I am trying to sort out my badly installed woodburner with back boiler
plumbed incorrectly.

Fitting a Dunsley Baker Neutraliser would be very difficult, and as an
alternative I am exploring the use of normally-open motorised valves.

Is there such a thing as a non return valve available for 28mm copper
pipework? I think this would help get a better result. If so, could
someone post a link and/or the proper name for me?

Keith

On 27 July, 19:39, Keefiedee wrote:
I am trying to sort out my badly installed woodburner with back boiler
plumbed incorrectly.

Fitting a Dunsley Baker Neutraliser would be very difficult, and as an
alternative I am exploring the use of normally-open motorised valves.

Is there such a thing as a non return valve available for 28mm copper
pipework? *I think this would help get a better result. *If so, could
someone post a link and/or the proper name for me?

Keith

Yes one version is mentioned in the instructions for an Aga/Rayburn,
which has a particularly low pressure to open requirement. From memory
it was called a featherweight check valve.
Keep in mind the heat input from a solid fuel fire and what will
happen if there is a power cut for whatever reason. Gravity
circulation to an adequate heat dump is a basic essential to deal with
this eventuality

On 27 July, 19:39, Keefiedee wrote:
I am trying to sort out my badly installed woodburner with back boiler
plumbed incorrectly.

What's the problem, is there another boiler or a pump in the same
heating system?

Is there such a thing as a non return valve available for 28mm copper
pipework? *I think this would help get a better result. *If so, could
someone post a link and/or the proper name for me?

Yes, there are swing-check (hinged flap, closes under it's own weight,
observe fitting orientation) and spring-check (spring assisted, can
usually be adjusted) types. I'm dubious that they'd fix the problem,
but that depends on what the problem is.
There shouldn't be any valves in the pipes between the boiler, open
vent, heat dump radiator, cold feed.

On Jul 27, 9:53*pm, Onetap wrote:


What's the problem, is there another boiler or a pump in the same
heating system?

The problem is that the woodburner back boiler feeds and returns have
been simply plumbed into the main central S plan heating arrangement
with plain T joints - at some considerable distance from the oil
boiler. The result is of course that the oil boiler ends up heating
the water in the back boiler (along with long runs of 28mm pipework)
as well as the rest of the house . I discovered this problem when
balancing the radiators after replacing several of them using one of
those clever infrared temperature thingys. The input temp at the
radiators was 5 degree C or more less than it should be.

I solved the problem initially using simple ball valves on the
woodburner flows and returns and remembering to open them when I lit
the woodburner - highly unsatisfactory (and potentially dangerous). I
had a heating engineer round about fitting a Dursley Neutraliser. He
seemed to know his stuff but couldn't really work out a way to sort it
without considerable expense.

The point is that we never need to use the oil boiler and woodburner
together. Also the woodburner is rated at a much lower output than
the oil boiler, and procuring and lugging into the room all the wood
needed to keep the woodburner going at full tilt simply does not
really fit in with our lifestyle. It isn't really necessary anyway -
it is a big house, but having the oil boiler running for up to 4 hours
in the morning, with perhaps the occasional topup during the day, is
adequate to keep it reasonably warm. The woodburner is in the room we
sit in at night, and a fairly small fire is enough for our needs.

The only fail-safe answer I can come up with is using 4 "normally
open" motorised valves, wired so they close when the boiler comes on,
but these cost a minimum of £65 each for 28mm valves as far as I can
see. So I was toying with the idea of just fitting two on the central
heating side of the woodburner pipework and somehow working out if I
could make do with non-return valves on the HW side - if such things
existed - hence my question.

At least I know they do exist now, I just haven't quite yet got my
head round where I should fit them and whether they would help.

Keith

We were somewhere around Barstow, on the edge of the desert, when the
drugs began to take hold. I remember Keefiedee
saying something like:

The only fail-safe answer I can come up with is using 4 "normally
open" motorised valves, wired so they close when the boiler comes on,
but these cost a minimum of £65 each for 28mm valves as far as I can
see. So I was toying with the idea of just fitting two on the central
heating side of the woodburner pipework and somehow working out if I
could make do with non-return valves on the HW side - if such things
existed - hence my question.

