My mother had her central eating boiler replaced a couple of months
ago, and I went up to see her for the first time last week (I know, I
know, but I do phone her every week). I was amazed at what has been
installed.

The original system dated from the 1970s, with no room thermostats.
TRVs were added later to all radiators. The new boiler has been
installed, but there is no by-pass circuit, much less a valve or flow
switch, so one radiator must be left on permanently. The only
effective control over heat is the boiler thermostat. I don't know
whether the system had a by-pass circuit before. Could there have
been a flow switch in the old boiler?

Putting aside the question of complying with the Building Regulations
(which it doesn't), how dangerous is it to have a heating circuit
entirely controlled by TRVs with no by-pass? I tried closing all the
TRVs, but the boiler continued firing and I could hear the pump
beginning to strain. What would happen if i had let this continue, or
my mother (who's nearly 80, and a bit forgetful) decides to lower the
only open TRV?
--
Hugo Nebula
'What you have to ask yourself is, "if no-one on the internet wants
a piece of this, just how far from the pack have you strayed?"'

In an earlier contribution to this discussion,
Hugo Nebula abuse@localhost wrote:

My mother had her central eating boiler replaced a couple of months
ago, and I went up to see her for the first time last week (I know, I
know, but I do phone her every week). I was amazed at what has been
installed.

The original system dated from the 1970s, with no room thermostats.
TRVs were added later to all radiators. The new boiler has been
installed, but there is no by-pass circuit, much less a valve or flow
switch, so one radiator must be left on permanently. The only
effective control over heat is the boiler thermostat. I don't know
whether the system had a by-pass circuit before. Could there have
been a flow switch in the old boiler?

Putting aside the question of complying with the Building Regulations
(which it doesn't), how dangerous is it to have a heating circuit
entirely controlled by TRVs with no by-pass? I tried closing all the
TRVs, but the boiler continued firing and I could hear the pump
beginning to strain. What would happen if i had let this continue, or
my mother (who's nearly 80, and a bit forgetful) decides to lower the
only open TRV?

I don't think it will actually explode - but it's extremely bad practice.
The worst that will happen is that the boiler will overheat, its overheat
stat will trip, and your mother will have no heating. The pump will also get
a bit frenzied - but may be able to run in a stalled condition without
coming to any actual harm.

Does the boiler also heat the hot water? Is this the same system which you
mentioned in your earlier thread about not having a room stat?

--
Cheers,
Set Square
______
Please reply to newsgroup. Reply address is invalid.

"Set Square" wrote in message
...
In an earlier contribution to this discussion,
Hugo Nebula abuse@localhost wrote:

My mother had her central eating boiler replaced a couple of months
ago, and I went up to see her for the first time last week (I know, I
know, but I do phone her every week). I was amazed at what has been
installed.

The original system dated from the 1970s, with no room thermostats.
TRVs were added later to all radiators. The new boiler has been
installed, but there is no by-pass circuit, much less a valve or flow
switch, so one radiator must be left on permanently. The only
effective control over heat is the boiler thermostat. I don't know
whether the system had a by-pass circuit before. Could there have
been a flow switch in the old boiler?

Putting aside the question of complying with the Building Regulations
(which it doesn't), how dangerous is it to have a heating circuit
entirely controlled by TRVs with no by-pass? I tried closing all the
TRVs, but the boiler continued firing and I could hear the pump
beginning to strain. What would happen if i had let this continue, or
my mother (who's nearly 80, and a bit forgetful) decides to lower the
only open TRV?

I don't think it will actually explode - but it's extremely bad practice.
The worst that will happen is that the boiler will overheat, its overheat
stat will trip, and your mother will have no heating. The pump will also
get
a bit frenzied - but may be able to run in a stalled condition without
coming to any actual harm.

Does the boiler also heat the hot water? Is this the same system which you
mentioned in your earlier thread about not having a room stat?

--
Cheers,
Set Square
______
Please reply to newsgroup. Reply address is invalid.



What sort of boiler is it, some ahve bypass vlaves fitted as standard.

On Sun, 17 Oct 2004 12:47:16 +0100, a particular chimpanzee named "Set
Square" randomly hit the keyboard and produced:

Does the boiler also heat the hot water? Is this the same system which you
mentioned in your earlier thread about not having a room stat?

It is, yes. It also heats the hot water, which has a cylinder stat.
--
Hugo Nebula
'What you have to ask yourself is, "if no-one on the internet wants
a piece of this, just how far from the pack have you strayed?"'

On Sun, 17 Oct 2004 12:51:08 GMT, a particular chimpanzee named
"Stephen Dawson" randomly hit the
keyboard and produced:

What sort of boiler is it, some ahve bypass vlaves fitted as standard.

It's an Ideal Classic. The installation guide says that a by-pass
circuit or by-pass valve must be fitted, which implies that there
isn't one already. Would a Thorn boiler of the 1970's have had an
integral by-pass or flow switch?
--
Hugo Nebula
'What you have to ask yourself is, "if no-one on the internet wants
a piece of this, just how far from the pack have you strayed?"'

"Set Square" wrote in message ...

Pumps run fine in stalled water, in fact they run like that easier
than with flow. A little oddity of centrifugal pumps. Same with
cylinder vacs which use the same basic concept of pump: block the tube
and the motor speed increases.

NT

On Sun, 17 Oct 2004 18:40:11 +0100, Hugo Nebula wrote:

On Sun, 17 Oct 2004 12:51:08 GMT, a particular chimpanzee named
"Stephen Dawson" randomly hit the
keyboard and produced:

What sort of boiler is it, some ahve bypass vlaves fitted as standard.

It's an Ideal Classic. The installation guide says that a by-pass
circuit or by-pass valve must be fitted, which implies that there
isn't one already. Would a Thorn boiler of the 1970's have had an
integral by-pass or flow switch?

I was about to respond to your earlier posts and say 'it depends on the
boiler'. In this case if the makes say it needs a bypass that's what it
needs.

As for the previous installation: It would be have been noteworthy to have
had a flow switch. It could conceivably have had a bypass if it had had
S-plan controls or equiv. However with an installation of that period it
is much more likely that it used the
HW cylinder coil as the bypass and it always heated the HW when the CH was
on.

--
Ed Sirett - Property maintainer and registered gas fitter.
The FAQ for uk.diy is at www.diyfaq.org.uk
Gas fitting FAQ http://www.makewrite.demon.co.uk/GasFitting.html
Sealed CH FAQ http://www.makewrite.demon.co.uk/SealedCH.html

My mother had her central eating boiler replaced a couple of months
ago, and I went up to see her for the first time last week (I know, I
know, but I do phone her every week). I was amazed at what has been
installed.

It was illegal to install the new boiler in that manner. The heating
controls must be brought up to modern Part L1 standards when a boiler is
replaced.

Christian.