Hi all
I have a plan ... a yen really ... to improve our CH heating system. It
currently has a 4-port back boiler running a gravity feed HW, pumped CH
system. I installed a Sunvic select (207, I think) programmer a while ago,
and replaced the pump with a Grundfoss when the original died.

We do suffer from lack of HW after someone has had a bath etc. I don't want
to change the back boiler, even though I realise it's old-skool.

I have in mind to either:

a) add a Cylinder thermostat and 2-port valve, and convert to C-plan. The
valve will have to be on the return from the boiler, there's no room in the
flow pipe.
b) add a mid-position valve and convert to Y plan (no zoning envisaged).

I've read lots about doing this sort of work on the archives of this fine
newsgroup, and on the wiki. I've also identified all the pipes in the
current arrangement and understand the need for siting the valve with
respect to the flow & return to the F&E tank etc. I do still have a few
questions which might help me decide the route to take. Answers gratefully
received.

1) with my devil's advocate hat on, would there be any real benefit of a C-
plan over our current arrangement?

2) Y-plan seems to be talked of slightly disparagingly in comparison to S-
plan, due to reliabilty problems, difficulty with problem diagnosis, and
lack of zone expansion capability. Given that I don't intend to have any
zoning, are the other problems real (eg. these days)?

3) If I were to change to Y-plan, I understand that I'd need to cap off part
of the boiler. As I mentioned, the back boiler has 4 ports - 2x22mm
(currently CH), and 2x28mm (currently to the heat exchanger for HW). Is this
just a matter of capping off the two 28mm pipes (and moving the feed and
vent pipes) ?

3a) I assume that the reason that the pipes from the boiler are different
diameters for the two circuits is that the larger 28mm dia. gives less
resistance and better allows the HW to be unpumped - is that right?

4) what, exactly, should I be looking for spec-wise in a gate valve, apart
from the pipe diameter? I have a part number for a 2-port Honeywell valve
but I'm curious about what the spec actually calls for. There are a lot of
valves for sale on eBay ...

Thanks a lot in advance

regards
Jon N

Slight correction to my posting:
a) add a Cylinder thermostat and 2-port valve, and convert to C-plan.

The valve will have to be on the *flow from* the boiler, there's no room in
the *return* pipe.

On Tue, 31 May 2011 23:32:59 +0100, The Night Tripper wrote:

1) with my devil's advocate hat on, would there be any real benefit of a
C- plan over our current arrangement?

It would stop the hot water getting too hot, but wouldn't make it heat
up any quicker.


2) Y-plan seems to be talked of slightly disparagingly in comparison to
S- plan, due to reliabilty problems, difficulty with problem diagnosis,
and lack of zone expansion capability. Given that I don't intend to have
any zoning, are the other problems real (eg. these days)?

Y-plan is actually a special case of 2 zones: CH and HW. As for
reliability there must be millions of them in service, and 2-port (S-
plan) valves fail too.

3) If I were to change to Y-plan, I understand that I'd need to cap off
part of the boiler. As I mentioned, the back boiler has 4 ports - 2x22mm
(currently CH), and 2x28mm (currently to the heat exchanger for HW). Is
this just a matter of capping off the two 28mm pipes (and moving the
feed and vent pipes) ?

3a) I assume that the reason that the pipes from the boiler are
different diameters for the two circuits is that the larger 28mm dia.
gives less resistance and better allows the HW to be unpumped - is that
right?

Yup.


4) what, exactly, should I be looking for spec-wise in a gate valve,

gate valve? you mean 3-port valve? should be some blather about it on the
wiki.

Your other option would be to put a pump on the HW side, but that would
require some savvy with the controls wiring: specifically, using a relay
(or two[1]) to wire-OR the CH and HW demand signals to control the
boiler. You'd probably also need to change the pipework to get the feed
and vent pipes close together to prevent pumping over with your newly
pumped HW circuit.


[1] it can be done with one relay but easier to understand with two





--
John Stumbles -- http://yaph.co.uk

Many hands make light work. Too many cooks spoil the broth.

On May 31, 11:32*pm, The Night Tripper wrote:
Hi all
* * I have a plan ... a yen really ... to improve our CH heating system. It
currently has a 4-port back boiler running a gravity feed HW, pumped CH
system. I installed a Sunvic select (207, I think) programmer a while ago,
and replaced the pump with a Grundfoss when the original died.

We do suffer from lack of HW after someone has had a bath etc. I don't want
to change the back boiler, even though I realise it's old-skool.

