HI All

I've not used float-type auto air vents before - so I may be doing
something wrong - expert advice welcomed !

Regular readers may recall the saga of my heatpump system - which was
causing the CH header tank to regularly overflow. This was finally
sorted by bleeding trapped air out of the heat store.

Systems looks like a conventional CH boiler - except that the 'boiler'
is a heatpump, and the return from radiator and DHW circuits passes
through a 200 litre, heavily insulated copper 'heat-store' before it
goes back to the heatpump. When the heat pump switches off the system
circulates water from the store through the DHW / CH until it's cooled
sufficiently.

Anyway....

The whole thing's piped up in copper / pex - the circulating pump has a
little brass float-type auto air vent on the highest point of the
circuit - but the feed to the top of the heat store had no such vent.

The only way to bleed the air from the heat store was to slacken off the
compression fitting at the top of the store and wait while the air finds
its way out - necessitates leaning over the store and applying lateral
pressure to the pex pipe to slightly unseat the pipe - a slow and
uncomfortable process!

So - I bought another auto air vent and fitted it as close as possible
to the feed into the heat store - confidently expecting it to vent air
... automatically ....

Trouble is - it doesn't grr
It's still necessary to do the 'lean over the heat store for a hour at a
time to let the air out'....

So - what don;t I understand about using these auto air vents ?
It's fitted pretty much at the high point of the circuit - certainly on
a level with the union into the heat store. Fitted into a 3/4" x 3/4" x
female threaded 'tee' - with the air valve fitted vertical and into the
threaded part of the tee...

Any ideas please ??

TIA
Adrian

"Adrian" wrote in message
...

Questions:
You have a thermal store/heat bank heated via a heat pump. It serves CH and
DHW via a plate heat exchanger. Is that so?

Is it a pressurised thermal store? Or is it open vented - uses an F&E tank
to top it up?

HI

Doctor Drivel wrote:

"Adrian" wrote in message
...

Questions:
You have a thermal store/heat bank heated via a heat pump. It serves CH
and DHW via a plate heat exchanger. Is that so?

Not quite.

The heat store is simply a large tank containing water that's circulated
through the radiators / dhw tank. The circulating water is heated by a
heat pump (ground source)


Is it a pressurised thermal store? Or is it open vented - uses an F&E
tank to top it up?

No - not pressurised - it's part of the open f&e-tank-fed heating circuit.

Adrian

"Adrian" wrote in message
...
HI All

I've not used float-type auto air vents before - so I may be doing
something wrong - expert advice welcomed !

Regular readers may recall the saga of my heatpump system - which was
causing the CH header tank to regularly overflow. This was finally sorted
by bleeding trapped air out of the heat store.

Systems looks like a conventional CH boiler - except that the 'boiler' is
a heatpump, and the return from radiator and DHW circuits passes through a
200 litre, heavily insulated copper 'heat-store' before it goes back to
the heatpump. When the heat pump switches off the system circulates water
from the store through the DHW / CH until it's cooled sufficiently.

Anyway....

The whole thing's piped up in copper / pex - the circulating pump has a
little brass float-type auto air vent on the highest point of the
circuit - but the feed to the top of the heat store had no such vent.

The only way to bleed the air from the heat store was to slacken off the
compression fitting at the top of the store and wait while the air finds
its way out - necessitates leaning over the store and applying lateral
pressure to the pex pipe to slightly unseat the pipe - a slow and
uncomfortable process!

So - I bought another auto air vent and fitted it as close as possible to
the feed into the heat store - confidently expecting it to vent air ..
automatically ....

Trouble is - it doesn't grr
It's still necessary to do the 'lean over the heat store for a hour at a
time to let the air out'....

So - what don;t I understand about using these auto air vents ?
It's fitted pretty much at the high point of the circuit - certainly on a
level with the union into the heat store. Fitted into a 3/4" x 3/4" x
female threaded 'tee' - with the air valve fitted vertical and into the
threaded part of the tee...

Any ideas please ??

TIA
Adrian

Perhaps the air is getting into the tank (ie, as bubbles) faster than it can
go up the vent tube. Only when the water stops circulating will the bubbles
rise to the top. So really you need the vent in the high point of the tank
itself. You can also put it on an extended tube to maximise the volume of
air in the tube instead of in the tank: but obviously you can't go higher
than the header tank, or the float won't float.

