I posted this a while ago but I cant see it on E-S apologies if this is
a duplicate.

I am assisting with the recovery of an inherited property. The existing
heating scheme was designed and installed by the (now deceased) owner in
the mid 70s or early 80s.

It consists of a floor standing Potterton Diplomat with 2 water outlets
one labelled DHW+Upstairs which is split to supply two separate pumps,
the other labelled downstairs, with its own pump.

Timers/thermostats for upstairs and downstairs but no timer on DHW (Just
a tank thermostat). And a relay box to ensure only two of the three
pumps can run simultaneously. (or maybe its just to ensure upstairs and
DWH don't run together)

No TRVs anywhere, obliviously.

Massive twin panel radiators (no fins) in every room, no obvious signs
of corrosion on any of them (I would assume it has been regularly
inhibited at least until the last 5 years or so)

The current water supply temperature from the boiler is 49C (this is
clearly as designed as each pipe has a clip on thermostat with an arrow
marked on the glass. The water temp is on the arrow.

The system certainly used to function as the house was always warm when
visited - but I have no idea what the gas bills were.

From discussions with the owners brother he believed that large
radiators at low temp was the most efficient way to run the heating.

That might well be true and it might well work if you are in the house
all day but we have recently discovered that it takes 9 hours to bring
the house up from 15C to 21C. (Outside temp 8-12C, the property has DG
and Cavity wall insulation)

All the radiators are barely warm at the top and cold at the bottom.

So something has to be done in the short term but the house may be
undergoing major upgrades in the intermediate future (Showers fitted ,
possibly en suite etc) but the exact detail/layout of all this is still TBD.

The new owners are considering a modern boiler, I think as much for
safety reasons as any other as they don't trust this huge great lump in
the kitchen not to be leaking noxious gasses, (a CO monitor has been
fitted as a temporary measure) and the chances of getting anyone to
service it are pretty close to zero.

So my questions are.
1) I am planning to remove all the radiators take them outside and give
them a good hosing through. Would this leave sludge in the pipes and if
so how can it be removed prior to fitting a new boiler. Would this be
adequate or with radiators of this age should they be replaced along
with the boiler?

2) Would the system described above be suitable for adding a modern
boiler pretty much one for one swap with the existing (having flushed
out all of the radiators and fitted TRVs) or would major changes be
necessary. I have looked at the DIY WIKI and it states that with modern
TRVs oversized radiators are not a problem.

3) If a modern boiler is fitted this winter are they all suitable for
using with a pressurised water cylinder if that is the route taken in a
year or so when other modernisation work is done? The Worcester Bosh
website seems to state that their regular Greenstar boilers are
compatible with gravity HW or their own Greenstore (pressurised) cylinder.

Any helpful advice appreciated.
--
Chris B (News)

In message , Chris B
writes
Would this be adequate or with radiators of this age should they be
replaced along with the boiler?

I cannot add anything particularly useful to most of your points except
to say that our ex shop, which is now my play room (!) had huge old non
finned single panel radiators which were installed 1979. They worked,
but no TRVs, which was a nuisance, so when fitting TRVs the rads were
replaced with modern twin panel finned versions. The difference in
controllability and heat output is amazing. Bottom line, the new rads
are shorter than the old, yet give out far more heat.
--
Graeme

Chris B wrote:
I posted this a while ago but I cant see it on E-S apologies if this is
a duplicate.

I am assisting with the recovery of an inherited property. The existing
heating scheme was designed and installed by the (now deceased) owner in
the mid 70s or early 80s.

It consists of a floor standing Potterton Diplomat with 2 water outlets
one labelled DHW+Upstairs which is split to supply two separate pumps,
the other labelled downstairs, with its own pump.

Timers/thermostats for upstairs and downstairs but no timer on DHW (Just
a tank thermostat). And a relay box to ensure only two of the three
pumps can run simultaneously. (or maybe its just to ensure upstairs and
DWH don't run together)

No TRVs anywhere, obliviously.

Massive twin panel radiators (no fins) in every room, no obvious signs
of corrosion on any of them (I would assume it has been regularly
inhibited at least until the last 5 years or so)

The current water supply temperature from the boiler is 49C (this is
clearly as designed as each pipe has a clip on thermostat with an arrow
marked on the glass. The water temp is on the arrow.

The system certainly used to function as the house was always warm when
visited - but I have no idea what the gas bills were.

From discussions with the owners brother he believed that large
radiators at low temp was the most efficient way to run the heating.

That might well be true and it might well work if you are in the house
all day but we have recently discovered that it takes 9 hours to bring
the house up from 15C to 21C. (Outside temp 8-12C, the property has DG
and Cavity wall insulation)

All the radiators are barely warm at the top and cold at the bottom.

So something has to be done in the short term but the house may be
undergoing major upgrades in the intermediate future (Showers fitted ,
possibly en suite etc) but the exact detail/layout of all this is still
TBD.

The new owners are considering a modern boiler, I think as much for
safety reasons as any other as they don't trust this huge great lump in
the kitchen not to be leaking noxious gasses, (a CO monitor has been
fitted as a temporary measure) and the chances of getting anyone to
service it are pretty close to zero.

So my questions are.
1) I am planning to remove all the radiators take them outside and give
them a good hosing through. Would this leave sludge in the pipes and if
so how can it be removed prior to fitting a new boiler. Would this be
adequate or with radiators of this age should they be replaced along
with the boiler?

2) Would the system described above be suitable for adding a modern
boiler pretty much one for one swap with the existing (having flushed
out all of the radiators and fitted TRVs) or would major changes be
necessary. I have looked at the DIY WIKI and it states that with modern
TRVs oversized radiators are not a problem.