You don't need two of anything. Just the one would do, but as a general
rule, nothing that could stick closed should be put into a gravity loop.
It works, that I do know - I've come across it, but I wouldn't do it,
just in case.
Have you seen the results of a steam explosion in a house?

On Wed, 28 Jul 2010 07:26:19 +0100, Grimly Curmudgeon wrote:

You don't need two of anything. Just the one would do,

I can't get me 'ed around the requirement for four and then dragging
the HW circuit into the equation. I guess there could be a second
loop from the wood burner to a coil in the HW cylinder...

As for spring valves I doubt very much that gravity would have enough
'umph to open them. A biased open(*) flap valve that closes when the
pump for the oil boiler tries to cause flow through the woodburner
loop might work.

But still doesn't avoid the problem of no flow through the
woodburner. At least with only one valve the woddburner boiler would
still be open but could still boil, Maybe adding another vent
vertically close to the woodburner with a whistle on the end... B-)

(*) By orientating it so gravity makes it open.

--
Cheers
Dave.

On 28 July, 09:06, "Dave Liquorice"
wrote:
On Wed, 28 Jul 2010 07:26:19 +0100, Grimly Curmudgeon wrote:
You don't need two of anything. Just the one would do,

I can't get me 'ed around the requirement for four and then dragging
the HW circuit into the equation. I guess there could be a second
loop from the wood burner to a coil in the HW cylinder...

As for spring valves I doubt very much that gravity would have enough
'umph to open them. A biased open(*) flap valve that closes when the
pump for the oil boiler tries to cause flow through the woodburner
loop might work.

But still doesn't avoid the problem of no flow through the
woodburner. At least with only one valve the woddburner boiler would
still be open but could still boil, Maybe adding another vent
vertically close to the woodburner with a whistle on the end... B-)

(*) By orientating it so gravity makes it open.

--
Cheers
Dave.

Our woodburner in a similar set up has a motorised valve and pump on
the pipe that links the woodburner's boiler to the main heating loop
and these are controlled by a thermostat on the flow pipe by the
burner. For safety reasons that are two radiators that are directly
linked to the woodburner to dissipate any excess heat.

Jonathan

On Jul 28, 9:06*am, "Dave Liquorice"
wrote:

I can't get me 'ed around the requirement for four and then dragging
the HW circuit into the equation. I guess there could be a second
loop from the wood burner to a coil in the HW cylinder...

In both boilers the CH and HW circuits are connected - i.e. each have
two loops from the heating chamber - thus four pipes. My concern was
that it might be possible for the return flow from the radiators,
which is connected by a T-junction to the return flow of the
woodburner, to not just go back to the oil boiler but also to go
through the woodburner CH return, through the woodburner boiler and
then through the woodburner HW return and generally lose heat where it
shouldn't before finding its way back to the oil boiler return.

I imagine one could argue that the suction effect of the CH pump is
likely to draw the water flow back towards the oil boiler and so it's
not likely to flow towards the woodburner CH return, but a little
experiment I have just done - switching on the oil boiler and closing
the feeds but not the returns to the woodburner for a short while -
soon resulted in a small, but significant increase in the temperature
of the woodburner CH return. So as far as I can see, 4 normally open
valves would be needed to completely stop any possible flow throuhg
the woodburner boiler.

I assume standard normally open motorised valves cannot stick closed
and are normally used in solid fuel systems and fail safe in the event
of a power failure.

And to reassure the guy concerned about a steam explosion, although
the plumbing of the woodburner has generally been bodged, they did at
least fit a steam release valve!!!

Keith

On Jul 28, 9:06*am, "Dave Liquorice"
wrote:

I can't get me 'ed around the requirement for four and then dragging
the HW circuit into the equation. I guess there could be a second
loop from the wood burner to a coil in the HW cylinder...

In both boilers the CH and HW circuits are connected - i.e. each have
two loops from the heating chamber - thus four pipes. My concern was
that it might be possible for the return flow from the radiators,
which is connected by a T-junction to the return flow of the
woodburner, to not just go back to the oil boiler but also to go
through the woodburner CH return, through the woodburner boiler and
then through the woodburner HW return and generally lose heat where it
shouldn't before finding its way back to the oil boiler return.

