Baxi Instant 105E Gaining Pressure!

[Saturn6]

Hi, I've done a fair bit of reading regarding my boilers latest problem, the closest to my symptoms seems to be this thread: http://www.diynot.com/forums/viewtopic.php?t=80383 where this guy had working CH & DHW and pressure increases until the PRV operates, reduce the pressure and again it rises. In his case it turned out to be the filling loop passing where my filling loop checks out fine, I've just replaced the expansion vessel for a new unit (the old one had lost pressure/would not hold pressure and had water on the air side of the diaphragm). So I am now suspecting plate heat exchanger as mentioned in the thread linked above. If I turn the cold water supply off to the boiler overnight the pressure does NOT increase. If I electrically isolate the boiler overnight but leave the cold water supply on the pressure DOES increase, wish I had seen the above thread before I changed the expansion vessel then I could have done the plate heat exchanger at the same time because even though the manual does not say so, it looks to me like the boiler has got to come off the wall again. Can anyone confirm that it looks like the DHW plate heat exchanger is faulty and needs replacement and if I do need to remove it from the wall to change it. Thanks in advance.
P.S. The two small diaphragms have also been checked and are ok.

 

[baxpoti]

As you say, the plate heat is faulty.

 

[Saturn6]

Thanks, I just needed a second opinion before I spent the money, found one for £44 which I don't think is too bad, only paid £20 for new expansion vessel inc' delivery! Have you ever fitted one? can you confirm if I need to remove boiler from wall again? Like I said the manual does not mention removing the boiler but I can see no way of getting the heat exchanger out without removing boiler? Many thanks.
Another quick question- are the seals on heat exchanger metric rubber O' rings or are they flat rubber washers etc? I want to be prepared and not get caught out like I with the expansion vessel seals (I presumed all the fittings would be compression with olives etc!)

 

[holty]

Have you ever fitted one?

pretty sure baxpoti has fitted one before now,think his name might be clue

and no the boiler doesnt have to come of the wall to fit a plate heat ex.

 

[namsag]

Ten mins from start to finish. 2 screws it all comes out the front

 

[Saturn6]

Thanks for your replys guys, yep your right with a name like that and a reputation like the 105e seems to have I suppose he's fitted the odd one

 

[gaspro1981]

Ten mins from start to finish. 2 screws it all comes out the front

in your dreams sunny boy

 

[namsag]

No in reality
Standing in front of boiler
10 secs to turn off isolating valves
15 secs to undo 2 screws holding front panel
open safety valve (never had one on them of not reseat)to empty boiler as it doing that open hot tap max 90 secs boiler empty
2 screws holding plate 15 secs
Wiggle plate out and through the front max 2 mins.
Reverse procedure same so adds to less than ten mins
Some do and some fanny about to justify stupid prices

 

[gaspro1981]

fair point namsag but in all reality the phe dont always go back in without a bit of a fight

 

[namsag]

Apology accepted

 

[baxpoti]

8 minutes easy

 

[powell30]

Hate to stir things up but did the op say he removed boiler off the wall....flue? gas line?.......oh and i hear Baxpoti takes 3 mins to change heat ex...the other 5 is the paperwork

 

[holty]

theres a 9 page debate about people working on there own boilers lets not bring it up again.or we'll be banging our heads.

 

[Saturn6]

Thanks again for the replies but I'm still unsure about getting this thing out from the front, I've had another look while I'm waiting for it to arrive and can some one confirm it comes out from the right looking at it and above the pump - I'm sure it can't go to the left as one of the pipes to the exp' vessel blocks it???
I'm confident in removing boiler/flue/gas line as I've worked 6 yrs in ceramics industry on gas fired kilns and more recently 3 yrs on HVAC for the health service, I've also maintained gas/oil fired incineration plant for around 3 yrs and have been a qualified engineer since leaving school in 1983, so yes I did say I removed the boiler. So I'd deem myself competent which is what is stated in the post "DIY GAS", whether that would stand up in court is a different matter. I'm not trying to take work off anyone and would never belittle a trade or tradesman/woman. I would love for my employer to send me to college to get corgi/gas safe (or whatever it's called this week!) papers but it's not relevant to the field I currently work in . I would also never work on anyones system but my own and would never knowingly endanger my family.

 

[powell30]

Look, it comes out trust me, i have changed enough, as i am sure has baxpoti. Either give it a go and succeed or get someone in to do it and....pay them.