baxi instant 105he

[desrob]

when heating is called for nothing ,but if i run the tap and the heating is still being called for when i turn the tap off it will switch to heating and work fine,but it will not hav it whn you call for heat, you have two valves on this model,ch ,dhw,

 

[diamondgas]

Does the radiator demand light light up desrob?

 

[desrob]

Does the radiator demand light light up desrob?

yes my friend and i think( not sure)the pump runs

 

[desrob]

could the pin be failing to make micro switch

 

[diamondgas]

The pin on the pump flow switch? You'd think if it wasn't making you'd get the same for the hot water or at least it would drop out again ... If you're getting pump but no fan starting then I'd be looking at the pump flow switch first of all for sure! These pcb's have an anti cycle time delay by-the-way that putting the hot water on overrides!

 

[desrob]

The pin on the pump flow switch? You'd think if it wasn't making you'd get the same for the hot water or at least it would drop out again ... If you're getting pump but no fan starting then I'd be looking at the pump flow switch first of all for sure! These pcb's have an anti cycle time delay by-the-way that putting the hot water on overrides!

as said when i run the hot tap and knock it off when calling for heat the boiler will act accordingly,can the systems pressure have an effect on the pumps flow switch

 

[diamondgas]

The pressure shouldn't effect the flow switch ... I'd be wanting to know what is happening from start up desrob. At what point is the lighting up sequence failing ... The flow switch has to be made before ignition sequence comences that's for sure

 

[desrob]

sorry not pump flow switch

 

[desrob]

when you call for heat, you have a 2 min time delay from stat to boiler ?, rad light will come on, pump will run constantly and nothing else.! if i run hot tap boiler light will tranfer to tap and lighing sequence commence's,turn tap off and it will tranfer over to ch if demand is still calling

 

[Billy Bob Bob]

tried turning the pre heat off?

 

[desrob]

......../////

 

[desrob]

tried turning the pre heat off?

no mate,i only had a quick 2 min look ,what will turning pre heat tell me

 

[desrob]

just thinking when you first turn this boiler on and you select ch/dhw and the pre heat is turned on,will priority be given to the pre heat store and if the pre heat store/exspansion vessel is faulty (full of water),will this confuse the boiler and give the symptoms i described

 

[Billy Bob Bob]

it will give priority to the store but no it wont confuse the boiler if the ev has failed try turning the dhw stat off this disables the per heat,pull the clip and remove black motor off the LH dv,see if the bush has failed and the pin can be pushed down shake the motor if you can hear water in there its shot you could still have a sticking motor another thing that can throw people and cause this fault are leaking main heatex o rings water can run in to the pcb and cause weird faults so have a good check on the heatex for leaks

 

[desrob]

it will give priority to the store but no it wont confuse the boiler if the ev has failed try turning the dhw stat off this disables the per heat,pull the clip and remove black motor off the LH dv,see if the bush has failed and the pin can be pushed down shake the motor if you can hear water in there its shot you could still have a sticking motor another thing that can throw people and cause this fault are leaking main heatex o rings water can run in to the pcb and cause weird faults so have a good check on the heatex for leaks

i'll do thaat gas man, if the ex vessel is to come out ,i've done the 80/105e, but i have noticed on another thread you mentioned the instant are a bit more difficult,why is that.?

 

[Billy Bob Bob]

i'll do thaat gas man, if the ex vessel is to come out ,i've done the 80/105e, but i have noticed on another thread you mentioned the instant are a bit more difficult,why is that.?

they are twice as heavy,twice as big the rubber hose and recuperator spigot get in the way as well,the other option you have is disable the pre heat,the customer wont notice the DHW gets just as hot and fit a remote one

 

[Js58gas]

I'm pretty sure that baxi say you can't fit a remote vessel on the instant due to water flowing round the old vessel which can eventually corrode the diaphragm which causes problems later on

 

[desrob]

I'm pretty sure that baxi say you can't fit a remote vessel on the instant due to water flowing round the old vessel which can eventually corrode the diaphragm which causes problems later on

i'm sure your right, can't see baxi telling you to leave faulty vessel in situ

 

[Billy Bob Bob]

BAXI do tell you to leave the old one in-FACT

 

[diamondgas]

Stupid f in design!!!!!! Honestly what were they thinkin????? regards leaving in situ, why not? with a deflated diaphragm the pre heat will have a boat load 'stored' water

 

[Billy Bob Bob]

Stupid f in design!!!!!! Honestly what were they thinkin????? regards leaving in situ, why not? with a deflated diaphragm the pre heat will have a boat load 'stored' water

it is a stupid design,they took the very reliable 105,made it crap,and managed to achieve better flow rates? quicker warm up time? eh no it remained the same as the simpler 105

 

[mattyp]

Try running the heating and then turn off the flow isolation valve under the boiler, does it fire then ? ( dont forget to turn it on again !!)

 

[desrob]

BAXI do tell you to leave the old one in-FACT

....ok