We have a float bleed on our ch and it can be tricky to set it up so that
the float doesn't get stuck. Ours has a tyre valve like nipple at the top
which you can depress from the outside to jiggle the float and bleed the air
manually from time to time to make sure it is topped right up. It's very
like an old carburettor float chamber; that one used to have to tickle to
get it to fill right up.

S

HI S

Spamlet wrote:
"Adrian" wrote in message
...
HI All

I've not used float-type auto air vents before - so I may be doing
something wrong - expert advice welcomed !

Regular readers may recall the saga of my heatpump system - which was
causing the CH header tank to regularly overflow. This was finally sorted
by bleeding trapped air out of the heat store.

Systems looks like a conventional CH boiler - except that the 'boiler' is
a heatpump, and the return from radiator and DHW circuits passes through a
200 litre, heavily insulated copper 'heat-store' before it goes back to
the heatpump. When the heat pump switches off the system circulates water
from the store through the DHW / CH until it's cooled sufficiently.

Anyway....

The whole thing's piped up in copper / pex - the circulating pump has a
little brass float-type auto air vent on the highest point of the
circuit - but the feed to the top of the heat store had no such vent.

The only way to bleed the air from the heat store was to slacken off the
compression fitting at the top of the store and wait while the air finds
its way out - necessitates leaning over the store and applying lateral
pressure to the pex pipe to slightly unseat the pipe - a slow and
uncomfortable process!

So - I bought another auto air vent and fitted it as close as possible to
the feed into the heat store - confidently expecting it to vent air ..
automatically ....

Trouble is - it doesn't grr
It's still necessary to do the 'lean over the heat store for a hour at a
time to let the air out'....

So - what don;t I understand about using these auto air vents ?
It's fitted pretty much at the high point of the circuit - certainly on a
level with the union into the heat store. Fitted into a 3/4" x 3/4" x
female threaded 'tee' - with the air valve fitted vertical and into the
threaded part of the tee...

Any ideas please ??

TIA
Adrian

Perhaps the air is getting into the tank (ie, as bubbles) faster than it can
go up the vent tube.


Hmm - possibly

Only when the water stops circulating will the bubbles
rise to the top. So really you need the vent in the high point of the tank
itself.

That would be ideal - but it seems that the manufacturers of the tank
didn't think of that g

You can also put it on an extended tube to maximise the volume of
air in the tube instead of in the tank: but obviously you can't go higher
than the header tank, or the float won't float.

I'd thought of that - maybe fabricate a nice little 'J-shaped' piece of
copper tube that could connect to the tank inlet, then have a 'tee' so
that the valve can sit a few inches above the tank inlet - and the
return from the heating can come in the short leg of the tee...


We have a float bleed on our ch and it can be tricky to set it up so that
the float doesn't get stuck. Ours has a tyre valve like nipple at the top
which you can depress from the outside to jiggle the float and bleed the air
manually from time to time to make sure it is topped right up. It's very
like an old carburettor float chamber; that one used to have to tickle to
get it to fill right up.

Ah - that takes me back - BSA 350 single - a right pig to start!

Both of these valves have a removable cap on the top - but the odd ting
is that when you remove the cap from the one that's on the heat store
and slide a piece of tin wire down to depress the float there's only a
tiny amount of air that escapes - while loosening the union on the tank
itself allows air out, and you can hear the water trickling inside the
tank.

When I got it sorted the last time (before I drained everything down to
add a proper drain cock and this air-valve) I managed to get it to the
point where the circulating water was silent in the tank - but it took a
couple of hours with the union slackened off and 'jiggling' the pex pipe
to get the air to come out - I was hoping to 'automate' the process!

Before anybody asks g - yes - the air is coming _out_ rather than 'in'
- soap solution blows bubbles when wiped around the loosened union.

Thanks
Adrian

"Adrian" wrote in message
...
HI

Doctor Drivel wrote:

"Adrian" wrote in message
...

