A house I used to live in had an early 1970s cast iron lump [1] for a boiler
and a mechanical time clock. One 'feature' of this system was that you
always heated the hot water when you turned the heating on. I understand
that was common in older systems.

I'm curious as to how this was plumbed. I understand about S and Y plan
systems, but I can't see how that would cause this effect. Was this set up
with the boiler output always going through the coil first? Or with a
single heating on/off valve? Or was it an S plan where the controller just
told the hot water valve to open when the heating was on?

Anyone know?

Thanks
Theo

[1] Potterton Kingfisher I think it was, although I gather there have been a
lot more recent Kingfishers since then

On 2021-05-14 20:56:20, Theo wrote:
A house I used to live in had an early 1970s cast iron lump [1] for a boiler
and a mechanical time clock. One 'feature' of this system was that you
always heated the hot water when you turned the heating on. I understand
that was common in older systems.

I'm curious as to how this was plumbed. I understand about S and Y plan
systems, but I can't see how that would cause this effect. Was this set up
with the boiler output always going through the coil first? Or with a
single heating on/off valve? Or was it an S plan where the controller just
told the hot water valve to open when the heating was on?

The uk.diy wiki suggests C plan:

http://wiki.diyfaq.org.uk/index.php/...ty_DHW:_C-Plan


Was there an earlier version without a zone valve in the hot water side, so
hot water was always heated via gravity?

--
Graham Nye
news(a)thenyes.org.uk

Was there an earlier version without a zone valve in the hot water
side, so hot water was always heated via gravity?


I once adapted such a system by fitting a motorised valve to the gravity
feed, conrolled by a tank Thermostat.The switches in the valve head
controlled the boiler / or the room stat and pump.

On 14/05/2021 20:56, Theo wrote:
A house I used to live in had an early 1970s cast iron lump [1] for a boiler
and a mechanical time clock. One 'feature' of this system was that you
always heated the hot water when you turned the heating on. I understand
that was common in older systems.

I'm curious as to how this was plumbed. I understand about S and Y plan
systems, but I can't see how that would cause this effect. Was this set up
with the boiler output always going through the coil first? Or with a
single heating on/off valve? Or was it an S plan where the controller just
told the hot water valve to open when the heating was on?

Anyone know?

It was quite common to have a big cast iron lump HX with high water
content (couple of gallons). That would have 4 bosses on it - two
outputs and two returns. One set would be used for the feed and return
on the pumped circuit through the rads, and the other two would be used
for a gravity (i.e. convected circuit) to heat an indirect cylinder.

The convention circuit required that the hot water cylinder would be
placed some distance above the boiler and not too far displaced from it.
It would also typically be piped in 28mm pipe to better allow convection
flow. Hot water from the gravity output would rise up through the pipe,
and through the coil in the cylinder, the heavier cooler water would
fall and return to the boiler. Basically it sets up a thermosyphon.

Some refinements of the system introduced and anti gravity valve to stop
heat being lost out of the cylinder through the boiler when it was off.
Some had a kind of thermostatic valve in the gravity loop to limit the
maximum temperature of the cylinder DHW. Some would add a motorised
valve to make it a fully controlled zone. (aka C plan)

[1] Potterton Kingfisher I think it was, although I gather there have been a
lot more recent Kingfishers since then

Yup, I know someone with one of those and a gravity circulation loop...


--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

On Fri, 14 May 2021 20:56:20 +0100, Theo wrote:

A house I used to live in had an early 1970s cast iron lump [1] for a
boiler and a mechanical time clock. One 'feature' of this system was
that you always heated the hot water when you turned the heating on. I
understand that was common in older systems.

I'm curious as to how this was plumbed. I understand about S and Y plan
systems, but I can't see how that would cause this effect. Was this set
up with the boiler output always going through the coil first? Or with
a single heating on/off valve? Or was it an S plan where the controller
just told the hot water valve to open when the heating was on?

Anyone know?

Thanks Theo

[1] Potterton Kingfisher I think it was, although I gather there have
been a lot more recent Kingfishers since then


For many years in the 70s I had a back boiler behind the living room fire.
We would use drift wood to keep the fire burning which supplied nearly
boiling water for the kitchen and bathroom. Superb arrangement, but don't
know how it was fed with mains water, but it just worked.

