BAXI 105e Instant - Pressure drop

[Sat]

Baxi 105 e instant boiler fitted 18 months ago. over the last 4-5 months been noticing the pressure dropping to 0. Having constantly to topping up every 2 days when just demanding hot water. With the recent cold spells, using the central heating, am having to check the boiler and fill twice a day. When the heating is running, the pressure increases, eventually the prv kick in release the over flow. When the heating is turned off, the pressure will decrease eventually to zero.

Baxi have state there may be a leak in the system. this has been checked, There isn't, a leak by now would be very visible. They then state its the PRV. I Have recently had this change. No improvement and there is no air lock situation either.

Does any one know what this can be?
Is there a re-occurring problem with Baxi boilers?

some one has suggested the expansion vessel?

Sat

 

[jona]

check the pressure in the expansion vessel with a tyre gauge when cold. if there is no air in the bag the hot water has no where to expand to and eventually goes over pressure and discharges.if the pressure is down top it up to the maufacturers recs.(1-1.5 bar normally).

 

[Baxi-Remeha]

top the system up to just above 1 bar, then turn on your heating....

if the preasure guage rises upto 3 bar when the system starts to get hot, this means the expansion vessel has lost its air... you will also get water coming out of the prv pipe which goes out through the wall to outside..

if this is the case, you need to isolat the flow and return pipes (left and right underneath) and drain the boiler through the drain off.

once this is done, take the top plate off of the top of the boiler, and you will see a shrader valve on a large orange tank. measure the preasure, which should be at 1 bar. if its not, top up with a foot pump.

if this problem keeps reoccuring, there is a fault with the expansion vessel and it will need replacing.......a temp fix is to drain a rad of all the water and fill the system again as this rad full of air will work as your expansion vessel, but this will only be a temp fix.

if it need replacing, i would sugest you call heateam, the number is in the back of the instruction book, as they will be cheaper than most...