I have in mind to either:

a) add a Cylinder thermostat and 2-port valve, and convert to C-plan. The
valve will have to be on the return from the boiler, there's no room in the
flow pipe.
b) add a mid-position valve and convert to Y plan (no zoning envisaged).

I've read lots about doing this sort of work on the archives of this fine
newsgroup, and on the wiki. I've also identified all the pipes in the
current arrangement and understand the need for siting the valve with
respect to the flow & return to the F&E tank etc. I do still have a few
questions which might help me decide the route to take. Answers gratefully
received.

1) with my devil's advocate hat on, would there be any real benefit of a C-
plan over our current arrangement?

2) Y-plan seems to be talked of slightly disparagingly in comparison to S-
plan, due to reliabilty problems, difficulty with problem diagnosis, and
lack of zone expansion capability. Given that I don't intend to have any
zoning, are the other problems real (eg. these days)?

3) If I were to change to Y-plan, I understand that I'd need to cap off part
of the boiler. As I mentioned, the back boiler has 4 ports - 2x22mm
(currently CH), and 2x28mm (currently to the heat exchanger for HW). Is this
just a matter of capping off the two 28mm pipes (and moving the feed and
vent pipes) ?

3a) I assume that the reason that the pipes from the boiler are different
diameters for the two circuits is that the larger 28mm dia. gives less
resistance and better allows the HW to be unpumped - is that right?

4) what, exactly, should I be looking for spec-wise in a gate valve, apart
from the pipe diameter? I have a part number for a 2-port Honeywell valve
but I'm curious about what the spec actually calls for. There are a lot of
valves for sale on eBay ...

Thanks a lot in advance

* * regards
* * Jon N
You don't even mention what fuel you are burning.
Do you mean by back boiler a thing behind an open coal fire?
Or a gas boiler behind a gas fire?

Hardly seems worth the effort. The heat exchanger in your tank may
well be scaled up. I would start by a thorough clean and descale of
your DHW tank(cylinder).
This may well resolve your problem.
And make sure the tank is well insulated.

In message
,
harry writes
On May 31, 11:32*pm, The Night Tripper wrote:
Hi all
* * I have a plan ... a yen really ... to improve our CH heating system. It
currently has a 4-port back boiler running a gravity feed HW, pumped CH
system. I installed a Sunvic select (207, I think) programmer a while ago,
and replaced the pump with a Grundfoss when the original died.

We do suffer from lack of HW after someone has had a bath etc. I don't want
to change the back boiler, even though I realise it's old-skool.

I have in mind to either:

a) add a Cylinder thermostat and 2-port valve, and convert to C-plan. The
valve will have to be on the return from the boiler, there's no room in the
flow pipe.
b) add a mid-position valve and convert to Y plan (no zoning envisaged).

I've read lots about doing this sort of work on the archives of this fine
newsgroup, and on the wiki. I've also identified all the pipes in the
current arrangement and understand the need for siting the valve with
respect to the flow & return to the F&E tank etc. I do still have a few
questions which might help me decide the route to take. Answers gratefully
received.

1) with my devil's advocate hat on, would there be any real benefit of a C-
plan over our current arrangement?

2) Y-plan seems to be talked of slightly disparagingly in comparison to S-
plan, due to reliabilty problems, difficulty with problem diagnosis, and
lack of zone expansion capability. Given that I don't intend to have any
zoning, are the other problems real (eg. these days)?

3) If I were to change to Y-plan, I understand that I'd need to cap off part
of the boiler. As I mentioned, the back boiler has 4 ports - 2x22mm
(currently CH), and 2x28mm (currently to the heat exchanger for HW). Is this
just a matter of capping off the two 28mm pipes (and moving the feed and
vent pipes) ?

3a) I assume that the reason that the pipes from the boiler are different
diameters for the two circuits is that the larger 28mm dia. gives less
resistance and better allows the HW to be unpumped - is that right?

4) what, exactly, should I be looking for spec-wise in a gate valve, apart
from the pipe diameter? I have a part number for a 2-port Honeywell valve
but I'm curious about what the spec actually calls for. There are a lot of
valves for sale on eBay ...

Thanks a lot in advance

* * regards
* * Jon N
You don't even mention what fuel you are burning.
Do you mean by back boiler a thing behind an open coal fire?
Or a gas boiler behind a gas fire?

Hardly seems worth the effort. The heat exchanger in your tank may
well be scaled up. I would start by a thorough clean and descale of
your DHW tank(cylinder).
This may well resolve your problem.
And make sure the tank is well insulated.

