- Hold tight.
If you've been lucky enough to stumble across this video
because you've got a problem with the pressure
in your boiler and and the fact it's constantly dropping,
then lucky you and any second now we're gonna get started.
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Plumberparts.co.uk, honest reviews and advice.
So you've been noticing lately that the pressure gauge
on the front of your boiler that looks very similar
to some of the pressure gauges
that I've got going on behind me at the moment
has been dropping down.
Now if it goes anywhere below kind of half a bar,
then you know that you've got a problem
and obviously if it's constantly going down all the time
or that reckedly you're topping it up
using a filling loop like the ones that we've got
going on behind us at the moment,
then you'll know that you've definitely got a problem.
Now there's a few things that can cause this
and we're just gonna go through them step by step
and also give you a quick idea about
how you can maybe fix the problem.
I've seen a few other videos on YouTube about this
and I don't really feel like they're covering very well.
So we're gonna try and do that now for you
and I hope you enjoy the video.
So let's go.
You may be aware that we've already done videos
on how pressurized heating systems work
and it's quite important to know the basics of how they work
when it comes to finding out
why you've got a problem with pressure drop.
The main things to think about are that when cold water
is heated up inside a boiler and inside a heating system,
the cold water atoms and molecules start to move
and get very, very excited and because of that, they expand.
They usually on an unpressurized system,
you have a tank in the loft with an expansion pipe
that goes up there and that allows the water
to expand up and down without there being a problem.
On a pressurized system,
instead of having the expansion pipe,
you have what's called an expansion vessel.
How they work is very simple.
It's very difficult to compress water
and so therefore you have an expansion vessel
with a rubber diaphragm and on one side of the diaphragm
you have compressed air that's usually compressed to one
or one and a half bar
and on the other side you have your heating system water.
So as that water heats up and expands,
it gets more and more happy,
it can expand into the easily compressed air
without letting air into the heating system
because there's a rubber diaphragm in the way.
So make sure that your heating system is nice and full
of water at all times, you have a filling loop
that fills up the cold water from the cold water main system
and make sure that everything's okay.
It's worth noting as well that the filling loop
is not in all the time, okay.
When you filled up the system, when you've done anything,
you should turn off both the valves at each size
and remove the filling loop braided hose
and just hang that behind the pipe.
The main reason we do that is because
if you've got a problem with one of the valves,
you could overpressurize the heating system and actually
pressurize the whole heating system up to main's pressure.
So now you've got a basic idea
about how a pressurized heating system works.
Let's look at problem number one
that could cause a pressure drop.
Firstly and most obviously of all,
you could have a leak on your heating system somewhere.
When it comes to finding leaks, the best thing to do
is pop around all the radiator valves for a start
and just make sure there's no leaks on them.
Make sure you lift up the heads as well
to make sure that there's no weep on top of the valves.
Make sure that the compression fittings
on each side of the radiator valves
are nice and tight and there's no water anywhere.
Just go around, run around with your hands
and make sure that you've got no leaks there at all.
That's number one on the list.
Try and stop the leaks.
If you find that you can't find any leaks anywhere,
always look out for sort of
dark brown patches on the ceiling.
They can indicate leaks.
After that, you're into the gnarly world
of pulling up floorboards and having a look under the floor.
Things like that can get pretty horrible.
So that's number one.
You might actually have a leak on your heating system.
Number two, most modern combi boilers
have what's called automatic air vents on them.
Now they're great for when it comes to venting a system out.
Everything gets vented automatically
and it works brilliantly.
But they can cause problems if the heating system
hasn't got an adequate amount of inhibitor in it
or if the pump setting is set too high for the speed.
Let's go through both of those quickly now.
What an inhibitor does is stops the water
from reacting with the inside of the radiators
and the inside of the components
of the heating system itself.
If that's not in there, you've got normal water
going up against the insides of a radiator
and causing horrible things to happen.
Many, many months ago I started an experiment
with two jars just like this,
one with inhibitor in it and one with just water in it
and then popped about 10 nails in each
and I think you can see the difference.
If I just pop these down so you can have a closer look
at them, you can see the different state in the nails
and if inhibitor is not inside your radiators,
that's exactly what's gonna happen to the inside.
Now, another byproduct of this
is not just sludge and rust that goes around
and stops a heating system from working properly,
it's also hydrogen and other gases.
What happens is the hydrogen can work its way around
to an automatic air vent
and the automatic air vent's just doing it's job,
it's just sitting there having a nice chilled out day,
a little bit of gas comes along
and it lets it out quite happily, but what happens then
is the pressure drops down on your boiler.
So make sure that you've got a nice amount
of inhibitor in your heating system.
We've done a video about how to do that
and that'll be appearing in the card right now.
