Constantly Losing Water Pressure


Postby erskine0812 » Sun May 04, 2008 10:54 am

I have a Vokera Synergy 29 condenser boiler and have had problems since it was installed 2.5 years ago.

The original heating system in the house was fitted with plastic pipes and eventually I needed to replace the radiators which had become so contaminated with sludge that they could not be cleared. I decided at the same time to have the boiler replaced and the pipework replaced with copper pipes to avoid the problem recurring.

Initially. the boiler would lose pressure over a 4 week period dropping from 1.5 to 0.3 on average. I gave up trying to get the installer to correct the problem and rather than take him to court, I gave up when the pressure held for about 3/4 months at a time.

Since this heating season started, the problem has got worse. In October, the system was needing topped up every 2 weeks. It now needs topped up every day when the pressure has dropped from 1/1.5 to virtually 0.

I have been under the boards a few times and can find no trace of a leak. What I have discovered is that the installer did not replace all the heating pipes with copper and has left a significant number of the original plastic pipes in place under the boards and has connected new plastic coated copper pipes to these then to the radiators.

There is no trace of water being released through the small pipe outside the house and, as I say, although there are traces of green tarnishing on some of the older joints, they all seem sound.

Any help would appreciated on this as it is now driving me crazy.
erskine0812
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Postby ALDA » Wed May 07, 2008 6:52 pm

E,

IF YOU STILL HAVE A PROBLEM!!!

ARE YOU BLEEDING AIR FROM THE SYSTEM WHEN RE-PRESSURISING/FILLING SYSTEM?

DOES THE PRESSURE DROP WHEN THE EXTERNAL FILLING LOOP/INTEGRAL FILLING VALVE IS DISCONNECTED/ISOLATED?

DOES THE PRESSURE DROP WHEN THE SYSTEM IS SHUT DOWN?
THIS IS THE BEST TIME TO LOOK FOR WATER LEAKS AS DOING SO WHEN SYSTEM IS RUNNING IS MADE DIFFICULT BY THE EVAPORATION OF THE SEEPAGE/WEEPAGE.

CHECK THE PIPEWORK AND FITTINGS WITHIN THE BOILER CASING AS A SLIGHT WEEP HERE WILL ALWAYS EVAPORATE VERY QUICKLY AS IS EXTREMELY HOT WHEN OPERATING.

HAVE YOU ATTEMPTED TO TIGHTEN ANY JOINTS?
START WITH THOSE THAT APPEAR TO HAVE LEAKED (OXIDISED ONES)!!!

DOUBLE CHECK ON THE PRV VENT PIPE!!!

SEEK AND THOW SHALL FIND.

ALDA.
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Postby htg engineer » Wed May 07, 2008 7:19 pm

If there's no sign of any leaks on boiler, pipework or radiators.
There's no sign of a leak from the pressure relief valve.
The pressure doesn't rise to 3.0bar when the central heating is on.

Then the first thing I would suggest doing is to get rid of the plastic pipe, they tend to break down inside over the years and can become porous, this may be where the pressure is being lost. I would imagine there would be signs of a leak though.

Also check radiator valves thoroughly, if they're old think about replacing you could have small leaks on them that will not be noticeable but enough to drop the pressure, also prone to leak are automatic airvents, check the auto airvent on the boiler.

The leak will not be large, it doesn't take much to drop the pressure and yours is holding for a couple of weeks so will be tiny. After replacing the plastic pipes if you still have the problems and there's no signs of leaks. You could try adding leak sealer to the system, this will seal any small leaks and hopefully solve the pressure loss problem.

htg
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Postby erskine0812 » Wed May 07, 2008 8:50 pm

Thanks, [b]htg engineer[/b]

The radiator valves are only 2.5 years old. The loss of water is now [b]daily[/b]......until recently it was every couple of weeks. This is what puzzles me. I would think that I should be able to find a trace of this amount of water leak.

Replacing the remaining plastic pipes would be a big task but it may be something that needs done to sort this once and for all.
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Postby yewtree » Fri May 09, 2008 2:36 pm

I would be very interested to find out how you get on with this as I have the same problem. System loses pressure daily. It holds it's pressure better when the heating is on but drops fairly rapidly when it switches off.
I can't find any leaks anywhere although I do have concrete ground floors.
I've just tried the leak sealant but no joy after 24 hours. I'll let you know how I get on.
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Postby erskine0812 » Fri May 09, 2008 3:18 pm

[quote="ALDA"]E,

IF YOU STILL HAVE A PROBLEM!!!

