baxi 105e temp fluctuation

[bongle]

just refitted 2 year old Baxi 105e to two bed flat so it should be able to cope with demand but find hot water temp fluctuates too much for showering (even using thermostatic shower for combis) plus filling bath is unreliable,ie comes through hot initially then goes cold and takes ages to come through hot again

any ideas?

 

[weargas]

blocked/ restricted dhw heat exchanger
faulty thermistor
incorrect gas pressure settings

pick one or more.

 

[bongle]

jesus that was quick! thank you very much, will try later.

 

[ChrisR]

Also what's your water pressure/flow like. At bath taps, turn HW on full. Then turn cold on full - is hot affected? (May need 2 taps if all mixers!)

WHich shower mixer? Thermostatic or pressure balanced.

the thinking - thermo mixer reduces HW flow say. so it gets hotter, AND CW pressure/flow then increases so you get a battle. Hotter hot so th valve may reduce hw even more. If HW flow reduces too much boiler has to cut out (though yes it modulates) then shower cools, cycle repeats.

HW on full you should get say 12 litres a min, AND at least 10 l/min from CW at the same time. Ideals rarely achieved in a conversion flat (shared mains)

 

[bongle]

Water pressure is adequate as we have a separate mains and I see your point re the mixer but temp fluctuation occurs even when not mixing with the bath tap on hot only