I imagine one could argue that the suction effect of the CH pump is
likely to draw the water flow back towards the oil boiler and so it's
not likely to flow towards the woodburner CH return, but a little
experiment I have just done - switching on the oil boiler and closing
the feeds but not the returns to the woodburner for a short while -
soon resulted in a small, but significant increase in the temperature
of the woodburner CH return. So as far as I can see, 4 normally open
valves would be needed to completely stop any possible flow throuhg
the woodburner boiler.

I assume standard normally open motorised valves cannot stick closed
and are normally used in solid fuel systems and fail safe in the event
of a power failure.

And to reassure the guy concerned about a steam explosion, although
the plumbing of the woodburner has generally been bodged, they did at
least fit a steam release valve!!!

Keith

The problem is that the woodburner back boiler feeds and returns have
been simply plumbed into the main central S plan heating arrangement
with plain T joints...

Isn't this an application for injector tee's?

http://shop.ebay.co.uk/i.html?_nkw=i...286.m270.l1313

If you want use a swing check valves, BES has a good range:

http://www.bes.co.uk/ (search for "swing check valve")

We were somewhere around Barstow, on the edge of the desert, when the
drugs began to take hold. I remember Keefiedee
saying something like:

And to reassure the guy concerned about a steam explosion, although
the plumbing of the woodburner has generally been bodged, they did at
least fit a steam release valve!!!

One hopes it works

If they fitted it close to the stove, then fine.

On Wed, 28 Jul 2010 04:34:01 -0700 (PDT), wrote:

Isn't this an application for injector tee's?

http://www.injector-tee.co.uk

You can see the construction but it doesn't explain in detail how it
works... I'd have thought the flow through the injector would tend to
draw water from the branch and thus through that loop.

--
Cheers
Dave.

"Dave Liquorice" wrote in message
ll.co.uk...
On Wed, 28 Jul 2010 04:34:01 -0700 (PDT), wrote:

Isn't this an application for injector tee's?

http://www.injector-tee.co.uk

You can see the construction but it doesn't explain in detail how it
works... I'd have thought the flow through the injector would tend to
draw water from the branch and thus through that loop.

--
Cheers
Dave.




It looks as if it could be venturi effect.
http://www.google.co.uk/search?num=5...effect&spell=1

Baz

It looks as if it could be venturi effect.http://www.google.co.uk/search?num=5...&safe=off&pwst...

Baz

Injector tee's sound promising! Are you suggesting I fit one at each
of the four T junctions where the feeds and returns form the oil
boiler are joined to the feeds and returns of the woodburner boiler -
giving the oil boiler preference. Presumably this would be sort of
the equivalent of fitting a Dursley Neutraliser. Or would you suggest
I fit normally open motorised valves on the woodburner boiler feeds
and injector tee's on the returns.

And yes the steam release valve is within 3 feet of the boiler!

Keith

On 28 July, 17:06, Keefiedee wrote:
It looks as if it could be venturi effect.http://www.google.co.uk/search?num=5...&safe=off&pwst...

It is that Bernouilli bloke at work again; the energy in the fluid
stream is constant so, increasing the velocity (reducing the c.s.a.)
causes a reduction in the pressure. The pressure can be reduced to
induce flow from the tee branch &/or make a vacuum pump.

http://en.wikipedia.org/wiki/Eductor-jet_pump


Injector tee's sound promising! *Are you suggesting I fit one at each
of the four T junctions where the feeds and returns form the oil
boiler are joined to the feeds and returns of the woodburner boiler -
giving the oil boiler preference.

No.

On Wed, 28 Jul 2010 09:06:43 -0700 (PDT), Keefiedee wrote:

Injector tee's sound promising!

But I don't think they will do what you want ie stop the flow through
the woodburner loops when the oil boilers pump is running. Mr
Bernoulli and/or the venturi effect will draw water from the stub of
the T.

At anything they may make it worse by evening up the flows. The site
says they are for use with Agas and Rayburns, things that are on and
hot 24/7...

With the four pipes on both boilers(?) it does become a nightmare, as
you say any incoming flow on any pipe could find it's way back via
any of the other three pipes.

--
Cheers
Dave.

