Hi wondering if any one could offer some advice , wen central heating is running the pressure increases by a lot ie from 1 to 3 bar , then wen cools it looses pressure , water is coming out of over flow outside of the house , plus water through the hot tap is not as hot as used to be , I've bled the radiators to see if there was a air blockage and there was , but symptoms still the same . Any advice would be appreciated . [/b]
Vaillant max plus 824e
- Thread starter Gixxer40
- Start date
Check air charge in expansion vessell
Thanks for your help , I found the pressure release valve to be leaking at very low pressure ! Replaced the switch and seems to be working ok now pressure rise is only .6 of a bar wen hot 
. Still got the hot water problem tho burner kicks in and heat to approximate 90 d and then knocks of until cools down too 65 , then kicks in again any ideas ? No fault warnings just goes through its cycle again ???
. Still got the hot water problem tho burner kicks in and heat to approximate 90 d and then knocks of until cools down too 65 , then kicks in again any ideas ? No fault warnings just goes through its cycle again ???
U asked for advice mate then didn't take it 
The 2 problems you have are SYMPTOMS of what the fault is . The vessel is flat, ur prv has been doing its job an relieving pressure, u have left it to long and have been refilling with fresh water, this has probably caused the plates on the dhw ht exch to be contaminated causing poor hot water...changing the prv will just mask the original problem ie expansion vessel needs recharging
The 2 problems you have are SYMPTOMS of what the fault is . The vessel is flat, ur prv has been doing its job an relieving pressure, u have left it to long and have been refilling with fresh water, this has probably caused the plates on the dhw ht exch to be contaminated causing poor hot water...changing the prv will just mask the original problem ie expansion vessel needs rechargingI did take the advice mate ! The exspansion vessel was charged I located the Schrader valve on top bk of boiler and released air from it no water I then recharged it to 10 lbs , as per vaillant spec . So really looks as if it was the pv as heating was on all afternoon slight increase come in from nights and no pressure drop from where I set it ! Wasn't being a smart arse just thought if posted the result might help some one in the future !
It would hav helped someone in the future if u said you refilled expansion tank? But you said you changed prv an all was ok now happy days? Now you just need to remove your dhw ht exch run some acid through it ( not on the domestic water side )
Removed the plate to plate heat exchanger today and cleaned it with cosmic soda , also after emptied the costic I hit it with a hammer lightly of course then flushed it. Out then repeated the proses until no more sediment etc was coming out , refitted , boiler working fine now !
I'm not sure what was the actual stuff that was blocking it , it came of in black flakes but you could rub these flakes between you fingers and the would disappear , used costic because I had seen some one mention it either on here or another forum , oust was another one people had used , all I know it did the job !
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