my wood burner won't gravity feed!!!!!!

[ericmark]

Pre having two boilers one for domestic water and one for central heating my one boiler did the lot. I did not have a motorised valve just a switch to turn off the pump.

With pump off boiler would only heat domestic water but if the pump ran once pipes were hot then all upstairs radiators would continue to work.

Point is of course pipes should be lagged and if lagged then once started it's only boiler and tank temperature that matters but with a low head likely needs that push to get it started.

Same with narrow boat once running thermo-siphon would work but it needed pump to get it started.

With wood burners start the water flowing before fire is lit and it can be a real pain to get fire started. Pump on narrow boat had a thermostat on the pipe right by the stove so no pump until water started to get warm. This was in fact duplicated two pumps, two thermostats and non return valves as should it not start water could boil and pumps were 12 volt to ensure no loss of supply.

It's been many years since I have used wood and coke stoves but know they can be dangerous when boilers burst so would not expect to see any stove without some fail safe. I have been there in the old days raking out the fire onto a shovel to take outside this is why we had quarry tiled floors.

 

[cornishsteve333]

hey sorry for the slow reply, didn't expect so much response.

the system run's up hill from the cylinder and does seem to push water through when the boiler boils, heat leak get's hot at this point too.

so if it runs down hill from the cylinder to the tank it should work?

thanks for your help

 

[Corgigrouch]

Where in all this is the stove/boiler? Is the cylinder and heat leak higher than the stove? There should be continuous rise from the boiler to the heatleak and the cylinder...

 

[cornishsteve333]

hello, thanks for all of your previous comments.
I've rerouted the return to run down hill back to the boiler. it's a very slight gradient for the first meter, a couple inches in a couple of meters roughly. theres a very slight rise before the back of the boiler 2, inches. as I said before it runs straight up for almost the first third and then slightly up hill before doping into the cylinder theres a vent at the top of the system.

trouble is it gravity feeds, but not with enough oomph.

would either of these options help?

a) raise the highest point slightly or lengthen the pipe in the loft (it's currently at the bottom of the header.

b) adjust the pipes leading into the boiler to remove any dips.

thanks for your time

 

[cornishsteve333]

p.s the cylinder is the height of the top of the burner

 

[prettygoodgasman]

Gravity through an indirect coil? - coils are intended for circulating pumps!

Depends on age of coil. How do you think gravity BB's heated water?

 

[MrTherm]

Q: How do you think gravity BB's heated water?

A: By gravity circulation thermal displacement piped directly into a bulk volume stored from top downwards normally aided by stratification and vented to atmosphere, the 'tank' system - with no pump obviously.

 

[FiremanT]

Q: How do you think gravity BB's heated water?

A: By gravity circulation thermal displacement piped directly into a bulk volume stored from top downwards normally aided by stratification and vented to atmosphere, the 'tank' system - with no pump obviously.

Until relatively recently indirect (coiled) cylinders were used for gravity circulation. A modern one woul struggle though.