RE: BOILER PRESSURE PROBLEM - PLEASE HELP!!!

[GPMANCHESTER10]

Afternoon - I'm a new poster on here so i'm hoping someone can give me some advice.

I have a Valliant Combi boiler. The central heating is working fine as is my water flow from both hot and cold taps.

The problem is when I turn my hot tap on the pressure on the boiler drops rapidly to zero. This doesn't happen when the central heating is on or when I turn the cold taps on.

Is this a common problem or does anyone know what the fault might be?

Also the boiler itself doesn't seem to be leaking externally.

PLEASE HELP!!!

Kind Regards

 

[ChrisR]

YOu need a new tap water heat exchanger, yours is passing water from the boiler to the tap water.
ALso known as Plate, Secondary or DHW heat exchanger
If the boiler's less than about 10 years old they cost about £130 iirc, plus an hour to fit.

 

[GPMANCHESTER10]

Thanks for the reply ChrisR

I presume this is something a qualifed plumber would have to do?

Also can you purchase these Heat Exchangers off the Internet?

Regards

 

[jackecole]

I thought a holed plate heat exchanger would make the system pressure rise to approx 3 bar and the prv to open?

 

[spraggo]

Check that the fill loop that you use to pressurize your boiler is not turned on, even better disconnect it from the boiler when not in use.

 

[misterdubya]

I thought a holed plate heat exchanger would make the system pressure rise to approx 3 bar and the prv to open?

Depends on your mains pressure.

Mr. W.

 

[jackecole]

I guess, must be rare to have less than 1.5 bar mains pressure

 

[onlyfitidealboilers]

i take it you dont have a water meter?

 

[GPMANCHESTER10]

No unfortunately I don't have a water meter.

At the moment I just keeping topping the pressure back up to 1.5 and I'm still getting hot water. I presume this can't be good for the system though?

 

[onlyfitidealboilers]

can you test your water pressure in bar? it can't be very high other wise the cold water (main) would over power the central heating pressure an force the pressure up on the gauge. causing the prv to open an dump water all the while out the copper pipe outside.

if say you only can get 1.5 bar pressure (cold main) then the boiler comes on an the pressure in the central heating system went to 2 bar the central heating pressure would over pressure the cold inlet an the pressure would leave the boiler..