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Baxi 105e combi boiler problems (Read 8925 times)
IanJowitt56
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Baxi 105e combi boiler problems
Apr 1st, 2013, 10:08am
 
We've being having an ongoing problem with our boiler for a while now and we are covered by British Gas, but they don't seem to solve the problems. The engineer just says that he's changed the 'pressure vessel' and everything should be OK. The annual service is due, so I'd like a few suggestions as to what might be wrong with our system so that I can suggest them to the engineer.

We have a problem with getting hot water to the bath upstairs, this can now only be achieved by slowing down the flow from the tap to a trickle (on his last visit the engineer said that this was because the cold water was very cold due to the time of year!!!). The radiators get blisteringly hot though, so I can't work out what he's on about.

The hot water to the kitchen sink can also just stop mid-flow, even though all the lights on the boiler say that we should be getting hot water. The only way I have found to rectify this is to turn off the boiler at the mains and then turn it on again.

Also, quite often we get a rushing / jet engine noise coming from the boiler which sounds like somebody is tipping gravel into a big steel drum, this can be heard from upstairs, and the boiler is downstairs in a cupboard, and happens both when the heating is on or off!!

We also have to constantly top up the boiler pressure. The boiler is now 10 years old.

Thanks for reading, and I hope you can help me (and British Gas) out.
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big_all
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heeelllooo
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Re: Baxi 105e combi boiler problems
Reply #1 - Apr 1st, 2013, 11:22am
 
heeelllooo and welcome IanJowitt56  Smiley Smiley Smiley

the heating and hot water are 2 separate circuits
hot water comes out the ground and has to be heated from cold to hot in seconds

the heating is a closed loop between boiler and radiators

i dont know the the answer to your other questions but someone will be along soon with an answer
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« Last Edit: Apr 1st, 2013, 11:24am by big_all »  

big all ---------------  we are all still learning
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IanJowitt56
Re: Baxi 105e combi boiler problems
Reply #2 - Apr 1st, 2013, 12:21pm
 
Thanks Big_All. Sewers are my specialty, not boilers!!
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thescruff
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Re: Baxi 105e combi boiler problems
Reply #3 - Apr 1st, 2013, 4:15pm
 
Hi,

The easy bit first, if you are loosing water you could have a leak which will be related to the last part of the question.

You say they changed the pressure vessel, what does the pressure rise too from say 1.3bar cold when the boiler is fired up.

Is the pressure relief valve dripping/letting by ( the copper pipe sticking through the wall to outside).

The alternative is a leak somewhere.

The hot water problem is likely to be scale or sludge in the HX, continually adding fresh water will cause/make worse the problem, and BG will be suggesting a powerflush at an inflated price. Your best bet would be to get an independent in.
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IanJowitt56
Re: Baxi 105e combi boiler problems
Reply #4 - Apr 2nd, 2013, 8:12am
 
This morning the boiler pressure was about 0.4bar. Turning on the hot water or heating reduced it to about 0.2bar. After about 10 minutes of heating the pressure was upto 0.8bar. There's no dripping form the overflow pipe now, but the engineer said that it was leaking last time he visited (according to my wife).

Is HX short for heat exchanger?

Thanks
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Re: Baxi 105e combi boiler problems
Reply #5 - Apr 2nd, 2013, 8:56am
 
HX is Heat exchanger.

You need to test and answer all the above questions
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Re: Baxi 105e combi boiler problems
Reply #6 - Apr 2nd, 2013, 12:28pm
 
What thescruff said.

Set the pressure when cold.
Turn on the heating and monitor the pressure rise.
Check the Pressure Relief Valve pipe to see if any water came out.

Once a PRV starts letting water out (for whatever reason) they can be prone to letting water out at lower pressures then they are meant to.
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IanJowitt56
Re: Baxi 105e combi boiler problems
Reply #7 - Apr 3rd, 2013, 8:09am
 
Last night I set the pressure to 1.5bar before the heating came on. The pressure remained constant and there was no leak from the prv. This morning the pressure was back down to about 0.7bar and I repressurised it to 1.5bar again. No signs of leaks from the prv or any of the boiler pipework I could see.
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Re: Baxi 105e combi boiler problems
Reply #8 - Apr 3rd, 2013, 11:21am
 
Check carefully around the rad valves. Common place for small leaks.
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Re: Baxi 105e combi boiler problems
Reply #9 - Apr 3rd, 2013, 5:45pm
 
If you set the pressure to say 1.5bar with the system cold, shouldn't it go up to over 2 as the system heats up? Mine does, or it did when it was working.

Ian I had numerous leaks on my heating system when I moved into my house; a green verdigris was a tell tale for some leaks even though it looked dry. The pipework within the boiler is a good source of exexplicable leaks as the heat makes the water evaporate.

I'd try pressurising the (cold) system to 1.5bar then leave it overnight without the heating on and see if the pressure has dropped; that way you will get an idea if it is the expansion due to heating that is causeing the problem perhaps showing that the pressure relief valve is leaking. But I'm only a chippy so that may be a rubbish idea.
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