On 28 July, 23:36, "Dave Liquorice"
wrote:
On Wed, 28 Jul 2010 09:06:43 -0700 (PDT), Keefiedee wrote:
Injector tee's sound promising!

But I don't think they will do what you want ie stop the flow through
the woodburner loops when the oil boilers pump is running. Mr
Bernoulli and/or the venturi effect will draw water from the stub of
the T.

Injector tees are really meant for linking a gravity flow solid fuel
boiler to a pumped central heating system. The gravity circulation
works when the pump is off and the circulation through the solid fuel
boiler is assisted when the pump is on.

The nuisance flow is caused by a pressure difference across the flow
and return connections. The neutraliser works by ensuring that the
pressure on all the flows and returns connected to it are the same.
You would typically have a pumped input from an oil/gas boiler,
gravity input from a solid fuel boiler, and pumped distribution(s) to
a central heating system and hot water cylinder(s).

You can achieve the same effect witha low loss header; the header is
a pipe that is large enough that the flow through it causes a
negligible pressure loss due to friction along its length. Have a
google for "closely-spaced tees" and "primary-secondary systems".

In your case, the heat distribution system could be a pumped primary
circuit. The oil boiler could then be connected as a pumped secondary
circuit through a low loss header. The circulation in the primary
circuit is not affected by whether the oil boiler and pump is on or
off. Similarly, no heat from the primary circuit enters the oil
boiler's secondary circuit when the boiler pump is off.

Similarly, the wood burner could be connected ,as a separate
independent system with a heat dump radiator and linked the primary
distribution system via closely spaced tees. If the pipe sizes are
calculated correctly, it will work by gravity circulation without a
pump.

The primary flow has to be greater than the secondary flow rate or you
get reverse flow in the common pipework.

The usual problems arise by connecting both boilers to the flow and
return pipes in order to generate flow through them. This results in
uncontrolled flow through unfired boilers and, usually, a major heat
loss to the atmosphere.

Just picked up this thread. We have two wood stoves fitted to the cylinder. All gravity fed and with heat dump rads. We get backflow from ine stove to the other when we only light one and they tend to form a loop and bypass the water when we light both. Thinking of fitting a non rerurn valve to help stop this but would welcome some advice. We know it's not conventional but the heat sink rads work well to prevent overheating we just need to stop the flow heading off down the other 28mm at the T to the cylinder

wrote:

Just picked up this thread. We have two wood stoves fitted to the
cylinder. All gravity fed and with heat dump rads. We get backflow from
ine stove to the other when we only light one and they tend to form a
loop and bypass the water when we light both. Thinking of fitting a non
rerurn valve to help stop this but would welcome some advice. We know
it's not conventional but the heat sink rads work well to prevent
overheating we just need to stop the flow heading off down the other
28mm at the T to the cylinder

I'm going to assume that whatever you are replying to is a long gone
thread and treat this as a new question. The problem with non return
valves is that they tend to have both significant operating pressure and
some flow resistance, and would probably stop the gravity circulation
working properly.

Hopefully someone has a solution. One would be 28mm full bore
electrically operated valves and temperature sensors. But, if they
exist, they would probably cost more than the rest of the heating
system, so I don't know.

--

Roger Hayter

On Sat, 17 Feb 2018 13:16:26 +0000, Roger Hayter wrote:

We get backflow from ine stove to the other when we only light one and
they tend to form a loop and bypass the water when we light both.
Thinking of fitting a non rerurn valve to help stop this ...

I'm going to assume that whatever you are replying to is a long gone
thread and treat this as a new question. The problem with non return
valves is that they tend to have both significant operating pressure and
some flow resistance, and would probably stop the gravity circulation
working properly.

+1

Hopefully someone has a solution.

google "dunsley neutraliser". Essentially a sealed box with lots of
pipe ports for the flows and returns of the various loops. The idea
is to have everything at the same "level" and nothing sharing a pipe
so that the only thing that drives circulation in a given gravity
loop is the density of the water in that loop.

One would be 28mm full bore electrically operated valves and temperature
sensors.

Needs to be fail safe without power or manual intervention. What's
the point of having stoves if you can't light them when the powers
off...

--
Cheers
Dave.