hi,


Roger Mills wrote:

In an earlier contribution to this discussion,
raesene wrote:

Hi,

I've got a problem with the hot water in my house which I'd really
appreciate it if anyone could shed some light on.

Background -

House is ~20 years old and all I know about the boiler is it's a Baxi
and I think from the piping that it's a direct boiler system as the
description I found here seems to fit
http://www.diydoctor.org.uk/projects...er%20s ystem:
. There's no thermostats on the system it's just time based and the
boiler runs both the Central Heating and hot water.

I'm not sure what you mean by a "direct boiler system". You will almost
certainly *not* have a direct HW cylinder - but an indirect one - like the
right-hand picture in the above reference. This has an internal coil through
which water from the boiler passes, heating the surrounding water in the
cylinder without mixing with it. Unless you have a (diabolical!) primatic
cylinder, the primary (boiler/heating coil/radiators) circuit is entirely
separate from the secondary domestic hot water circuit - each having its own
cold header tank.


Problem -

I drained down the water today to have a look at a problem with a
shower valve. I did this by turning off the boiler at the control
then closing the mains water valve and running the hot and cold taps
in the bathrooms till they ran out.

After looking at the shower I opened the mains water valve and left it
to refill the tanks. Now the cold water system is working fine, but
there doesn't appear to be any hot water coming from the taps.

The central heating works fine and the pilot light on the boiler seems
lit. If I check the pipes running to the hot water tank when the hot
water is on they seem to be warm to the touch and also I've checked
the small cold water tank at the back of the hot water tank (which
seems to feed the tank) and there is water in that ok.

I'm guessing that there's something obvious that I'm missing here, so
if anyone can point me in the right direction that'd be great


Assuming that you *haven't* got a primatic system, the most likely
explanation is that you've got an air-lock in the DHW system. The classical
cure for this is to use a hosepipe to connect mains cold water to the outlet
of one of the hot taps, forcing water up into the header tank, and clearing
any trapped air in the process.

But I think we need to bottom out exactly what you *have* got, first. Any
chance that you could take a few digital photos of your installation -
particularly HW cylinder and header tank(s) - and upload them somewhere, and
post a URL here?

here's some pictures.

Here's the boiler http://www.mccune.org.uk/plumb/boiler.jpg

here's the controller http://www.mccune.org.uk/plumb/controller.jpg

here's a view of the tanks http://www.mccune.org.uk/plumb/tanks2.jpg .

The hot water tank is the one on the left hand side the cold water tank
is on the right.

here's a view of the pipes running to/from the hot water tank
http://www.mccune.org.uk/plumb/pipes.jpg

the two running away on the left seem to go to the boiler.

Here's a view of the small water tank at the back/top of the hot water
tank http://www.mccune.org.uk/plumb/flow-tank.jpg


Hope this helps answer what it is... Thanks for the help so far :O)



--
Cheers,
Roger
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