I have a closed oil central heating system. Just last year for no
apparent reason the hot press stopped getting hot. I replaced the pump
and the expansion vessel.

I also notice that the pressure at the expansion vessel is quite low -
about 0.5 bar.

I cannot see any leaks

I have blead all of the radiators

All of the radiators heat up properly - except the tank in the hot
press

Please help - Thanks

Rob

In an earlier contribution to this discussion,
Robert wrote:

I have a closed oil central heating system. Just last year for no
apparent reason the hot press stopped getting hot. I replaced the pump
and the expansion vessel.

I also notice that the pressure at the expansion vessel is quite low -
about 0.5 bar.

I cannot see any leaks

I have blead all of the radiators

All of the radiators heat up properly - except the tank in the hot
press

Please help - Thanks

Rob


Please explain what you mean by the "hot press". It's not a term I've come
across!
--
Cheers,
Set Square
______
Please reply to newsgroup. Reply address is Black Hole!

A hot press is a very small room in which you place a big copper tank.
A worm from the heating system goes in and out of it. The worm heats
the water inside and supplies the hot water tap.

Some people call it an airing cupboard.

So it is this tank that is not heating proberly.

Thanks for the reply

Any suggestions

Robert
Please explain what you mean by the "hot press". It's not a term I've come
across!

On 9 Mar 2004 05:10:36 -0800, in uk.d-i-y
(Robert) strung together this:

A hot press is a very small room in which you place a big copper tank.
A worm from the heating system goes in and out of it. The worm heats
the water inside and supplies the hot water tap.

Some people call it an airing cupboard.

So it is this tank that is not heating proberly.

Thanks for the reply

Any suggestions

Hmm, novel terminology!
What type of heating system have you got? Is it a gravity, y\s plan or
something else entirely?
If it's a pressurised system you did refill it didn't you? Do you mean
it's dropping to .5 bar or will not fill to above .5 bar, or has it
ever been above .5 bar?
--

SJW
A.C.S. Ltd.

I also notice that the pressure at the expansion vessel is quite low -
about 0.5 bar.

Do you mean the water pressure when filled, or the pre-charge pressure?

If the former, increase the pressure to 1 bar* by connecting and opening up
the filling loop for a few seconds. If this doesn't fix it, then you may
have an airlock, or a control system problem.

Alternatively, you may have a gravity circulated system, which just doesn't
work. This type of system is very unlikely on a sealed system.

Control system problems might be:

1. Failed cylinder thermostat.
2. Cylinder thermostat set very low.
3. Failed zone valve.
4. Failed programmer.
5. Programmer not set to heat.
6. Wiring damaged
7. Balance valve closed off.

Christian.

* If your house has more than 3 storeys, a more careful calculation must be
done.

It is a pressurised system - I did remember to refill it - When I
measure the pressure at the expansion vessel the pressure is 0.5 bar -
it used to be just over 1 bar.

The pipes are mainly microbor (3/8")

There is definetly no air locks in the system. Since all of the
radiators heat proberly I don't think there is a problem with the
boiler or programmer.

We have a 2 storey house

What is a filling loop??

Thanks for the reply

Rob

Robert wrote:
It is a pressurised system - I did remember to refill it - When I
measure the pressure at the expansion vessel the pressure is 0.5 bar -
it used to be just over 1 bar.

The pipes are mainly microbor (3/8")

There is definetly no air locks in the system. Since all of the
radiators heat proberly I don't think there is a problem with the
boiler or programmer.

We have a 2 storey house

What is a filling loop??

Thanks for the reply

Rob

Filling loop is hte connection between mains water and your pressurised
heating circuit, and the means by which you refill it.... but I am
suprised you didn't know this if you've got as far as refilling the
system :-) You *did* use this method, I hope?

I have a sealed system with a potterton puma, and the boiler gives the
recommended pressure of the system in all it's gumph. It also has a
built in pressure gauge on the boiler. It's normally around 1.5bar, but
it may well be different for your boiler so don't assume that's right
for all systems.

Velvet

On 11 Mar 2004 01:16:59 -0800, in uk.d-i-y
(Robert) strung together this:

It is a pressurised system - I did remember to refill it - When I
measure the pressure at the expansion vessel the pressure is 0.5 bar -
it used to be just over 1 bar.

The pipes are mainly microbor (3/8")

There is definetly no air locks in the system. Since all of the
radiators heat proberly I don't think there is a problem with the
boiler or programmer.

Not neccesarily.

We have a 2 storey house

And?

What is a filling loop??

If you re-pressurised the system you should already know this one.
It's a connection, usually a braided silvery flexible pipe, between
the cold water supply and the heating return.
I still don't know what type of heating you've got.
--

SJW
A.C.S. Ltd.

I leave the stop cock open on the filling loop - so that any water
that the system loses, due to the pressure release valve, can be
refilled easily - so the filling loop is always open - is this okay.
There is still not enough pressure.

The pressure release valve doesn't operate until the pressure is well
over 1 bar.

I'm not sure what kind of boiler I have - I'll check it and post it
soon.

Thanks again for the reply

Rob

In message , Robert
writes
I leave the stop cock open on the filling loop - so that any water
that the system loses, due to the pressure release valve, can be
refilled easily - so the filling loop is always open - is this okay.
There is still not enough pressure.

The pressure release valve doesn't operate until the pressure is well
over 1 bar.

I'm not sure what kind of boiler I have - I'll check it and post it
soon.

Is this a wind up?

--
geoff

On 11 Mar 2004 07:18:54 -0800, in uk.d-i-y
(Robert) strung together this:

I leave the stop cock open on the filling loop - so that any water
that the system loses, due to the pressure release valve, can be
refilled easily - so the filling loop is always open - is this okay.
There is still not enough pressure.

The pressure release valve doesn't operate until the pressure is well
over 1 bar.

I'm not sure what kind of boiler I have - I'll check it and post it
soon.

Thanks again for the reply

I think you'd better get a plumber in. You are obviously way out of
your depth here.
--

SJW
A.C.S. Ltd.

On Thu, 11 Mar 2004 07:18:54 -0800, Robert wrote:

I leave the stop cock open on the filling loop - so that any water
that the system loses, due to the pressure release valve, can be
refilled easily - so the filling loop is always open - is this okay.
There is still not enough pressure.

The pressure release valve doesn't operate until the pressure is well
over 1 bar.

I'm not sure what kind of boiler I have - I'll check it and post it
soon.

Thanks again for the reply

Check out the Sealed CH FAQ below.
It applicable to oil fired heating aswell.
Perhaps your mains pressure is very low?



--
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