baxi 105e problems

[scarfeuk]

my Baxi 105e, not the instant is only delivering slightly warm water. also with DWH preheat switched on, the radiators warm up.
When a hot tap is switched on the boiler ignites, the DWH neon comes on and stays on until the tap is turned off, so I'm guessing the it's the diverter valve.

any advice please.

 

[Blake]

I'd check the DHW diaphragm first, they normally perish or start leaking onto the micro switch. Common fault with these and I always carry a diaphragm in the van as I do one a month at least.

 

[Toddyplumb]

The 105E does not have preheat You say it is not the instant are you sure ?

 

[desrob]

i have the105e instant with pre heat,when pre heat is off the hot water heats up red hot the boiler knocks off for say 30 seconds and relights again giving me luke warm water,this is of course when the hot tap is running constantly ,when i try to turn pre heat up the boiler knocks off straight away and will not relight heating side seems ok

 

[scarfeuk]

sorry my mistake it is not an instant and does not have pre-heat.

 

[washer]

If the water is cycling from very hot to luckwarm, and the radiators are staying cold, it is more than likely the plate heat exchanger is blocked.

But if the radiators are getting warm when you open that tap, the diverter valve would be passing, robbing the heat from the hot water, which is why it would be lukewarm.

 

[desrob]

but why do these baxis knock on and off all the time when i have hot tap running constantly,is it a baxi thing do they not regulate the gas flow decreasing when temp is met and increasing when heat is called for,not done much on baxi,so forgive me for my ignorance and the what about the pre heat why does it knock off when i turn it on and the rads dont get hot when hot tap is running

 

[washer]

They do regulate the temperature, but if the plate heat exchanger is blocked, the boiler overheats and cuts itself off before it has a chance to modulate.

 

[desrob]

but cools down slightly and knocks back on, could it be hot water temp sensor,saftey thermostat?and its not showing a fault mode and in the heat exchanger do you mean the primary side is blocked or hot through exchanger water

 

[washer]

Sorry when I say overheat, it just reaches it's max temperature very quickly and then cuts of on its stat, the boiler would not need to be reset, just cool down and then re-fire.

If it is blocked, it would be on the primary side, just whip the plate out and pour in some hardcore descale to clean, if it works great, if not at least you havent paid out on any parts.

 

[desrob]

thankyou i'll do that,but the pre heat still bugging me,why would it turn off straight away,could it be when i'm trying the boiler is simply in a to higher temp ,if it cooled down further or even turn pre heat on prior to running any idea's mate

 

[diesel_ltd]

is this boiler a 105e or a 105e instant???

if it is just a 105e the knob for the HW is your HW temp control and if you have it turned "off" your boiler will cut off because it is reaching temp on the stat, try turning it up

 

[oldplumber]

If the boiler is cycling on and off then it could also be a aps problem or a hole in the aps pipes.

 

[desrob]

central heating side ok

 

[diesel_ltd]

is this boiler a 105e or a 105e instant???

if it is just a 105e the knob for the HW is your HW temp control and if you have it turned "off" your boiler will cut off because it is reaching temp on the stat, try turning it up

well????