Baxi 80Eco Pressure buildup

[cuchulain001]

My baxi is not behaving. The pressure in the central heating builds up to 2 bar (local mains pressure). When the CH is running it reaches 3 bar and the safety valve kicks in.
I was told it might be the diverter valve so i replaced it. No improvement.

Would you have any idea what else might cause this?

My boiler has separate heat exchangers for CH and hot water so there can be no leakage between the two.

Thanks
Pat

 

[Agile]

My boiler has separate heat exchangers for CH and hot water so there can be no leakage between the two.

Thanks
Pat

As you clearly know all about your boiler you obviously dont need the help of any experienced boiler engineers on here.

Have you removed the filling loop and seen what happens then?

Tony

 

[baxpoti]

You learn something everyday

 

[BingoBongo]

or checked the expansion vessel

 

[namsag]

You can get leakage from the cold mains into your plate heat exchanger that could cause pressure to rise.
You should disconnect the filling loop an make sure its not passing

 

[baxpoti]

Namsag, can't you read? This boiler has seperate heat exchangers

 

[namsag]

Missed that bax we must be thinking something else

 

[cuchulain001]

Thanks for your suggestions

I had already isolated the filling loop with no effect

Agile - I did not mean to imply i knew everything about the boiler, but two forums and a plumber convinced me the problem was the heat exchanger allowing water to leak between the two systems. When i went to buy the part i was set straight.

I have bitten the bullet and asked an engineer to fix it. Ouch!

He reckons it is the expansion vessel. Fingers crossed.

Again thanks for your help.

 

[corgiman]

who set you straight?

as it could well be the DHW HEX letting by

 

[Agile]

My boiler has separate heat exchangers for CH and hot water so there can be no leakage between the two.
Thanks
Pat

Firstly, we know exactly what is in your boiler!

Secondly, we also know that the secondary heat exchanger can leak and cause an increase in the pressure.

However when you make such a bold statement ( which we know is wrong ) then we perceive that as an indication that you think anyone who fixes boilers is a "plumber" and that , as everyone knows, a plumber by definition left school at 15 and is thick! Thats is evidenced by:-

1. We are ignorant so YOU have to tell us whats inside your boiler!

2. YOU know more about boilers than we do so you need to tell us what cannot happen ( Wrongly! )

In your case it sounds as if the plate HE is leaking although thats unusual on your model AND as well it sounds as if the EXV needs checking and recharging or replacing as required. See FAQ as it can be a DIY job.

Tony

 

[namsag]

Ask yourself a question if filling loop is not connected and the pressure is rising then being dumped out of the PRV .
WHERE???? is the the water coming from to replace the water being dumped .

It is NOT your expansion vessel at fault
Who sert you straight it was not the heat exchanger????? someone who sells parts ,get real

 

[baxpoti]

 

[joop1977]

oh seperate heat exchangers?now theres a novelty.as you have pointed out that there are two heat exchangers,so they are completely seperate from each other,i would suggest looking at both combustion chambers,make sure each candle is alight,if need be put more coal in and stoke as required,hope this helps.

 

[Agile]

Two completely seperate old boilers?

 

[cuchulain001]

My apologies for winding up so many of you by making such a bold statement. I should have added the following explanation to the first post but i was trying to keep it short and to the point.

When i went to the suppliers, another customer overheard me and after a very convincing explanation he climbed into a van with heating and boiler installation and repair written on the side. Now i might have made a mistake by adding 2 and 2 together and getting a boiler engineer (in hindsight he might have been a gofor)

Using the boilers "installation and servicing instruction" booklet, he pointed out that the boiler had a plate heat exchanger and a heat exchanger. One for hot water and the other for central heating. He claimed that in the exchangers there could be no mixing of water between the two systems and that the only place mixing between the two systems could happen was in the diverter valve.

In hindsight again, since replacing the diverter valve didn't cure the problem i should have questioned his convincing explanation. But i didn't and made a statement which wound up some of you. Again my apologies for that.

Was this gent in error, how do the heat exchangers works?