Also consider the need for the cistern to act as a heat dump if using
solid fuel. IANAP:-)

regards


--
Tim Lamb

On 31/05/2011 23:32, The Night Tripper wrote:
Hi all
I have a plan ... a yen really ... to improve our CH heating system. It
currently has a 4-port back boiler running a gravity feed HW, pumped CH
system. I installed a Sunvic select (207, I think) programmer a while ago,
and replaced the pump with a Grundfoss when the original died.

We do suffer from lack of HW after someone has had a bath etc. I don't want
to change the back boiler, even though I realise it's old-skool.

I have in mind to either:

a) add a Cylinder thermostat and 2-port valve, and convert to C-plan. The
valve will have to be on the return from the boiler, there's no room in the
flow pipe.
b) add a mid-position valve and convert to Y plan (no zoning envisaged).

I've read lots about doing this sort of work on the archives of this fine
newsgroup, and on the wiki. I've also identified all the pipes in the
current arrangement and understand the need for siting the valve with
respect to the flow& return to the F&E tank etc. I do still have a few
questions which might help me decide the route to take. Answers gratefully
received.

1) with my devil's advocate hat on, would there be any real benefit of a C-
plan over our current arrangement?

The advantages are that the HW temperature will be controlled - so you
can run the boiler hotter for the CH if desired - and you will have
"boiler interlock", stopping the boiler cycling on and off when all
demands are satisfied.

However, since it will still be a gravity HW system, the water won't get
hot any more quickly.


2) Y-plan seems to be talked of slightly disparagingly in comparison to S-
plan, due to reliabilty problems, difficulty with problem diagnosis, and
lack of zone expansion capability. Given that I don't intend to have any
zoning, are the other problems real (eg. these days)?

You pays your money . . . Personally I prefer S-Plan but Y-Plan is ok.
It's just a bit more "all your eggs in one basket".

3) If I were to change to Y-plan, I understand that I'd need to cap off part
of the boiler. As I mentioned, the back boiler has 4 ports - 2x22mm
(currently CH), and 2x28mm (currently to the heat exchanger for HW). Is this
just a matter of capping off the two 28mm pipes (and moving the feed and
vent pipes) ?

You'll need to have just one flow and one return to the boiler, with the
other connections capped off. How easy the conversion is will depend on
the current pipe layout. You need a convenient place to put the pump and
valve(s) - with the two circuits splitting after the pump and before the
valves. If starting from scratch, this would normally be in the airing
cupboard.

3a) I assume that the reason that the pipes from the boiler are different
diameters for the two circuits is that the larger 28mm dia. gives less
resistance and better allows the HW to be unpumped - is that right?


Yes.

4) what, exactly, should I be looking for spec-wise in a gate valve, apart
from the pipe diameter? I have a part number for a 2-port Honeywell valve
but I'm curious about what the spec actually calls for. There are a lot of
valves for sale on eBay ...

You need a 28mm valve which is normally closed, and opened by a motor
and closed by a return spring when power is removed. It needs to have
auxilliary contacts in the form of a *change-over* switch (i.e. NO, NC
and COM contacts) which changes state when the valve is fully open.

As someone else has suggested, you could consider adding another pump,
for just the HW circuit. You would then need to devise some relay logic
to fire the boiler *only* when there is a demand from either or both
circuits.
--
Cheers,
Roger
____________
Please reply to Newsgroup. Whilst email address is valid, it is seldom
checked.

On 31/05/2011 23:39, The Night Tripper wrote:
Slight correction to my posting:
a) add a Cylinder thermostat and 2-port valve, and convert to C-plan.

The valve will have to be on the *flow from* the boiler, there's no room in
the *return* pipe.


Be very careful! You must have a clear unrestricted path from the boiler
to the vent pipe - with no vales in the way
--
Cheers,
Roger
____________
Please reply to Newsgroup. Whilst email address is valid, it is seldom
checked.

"The Night Tripper" wrote in message
o.uk...
Hi all
I have a plan ... a yen really ... to improve our CH heating system. It
currently has a 4-port back boiler running a gravity feed HW, pumped CH
system. I installed a Sunvic select (207, I think) programmer a while ago,
and replaced the pump with a Grundfoss when the original died.

We do suffer from lack of HW after someone has had a bath etc. I don't
want
to change the back boiler, even though I realise it's old-skool.
snip

It isn't clear to me if your problem is the slow reheating of water, or just
that your hot water cylinder doens't have the capacity to fill the bath and
still have a bit of hot water left over.

If the water heats up reasonably quickly then perhaps you just need a larger
hot water cylinder?

--
No plan survives contact with the enemy.
[Not even bunny]

Helmuth von Moltke the Elder

(\__/)
(='.'=)
(")_(")

Hi Harry

[...]
You don't even mention what fuel you are burning.
Do you mean by back boiler a thing behind an open coal fire?
Or a gas boiler behind a gas fire?

