Our old Valliant Turbomax is humming away with the central heating
light on, and every 5 mins or so firing up for a few secs and then
firing down, but both heating and hot water are turned off at the
controller.

I've noticed that the boiler pressure is over 2.5 bar.

It's an unvented system with a hot water tank and (blue) expansion vessel.

Am I right to suspect the expansion vessel - it either is failing or
needs recharging. I guess not a DIY job.

John Smith wrote:

Our old Valliant Turbomax is humming away with the central heating
light on, and every 5 mins or so firing up for a few secs and then
firing down, but both heating and hot water are turned off at the
controller.

I've noticed that the boiler pressure is over 2.5 bar.

It's an unvented system with a hot water tank and (blue) expansion vessel.

Am I right to suspect the expansion vessel - it either is failing or
needs recharging. I guess not a DIY job.

You have a problem with your control system or wiring, as this should
not be happening if both hot water and central heating are off. Do you
actually get sustained hot water if you turn on the tap while the hot
water is nominally switched off.

It seems likely the expansion vessel has failed, but to confirm this it
would be useful to turn of all electrical supply to the boiler, let it
cool down, and confirm the pressure falls.

--

Roger Hayter

On 2020-04-24 11:45:27 +0000, Roger Hayter said:

John Smith wrote:

Our old Valliant Turbomax is humming away with the central heating
light on, and every 5 mins or so firing up for a few secs and then
firing down, but both heating and hot water are turned off at the
controller.

I've noticed that the boiler pressure is over 2.5 bar.

It's an unvented system with a hot water tank and (blue) expansion vessel.

Am I right to suspect the expansion vessel - it either is failing or
needs recharging. I guess not a DIY job.

You have a problem with your control system or wiring, as this should
not be happening if both hot water and central heating are off. Do you
actually get sustained hot water if you turn on the tap while the hot
water is nominally switched off.

It seems likely the expansion vessel has failed, but to confirm this it
would be useful to turn of all electrical supply to the boiler, let it
cool down, and confirm the pressure falls.

It's an unvented system with a hot water tank so of course it delivers
hot water as long as there's some in the tank.

The heating and hot water are working normally otherwise.

I've tried bleeding a rad taking out a litre or so and that drops the
pressure to about 2 bar for a bit. I presume I'll need to open the
filling loop to replace the water though and that raises the pressure.

I'll try switching it off as you suggest.

On Fri, 24 Apr 2020 12:28:03 +0100
John Smith wrote:

Our old Valliant Turbomax is humming away with the central heating
light on, and every 5 mins or so firing up for a few secs and then
firing down, but both heating and hot water are turned off at the
controller.

I've noticed that the boiler pressure is over 2.5 bar.

It's an unvented system with a hot water tank and (blue) expansion
vessel.

Am I right to suspect the expansion vessel - it either is failing or
needs recharging. I guess not a DIY job.


Check that you don't have a motorised valve that has failed, leaving a
microswitch closed, faking a demand condition. Do you have a test meter
and a wiring diagram, and a suitable junction box for testing power at
different points of the wiring?

--
Davey.

On 2020-04-24 11:58:39 +0000, Davey said:

On Fri, 24 Apr 2020 12:28:03 +0100
John Smith wrote:

Our old Valliant Turbomax is humming away with the central heating
light on, and every 5 mins or so firing up for a few secs and then
firing down, but both heating and hot water are turned off at the
controller.

I've noticed that the boiler pressure is over 2.5 bar.

It's an unvented system with a hot water tank and (blue) expansion
vessel.

Am I right to suspect the expansion vessel - it either is failing or
needs recharging. I guess not a DIY job.


Check that you don't have a motorised valve that has failed, leaving a
microswitch closed, faking a demand condition. Do you have a test meter
and a wiring diagram, and a suitable junction box for testing power at
different points of the wiring?

I replaced both the hot water and heating motorised valve motors as
they were failing last year so I would hope they are OK but I'll check.

Yes I can test things with a meter and can get at the wiring box but
it's awkward.