Questions:
You have a thermal store/heat bank heated via a heat pump. It serves CH
and DHW via a plate heat exchanger. Is that so?

Not quite.

The heat store is simply a large tank containing water that's circulated
through the radiators / dhw tank. The circulating water is heated by a
heat pump (ground source)


Is it a pressurised thermal store? Or is it open vented - uses an F&E
tank to top it up?

No - not pressurised - it's part of the open f&e-tank-fed heating circuit.

Adrian, where is the thermal store vented from, on the store and where is
the cold feed connected to it?

HI

Doctor Drivel wrote:

"Adrian" wrote in message
...
HI

Doctor Drivel wrote:

"Adrian" wrote in message
...

Questions:
You have a thermal store/heat bank heated via a heat pump. It serves
CH and DHW via a plate heat exchanger. Is that so?

Not quite.

The heat store is simply a large tank containing water that's
circulated through the radiators / dhw tank. The circulating water is
heated by a heat pump (ground source)


Is it a pressurised thermal store? Or is it open vented - uses an
F&E tank to top it up?

No - not pressurised - it's part of the open f&e-tank-fed heating
circuit.

Adrian, where is the thermal store vented from, on the store and where
is the cold feed connected to it?



The easiest way for me to describe it is....

Imagine a conventional, non-pressurised, boiler system.
Replace the boiler with the Heatpump.
On the return circuit from the radiators / hot-water tank to the
'boiler' (and immediate 'before' the boiler), insert a big water tank -
with the return from the heating circuit piped to the top of the tank
and the return to the boiler piped from the bottom of the tank.

No separate vents or feeds connected to the store.

Heatpump and store are at ground-level, f&e tank is in the loft...

Hope that makes it clearer?

Adrian

"Adrian" wrote in message
...
HI All

I've not used float-type auto air vents before - so I may be doing
something wrong - expert advice welcomed !

The float vent I have in my hand has a screw on the top that appears to
close the vent even if the float is not floating.
I believe it is really for fast filling a pressurised system and not
actually an auto vent to release trapped air.
It looks like you open it to let the air out while filling and then close it
to ensure air can't get drawn in by the circulating water.
Maybe yours is the same and you have it closed?

"Adrian" wrote in message
...
HI

Doctor Drivel wrote:

"Adrian" wrote in message
...
HI

Doctor Drivel wrote:

"Adrian" wrote in message
...

Questions:
You have a thermal store/heat bank heated via a heat pump. It serves
CH and DHW via a plate heat exchanger. Is that so?

Not quite.

The heat store is simply a large tank containing water that's circulated
through the radiators / dhw tank. The circulating water is heated by a
heat pump (ground source)


Is it a pressurised thermal store? Or is it open vented - uses an F&E
tank to top it up?

No - not pressurised - it's part of the open f&e-tank-fed heating
circuit.

Adrian, where is the thermal store vented from, on the store and where is
the cold feed connected to it?



The easiest way for me to describe it is....

Imagine a conventional, non-pressurised, boiler system.
Replace the boiler with the Heatpump.
On the return circuit from the radiators / hot-water tank to the 'boiler'
(and immediate 'before' the boiler), insert a big water tank -
with the return from the heating circuit piped to the top of the tank and
the return to the boiler piped from the bottom of the tank.

No separate vents or feeds connected to the store.

Heatpump and store are at ground-level, f&e tank is in the loft...

Hope that makes it clearer?

As clear as mud. Firstly, is this right? "the return from the heating
circuit piped to the top of the tank and the return to the boiler piped from
the bottom of the tank".

The return from the DHW cylinder and CH to the "top" of the thermal store?
Is that right?

Where is the CH flow connected to the system?
Where is the heat pump's flow connected to the system?

The vent pipe from the F&E tank. Where is it connected to the system?
The cold feed pipe from the F&E tank. Where is it connected to the system?

HI

Doctor Drivel wrote:

"Adrian" wrote in message
...
HI

Doctor Drivel wrote:

"Adrian" wrote in message
...
HI

Doctor Drivel wrote:

"Adrian" wrote in message
...

Questions:
You have a thermal store/heat bank heated via a heat pump. It
serves CH and DHW via a plate heat exchanger. Is that so?

Not quite.

