Boiler pressure dropping slowly

kyleporter

The pressure on my boiler is slowly falling. I used to have a leak at a one of the lockshield valves, but that is now fixed. But ever since i have started using the central heating its slowly dropping, in about 2 weeks its dropped 0.2 of a bar.

I looked out the back the building and the is a rustly mark most of the way down the building below the pipe that comes out the radiator, i think it may be an overflow pipe. Could this be the cause of the pressure dropping?

Or what are the other reasons it could be falling

karl-123

the pipe outside the house should terminate in a safe place
it is the pressure relief valve outlet it cane be stripped out cleaned or replace if it is dripping
when the boiler heats up the expansion vessel may be failng or pipework to the expansion vessel
may be blocked with sludge " however " the rusty stain may just be there from a previous problem

fire up your central heating and see if the pressure relief outlet pipe drips
if your pressure is dropping slightly over a period you may have a leaking radiator valve that is simply evaporating so you are unable to trace it that easily....fernox leak sealer liquid may be a possible remedy
but introduce it as far away from the boiler as possible so it gets chance to dilute before it does its work

karl-123

i have actually met the chemist from fernox on an institute of plumbing doo when i was an apprentice
30 years ago he was a lovely man and i learnt a lot from him
one of his friends had a mexico floor standing cast iron boiler ( a brilliant boiler )
it had a pin hole leak in the cast iron heat exchanger he put fernox leak selaer in
that was five years ago he said its still going strong ... the reason why i make sure it is diluted before i put it into heating systems is it can cause problems around modern day boilers with small pipes and rubber in the heating system so i allways introduce leak sealer as far away from the boiler as possible ....karl
ideal pressure for pressurised systems is (1 to 1.25 bar)
one to one and a quarter ...........

kyleporter

when i look outside i cant see the leak but my flat is on the second floor so its quite hard to see. Is it possible a leak could have developed under the floor, or is it more likely to be at a valve. i keep going round checking all the valves by rubbing my finger around them all but none are wet

how do i put in the stuff that can block up leaks?

Its only a rented flat so i dont really want to bother the landlord

karl-123

the leak can be from the boiler/radiator valves/copper fittings kyle
as i said if it is a slight leak like yours is it will be difficult to trace as water evaporates in air

http://www.fernox.com/products/water+treatment+chemicals/leak+sealers/leak+sealer+f4+express

karl-123

all the best any problems come back best of luck karl.......

kyleporter

You say in an earlier post that the ideal pressure is 1 - 1.25, mine is an ariston microgenus boiler and i'm pretty sure the plumber set mine to 1.5 is this to high?

keystone

kyleporter wrote: »

You say in an earlier post that the ideal pressure is 1 - 1.25, mine is an ariston microgenus boiler and i'm pretty sure the plumber set mine to 1.5 is this to high?

No 1 - 1½ bar when cold is fine. When it heats up it shouldn't go over 2 - 2½ bar.

Cheers