Baxi 105e - luke warm DHW

[beefster]

Baxi 105e. (not instant)
I have a similar problem to some other posts on here but with a couple of subtle differances!
The DHW temp has got lower in recent weeks. On initial start it reaches full temp then fades away and regains to just warm enough for a shower. Stays steady at this point.
I have isolated the heating flow as mentioned to try in other posts but symptoms remain. throttling down the tap see's the burner controlled and reduce. From reading some other threads either the gas valve isnt opening fully to provide full gas flow... poss Faulty actuator - temp sensor?? or ... the heat exchanger is blocked on the primary side??

Would welcome some help / offers of advice on the matter please.
Thanks

 

[beefster]

Anyone..... please

 

[baxpoti]

Plate heat exchanger is partially blocked.

 

[beefster]

Thanks Baxipoti.

Would that be primary or secondary???

Best way to clean it if its the secondary (dhw side) ???
Can it be removed and soaked in descaler?

On another forum i was told dhw thermostat??

 

[baxpoti]

Would that be primary or secondary???

The plate heat is sometimes incorrectly referred to as the secondary.

Best way to clean it if its the secondary (dhw side) ???

Apparently they're cheap to buy!

Can it be removed and soaked in descaler?

Yes

On another forum i was told dhw thermostat??

There is no thermostat. Believe who you like. If you have the old black/chrome thermistor it would be worth replacing. (new ones are gold/white).

 

[beefster]

Blimey.... Heat exchanger is only £48! was expecting another £100 on that.

Re the thermostat... sorry meant temp sensor/thermistor. Might change it at same time as its only a tenner.

Re. Would that be primary or secondary???

The plate heat is sometimes incorrectly referred to as the secondary.


What i meant was which do you think is blocked? The dhw flow is 9+ L per min which i thought was ok? If its the primary i thought i might add a flushing agent to the ch system and give it a clean out prior to putting the new parts in.

thanks for your input, much appreciated.

 

[gavinda]

the plate heat exhchanger gets blocked on the 'boiler side' so flow rate is not affected(unless its scale).

read the instructions for this job and get new washers/o-rings for AND joints you may break.

 

[beefster]

Going for the flush out, change the thermistor (dhw temp sensor) and the plate heat exchanger.

Fingers crossed that should sort it out.