On 17/08/2018 09:15, David wrote:
On Fri, 17 Aug 2018 00:51:58 +0100, John Rumm wrote:

On 16/08/2018 12:33, David wrote:
On Thu, 16 Aug 2018 10:39:14 +0000, David wrote:

The ancient Radiant combi is mounted on an outside wall, and there is
a copper pipe (I assume the condensate drain) sticking out of the wall
with a downwards bend which is more or les constantly dripping.

I assume that this should go into some form of drainage. This may
explain why the concrete lintel below is rotting away.

Anyway, there is a rainwater down pipe close to it. Is it acceptable
to put some kind of joint in the downpipe so that the copper pipe
drips into it? The drain below is where some of the condensate will go
eventually.

Guttering is "interesting" and I'm not looking forward to fixing it
although it looks as though most of the grass growing out of the
shonky joints has been killed by the recent hot dry weather.

Model is Radiant RSF 20 E.

Looks as though it was installed in 2000.

After a bit of confusion which I think was due to the pilot light going
out I managed to get the heating running. It seems to work. :-).
I am online manual surfing and have found a couple of sites, but so far
I haven't been able to establish if it is a condensing boiler.

Looking at the manual for the RSF 30 E, its not.

Looking at the SEDBUK database:

http://www.ncm-pcdb.org.uk/sap/pcdbdetails.jsp?
pid=26&id=008548&type=105&mid=000088

says non condensing as well.

The blinken lights on the front seem to indicate that pressure is fine
so it may not be a leak from the expansion whatsit (but where is the
outlet for the expansion valve if this isn't it?).

Unless you have a leak between the primary and secondary sides of the
*secondary* plate heat exchanger, (rare), my money would be on the
valve.

Yes, if it was condensing there would have to be two drains.

It looks as though the boiler has been leaking over an extended period
given the staining down the wall below the copper pipe.

However the boiler says that the pressure is O.K. (nothing as fancy as a
gauge, just a red light for low pressure, one for 1 bar and one for 1.5
bar). The 1 and 1.5 are both lit.

That alas does not sound like it would tell you when the pressure is 3
bar... too much pressure being the issue here rather than too little.

so it looks as though something is maintaining the system pressure despite
the leaks.

Possibly, as suggested, the pressurising loop is permanently open?

or letting by...

Noted that this would not maintain any inhibitor in the system.

The boiler is noted as needing replacement but I'm wondering if at the
moment the fact that it is working is enough to justify leaving it alone
and keeping a wary eye on it.

It could be as simple as a failed (or run out of air) expansion vessel.
That would result in the pressure rising excessively every time the
system got hot, and water would be vented outside. If the filling loop
is open then it would auto reset.

You can check if the valve is still letting by - attach a plastic
sandwich bag over the blow off pipe with a rubber band and see if it
collects any water over a day or so. If you suspect the pressure vessel,
then you can make a stopgap one by bleeding some water from a rad and
leaving a pocket of air in the top of it.

--
Cheers,

John.

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