John Rumm wrote:

It was quite common to have aÂ* big cast iron lump HX with high water
content (couple of gallons). That would have 4 bosses on it - two
outputs and two returns. One set would be used for the feed and return
on the pumped circuit through the rads, and the other two would be used
for a gravity (i.e. convected circuit) to heat an indirect cylinder.

shhhh! don't go upsetting my boiler now ....

John Rumm wrote:
It was quite common to have a big cast iron lump HX with high water
content (couple of gallons). That would have 4 bosses on it - two
outputs and two returns. One set would be used for the feed and return
on the pumped circuit through the rads, and the other two would be used
for a gravity (i.e. convected circuit) to heat an indirect cylinder.

Ah, so 'gravity' meant there was no pump on the HW side, only for the
heating?

The convention circuit required that the hot water cylinder would be
placed some distance above the boiler and not too far displaced from it.
It would also typically be piped in 28mm pipe to better allow convection
flow. Hot water from the gravity output would rise up through the pipe,
and through the coil in the cylinder, the heavier cooler water would
fall and return to the boiler. Basically it sets up a thermosyphon.

That's neat. Horribly inefficient, but neat

That sounds about right - cylinder was above the boiler and about 2.5m
displaced, so that would probably work.

Some refinements of the system introduced and anti gravity valve to stop
heat being lost out of the cylinder through the boiler when it was off.
Some had a kind of thermostatic valve in the gravity loop to limit the
maximum temperature of the cylinder DHW. Some would add a motorised
valve to make it a fully controlled zone. (aka C plan)

I never investigated but I imagine there was just on/off control for the
boiler (gas valve only, since there was an always-on pilot that had a piezo
spark-button to relight it if it went out), and an additional time clock
output that was in series with a thermostat to run the pump for the heating.

How was the boiler turned off in this system, when the thermostat said the
house was hot enough and so was the water? If the heating called for heat
and the hot water was up to temp, surely that would overheat the water?

Theo

Theo wrote:
John Rumm wrote:
It was quite common to have a big cast iron lump HX with high water
content (couple of gallons). That would have 4 bosses on it - two
outputs and two returns. One set would be used for the feed and return
on the pumped circuit through the rads, and the other two would be used
for a gravity (i.e. convected circuit) to heat an indirect cylinder.

Ah, so 'gravity' meant there was no pump on the HW side, only for the
heating?

The convention circuit required that the hot water cylinder would be
placed some distance above the boiler and not too far displaced from it.
It would also typically be piped in 28mm pipe to better allow convection
flow. Hot water from the gravity output would rise up through the pipe,
and through the coil in the cylinder, the heavier cooler water would
fall and return to the boiler. Basically it sets up a thermosyphon.

That's neat. Horribly inefficient, but neat

That sounds about right - cylinder was above the boiler and about 2.5m
displaced, so that would probably work.

Some refinements of the system introduced and anti gravity valve to stop
heat being lost out of the cylinder through the boiler when it was off.
Some had a kind of thermostatic valve in the gravity loop to limit the
maximum temperature of the cylinder DHW. Some would add a motorised
valve to make it a fully controlled zone. (aka C plan)

I never investigated but I imagine there was just on/off control for the
boiler (gas valve only, since there was an always-on pilot that had a piezo
spark-button to relight it if it went out), and an additional time clock
output that was in series with a thermostat to run the pump for the heating.

How was the boiler turned off in this system, when the thermostat said the
house was hot enough and so was the water? If the heating called for heat
and the hot water was up to temp, surely that would overheat the water?

Theo


Water temperature would be limited by the boiler stat.

It was never a terribly efficient system but it was simple and reliable
with no new-fangled motorised valves to go wrong. ;-)

Tim

--
Please don't feed the trolls

Theo wrote on 14/05/2021 :
A house I used to live in had an early 1970s cast iron lump [1] for a boiler
and a mechanical time clock. One 'feature' of this system was that you
always heated the hot water when you turned the heating on. I understand
that was common in older systems.

I'm curious as to how this was plumbed. I understand about S and Y plan
systems, but I can't see how that would cause this effect. Was this set up
with the boiler output always going through the coil first? Or with a
single heating on/off valve? Or was it an S plan where the controller just
told the hot water valve to open when the heating was on?

Anyone know?

Thanks
Theo

[1] Potterton Kingfisher I think it was, although I gather there have been a
lot more recent Kingfishers since then

A friend of mine used to have a system installed when the house was
built, where he had to select where the heat went via a manual 3-port
valve.