John Smith wrote:

On 2020-04-24 11:45:27 +0000, Roger Hayter said:

John Smith wrote:

Our old Valliant Turbomax is humming away with the central heating
light on, and every 5 mins or so firing up for a few secs and then
firing down, but both heating and hot water are turned off at the
controller.

I've noticed that the boiler pressure is over 2.5 bar.

It's an unvented system with a hot water tank and (blue) expansion vessel.

Am I right to suspect the expansion vessel - it either is failing or
needs recharging. I guess not a DIY job.

You have a problem with your control system or wiring, as this should
not be happening if both hot water and central heating are off. Do you
actually get sustained hot water if you turn on the tap while the hot
water is nominally switched off.

It seems likely the expansion vessel has failed, but to confirm this it
would be useful to turn of all electrical supply to the boiler, let it
cool down, and confirm the pressure falls.

It's an unvented system with a hot water tank so of course it delivers
hot water as long as there's some in the tank.
Yes, sorry I'm confused. But the boiler still should not be cycling if
the hot water is off and the CH off. And there should also be a way of
preventing it doing so when the water thermostat is not demanding heat
in a modern compliant system.


The heating and hot water are working normally otherwise.

I've tried bleeding a rad taking out a litre or so and that drops the
pressure to about 2 bar for a bit. I presume I'll need to open the
filling loop to replace the water though and that raises the pressure.

You don't need to replace the water unless the pressure drops too low
when cold.



I'll try switching it off as you suggest.


--

Roger Hayter

On 24/04/2020 12:28, John Smith wrote:

Our old Valliant Turbomax is humming away with the central heating light
on, and every 5 mins or so firing up for a few secs and then firing
down, but both heating and hot water are turned off at the controller.

I've noticed that the boiler pressure is over 2.5 bar.

Not necessarily exceptional for a "hot" system. How many rads on the system?

It's an unvented system with a hot water tank and (blue) expansion vessel.

So you have an unvented primary (aka "sealed") system for the heating
circuit, and you also have an unvented (mains fed) hot water cylinder?

(In which case there will be two separate expansion vessels - one
(probably in the boiler) for the primary CH system, and another
connected to the unvented cylinder.

I take it the cylinder is an "indirect" type?

http://wiki.diyfaq.org.uk/index.php/...rect_sys tems


Could you explain what type of control system your setup uses? i.e. Does
it have a time switch or "programmer", room stat, cylinder stat, one or
more two or three port valves?

If you refer to :

http://wiki.diyfaq.org.uk/index.php/...ols_and_Zoning

You should be able to identify the layout - e.g. Y plan or S Plan.

Once you know the layout and the control system, you now need to
logically step through the controls, and work out why a call for heat is
reaching the boiler when it should not be.

Am I right to suspect the expansion vessel - it either is failing or
needs recharging.
Its possible, however it does not explain the cycling boiler problem.

I guess not a DIY job.

Its a fairly easy DIY job IME.


--
Cheers,

John.

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You might find this useful.
https://www.vaillantservicing.co.uk/turbomax-2000-05

On Fri, 24 Apr 2020 12:28:03 +0100
John Smith wrote:

Our old Valliant Turbomax is humming away with the central heating
light on, and every 5 mins or so firing up for a few secs and then
firing down, but both heating and hot water are turned off at the
controller.

I've noticed that the boiler pressure is over 2.5 bar.

It's an unvented system with a hot water tank and (blue) expansion
vessel.

Am I right to suspect the expansion vessel - it either is failing or
needs recharging. I guess not a DIY job.


Was this ever resolved?

--
Davey.

On 24/04/2020 12:28, John Smith wrote:
Our old Valliant Turbomax is humming away with the central heating light
on, and every 5 mins or so firing up for a few secs and then firing
down, but both heating and hot water are turned off at the controller.

I've noticed that the boiler pressure is over 2.5 bar.

It's an unvented system with a hot water tank and (blue) expansion vessel.

Am I right to suspect the expansion vessel - it either is failing or
needs recharging. I guess not a DIY job.

