BIASI 28S Excessive Water Pressure

[diywanabee]

Hello

I have just completed on my new house and moved in. I have a BIASI 28s boiler.

Water is escaping from the overflow, not excessively, but enough for a non DIY fundi to notice. I checked the water pressure gauge to find it registering 2.5 bar and know that is too high, yet I am unable to reduce it. I have bled all the radiators and drained a few liters out via the bottom radiator drain cock and it still remains on 2.5 bar.

I would not worry about it if it was not overflowing. Is there a setting somewhere to keep it that high or is something else the matter?

Any ideas would be welcome.

Thanks
Geoff

 

[GasAid]

Check that the filling loop is turned off.

 

[diywanabee]

Thanks for that, filling loop definitely switched off.

 

[GasAid]

With the filling loop off and draining the appliance; with the appliance off does the pressure still increase?

If so; turn the cold mains off to the appliance and see what happens... If this stops the pressure rising; then you need a new dhw heat-exchanger.


If it doesn't solve the fault then I'm out of ideas and will put it down to magic unless I see it doing it.

 

[Agile]

Unless it was made during 2002/3 then I will bet you a plate HE that its not that leaking!

Remove the filling loop and only then can you tell us that the filling valve is not pressurising the boiler.

Tell us the result!

Its theoretically possible that a drunken plumber has mixed up water supplies with heating pipes but thats unlikey on an "old" house ! It cannot be a "new" house as you say either as the 28S was not made after 2002.

Tony

 

[diywanabee]

Thanks guys, will try the draining and removal of the filling loop when I get home tobight. I did wonder why the loop was still in place as it says in the installation guide to remove it. Maybe left to ensure it does not get lost if needed again.

Cheers

 

[diywanabee]

Hi All

It sounds like I need a new heat exchanger then. Removing the filling loops only, made no difference. When drained and off, the pressure stayed down. As soon as I turned it back on, it rose straight back to 2.5 bar. And the overflow still leaks all the time. that is probably another pointer.

Thanks for the help, I need to study up on trying to change the HE myself.

Cheers
Geoff

 

[GasAid]

It's only the domestic hot water heat exchanger, not the main heat exchanger

When you go down the plumbing merchants; buy yourself a pressure relief valve as well and change that; save you having to drain the appliance again if some crud has got on the seating (Which stops it from closing again)... And treat yourself a combi capping kit; as per the water regs; the filling loop is supposed to be disconnect to prevent back-filling the cold mains with central heating water... However; most people are lazy and leave it on... But a capping off kit is as cheap as chips and keeps you upto date on best practice guidelines.

 

[jamble]

Hi folks,

Having a similar problem with an older Ravenheat boiler where the pressure is going all the way up to 4.

How do I check the filling loop? (total novice DIY'er here) or should I just get a plumber out?

Many thanks.

 

[Agile]

Which part of Dorset and serial number of boiler?

Email me through my profile please!

Tony