In article ,
Theo wrote:
A house I used to live in had an early 1970s cast iron lump [1] for a
boiler and a mechanical time clock. One 'feature' of this system was
that you always heated the hot water when you turned the heating on. I
understand that was common in older systems.

I'm curious as to how this was plumbed. I understand about S and Y plan
systems, but I can't see how that would cause this effect. Was this set
up with the boiler output always going through the coil first? Or with
a single heating on/off valve? Or was it an S plan where the controller
just told the hot water valve to open when the heating was on?

Mechanical time clock suggested it was designed to work on thermo
circulation only - at least at one time. With likely a mechanical valve to
add on the heating - again likely thermo, using larger bore pipes than
we're used to these days. With the advantage it worked during a power cut.

Later systems still used thermo circulation for the hot water, with a pump
for the heating. Pump not running, hot water only.

--
*WHERE DO FOREST RANGERS GO TO "GET AWAY FROM IT ALL?"

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

On 15/05/2021 11:27, Theo wrote:

I never investigated but I imagine there was just on/off control for the
boiler (gas valve only, since there was an always-on pilot that had a piezo
spark-button to relight it if it went out), and an additional time clock
output that was in series with a thermostat to run the pump for the heating.

How was the boiler turned off in this system, when the thermostat said the
house was hot enough and so was the water? If the heating called for heat
and the hot water was up to temp, surely that would overheat the water?

https://assets.danfoss.com/documents...6en-GB0201.pdf

Were the common programmers of the time


--
Adam

On 15/05/2021 11:27, Theo wrote:
John Rumm wrote:
It was quite common to have a big cast iron lump HX with high water
content (couple of gallons). That would have 4 bosses on it - two
outputs and two returns. One set would be used for the feed and return
on the pumped circuit through the rads, and the other two would be used
for a gravity (i.e. convected circuit) to heat an indirect cylinder.

Ah, so 'gravity' meant there was no pump on the HW side, only for the heating?

Yup, DHW looked after itself, and the pump only served the rads.

(thermosyphon systems could also run with solid fuel heating boilers,
where the inability of a pump fault or electrical failure or power
interruption to affect the operation of a system that could not easily
be "turned off" was seen as an important benefit)

The convention circuit required that the hot water cylinder would be
placed some distance above the boiler and not too far displaced from it.
It would also typically be piped in 28mm pipe to better allow convection
flow. Hot water from the gravity output would rise up through the pipe,
and through the coil in the cylinder, the heavier cooler water would
fall and return to the boiler. Basically it sets up a thermosyphon.

That's neat. Horribly inefficient, but neat

Inefficient yes, although possibly not that much less than some pumped
systems that could only extract say 3 to 5kW of power from the boiler to
the cylinder via a short indirect coil. Those would have to short cycle
the boiler to load match its much higher output to the input of the
cylinder (or run it in parallel with the rads to present enough load -
hence the popularity of Y plan systems)

That sounds about right - cylinder was above the boiler and about 2.5m
displaced, so that would probably work.

Some refinements of the system introduced and anti gravity valve to stop
heat being lost out of the cylinder through the boiler when it was off.
Some had a kind of thermostatic valve in the gravity loop to limit the
maximum temperature of the cylinder DHW. Some would add a motorised
valve to make it a fully controlled zone. (aka C plan)

I never investigated but I imagine there was just on/off control for the
boiler (gas valve only, since there was an always-on pilot that had a piezo
spark-button to relight it if it went out), and an additional time clock
output that was in series with a thermostat to run the pump for the heating.

The boiler would have its own internal water temperature stat that would
interrupt power to the gas valve when the set point was reached (there
was often a knob on the boiler to tweak that set point).

How was the boiler turned off in this system, when the thermostat said the
house was hot enough and so was the water? If the heating called for heat
and the hot water was up to temp, surely that would overheat the water?

That was one of the limitations - there was no system interlock as such
that could shut down everything once the cylinder was up to temperature.
Most programmers of the era would usually just run a timed heating cycle
for the cylinder. If heating the DHW alone, the boiler would run and
cycle. As the cylinder came up to temp, the rate of heat transfer would
fall, and the boiler cycle would shorten. However if not turned off with
the programmer (or manual override) it would carry on indefinitely.