I mean behind a gas fire. does that make it a 'gas boiler'? I wouldn't have
thought so, but ...


Hardly seems worth the effort. The heat exchanger in your tank may
well be scaled up. I would start by a thorough clean and descale of
your DHW tank(cylinder).
This may well resolve your problem.

This is a fair point - we live in a hard-water area (south Coast) and there
may be a fair bit of scale. As I say, it's partly a 'yen' ...

And make sure the tank is well insulated.

Yes, it's well insulated, thanks.

J^n

Hi Roger



Be very careful! You must have a clear unrestricted path from the boiler
to the vent pipe - with no vales in the way

Yes, I appreciate that (thanks in part to your previous postings on the
subject) - thanks.

Actually, I may post links to a few pictures. Some of the current plumbing
is a bit ... novel ...

Cheers
J^n

On Jun 1, 11:12*pm, The Night Tripper wrote:
Hi Roger



Be very careful! You must have a clear unrestricted path from the boiler
to the vent pipe - with no vales in the way

Yes, I appreciate that (thanks in part to your previous postings on the
subject) - thanks.

Actually, I may post links to a few pictures. Some of the current plumbing
is a bit ... novel ...

* * Cheers
* * J^n

Well if it worked in the past, it can work again. If you are in a
hard water area you need to drain the tank try and wash the limestone
sludge out with a hose pipe.This is difficult in practice, you may
have to take the tank out in the garden where you can hose and roll it
about. If there is an immersion heater you can remove (saw the joint
out don't use violence) this is a good place to inspect with a torch.

Some tanks have the HX coil right in the bottom, it may be completely/
partially covered in sludge. There can be hard scale adhering to it
as well. Hard to remove, you may have to consider chemicals. As a
last resort, new tank. Different areas have different sorts of scale
as regards how well it sticks.
The copper should be in good condition in hard water area.

But if it is bunged up with scale, it will have to be cleaned whatever
else you do. And nothing else may be neccessary.

Hi Harry

[...]

Well if it worked in the past, it can work again.

I have no knowledge that it worked (any better) in the past. And when all's
said and done it will have the limitations of the topology installed.

J^n

"The Night Tripper" wrote in message
o.uk...
Hi Harry

[...]
You don't even mention what fuel you are burning.
Do you mean by back boiler a thing behind an open coal fire?
Or a gas boiler behind a gas fire?

I mean behind a gas fire. does that make it a 'gas boiler'? I wouldn't
have
thought so, but ...


Hardly seems worth the effort. The heat exchanger in your tank may
well be scaled up. I would start by a thorough clean and descale of
your DHW tank(cylinder).
This may well resolve your problem.

This is a fair point - we live in a hard-water area (south Coast) and
there
may be a fair bit of scale. As I say, it's partly a 'yen' ...

And make sure the tank is well insulated.

Yes, it's well insulated, thanks.


If it is behind a gas fire it will run on gas, and work even when the gas
fire is not lit.
This makes it a gas boiler.
Sounds like the Baxi back boiler we had in Berkshire.
Is it, perchance, a Baxi?
How old is the system?
When we had ours replaced (probably installed a long time ago - '60s?) the
plumber drained the CH but had to drain down everything eventually because
the heat exchanger was leaking and kept filling the heating up again from
the hot water header tank.
He needed another person to help remove the hot tank because it was so full
of scale and gunge.

My lady wife sold the tank for scrap to a couple of door knockers and you
could see the trail of scale where they had staggered from our front drive.
I don't know how you clean up such a cyclinder to sell for scrap - just
weigh it in and hope the yard doesn't notice it is paying copper prices for
limescale?

So - unless it is a very recent installation and has also been always
treated with central heating inhibitor products there could be problems on
the heating side.
In a hard water area, unless you use a water softener, there is likely to be
a build up of scale over time in the hot water cylinder.
As advised elsewhere it is a good idea to take out the hot water cylinder
and give it a thorough checking.
If it is gunged up and/or leaking at the heat exchanger you may solve most
or all of your problems by fitting a new more efficient (and possibly
larger) cyclinder.
You may be 'polishing a turd' if you just modify the pipework without
confirming that the hot water tank is functioning correctly.

HTH

Dave R
--
No plan survives contact with the enemy.
[Not even bunny]

Helmuth von Moltke the Elder

(\__/)
(='.'=)
(")_(")

On Jun 2, 9:59*am, "David WE Roberts"
wrote:
"The Night Tripper" wrote in messagenews:4cOdnebrot5BJXvQnZ2dnUVZ8oednZ2d@brigh tview.co.uk...