The heat store is simply a large tank containing water that's
circulated through the radiators / dhw tank. The circulating water
is heated by a heat pump (ground source)


Is it a pressurised thermal store? Or is it open vented - uses an
F&E tank to top it up?

No - not pressurised - it's part of the open f&e-tank-fed heating
circuit.

Adrian, where is the thermal store vented from, on the store and
where is the cold feed connected to it?



The easiest way for me to describe it is....

Imagine a conventional, non-pressurised, boiler system.
Replace the boiler with the Heatpump.
On the return circuit from the radiators / hot-water tank to the
'boiler' (and immediate 'before' the boiler), insert a big water tank -
with the return from the heating circuit piped to the top of the tank
and the return to the boiler piped from the bottom of the tank.

No separate vents or feeds connected to the store.

Heatpump and store are at ground-level, f&e tank is in the loft...

Hope that makes it clearer?

As clear as mud. Firstly, is this right? "the return from the heating
circuit piped to the top of the tank and the return to the boiler piped
from the bottom of the tank".

Absolutely right.


The return from the DHW cylinder and CH to the "top" of the thermal
store? Is that right?

Same as above...


Where is the CH flow connected to the system?

Flow goes from the heatpump, through the rads or dhw cylinder coil, then
back as the return.....


Where is the heat pump's flow connected to the system?

See above


The vent pipe from the F&E tank. Where is it connected to the system?

Top end of the dhw cylinder coil...

The cold feed pipe from the F&E tank. Where is it connected to the system?

Same place as the vent pipe.


Look - I'm clearly not explaining this well - I'll see if I can find
time to sketch the system tomorrow or early next week.

The original question was 'is there something that I don't know about
using automatic air vents on circulating water systems?' - - and it
seems that I maybe need to create a point on the return circuit that is
deliberately higher than the store - but very close to the store, and
fit the air vent there....

Thanks
Adrian

"Adrian" wrote in message
...
HI

Doctor Drivel wrote:

"Adrian" wrote in message
...
HI

Doctor Drivel wrote:

"Adrian" wrote in message
...
HI

Doctor Drivel wrote:

"Adrian" wrote in message
...

Questions:
You have a thermal store/heat bank heated via a heat pump. It serves
CH and DHW via a plate heat exchanger. Is that so?

Not quite.

The heat store is simply a large tank containing water that's
circulated through the radiators / dhw tank. The circulating water is
heated by a heat pump (ground source)


Is it a pressurised thermal store? Or is it open vented - uses an
F&E tank to top it up?

No - not pressurised - it's part of the open f&e-tank-fed heating
circuit.

Adrian, where is the thermal store vented from, on the store and where
is the cold feed connected to it?



The easiest way for me to describe it is....

Imagine a conventional, non-pressurised, boiler system.
Replace the boiler with the Heatpump.
On the return circuit from the radiators / hot-water tank to the
'boiler' (and immediate 'before' the boiler), insert a big water tank -
with the return from the heating circuit piped to the top of the tank
and the return to the boiler piped from the bottom of the tank.

No separate vents or feeds connected to the store.

Heatpump and store are at ground-level, f&e tank is in the loft...

Hope that makes it clearer?

As clear as mud. Firstly, is this right? "the return from the heating
circuit piped to the top of the tank and the return to the boiler piped
from the bottom of the tank".

Absolutely right.


The return from the DHW cylinder and CH to the "top" of the thermal
store? Is that right?

Same as above...


Where is the CH flow connected to the system?

Flow goes from the heatpump, through the rads or dhw cylinder coil, then
back as the return.....


Where is the heat pump's flow connected to the system?

See above


The vent pipe from the F&E tank. Where is it connected to the system?

Top end of the dhw cylinder coil...

The cold feed pipe from the F&E tank. Where is it connected to the
system?

Same place as the vent pipe.


Look - I'm clearly not explaining this well - I'll see if I can find time
to sketch the system tomorrow or early next week.

The original question was 'is there something that I don't know about
using automatic air vents on circulating water systems?' - - and it seems
that I maybe need to create a point on the return circuit that is
deliberately higher than the store - but very close to the store, and fit
the air vent there....

