Baxi Bahama pressure problems.

Coops · 16 Dec 2003

I hope someone can help me as my local heating engineers don\\\'t seem to have a qlue.
I have a pressure problem with my combi boiler. Basically when the heating is off the pressure gauge falls to zero.
Before I start the heating system I have to repressure the system to 1 Bar, when the heating has been on for a while the pressure continues to climb off the clock (3 bar +).
The pressure safety valve operates at this pressure as it should do, when the heating switches of the pressure falls to 0 Bar in approx 30 mins.
On an occasion that the pressure was at 3 Bar I noticed there was a small amount of water around the schrader valve on the expansion vessel, I also checked the pressure in the expansion vessel with a car tyre gauge and found that I was approx .25 Bar, I repressured the vessel again and this seemed to reduce the rate at which I was loosing pressure from the system when the heating was off.
I have also circulated 500ml of Fernox leak sealer around the system via on of the down stairs rads over a 24 hour period in case there are any small leaks on the system, but I can\\\'t find any.
I have done some detective work of my own and feel that the expansion vessel may be the problem area.
I would appreciate it if someone out there can assist me where my local engineer cannot.
It\\\'s costing me a fortune and getting nowhere.

oilman · 16 Dec 2003

Did you expel a small amount of air from the expansion vessel valve before you repressurised it? It seems, from the water round the valve, the vessel is full of water.

If this is the case it should have been easily discovered by any professional.

Coops · 16 Dec 2003

When I depressed the button inside the schrader valve to check for pressure some water came out.
Whilst I was working away from home my wife called the heating engineer out because of the water coming from the schrader valve, she told me as far as she was aware all he did was refill the heating system to 1 bar.
I understand that there is a diaphragm inside the expansion vessel, could I be right in thinking that the diaphragm may have ruptured if there is water coming from the schrader valve ?

antcain · 20 Jan 2004

The problem could lie with the pressure gauge itself, its a common problem, showing the wrong pressure. Also the safety valve may not be seating properly and your pressure may be escaping outside. Both the above problems I've had.

DP · 20 Jan 2004

Your pressure gauge would appear to be OK. Water on the schrader valve would indicate PV diaphragm problem. You do not say what boiler make is.

Check your dummy engineer is CORGI registered for CH systems.

AnonymousImport · 30 Mar 2004

Coops said:
I hope someone can help me as my local heating engineers don\\\'t seem to have a qlue.
I have a pressure problem with my combi boiler. Basically when the heating is off the pressure gauge falls to zero.
Before I start the heating system I have to repressure the system to 1 Bar, when the heating has been on for a while the pressure continues to climb off the clock (3 bar +).
The pressure safety valve operates at this pressure as it should do, when the heating switches of the pressure falls to 0 Bar in approx 30 mins.
On an occasion that the pressure was at 3 Bar I noticed there was a small amount of water around the schrader valve on the expansion vessel, I also checked the pressure in the expansion vessel with a car tyre gauge and found that I was approx .25 Bar, I repressured the vessel again and this seemed to reduce the rate at which I was loosing pressure from the system when the heating was off.

Did you get your boiler fitted. i work on these boilers all the time. They are crap. Replace the vessel / add leak sealer in the primary system.
I have also circulated 500ml of Fernox leak sealer around the system via on of the down stairs rads over a 24 hour period in case there are any small leaks on the system, but I can\\\'t find any.
I have done some detective work of my own and feel that the expansion vessel may be the problem area.
I would appreciate it if someone out there can assist me where my local engineer cannot.
It\\\'s costing me a fortune and getting nowhere.

weargas · 30 Mar 2004

if the pressure increases to around 3 bar hot when it started at 1 bar cold then it's definately an expansion problem. Depress the schrader valve slightly, if water comes out then your expansion vessel is knackered. If air comes out then you need to check the pressure in the vessel. this should only be done with the boiler drained (the bahama has handy little drain plugs underneath) and ideally one of the drain plugs left open otherwise water pressure in the system will give you a false reading. 0.75 to 1 bar is about right but someone else may know the exact pressure. if the pressure in the vessel is ok then you need to check that there's no obstructions in the pipe leading to the vessel. because the pipe leading to the vessel hasn't got water flowing through it there's more chance for fouling to occur.
you may find that the seat of the prv is dirty and the washer of the prv has a ring indent in it. once you know the expansion vessel is working correctly it's probably worth replacing the prv, at least you'll know it not going to be a problem then.

MrDBM · 31 Mar 2004

just to add that I've had exactly the same problem for a few weeks... (powerMax 155x) Not sure if it's a common issue but mine also de-pressurises when the shower/taps are used - in fact, I need to make sure the system is running beofre using too much hot water or else the pressure falls off to zero.

I also had a drop of water come from my exp vessel valve.

I'm having a British Gas guy out tomorrow (1st) to look at the issue - will post up the response if that helps.

weargas · 31 Mar 2004

MrDBM said:
I'm having a British Gas guy out tomorrow (1st) to look at the issue.

powerflush and a new system then

ollski · 31 Mar 2004

aawww weargas so cheap.....and to think I've stuck up for you, I'm disappointed.

weargas · 31 Mar 2004

ok, so it's not fair to tar all bg engineers with the same brush. i suppose we only hear the bad stories and never the good ones. i apologise to any good bg engineers.

roo2004 · 2 May 2004

Hi - I've got the same pressure problem with my Powermax 155x - anyone had this resolved? I'm going to call Scottish Power tomorrow...
Cheers

TheIce_Man · 8 May 2004

My god you guys really have not got a clue hehe , i work for potterton , the problem is that the expansion vessel is knackered and because it is not working the pressure will climb to above 3 bar then the expansion valve will open and dump all the system pressure so when it cools down it will read 0 , i suggest replacing the expansion vessel and do not even bother trying to repressurise it as it rarely works.

mahedy · 22 Aug 2005

Hi there
Could you please tell me how to repressurize my Baxi Bahama 100 system.
The Water Pressure Gauge is stuck at zero. I have hot water but no heating! I have looked through the manual but can't find where I can do this. I am sure it must be quite a straightforward thing to do?

Thanks for your time
regards
Mark

kevplumb · 22 Aug 2005

look for one of these or similar

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Baxi Bahama pressure problems.

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