The next thing to worry about is the pump speed.
Now the problem you have is
if the pump speed is set too high and the water
is not getting away from the pump quick enough,
it can do a thing called cavitation, which is what happens
where the pump impellers themselves split the water
and air up and then you again create hydrogen.
So turn your pump speed down, make sure you've got
an adequate flow around the holder system
and that should stop that from happening.
Now obviously the hydrogen has to escape somewhere
and guess what, it goes up to that naughty little automatic
air vent again and drops the pressure in the system.
So there are the other things you'd look at
if you've got a problem with a pressure drop
on your pressurized system.
The last two things to look at and unfortunately
the most common are problems with the expansion vessel
and also problems with your pressure relief valve.
Let's have a look at the expansion vessel first.
Like we described earlier on, the expansion vessel
allows the hot water to have somewhere to expand to
without pressurizing the heating system
anywhere above what is a safe limit.
Now, if the rubber diaphragm ruptures
and let's face it, it is actually a moving part,
then water will go into that,
the air will get into the heating system
and get taken out of the automatic air vent
and basically what you'll end up with
is an area of no expansion.
Now, you'll probably think
that's gonna make the system pressure go up.
That is kind of true, but only for a little while.
What'll happen is is the system pressure will go up and up
and up and actually force the pressure relief valve to open.
The way to know that if you've got a problem
with your expansion vessel is to find what looks like
a bike pump connector on the top of it or on the side,
press that and unfortunately you're probably gonna release
all the air out, but if water starts to come out,
then that's a bad thing, okay,
and you're gonna need to put a new expansion vessel on.
If you don't find there's any water come out,
it might've just lost its charge
through that straighter valve and you can get a bicycle pump
and repressurize it and then use a pressure gauge
to make sure that it's pumped up to one
or one and a half bar.
Another thing I'd also say is a lot of combi boilers
only have an expansion vessel that accounts
for the expansion of the boiler itself
and doesn't account for the expansion of the radiators.
I always say it's a great idea
if your plumber's in and he's putting a new boiler in,
ask him to whacker a moat expansion vessel
somewhere else on the heating system,
usually in the airing cupboard
and then you'll halve the risk of there being any problem
with the expansion vessel or the pressure relief valve
'cause you've got so much more expansion space.
Pressure relief valves are very simple.
All they are is a rubber valve
with a certain set spring on the back of the valve.
When the water gets up to a certain pressure,
the pressure pushes on that spring
and then dumps the water at a safe location outside.
They usually run with a little 15 mil copper pipe
that sticks out the back wall of the boiler
and usually the outlet is behind a hedge or something
so you can never see them running or dripping
and let's face it, most homeowners aren't gonna be
looking for that anyway.
So if you've got a problem with the expansion vessel,
the pressure is gonna go up so much
and it's gonna start dumping out the pressure relief valve
and then your pressure drop will happen that way.
Now a problem you can specifically get with the pressure
relief valve is again that it is a moving part.
The fact that you've got a spring on the back of the valve
will mean that it is a moving part
and it'll get weaker and weaker over time
and eventually 50% of pressure relief valves
will fail after about 10 years
and what happens is they'll start to slowly drip out
and you'll slowly notice the effect
if you've got a leak on the system,
but of course the pressure relief valve's piped up
to dump that little drip outside where you're not looking.
So a good idea is to just pop outside,
find that little 15 mil pipe
and just run your finger under that and see if that's where.
If it is, then you've probably got a problem
with the pressure relief valve
and you'll need to get a plumber out to replace it.
So there we go.
I hope this video's given you a better idea
about the problems you can have
when it comes to your pressurized heating system
and why you're getting a pressure drop.
There are a few reasons.
Let's face it, the most common are the expansion vessel,
the pressure relief pipe,
or obviously a leak on your system.
One thing I would say, it's always a good idea
just to top of the inhibitor in the heating system
if you're not sure anyway
and periodically ask your plumber to come out
and just do a nice little health check on it,
drain the whole heating system out, fill it all up again,
pop a couple of tubs of inhibitor in there
and your system should be nice and happy.
Also at the same time, if you haven't got one,
ask them to bang a magnetic filter
on the return to the boiler
and you're really halving any of the problems you might have
just through the running of the heating system.
If you need any more help or any more information,
pop over to our website,
Facebook, Twitter, give us a subscribe.
Mr. G, my cat will be over there.
He loves to be out that place.
Anyway, I hope you've enjoyed this video.
I do hope you subscribe
and remember everyone, once you've got all that sorted out
and you've figured out why you've got
this pressure drop going on, to hold tight.
See you later everyone, buh bye.
Plumberparts.co.uk, honest reviews and advice.