Gravity DHW appears to go in reverse; inefficient operation

[dieselhead]

My hot water appears to leave the boiler from the lower tapping and return via the upper tapping ie the lower pipe is much hotter; also on the hot water cylinder the hot water appears to enter at the bottom and leave at the top; surely this is the wrong way round? Why would this be? It happens like this both when the CH is on and off.

The HW is very inefficient.

Should there be an anti-gravity valve and/or injector tee somewhere (i can't see one). What is one of these;how does it work?

I can post photos of the boiler plumbing if these would be useful.

Thanks
diesel

 

[doitall]

Gravity cannot reverse, however it was common to take the flow into the botton tapping of the cylinder when pumped.

photos may be a good idea.

 

[corgiman]

aI agree with DIA

as for the cold entering the bottom and leaving the top i will just say hot water rises so the other way would be daft in the extreme

 

[dieselhead]

Yes I don't know what's going on here.

When I first moved in in March I looked at the radiator in the hall and thought it had been plumbed in the wrong way round because the hot was fed to the bottom. Weeks later I found the pump was pumping the water from the bottom of the heat exchanger (ie the wrong way) so I turned the pump round so that it now returns cool water to the bottom of the heat exchanger. The hall radiator is now fed correctly as well ie hot water to the top tapping. All the other rads in the house are connected only via their bottom tappings (why is this?)

I don't know if british gas at some point turned that pump around for a reason, i am not an expert in these systems. It really needs someone expert to take a look at the whole system. When I moved in I didn't continue the service contract with BG as I considered it poor value for money.

diesel

 

[dieselhead]

Here are the photos. You can just make out the arrow on the bottom of the pump (points to the left).

www.decandole.eclipse.co.uk/images/

I did the writing in marker pen.

It's a glo worm hideaway 50 with conventional flue. Some of the pipework round the boiler looks very shiny and new especially the CH connections in 22mm. The two HW connections are in 28mm.

Thanks Guys
diesel[/img]

 

[urbanspaceman]

change the boiler and upgrade the system

 

[ChrisR]

Can't see what the pump's connected to!
It's in the return, yes? OK.
Otherwise looks ok.
You could improve HW a couple of ways, but not trivial!

 

[dieselhead]

Yes the pump is in the return.

The boiler's instructions say the pump should be fitted on the flow if inside the boiler casing which it is. Does this matter

How would you upgrade/modify the system?

I bought a cylinder thermostat but the wiring would be quite difficult and have just had fitted carpets put down upstairs. A radio linked one would be good!

 

[dieselhead]

The efficiency of the boiler as given in its instructions is 77%.

A modern fanned flue one is only 80 - 85%

The annual saving in gas bills is let's say 10% so that would save me £50 a year. £2000 replacement cost ... it would never pay for itself.

And I also have a solid cast iron heat exchanger which will last for years, instead of some flimsy thing which will corrode thru in a 5 years, no fan to go wrong, no zone valve to sieze, no complex electronics to die ... even if the pump fails I still have hot water.

OK so maybe i'm not doing my bit for global warming!

diesel