The Dark Art of Open Vented Gravity Flow Systems

[muggles]

So just came across this article and it's pretty close to what I'm doing. So I am getting a solid fuel stove fitted in my house and really want to avoid it being pumped it only 1.5m max from the thermal store it will be heating there's no coil and he store is open vented. I can get around 15cm of rise on the flow to the store over that distance. Is this likely to work and what's the best way to go about it? Should I do a steady rise to the store or come out go verticle 10cm then 5cm rise over the horizontal? Also what safety valves should I be fitting? Swing loaded steam valve? I am a gas engineer but have only ever ripped out gravity systems so my knowledge in this area is lacking.

The generally accepted minimum height difference between the stove and the store is 1 metre - that's what HETAS say you need. Usually measured from centre of stove to centre of store connections

 

[The Baker]

Can those with a wood burning stove post up the make, model of stove/stoves they have.

Also, and this is the info I am most interested in is;

Flue diameter,

Flue surface temperature at tick over

thanks.

ps have also posted this request in an other forum and some one pointed out that as its not gone cool enoigh to lite up yet I may be waiting a few days for much respone,

 

[transam]

Gravity blimey

I recall minimum thermal centres

If I recall 3 foot centre of boiler flow and return on boiler to centre of coil on cylinder

Important when replacing and old cylinder as thermal centres on new cylinders can be less ???

Gravity in a bungalow with cylinder away from boiler

Flow up into loft drops down onto cylinder

Return back to boiler under the floor steps up out of floor into boiler return

This step up measurement was critical and I forgot what it was
100 mm ??? 4 inches

 

[oldbutnotdead]

@stats1987 Have a look at loading valves. I've used continuous gradient in my setup (Villager 12kw into thermal store), the height difference between the 2 centres is just shy of a metre. Thermosyphon works fine, loading valve prevents backflow through the woodburner when store is hotter than stove

EDIT for @The Baker - 6" flue, tickover flue temp (when fire damped down for the night) no idea, probably about 50 Deg C (if the fire has stayed in the water temp is usually about 50, if it's gone out temp will have dropped to about 25).

 

[Johntheo5]

Gravity blimey

I recall minimum thermal centres

If I recall 3 foot centre of boiler flow and return on boiler to centre of coil on cylinder

Important when replacing and old cylinder as thermal centres on new cylinders can be less ???

Gravity in a bungalow with cylinder away from boiler

Flow up into loft drops down onto cylinder

Return back to boiler under the floor steps up out of floor into boiler return

This step up measurement was critical and I forgot what it was
100 mm ??? 4 inches

You need everything right for gravity circulation only, as can be seen below, a circulating height of 2 meters with flow/return temp of 60C/40C produces a circulating head of 0.018M, a circ pump has a easy task with a pump head 3M,

 

[lostinthelight]

Pump it.

Not a solution, what if there's a power cut

 

[denso13]

Not a solution, what if there's a power cut

You are responding to a post which is 11½ years old.

Which is why I said...

What invariably happens is that people start responding to old posts in the thread and it just ends up a complete mess.

 

[lostinthelight]

You are responding to a post which is 11½ years old.

Which is why I said...

Cheers,better ditch my £1 Poundland specs and pay a visit to Specsavers