Hot water problem after drain down

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/domestic_hot_water_systems.htm#Direct%20boiler%20system : . There's no thermostats on the system it's just time based and the boiler runs both the Central Heating and hot water.
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
Thanks
Rory
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In an earlier contribution to this discussion,

http://www.diydoctor.org.uk/projects/domestic_hot_water_systems.htm#Direct%20boiler%20system :
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.

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?
--
Cheers,
Roger
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hi,
Roger Mills wrote:

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)

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In an earlier contribution to this discussion,

Thanks for the pictures. Unfortunately, nothing that I recognise!
Do you not also have a hot water cylinder in an airing cupboard? The tank which you describe as the HW tank doesn't look very big to me, and the F&E tank isn't where I would expect it to be, relative to the cylinder.
--
Cheers,
Roger
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Roger Mills wrote:

Those are the only tanks that I've seen whilst being in the house, and there's definately not any other tanks that I've ever seen in any of the rooms in the house.
One quick question. Would it be likely to cause any problems if I tried the remedy for an airlock (putting mains water pressure into one of the hot water taps) regardless? Just thinking it would be useful to eliminate that as a possibility before trying other things/calling out a plumber...
Thanks

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raesene wrote:

Just to say that it's fixed now. I went the safe route and got someone out to have a look at it. It was an airlock and all working now!
Thanks for the help
rory

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In an earlier contribution to this discussion,

Excellent. Probably the safest thing to do. I wouldn't advise using mains pressure unless you understand the system design and are sure that it will not cause any damage.
--
Cheers,
Roger
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