You have a "buffer" only on the return pipe to the heat pump to ensure cool
water is fed back to the heat pump. This give the large delta T needed for
heat pump operation. This is not a thermal store.

A large tall heat bank/thermal store using a plate heat exchanger for DHW
probaly would have been better and using off-peak electricty could be heat
up during the night.

If the auto air vent is not working it is duff.

In article ,
"dennis@home" writes:


"Adrian" wrote in message
...
HI All

I've not used float-type auto air vents before - so I may be doing
something wrong - expert advice welcomed !

The float vent I have in my hand has a screw on the top that appears to
close the vent even if the float is not floating.
I believe it is really for fast filling a pressurised system and not
actually an auto vent to release trapped air.
It looks like you open it to let the air out while filling and then close it
to ensure air can't get drawn in by the circulating water.

The closing is because they don't last long if left open. The ball has
to stay wet to seal, and this means there's moisture exposed. This dries
and eventually leaves deposits behind, and these build up and stop the
seal working, so the valve starts leaking water.

There isn't normally negative pressure anywhere in a system -- the header
tank is usually higher than the pump by more than the pressure differential
the pump can achieve, although there are some less well designed systems
which do manage to suck air in the expansion pipe.

Maybe yours is the same and you have it closed?

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

HI Dennis

dennis@home wrote:


"Adrian" wrote in message
...
HI All

I've not used float-type auto air vents before - so I may be doing
something wrong - expert advice welcomed !

The float vent I have in my hand has a screw on the top that appears to
close the vent even if the float is not floating.

Yes - mine have those - like a little threaded cap arrangment..

I believe it is really for fast filling a pressurised system and not
actually an auto vent to release trapped air.
It looks like you open it to let the air out while filling and then
close it to ensure air can't get drawn in by the circulating water.
Maybe yours is the same and you have it closed?

I've tried all combinations g.
There is a tiny amount of air let out if you unscrew the cap after it's
first been tightened down & left - but at the same time, the loosened
union on the tank can be 'bubbling' out trapped air...

It must be a thing with levels.
It's not that easy to see, behind the big tank / buffer / store - I
think the only way forwards is to make up a sort of 'swept' entry that
drops gracefully down into the inlet on the tanks and allows the air
back up to the air vent.... Life's way to short to spend hours hanging
over the tank, leaning on the loosened pipework to encourage the air out..

Shame the manufacturer didn't think to build in an air vent before they
wrapped the tank in yelow foam !

Thanks for the comments
Adrian

HI Andrew


Andrew Gabriel wrote:
In article ,
"dennis@home" writes:

"Adrian" wrote in message
...
HI All

I've not used float-type auto air vents before - so I may be doing
something wrong - expert advice welcomed !
The float vent I have in my hand has a screw on the top that appears to
close the vent even if the float is not floating.
I believe it is really for fast filling a pressurised system and not
actually an auto vent to release trapped air.
It looks like you open it to let the air out while filling and then close it
to ensure air can't get drawn in by the circulating water.

The closing is because they don't last long if left open. The ball has
to stay wet to seal, and this means there's moisture exposed. This dries
and eventually leaves deposits behind, and these build up and stop the
seal working, so the valve starts leaking water.

Ah - so they're not so much an auto-air-vent - more of an
'auto-air-seperator-with-manual-vent' - I didn't realise that.

So in normal operation you'd leave them with the cap screwed down tight
- and release any trapped air by unscrewing the valve from time to time...?



There isn't normally negative pressure anywhere in a system -- the header
tank is usually higher than the pump by more than the pressure differential
the pump can achieve, although there are some less well designed systems
which do manage to suck air in the expansion pipe.

Don;t think we've got problems in that department.
As I said - once the air in the big tank is removed then everything runs
very happily - but excessive amount of air in the tank causes the header
tank to overflow as the system warms up and the air expands...

Thanks
Adrian

In article ,
Spamlet wrote:
It's very like an old carburettor float chamber; that one used to have
to tickle to get it to fill right up.

The purpose of the tickler was to flood the carb thus giving an over rich
mixture for cold starting. Not to allow it to 'fill up'. In other words it
disabled the cut off valve by lowering the float.