Hi Harry

[...]
You don't even mention what fuel you are burning.
Do you mean by back boiler a thing behind an open coal fire?
Or a gas boiler behind a gas fire?

I mean behind a gas fire. does that make it a 'gas boiler'? I wouldn't
have
thought so, but ...

Hardly seems worth the effort. The heat exchanger *in your tank may
well be scaled up. I would start by a thorough clean and descale of
your DHW tank(cylinder).
This may well resolve your problem.

This is a fair point - we live in a hard-water area (south Coast) and
there
may be a fair bit of scale. As I say, it's partly a 'yen' ...

And make sure the tank is well insulated.

Yes, it's well insulated, thanks.

If it is behind a gas fire it will run on gas, and work even when the gas
fire is not lit.
This makes it a gas boiler.
Sounds like the Baxi back boiler we had in Berkshire.
Is it, perchance, a Baxi?
How old is the system?
When we had ours replaced (probably installed a long time ago - '60s?) the
plumber drained the CH but had to drain down everything eventually because
the heat exchanger was leaking and kept filling the heating up again from
the hot water header tank.
He needed another person to help remove the hot tank because it was so full
of scale and gunge.

My lady wife sold the tank for scrap to a couple of door knockers and you
could see the trail of scale where they had staggered from our front drive.
I don't know how you clean up such a cyclinder to sell for scrap - just
weigh it in and hope the yard doesn't notice it is paying copper prices for
limescale?

So - unless it is a very recent installation and has also been always
treated with central heating inhibitor products there could be problems on
the heating side.
In a hard water area, unless you use a water softener, there is likely to be
a build up of scale over time in the hot water cylinder.
As advised elsewhere it is a good idea to take out the hot water cylinder
and give it a thorough checking.
If it is gunged up and/or leaking at the heat exchanger you may solve most
or all of your problems by fitting a new more efficient (and possibly
larger) cyclinder.
You may be 'polishing a turd' if you just modify the pipework without
confirming that the hot water tank is functioning correctly.

HTH

Dave R
--
No plan survives contact with the enemy.
[Not even bunny]

Helmuth von Moltke the Elder

(\__/)
(='.'=)
(")_(")- Hide quoted text -

- Show quoted text -

And maybe fit a water softener.

On Tue, 31 May 2011 23:32:59 +0100, The Night Tripper wrote:

1) with my devil's advocate hat on, would there be any real benefit of a
C-plan over our current arrangement?

In your current arrangement the HW is heated whenever the CH is on.
The water circulating in the CH circuit should be around 70 to 80C,
this rather hot (scalding hot) for HW which would normally be around
60C.

Whenever the HW is on the boiler will cycle to keep the boiler and
gravity loop hot. Both of these "features" waste energy.

A tank stat could be fitted that would solve the last but not the
first.

--
Cheers
Dave.

Hi David

David WE Roberts wrote:

[lots of good stuff snipped, thanks]

You may be 'polishing a turd' if you just modify the pipework without
confirming that the hot water tank is functioning correctly.

fair point, well made. In some ways I would like a stop gap until the back
boiler needs replacing and we (probably) re-do with a new boiler in the
loft. I'm conscious that my plans are probably over-ambitious for this
stopgap situation. I *really* don't want to take the tank out though ;-(.

Hmm...

Cheers
J^n

On Jun 3, 8:12*am, The Night Tripper wrote:
Hi David

David WE Roberts wrote:

[lots of good stuff snipped, thanks]

You may be 'polishing a turd' if you just modify the pipework without
confirming that the hot water tank is functioning correctly.

fair point, well made. In some ways I would like a stop gap until the back
boiler needs replacing and we (probably) re-do with a new boiler in the
loft. I'm conscious that my plans are probably over-ambitious for this *
stopgap situation. I *really* don't want to take the tank out though ;-(.

Hmm...

* * Cheers
* * J^n

Well, it will have to be done. Whatever course of action you decide
upon.

On Thu, 02 Jun 2011 09:59:16 +0100, David WE Roberts wrote:

My lady wife sold the tank for scrap to a couple of door knockers and
you could see the trail of scale where they had staggered from our front
drive. I don't know how you clean up such a cyclinder to sell for scrap
- just weigh it in and hope the yard doesn't notice it is paying copper
prices for limescale?

The scrap merchants just give you a standard price for a cylinder. They
know it's useless weighing it.





--
John Stumbles -- http://yaph.co.uk

The ant has made himself illustrious through constant industry industrious
So what? Would you be calm and placid if you were full of formic acid?