PM
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No codes were generated. In addition I switched to the original hall effect sensor and it's working again at least temporarily. It seems that something else is wrong with the system.
Old 03-08-17, 11:56 AM
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You can reset the codes by turning the knob to R and holding three seconds, it will snap back to the winter mode. Then try your unit and see if you throw a code. The diagnostics for this unit rely heavily on the error codes. Make sure the hall switch is connected to the inlet group properly, sounds suspicious since your playing with it did give rise to different outcomes.

The table below are some things you can test with an ohm meter, the sensors and such.

From your description, sounds like the diverter valve may not be functioning. There are paddles inside that can be replaced, and the unit can get gunk in there and I think can be cleaned out.

Probably a good excuse to clean out the dhw heat exchanger as well. When no code is thrown, it is usually one of the flow or temp sensors with crud on it (or failed), a clogged heat exchanger or things involving the diverter valve.

Part Resistance
Gas Valve
380/1.330 1&3 -1250 5%
1.450/1.650 1&3 - 1180 5%
1.100 EV1620  5%
EV2 - 3356 5%
Pump 380/1.330 45  5%
3 Way Motor 380/1.330 1480  5%
Fan 380/1.330 9  5%
Spark Generator 380/1.330 370  5%
DHW Flow
380 2706  5%

I am not a pro, just a really self sufficient homeowner with experience with two Baxi's but not your model. So hope this gives a few ideas.
Old 09-05-18, 01:15 AM
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i also have a baxi ht 380 that was running DHW full time and because of that i had no heat ... did a bunch of stuff to the unit now its running CH full time... that being said is the hall effect sensor what tells the there is a call for heat ? im goin to image some made the magnet stick in the DHW inlet
i also have no codes!

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