BAXI Luna 3 - no hot water

[geofear]

I am trying to troubleshoot a Baxi Luna 3 Combi boiler 8 years old, that is not making any hot water. It is in a customers second home, and receives little usage.

Over 2 days, hot water was getting less hot, until now none at all. When I call for heat, and the unit fires fine. There are no error codes.

When there is HW demand, I sometimes hear a click, and the exhaust motor runs for less than 1 second. The gas valve does not open, nor is there any attempt to fire. Something is preventing it.

There are 3 ‘sensors’ in the DHW area; a pressure switch, a NTC sensor, and a ‘Rilevator’. (When calling for hot water, this rilevator flickers a faint red lite, indicating the
flow of water. Both the NTC sensor and the rilevator have been replaced.

I have re programmed the DHW programming.

I have removed the top of the diverter valve motor, and there are no leaks. I can push down the pin inside the valve with my finger. With the diverter motor un-attached, I can get hot water, so the exchanger is not plugged. When calling for heat, the rod at the base of the motor is firm. When calling for DHW, it is loose and easily moves back and forth. It appears to be functioning correctly.

Something is preventing the unit from firing in the DHW mode. Your thoughts on how to troubleshoot, please.

 

[oz-plumber]

OZ, are you in Britain?

No, I'm not.
I reside in one of the Colony's.

There is a plastic strainer at the bottom of this part and also a wire mesh strainer inside the part.

Just replace the whole part, they do a lot of work and if you get more than 4 years out of them you're doing well.
I always have 2 or 3 of them on hand due to necessity.

 

[geofear]

No, I'm not.
I reside in one of the Colony's.

There is a plastic strainer at the bottom of this part and also a wire mesh strainer inside the part.

Just replace the whole part, they do a lot of work and if you get more than 4 years out of them you're doing well.
I always have 2 or 3 of them on hand due to necessity.

Got one on order. Thanks.

You in the States?