Replacing the Expansion vessel is actually a really easy job but you'll
have to remove the flue pipe. (This is on my Turbomax Pro 828E)
My Flue pipe was already falling to bits on the outside of the house so
it made sense to get a new flue kit along with the expansion vessel.

Removing the vessel is simply the one wet connection at the bottom of
the vessel.
Take a picture of the air-pressure switch top right of boiler and remove
that and poke air pipes through the back plate (making a note of which
pipe goes to which connection). The expansion vessel then simply slides
up and out. I say simply but it's quite a heavy lump especially if it's
still got water in it (on the "dry" side of the membrane) so you have to
push it up as far as possible from the bottom then grip it from the top
and pull upwards.

On 02/05/2020 14:49:44, www.GymRatZ.co.uk wrote:
On 24/04/2020 12:28, John Smith wrote:
Our old Valliant Turbomax is humming away with the central heating light
on, and every 5 mins or so firing up for a few secs and then firing
down, but both heating and hot water are turned off at the controller.

I've noticed that the boiler pressure is over 2.5 bar.

It's an unvented system with a hot water tank and (blue) expansion vessel.

Am I right to suspect the expansion vessel - it either is failing or
needs recharging. I guess not a DIY job.

Replacing the Expansion vessel is actually a really easy job but you'll
have to remove the flue pipe. (This is on my Turbomax Pro 828E)
My Flue pipe was already falling to bits on the outside of the house so
it made sense to get a new flue kit along with the expansion vessel.

Removing the vessel is simply the one wet connection at the bottom of
the vessel.
Take a picture of the air-pressure switch top right of boiler and remove
that and poke air pipes through the back plate (making a note of which
pipe goes to which connection). The expansion vessel then simply slides
up and out. I say simply but it's quite a heavy lump especially if it's
still got water in it (on the "dry" side of the membrane) so you have to
push it up as far as possible from the bottom then grip it from the top
and pull upwards.

If there is room to fit one, I would be very tempted to add an external
expansion tank. One I can get good access to and recharge once in a while.

On 2020-05-01 23:21:24 +0000, Davey said:

Was this ever resolved?

Well I've finally got around to getting under the stairs to investigate.

One thing for certain - the motorised valve controlling the hot water
was jammed half open, and the valve body has a very small leak but it
seems to have destroyed the motor body, which is a shame as I only
replaced both actuator heads recently (the other for the heating
circuit).

So I need to replace the valve body but that's beyond me although I do
have the part as I bought it with the motor actuator. But It looks like
I need a new actuator...

i presume the system needs a drain down to do the valve but it's just a
couple of large screw nuts.

At the same time I guess I should get the expansion vessel serviced. I
think the boiler is fine - it's a bullet proof Valliant that was
serviced a year ago.

I've freed the valve spindle and applied a bit of lubrication for now
and will operate it manually til I find someone who can replace it and
the motor head - unless anyone thinks I can do it?

On Monday, 25 May 2020 21:29:58 UTC+1, John Smith wrote:

At the same time I guess I should get the expansion vessel serviced.

serviced? It's an empty container

On 2020-05-26 09:52:56 +0000, said:

On Monday, 25 May 2020 21:29:58 UTC+1, John Smith wrote:

At the same time I guess I should get the expansion vessel serviced.

serviced? It's an empty container

They can need repressurising.

On 25/05/2020 21:29, John Smith wrote:
On 2020-05-01 23:21:24 +0000, Davey said:

Was this ever resolved?

Well I've finally got around to getting under the stairs to investigate.

One thing for certain - the motorised valve controlling the hot water
was jammed half open, and the valve body has a very small leak but it
seems to have destroyed the motor body, which is a shame as I only
replaced both actuator heads recently (the other for the heating circuit).

So I need to replace the valve body but that's beyond me although I do
have the part as I bought it with the motor actuator. But It looks like
I need a new actuator...

i presume the system needs a drain down to do the valve but it's just a
couple of large screw nuts.

Yup in principle - although it does depend where in the system the valve
is, as to how much of a drain it will need (valves in a loft for example
can often be change with only a partial drain down).