--
*I don't suffer from insanity -- I'm a carrier

Dave Plowman London SW
To e-mail, change noise into sound.

In article ,
dennis@home wrote:
The float vent I have in my hand has a screw on the top that appears to
close the vent even if the float is not floating. I believe it is really
for fast filling a pressurised system and not actually an auto vent to
release trapped air. It looks like you open it to let the air out while
filling and then close it to ensure air can't get drawn in by the
circulating water. Maybe yours is the same and you have it closed?

The reason for that valve it is the device will leak past the float valve
when it gets older. So you shut it off after the venting is complete.

--
*Toilet stolen from police station. Cops have nothing to go on.

Dave Plowman London SW
To e-mail, change noise into sound.

"Andrew Gabriel" wrote in message
...
In article ,
"dennis@home" writes:


"Adrian" wrote in message
...
HI All

I've not used float-type auto air vents before - so I may be doing
something wrong - expert advice welcomed !

The float vent I have in my hand has a screw on the top that appears to
close the vent even if the float is not floating.
I believe it is really for fast filling a pressurised system and not
actually an auto vent to release trapped air.
It looks like you open it to let the air out while filling and then close
it
to ensure air can't get drawn in by the circulating water.

The closing is because they don't last long if left open. The ball has
to stay wet to seal, and this means there's moisture exposed. This dries
and eventually leaves deposits behind, and these build up and stop the
seal working, so the valve starts leaking water.

There isn't normally negative pressure anywhere in a system --

Venturii effects say that may not be true, I wouldn't take bets if it were
in a 22x22x15 reducing tee on the main drag in a none pressurised system.

the header
tank is usually higher than the pump by more than the pressure
differential
the pump can achieve, although there are some less well designed systems
which do manage to suck air in the expansion pipe.

That is easy to do, just put the expansion pipe on the other side of the
pump to the fill pipe.

"Adrian" wrote in message
...
HI Andrew


Andrew Gabriel wrote:
In article ,
"dennis@home" writes:

"Adrian" wrote in message
...
HI All

I've not used float-type auto air vents before - so I may be doing
something wrong - expert advice welcomed !
The float vent I have in my hand has a screw on the top that appears to
close the vent even if the float is not floating.
I believe it is really for fast filling a pressurised system and not
actually an auto vent to release trapped air.
It looks like you open it to let the air out while filling and then
close it to ensure air can't get drawn in by the circulating water.

The closing is because they don't last long if left open. The ball has
to stay wet to seal, and this means there's moisture exposed. This dries
and eventually leaves deposits behind, and these build up and stop the
seal working, so the valve starts leaking water.

Ah - so they're not so much an auto-air-vent - more of an
'auto-air-seperator-with-manual-vent' - I didn't realise that.

So in normal operation you'd leave them with the cap screwed down tight -
and release any trapped air by unscrewing the valve from time to time...?

Auto air vents are for filling purposes sonly. Once filled, the screw
should be tightened.

You should look at why air is being drawn in - or is it corrosion?
Look at where the cold feed & open vent pipes from the F&E tank is. The
relationship of these and the pump may solve matters.

Having an auto air vent permanently open will solve nothing as all it will
do is advance corrosion as air is being drawn in.

"Dave Plowman (News)" wrote in message
...
In article ,
Spamlet wrote:
It's very like an old carburettor float chamber; that one used to have
to tickle to get it to fill right up.

The purpose of the tickler was to flood the carb thus giving an over rich
mixture for cold starting. Not to allow it to 'fill up'. In other words it
disabled the cut off valve by lowering the float.

--
*I don't suffer from insanity -- I'm a carrier

Dave Plowman London SW
To e-mail, change noise into sound.

Er,

The flood on motorcycles is/was usually done by filling the carb right up
until it overflowed: some bikers might have had the patience to try
different levels of overfilling, but most, in my experience just kept
tickling, or holding the tickler down, until fuel ****ed out everywhere.

Ideally you don't want it to flood (out of the carb, or into the head), as
this wastes petrol and, especially on old bikes with external magnetos and
or coils, is rather a dodgy thing to do. Mind you, I think that many bikers
will have fond memories of holding the float depressed until the fuel gushed
forth and up their arm, and put their fag out! Ah, those permanently smelly
fingers and gloves... Still have the souvenir dermatitis.