--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

On 15/05/2021 15:57, John Rumm wrote:
On 15/05/2021 11:27, Theo wrote:
John Rumm wrote:
It was quite common to have aÂ* big cast iron lump HX with high water
content (couple of gallons). That would have 4 bosses on it - two
outputs and two returns. One set would be used for the feed and return
on the pumped circuit through the rads, and the other two would be used
for a gravity (i.e. convected circuit) to heat an indirect cylinder.

Ah, so 'gravity' meant there was no pump on the HW side, only for the
heating?

Yup, DHW looked after itself, and the pump only served the rads.


The upstairs rads (or some of them) would have warmed up (not to full
heat) if it was not for the anti gravity valve on the heating flow side.


--
Adam

On 15/05/2021 16:54, ARW wrote:
On 15/05/2021 15:57, John Rumm wrote:
On 15/05/2021 11:27, Theo wrote:
John Rumm wrote:
It was quite common to have aÂ* big cast iron lump HX with high water
content (couple of gallons). That would have 4 bosses on it - two
outputs and two returns. One set would be used for the feed and return
on the pumped circuit through the rads, and the other two would be used
for a gravity (i.e. convected circuit) to heat an indirect cylinder.

Ah, so 'gravity' meant there was no pump on the HW side, only for the
heating?

Yup, DHW looked after itself, and the pump only served the rads.


The upstairs rads (or some of them) would have warmed up (not to full
heat) if it was not for the anti gravity valve on the heating flow side.

Sometimes part of that was intentional, they might put the bathroom rad
in the gravity loop for the cylinder rather than as part of the heating
circuit.


--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

On 15/05/2021 17:32, John Rumm wrote:
On 15/05/2021 16:54, ARW wrote:
On 15/05/2021 15:57, John Rumm wrote:
On 15/05/2021 11:27, Theo wrote:
John Rumm wrote:
It was quite common to have aÂ* big cast iron lump HX with high water
content (couple of gallons). That would have 4 bosses on it - two
outputs and two returns. One set would be used for the feed and return
on the pumped circuit through the rads, and the other two would be
used
for a gravity (i.e. convected circuit) to heat an indirect cylinder.

Ah, so 'gravity' meant there was no pump on the HW side, only for
the heating?

Yup, DHW looked after itself, and the pump only served the rads.


The upstairs rads (or some of them) would have warmed up (not to full
heat) if it was not for the anti gravity valve on the heating flow side.

Sometimes part of that was intentional, they might put the bathroom rad
in the gravity loop for the cylinder rather than as part of the heating
circuit.



I had forgotten about that one.

A few years ago I did a combi as an S plan and the bathroom rad was one
of the zones. The flow sensor on the bath hot tap triggered a timer to
operate the bathroom 2 port valve

--
Adam

Dave Plowman (News) wrote

--
*WHERE DO FOREST RANGERS GO TO "GET AWAY FROM IT ALL?"

From the memoir of one of them in the 19th century in
the wilds of Burma or somewhere like that, to a different
forest from the one he normally operated in. Bizarre.

On Sun, 16 May 2021 03:30:49 +1000, cantankerous trolling geezer Rodent
Speed, the auto-contradicting senile sociopath, blabbered, again:

FLUSH the trolling senile asshole's latest troll**** unread

--
Richard addressing senile Rodent Speed:
"**** you're thick/pathetic excuse for a troll."
MID:

John Rumm wrote:
Sometimes part of that was intentional, they might put the bathroom rad
in the gravity loop for the cylinder rather than as part of the heating
circuit.

I'd forgotten about that - there was a heated towel rail that always came on
when the hot water came on. Made the bathroom nice and warm. In summer we
used the immersion 'because it was cheaper' - that might have been a reason
why! (I very much doubt it was cheaper)

While the gravity might have meant the system would work without power, the
timer was electric so there was no way to operate it during power cuts. I
don't remember a pump for the central heating but I imagine there must have
been one.

Theo

ARW wrote:
On 15/05/2021 11:27, Theo wrote:

I never investigated but I imagine there was just on/off control for the
boiler (gas valve only, since there was an always-on pilot that had a piezo
spark-button to relight it if it went out), and an additional time clock
output that was in series with a thermostat to run the pump for the heating.

How was the boiler turned off in this system, when the thermostat said the
house was hot enough and so was the water? If the heating called for heat
and the hot water was up to temp, surely that would overheat the water?

https://assets.danfoss.com/documents...6en-GB0201.pdf

Were the common programmers of the time

This was the one:
https://www.amazon.co.uk/LANDIS-GYR-.../dp/B072FSJP2N
which was just a simple 1 rev per day motorised dial plus some cams to
operate switches.