3) If a modern boiler is fitted this winter are they all suitable for
using with a pressurised water cylinder if that is the route taken in a
year or so when other modernisation work is done? The Worcester Bosh
website seems to state that their regular Greenstar boilers are
compatible with gravity HW or their own Greenstore (pressurised) cylinder.

Any helpful advice appreciated.

The boiler can be serviced, just about all parts are available. Up to
the point where the heat exchanger springs a leak, these units will go
on for many years. A modern boiler has a life of 7 years before
replacement.(gas fitter experience)

I'd change the radiators for modern twin panel finned units and fit TRVs.

On Wed, 8 Nov 2017 12:29:14 +0000
Chris B wrote:

That might well be true

Simple physics says it's not.

and it might well work if you are in the
house all day but we have recently discovered that it takes 9 hours
to bring the house up from 15C to 21C. (Outside temp 8-12C, the
property has DG and Cavity wall insulation)

All the radiators are barely warm at the top and cold at the bottom.

So something has to be done in the short term

You could just try turning the stats up and see what happens (the rad
valves might need adjusting too to get even heating from each one).

On 08/11/2017 12:29, Chris B wrote:

I posted this a while ago but I cant see it on E-S apologies if this is
a duplicate.

I am assisting with the recovery of an inherited property. The existing
heating scheme was designed and installed by the (now deceased) owner in
the mid 70s or early 80s.

It consists of a floor standing Potterton Diplomat with 2 water outlets
one labelled DHW+Upstairs which is split to supply two separate pumps,
the other labelled downstairs, with its own pump.
Timers/thermostats for upstairs and downstairs but no timer on DHW (Just
a tank thermostat).

They might be triggering the DHW pump direct from the stat.

And a relay box to ensure only two of the three
pumps can run simultaneously. (or maybe its just to ensure upstairs and
DWH don't run together)

No TRVs anywhere, obliviously.

Massive twin panel radiators (no fins) in every room, no obvious signs
of corrosion on any of them (I would assume it has been regularly
inhibited at least until the last 5 years or so)

The current water supply temperature from the boiler is 49C (this is
clearly as designed as each pipe has a clip on thermostat with an arrow
marked on the glass. The water temp is on the arrow.

That would limit the maximum DHW temperature to under 49 deg as well...
(not good from a sanitary point of view)

The system certainly used to function as the house was always warm when
visited - but I have no idea what the gas bills were.

From discussions with the owners brother he believed that large
radiators at low temp was the most efficient way to run the heating.

With a modern condensing boiler that might be true, for for an old cast
iron lump it just seems like a way of ensuring accelerated corrosion of
the main HX due to condensation of the flue gasses.

That might well be true and it might well work if you are in the house
all day but we have recently discovered that it takes 9 hours to bring
the house up from 15C to 21C. (Outside temp 8-12C, the property has DG
and Cavity wall insulation)

All the radiators are barely warm at the top and cold at the bottom.

That sounds like either a insufficient flow problem (check the pumps),
or a serious sludging up problem.

So something has to be done in the short term but the house may be
undergoing major upgrades in the intermediate future (Showers fitted ,
possibly en suite etc) but the exact detail/layout of all this is still
TBD.

Checking the pumps and doing a mains pressure flush as a short term fix:

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

The new owners are considering a modern boiler, I think as much for
safety reasons as any other as they don't trust this huge great lump in
the kitchen not to be leaking noxious gasses, (a CO monitor has been
fitted as a temporary measure) and the chances of getting anyone to
service it are pretty close to zero.

It should be fairly simple to service I would have thought... check the
combustion, sweep out the HE, etc.

So my questions are.
1) I am planning to remove all the radiators take them outside and give
them a good hosing through. Would this leave sludge in the pipes and if
so how can it be removed prior to fitting a new boiler. Would this be
adequate or with radiators of this age should they be replaced along
with the boiler?

If having flushed each rad, you do a final flush through the whole
system, that should be adequate. You can dump some system cleaner in a
week before doing the flush.

2) Would the system described above be suitable for adding a modern
boiler pretty much one for one swap with the existing (having flushed
out all of the radiators and fitted TRVs) or would major changes be
necessary. I have looked at the DIY WIKI and it states that with modern
TRVs oversized radiators are not a problem.

Over sized rads (in therms of performance rather than physical size
necessarily) are fine on a modern modulating condenser - it can run
lower flow temps for greater condensing efficiency.

3) If a modern boiler is fitted this winter are they all suitable for
using with a pressurised water cylinder if that is the route taken in a
year or so when other modernisation work is done?

Yup, from the CH / boiler point of view a unvented cylinder looks pretty
much the same as a fast recovery conventional cylinder.

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

The Worcester Bosh
website seems to state that their regular Greenstar boilers are
compatible with gravity HW or their own Greenstore (pressurised) cylinder.

Yup, and will also be compatible with any other make of unvented
cylinder as well.

You may need to look at a boiler that is capable of split temperature
operation so that you can run low flow temps on the rads, but still have
higher temps for a cylinder recharge. Its more normal to run the DHW
separately from the heating so that you don't heat the rads to DHW temps
or vice versa.

Any helpful advice appreciated.

A single pump and S Plan+ type system may suit the setup best. You
could look at a system boiler if you want less "clutter" in the system.

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

If its a larger house then consider weather compensating controls with
an external stat as well. That will allow the system to run cooler for
most of the year, but then automatically ramp up the flow temperature
when required on colder days.


--
Cheers,

John.

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