On my Ducati, where the front carb slopes at a different angle to the rear,
it is particularly fiddly to get the fuel level to cross the main jet in the
right place, and indeed, they made transparent float bowls to help. For the
front cylinder, I did, in fact, find that, if the tab on the float was high
enough to reach the end of the tickler at all, the cylinder was too rich all
the time, as the bumps on the road ensured it was being 'tickled all the
time'. No doubt the modern ones have solved this, but, as the back cylinder
picks up quite easily, it's no big deal.

S

"Doctor Drivel" wrote in message
...

You have a "buffer" only on the return pipe to the heat pump to ensure
cool water is fed back to the heat pump. This give the large delta T
needed for heat pump operation. This is not a thermal store.

If this buffer cylinder had a large coil in it and the cold feed to the DHW
cylinder run through it, it would pre-heat the DHW and ensure a cooler
return to the heat pump. It is enhances condensing boiler operation and
creates a larger temperature differential if the heat pump requires it. I
am surprised this was not done.

A large tall heat bank/thermal store using a plate heat exchanger for DHW
probably would have been better and using off-peak electricty could be
heated up during the night.

A heat bank/thermal store can ensure a large flow and return temperature
differential for a heat pump or condensing boiler, act as a buffer for the
heat pump and CH system and provide DHW - all off the same cylinder.
Wonderful things.

In article ,
Spamlet wrote:
On my Ducati, where the front carb slopes at a different angle to the
rear, it is particularly fiddly to get the fuel level to cross the main
jet in the right place, and indeed, they made transparent float bowls
to help. For the front cylinder, I did, in fact, find that, if the tab
on the float was high enough to reach the end of the tickler at all,
the cylinder was too rich all the time, as the bumps on the road
ensured it was being 'tickled all the time'. No doubt the modern ones
have solved this, but, as the back cylinder picks up quite easily, it's
no big deal.

I'd hope they have EFI. ;-)

--
*For every action, there is an equal and opposite criticism *

Dave Plowman London SW
To e-mail, change noise into sound.

"Dave Plowman (News)" wrote in message
...
In article ,
Spamlet wrote:
On my Ducati, where the front carb slopes at a different angle to the
rear, it is particularly fiddly to get the fuel level to cross the main
jet in the right place, and indeed, they made transparent float bowls
to help. For the front cylinder, I did, in fact, find that, if the tab
on the float was high enough to reach the end of the tickler at all,
the cylinder was too rich all the time, as the bumps on the road
ensured it was being 'tickled all the time'. No doubt the modern ones
have solved this, but, as the back cylinder picks up quite easily, it's
no big deal.

I'd hope they have EFI. ;-)


Actually, I've just been recalling the black plastic floats in the Ducati
carbs, and, in fact, the tickler plunger actually just bopped the top of the
float, cos I've just got a mental picture of the little dent it made thanks
to the float being bashed against it all the time by the road bumps...

S

In article ,
Spamlet wrote:

"Dave Plowman (News)" wrote in message
...
In article ,
Spamlet wrote:
On my Ducati, where the front carb slopes at a different angle to the
rear, it is particularly fiddly to get the fuel level to cross the
main jet in the right place, and indeed, they made transparent float
bowls to help. For the front cylinder, I did, in fact, find that, if
the tab on the float was high enough to reach the end of the tickler
at all, the cylinder was too rich all the time, as the bumps on the
road ensured it was being 'tickled all the time'. No doubt the
modern ones have solved this, but, as the back cylinder picks up
quite easily, it's no big deal.

I'd hope they have EFI. ;-)


Actually, I've just been recalling the black plastic floats in the
Ducati carbs, and, in fact, the tickler plunger actually just bopped
the top of the float, cos I've just got a mental picture of the little
dent it made thanks to the float being bashed against it all the time
by the road bumps...

That's how they all worked on every bike I've owned. Which isn't that
many, though. And the last one about 40 years ago.

--
*If a parsley farmer is sued, can they garnish his wages?

Dave Plowman London SW
To e-mail, change noise into sound.