Being on gravity makes a lot of sense - the neighbours moved their cast iron
boiler into the garage and 'it never worked properly after'. Which would
follow if the tank is suddenly further away from the boiler.

Theo

On 15/05/2021 11:27, Theo wrote:
John Rumm wrote:
It was quite common to have a big cast iron lump HX with high water
content (couple of gallons). That would have 4 bosses on it - two
outputs and two returns. One set would be used for the feed and return
on the pumped circuit through the rads, and the other two would be used
for a gravity (i.e. convected circuit) to heat an indirect cylinder.

Ah, so 'gravity' meant there was no pump on the HW side, only for the
heating?


Yes indeed, and no motorised valves either.


The convention circuit required that the hot water cylinder would be
placed some distance above the boiler and not too far displaced from it.
It would also typically be piped in 28mm pipe to better allow convection
flow. Hot water from the gravity output would rise up through the pipe,
and through the coil in the cylinder, the heavier cooler water would
fall and return to the boiler. Basically it sets up a thermosyphon.

That's neat. Horribly inefficient, but neat

Inefficient, yes because there was no boiler interlock. In other words,
the boiler continued to fire just to keep itself warm even when there
was no heating demand and the hot water was hot enough.

That sounds about right - cylinder was above the boiler and about 2.5m
displaced, so that would probably work.

Some refinements of the system introduced and anti gravity valve to stop
heat being lost out of the cylinder through the boiler when it was off.
Some had a kind of thermostatic valve in the gravity loop to limit the
maximum temperature of the cylinder DHW. Some would add a motorised
valve to make it a fully controlled zone. (aka C plan)

I never investigated but I imagine there was just on/off control for the
boiler (gas valve only, since there was an always-on pilot that had a piezo
spark-button to relight it if it went out), and an additional time clock
output that was in series with a thermostat to run the pump for the heating.

How was the boiler turned off in this system, when the thermostat said the
house was hot enough and so was the water? If the heating called for heat
and the hot water was up to temp, surely that would overheat the water?


The boiler had an electrically operated gas valve, so would only run
when power was applied - plus a safety interlock which prevented the gas
valve from opening unless the pilot was alight and heating its thermocouple.

As others have said, the hot water would eventually get up to boiler
temperature - which was too hot for comfort unless the boiler stat was
turned down. Then the radiators may not get hot enough. One solution -
which I installed in my first house in about 1969 - used a thermostatic
valve (a bit like a TRV) in the gravity return from the cylinder coil
and stopped the circulation when the hot water was hot enough. It didn't
stop the boiler cycling on its own stat, of course.

Such systems would typcially have a two-channel programmer
(electro-mechanical rather than digital of course!) to switch the boiler
on when hot water and/or heating were required and to switch the pump on
(often via a room thermostat) when heating was required.
--
Cheers,
Roger

Roger Mills wrote:

Inefficient, yes because there was no boiler interlock. In other words,
the boiler continued to fire just to keep itself warm even when there
was no heating demand and the hot water was hot enough.

Tank and room thermostats are both fitted here, with water and heating
times set separately.

ok, when the heating is "on" and the room stat is calling for heat, then
heat is always going to the hot water tank, up to the limit of the
boiler's own stat.

In article ,
jon wrote:
For many years in the 70s I had a back boiler behind the living room
fire. We would use drift wood to keep the fire burning which supplied
nearly boiling water for the kitchen and bathroom. Superb arrangement,
but don't know how it was fed with mains water, but it just worked.

We had similar in house built in the 1930s. But also had an external
storage cylinder, fed from the back boiler and with an immersion heater.
You'd not want a roaring fire in the living room just for hot water in the
summer. Even in the North of Scotland.

--
*No hand signals. Driver on Viagra*

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

On 15/05/2021 02:05, John Rumm wrote:

Yup, I know someone with one of those and a gravity circulation loop...



There are still Baxi Bermuda gas back boilers with the radiant fire
fixed to the front. One neighbour close by still uses his. That
has 28mm gravity feed to the hot tank and 22mm pumped rads,
with 4 tapped cores in the side of the Hx. House was built 1976

On 15/05/2021 11:27, Theo wrote:
John Rumm wrote:
It was quite common to have a big cast iron lump HX with high water
content (couple of gallons). That would have 4 bosses on it - two
outputs and two returns. One set would be used for the feed and return
on the pumped circuit through the rads, and the other two would be used
for a gravity (i.e. convected circuit) to heat an indirect cylinder.