2 port valves are easier to swap than three port - especially if the
valve is a close match and can re-use the existing back nuts and olives.
In principle, undo both nuts, swap valve and re-tighten. The devil is in
the detail, like how easy they are to get at, and how rigid the pipes
are (i.e. will they move enough to let you get the valve out).

At the same time I guess I should get the expansion vessel serviced. I
think the boiler is fine - it's a bullet proof Valliant that was
serviced a year ago.

You can check the pressure easy enough yourself. Not sure about the
Turbomax, but on the Ecotecs the expansion is readily accessible and the
shrader valve is right on the front right:

http://wiki.diyfaq.org.uk/index.php/...rIntakeOff.jpg

(expansion vessel is the silver thing on the right)

I've freed the valve spindle and applied a bit of lubrication for now
and will operate it manually til I find someone who can replace it and
the motor head - unless anyone thinks I can do it?

Its certainly DIYable... Turn boiler off, drain down, swap valve,
reconnect to wiring. Refill[1], and bleed, and set system pressure, and
turn boiler back on. If all looks good. The turn off again, and add some
fresh corrosion inhibitor. Turn back on.

However it depends on your level of confidence and having at least some
basic tools like spanners to fit the nuts etc.

[1] Vaillant boilers often have a handy test program you can get them to
run at startup, that will just run the pump and show you the system
pressure without trying to fire. Ideal for refilling and purging the air
from the system.


--
Cheers,

John.

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On 26/05/2020 11:21, John Smith wrote:
On 2020-05-26 09:52:56 +0000, said:

On Monday, 25 May 2020 21:29:58 UTC+1, John SmithÂ* wrote:

At the same time I guess I should get the expansion vessel serviced.

serviced? It's an empty container

They can need repressurising.

Just test with a car tyre style pressure gauge... For a full test you
can drain a few litres of water out of the system first to lower the
system pressure. Then most[1] of what you read will be the air pressure
in the vessel alone. However you can test at full system pressure - in
which case, it reads about the same as the system pressure (and so long
as its air that comes out of the refill valve and not water when you
measure it, you are probably fine!)

[1] If the boiler is physically lower than some of the system, then you
will still read some of the water pressure just from the "head" above
the test point.


--
Cheers,

John.

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On 2020-05-26 10:41:59 +0000, John Rumm said:

i presume the system needs a drain down to do the valve but it's just a
couple of large screw nuts.

Yup in principle - although it does depend where in the system the
valve is, as to how much of a drain it will need (valves in a loft for
example can often be change with only a partial drain down).

Thanks John. What do you think of this - it's the same Danfoss valve
and as the pipework is at the back under the stairs it may be easier
just to change the spindle but looks hairy without draining down. I
guess easy to do if drained down and guards against disturbing pipes as
the cylinder is very near.

https://youtu.be/1vYCkGtR-l8

On 26/05/2020 19:39, John Smith wrote:
On 2020-05-26 10:41:59 +0000, John Rumm said:

i presume the system needs a drain down to do the valve but it's just
a couple of large screw nuts.

Yup in principle - although it does depend where in the system the
valve is, as to how much of a drain it will need (valves in a loft for
example can often be change with only a partial drain down).

Thanks John. What do you think of this - it's the same Danfoss valve and
as the pipework is at the back under the stairs it may be easier just to
change the spindle but looks hairy without draining down. I guess easy
to do if drained down and guards against disturbing pipes as the
cylinder is very near.

https://youtu.be/1vYCkGtR-l8

I have never worked on a Danfoss valve, so that was an interesting vid.

It looks doable, and even if you decide to bail out and do a full drain
down mid process, you should be able to plug the valve base with
something to keep the water in the for duration. Easier than replacing
the whole valve body anyway.

(my plumbing kit has a set of conical rubber bungs for just such
eventualities. Also very useful for plugging the feed and expansion
pipes on vented HW systems or vented CH header tanks to keep most of the
water trapped in them)


--
Cheers,

John.

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