ARE YOU BLEEDING AIR FROM THE SYSTEM WHEN RE-PRESSURISING/FILLING SYSTEM?

DOES THE PRESSURE DROP WHEN THE EXTERNAL FILLING LOOP/INTEGRAL FILLING VALVE IS DISCONNECTED/ISOLATED?

DOES THE PRESSURE DROP WHEN THE SYSTEM IS SHUT DOWN?
THIS IS THE BEST TIME TO LOOK FOR WATER LEAKS AS DOING SO WHEN SYSTEM IS RUNNING IS MADE DIFFICULT BY THE EVAPORATION OF THE SEEPAGE/WEEPAGE.

CHECK THE PIPEWORK AND FITTINGS WITHIN THE BOILER CASING AS A SLIGHT WEEP HERE WILL ALWAYS EVAPORATE VERY QUICKLY AS IS EXTREMELY HOT WHEN OPERATING.

HAVE YOU ATTEMPTED TO TIGHTEN ANY JOINTS?
START WITH THOSE THAT APPEAR TO HAVE LEAKED (OXIDISED ONES)!!!

DOUBLE CHECK ON THE PRV VENT PIPE!!!

SEEK AND THOW SHALL FIND.

ALDA.[/quote]

1. I have checked the system for air when I have topped it up but it does not appear to have any air in the system.

2. Em, I'm not sure how I would do this. The filling loop has a couple of valves on it and these are shut until topping up the system.

3. The system does lose resseure when it is shut down. In fact, it seems to be more evident when it is shut down. I did check last week when the system was off, but couldn't find any trace of a leak.

4. I haven't attempted to tighten any joints as I could not find any trace of a leak. Do you mean to re-solder all the joints that show signs of oxidisation?

5. The PRV vent pipe seems OK and there is never any trace of a leak on the ground beneath that.
erskine0812
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Postby ALDA » Sat May 10, 2008 12:48 pm

ENSURE THE FILLING LOOP VALVES ARE CLOSED AND DICONNECT LOOP/PIPE.

DOES THIS HAVE ANY EFFECT ON THE PRESSURE DROP AND/OR ANY LEEKS VISIBLE?

ANY JOINTS WHETHER SOLDERED OR COMPRESSION THAT SHOW SIGNS OF LEEKING AND ARE ACCESSIBLE SHOULD BE REMEDIED.

H.E ASKED IF THE PRESSURE RISES EXCESSIVELY WHEN THE HEATING IS ON?
CAN YOU COME BACK WITH AN ANSWER TO THIS? CAN BE AN INDICATION OF EXPANSION VESSEL/DIAPHRAGM FAILURE AND THAT PRV CAN BLOW OPEN TO DISCHARGE SYSTEM PRESSURE UNTIL PRV CLOSES BUT DOES NOT NECESSARILY FULLY SEAL.
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Postby htg engineer » Sat May 10, 2008 1:59 pm

Yewtree

Leak sealer is no good for a system losing pressure daily, if it's losing that much it shouldn't be hard to find, i bet the leak is under the concrete floor - where the pipes have not been wrapped in a protective coating.
htg engineer
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Postby yewtree » Sat May 10, 2008 5:03 pm

Thanks, any idea why the system seems to hold it's pressure while the heating is on but falls quite quickly when the heating is switched off?
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Postby erskine0812 » Sat May 10, 2008 6:28 pm

[quote="yewtree"]Thanks, any idea why the system seems to hold it's pressure while the heating is on but falls quite quickly when the heating is switched off?[/quote]

It is likely to be the fact that some of the joints 'weep' when they contract.
erskine0812
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Postby htg engineer » Sat May 10, 2008 8:10 pm

Copper expands when hot, so when the heating is on the copper pipe will expand - if it's a poor joint that is the problem, the copper will expand in the fitting and seal tha gap. When it cools the gap will appear again.

Also, when the heating is needle on the pressure gauge will rise slightly. If you're gauge reads the same it's probably still dropping but the expansion in the system is balancing it out. So not showing as a drop.

Htg
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Postby plumbbob » Sat May 10, 2008 9:39 pm

Make sure you find this leak and have it fixed. Constantly re-filling a system with water will cause severe damage in the medium term.

Heating systems are designed to be a closed circuit which excludes oxygen from the circulating water. Along with the help of a suitable inhibitor, corrosion to radiators, pipes and the boiler heat exchanger is avoided.

If fresh water is constantly introduced, the inhibitor becomes diluted, and the oxygen dissolved in this new water will cause a build up of sludge and eventual failure of the metal parts of the system. New boiler required!
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