Ah, so 'gravity' meant there was no pump on the HW side, only for the
heating?

The convention circuit required that the hot water cylinder would be
placed some distance above the boiler and not too far displaced from it.
It would also typically be piped in 28mm pipe to better allow convection
flow. Hot water from the gravity output would rise up through the pipe,
and through the coil in the cylinder, the heavier cooler water would
fall and return to the boiler. Basically it sets up a thermosyphon.

That's neat. Horribly inefficient, but neat

In a 'modern' house, like the huge numbers built in the 70's, these
were standard fitment for many. The flues were class 2 flue blocks
that were part of the inner block wall, and typically went up through
the bedroom above, and then inside the loft, a 45 degree exit block
connected to the ridge vent tile with asbestos/cement pipe.

The heat emitting from the flue blocks in the bedroom allowed the
builders to fit a rad only half the size of the one in the back
double bedroom (similar room size).

With DG and cavity wall insulation, the only significant waste
of heat was that which escaped from the ridge vent (and the local
rook colony soon learned how to keep warm in winter), so they
may not have been as 'inefficient' as they are made out to be.

The downside was that with full C/H on, the hot tank got up to
80C which was dangerous to some people, but the excess heat
was still not lost to the outside.

Andrew wrote:

There are still Baxi Bermuda gas back boilers with the radiant fire
fixed to the front. One neighbour close by still uses his. That
has 28mm gravity feed to the hot tank and 22mm pumped rads,
with 4 tapped cores in the side of the Hx. House was built 1976

The houses on this estate were built in 1973 with gas backboilers, mine
was replaced by a cast-iron boiler before I bought it. Several
neighbours have fitted a condensing combi, and had to replace tem
already, my lump soldiers on ...

approx 11,000 kWh/year of gas, which covers heating and hot water of a 3
bed semi, at 2.7p/kWh that's £311/year ... where's the sense in
replacing it?

On 15/05/2021 22:30, Theo wrote:
ARW wrote:
On 15/05/2021 11:27, Theo wrote:

I never investigated but I imagine there was just on/off control for the
boiler (gas valve only, since there was an always-on pilot that had a piezo
spark-button to relight it if it went out), and an additional time clock
output that was in series with a thermostat to run the pump for the heating.

How was the boiler turned off in this system, when the thermostat said the
house was hot enough and so was the water? If the heating called for heat
and the hot water was up to temp, surely that would overheat the water?

https://assets.danfoss.com/documents...6en-GB0201.pdf

Were the common programmers of the time

This was the one:
https://www.amazon.co.uk/LANDIS-GYR-.../dp/B072FSJP2N
which was just a simple 1 rev per day motorised dial plus some cams to
operate switches.


On the back of that programmer there is a switch that allows you to
choose between gravity or fully pumped.

What this switch did was link the HW and CH sliders. So if both were off
and you moved CH to timed or ON it also moved the HW slider across to
timed or ON.

However moving the CH from ON to OFF left the HW slider where it was but
moving the HW from ON to OFF also turned off the CH.

Being on gravity makes a lot of sense - the neighbours moved their cast iron
boiler into the garage and 'it never worked properly after'. Which would
follow if the tank is suddenly further away from the boiler.

Yes they would have needed to put a pump in for the HW.


--
Adam

On 16/05/2021 13:42, Andrew wrote:


The downside was that with full C/H on, the hot tank got up to
80C which was dangerous to some people, but the excess heat
was still not lost to the outside.

And not much use in summer.

--
Adam

Andy Burns wrote:
The houses on this estate were built in 1973 with gas backboilers, mine
was replaced by a cast-iron boiler before I bought it. Several
neighbours have fitted a condensing combi, and had to replace tem
already, my lump soldiers on ...

approx 11,000 kWh/year of gas, which covers heating and hot water of a 3
bed semi, at 2.7p/kWh that's £311/year ... where's the sense in
replacing it?

This one suffered from being under a British Gas service plan, and hence
lots of sucking of teeth and 'ye cannae get the parts anymore', and
eventually they refused to cover it.

I don't know if you can actually get the parts these days, or whether
they're sufficiently pattern that you can find or fashion suitable
replacements.

