For the fearless

[Chrisdee]

Hey,
Problem: Solid fuel stove is boiling and causing a racket.
It has a gravity circuit 28mm.
It seems to circulate fine with a very light fire. But once the draughts are opened it just overheats.
The gravity flow rises all the way to the attic{two story house}, crosses horizontally for two meters and drops to the cylinder coil.
Return goes from the cylinder along the 1st floor joists and drops to the stove . About 15m in length.
The rads are taken from the stove separately in22m from the second two tappings on the stove.

Any ideas?


Also, The cylinder is upstairs. It is open vented to a storage tank in the attic. The highest point of the flow pipe is in the attic just before it goes horizontally to where it drops to the cylinder coil

 

[ecowarm]

Flow should rise to to the coil all the way, return should fall all the way to boiler.
Also the heating, does it have a pump or just gravity to the rads?
If pumped is it wired with a high limit stat to pump exess heat to rads?

 

[quality]

The highest point of the flow pipe is in the attic just before it goes horizontally to where it drops to the cylinder coil

A gravity hot water heating system cannot operate this way😕

 

[justlead1]

It is doing the job both hot water an rad ok. Try putting a couple of extra fire brick to reduce the direct surface area of the water jacket / boiler. Good Luck

 

[Robtheplumb]

A gravity hot water heating system cannot operate this way😕

I know of two that do work ok this way, one is on an oil boiler and the other is on an Aga.

 

[Billy Bob Bob]

A gravity hot water heating system cannot operate this way😕

i have never heard of gravity being done like this or seen any,wonder it works at all

 

[Robtheplumb]

Well... From what I have seen on these two systems, the flow is higher then the return and that must be how they work. The oil boiler is about 5m from the cylinder, up, along then down all in 28mm with the return going down under the floor back to the boiler. The Aga is about 6m from the cylinder and both the flow and return go up.

 

[justlead1]

Hi. By increasing the height of the gravity loop, in the way described is help the circulation and is not uncommeon to find the pipe work unlagged at the point it drops down to the cylinder. By cooling the water a few degrees its mass increases and falls quicker creating better circulation. Please bare in mind another knob of coal on the fire was not an issues in the days of gravity designed systems.

 

[Chrisdee]

Thanks for your opinions which seem to be varied.
I am wondering if there is anything I can do to make this work. Bearing in mind this is in a finished house so I don't want any destruction. Does anyone know where I can get any diagrams showing the proper piping for such a system.
The cylinder is also heated by solar panels and an oil boiler. Would the fact that the cylinder is nearly always heated be part of the problem. Not cooling the return water fast enough?
This link should provide a diagram of the existing pipe work and hopefully give a clearer idea of what i am dealing with. Take a look and see what ye think. Thanks

[DLMURL="http://picasaweb.google.com/chrrisdee/2010_05_23#5474560864398453522"]Picasa Web Albums - Christopher - 2010_05_23[/DLMURL]

 

[ecowarm]

Can you post some pictures of the Cylinder/pipework ?

 

[Robtheplumb]

From looking at your picture it should work, you say the cylinder is heated by solar, oil AND woodburner? Are these all in there own coils or is the oil boiler and woodburner on a netraliser? Maybe increasing the pipework from the woodburner to 35mm would help.

 

[ecowarm]

whats the stat set at?
if you turn it down a bit so the pump kicks in earlier the boiler wont overheat.

 

[stevetheplumber]

pipe work is ok in the layout you describe i would imagine the preheated cylinder is causing the problems by reducing the thermo syphon effect if it works ok when slumbering this is an ideal situation realy as your getting your free heat from the solar and just topping up with a woodburner and using your exspensive oil as last resort
if its heating the cylinder with the draughts shut why do you feel the need to open them ?

maybe incorperating the bathroom rads /towel rails onto the gravity circuit would increase the chance of dissapating the heat

 

[Chrisdee]

OK, Thanks . I will try and post some photos of the pipework soon.

Another problem has occurred which you guys might shed some light on.
The circulating pump on my solar system has ceased. Any ideas why or how this can happen. Its only a year old and was working fine. I would like to be assured that it wont happen again as the pump was expensive to replace
Thanks