I'm guessing you don't have the gravity hot water as described, though? It
sounds like that was a good reason to fit zone valves and controls on the
hot water, even if you kept the boiler.

Theo

Theo wrote:

I don't know if you can actually get the parts these days, or whether
they're sufficiently pattern that you can find or fashion suitable
replacements.

I've had to replace the thermocouple, obviously they're generic sostill
available, I think I have a spare somewhere, It has no electronics, if
the coil on the gas valve goes that might be curtains for it?

I'm guessing you don't have the gravity hot water as described, though?

I do.

It
sounds like that was a good reason to fit zone valves and controls on the
hot water, even if you kept the boiler.

it's sleeping dogs now ...

On 16/05/2021 15:14, Andy Burns wrote:
Theo wrote:

I don't know if you can actually get the parts these days, or whether
they're sufficiently pattern that you can find or fashion suitable
replacements.

I've had to replace the thermocouple, obviously they're generic sostill
available, I think I have a spare somewhere, It has no electronics, if
the coil on the gas valve goes that might be curtains for it?

Because old boiler are regularly decommissioned, I've never had an issue
with finding parts on eBay.

I'm guessing you don't have the gravity hot water as described, though?

I do.

It
sounds like that was a good reason to fit zone valves and controls on the
hot water, even if you kept the boiler.

it's sleeping dogs now ...

Maybe, but converting the rest of the system to take a heat only boiler
would make the fitting of a new boiler simpler.

I don't think a registered gas installer is allowed to replace a boiler
without bringing heating controls up to date at the same time.

In article ,
Theo wrote:
Andy Burns wrote:
The houses on this estate were built in 1973 with gas backboilers, mine
was replaced by a cast-iron boiler before I bought it. Several
neighbours have fitted a condensing combi, and had to replace tem
already, my lump soldiers on ...

approx 11,000 kWh/year of gas, which covers heating and hot water of a 3
bed semi, at 2.7p/kWh that's £311/year ... where's the sense in
replacing it?

This one suffered from being under a British Gas service plan, and hence
lots of sucking of teeth and 'ye cannae get the parts anymore', and
eventually they refused to cover it.

Our Village Hall boiler failed and the BG fitter hasd the usual "can't get
the parts". Using Yellow Pages (this was a few years ago) I found an
independant 'gas man'. He looked used his mobile "George have you got and
XX for a YY boiler?" "OK, I'll pick it up later today". We got another 5
years' life out of the boiler and never went near BG again. Currently we
have a service contract with the boiler manufacturer.

--
from KT24 in Surrey, England
"I'd rather die of exhaustion than die of boredom" Thomas Carlyle

Fredxx wrote:

but converting the rest of the system to take a heat only boiler
would make the fitting of a new boiler simpler.

I don't think a registered gas installer is allowed to replace a boiler
without bringing heating controls up to date at the same time.

I'm hoping that will become SEP.

On 16/05/2021 06:34, Andy Burns wrote:
Roger Mills wrote:

Inefficient, yes because there was no boiler interlock. In other
words, the boiler continued to fire just to keep itself warm even when
there was no heating demand and the hot water was hot enough.

Tank and room thermostats are both fitted here, with water and heating
times set separately.

ok, when the heating is "on" and the room stat is calling for heat, then
heat is always going to the hot water tank, up to the limit of the
boiler's own stat.

Presumably thentank stat controls the boiler when there's no central
heating demand - which is better than the default gravity system with no
tank stat.

Have you considered installing a motorised valve in the HW circuit in
order to convert your system to a C-Plan?
--
Cheers,
Roger
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Roger Mills wrote:

Presumably thentank stat controls the boiler when there's no central
heating demand - which is better than the default gravity system with no
tank stat.

yes, that's right.

Have you considered installing a motorised valve in the HW circuit in
order to convert your system to a C-Plan?

Not especially.

On 16/05/2021 21:03, Andy Burns wrote:
Roger Mills wrote:

Presumably thentank stat controls the boiler when there's no central
heating demand - which is better than the default gravity system with
no tank stat.

yes, that's right.

Have you considered installing a motorised valve in the HW circuit in
order to convert your system to a C-Plan?

Not especially.


It would provide a boiler interlock - turning the boiler off when both
demands are satisfied.That should save you some gas. It would also
prevent the hot water from overheating when the central heating is on.
--
Cheers,
Roger
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Please reply to Newsgroup. Whilst email address is valid, it is seldom
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