installation of woodburner to run rads and hot water

[shaunhighcock]

I have been asked to install a wood burner to run radiators and the hot water,
The main problem i have is that it all needs to be installed on the same level (ground level) I can possibly get the flow and returns to rise up and across at ceiling height into the next room where the cylinder is to be sited and both feeds tanks above cylinder, the reason im worried is because the F&R will be at the same height as the F&E tank..... so can i then run pipes down to cylinder for coil and spur off for heating using 3 port valve set up etc and from there take open vent up to F&E? or could i take the flow and return down from back of wood burner underfloor and up into airing cupboard? I've never done something like this before and to be honest i think it defies the laws of plumbing but i may be wrong.... plz help p.s there is no loft space above for F&E tanks

 

[justlead1]

Hi. Gravity circulation dies not like horizontal runs. Unless you can site the cylinder at high level along side fire breast /boiler you flogging a dead horse.

 

[shaunhighcock]

Hi. Gravity circulation dies not like horizontal runs. Unless you can site the cylinder at high level along side fire breast /boiler you flogging a dead horse.

so what your saying is it won't work not even if the return is pumped into woodburner right next to it

 

[Edgy]

Hello,

I'm just about to install a wood burning range in place of my oil-fired Stanley and would be grateful if anyone could advise on whether there are any shortcuts I can take to avoid over-modifying the existing plumbing.

My hot water cylinder is currently next to the range and at the same level as it is pumped.

I understand I need to incorporate the tank into a gravity circuit with tee injector, sink radiator and f&e tank.

I plan to site the f&e tank at the top of the house but wondered whether I could leave the hot water cylinder undisturbed with modified feed to it and the pumped side, place the leak radiator above it and simply pipe onward to the f&e.

Any advice would be gratefully received.

 

[tamz]

I could give you advice but obviously one of the mods is of the opinion i shouldn't

 

[Edgy]

Well, I suppose I'll have to make my own mistakes.

Slightly disappointed as I thought joining this forum would be quite useful and I might be able to make a contribution too.

Put this one down to experience.

 

[justlead1]

Hi. If you can not control the heat source (solid fuel/wood burners) and pipe work is to be added for hot water via a cylinder. Gravity circulation is the only safe method. Pipe work sizing must be adequate to allow heated water to circulate at a rate that matches to output of the boiler. This theme must also be applied to the design/size of the system. (A 15 kw boiler heating 8 kw of surface area would result in boiling under working conditions) You may have noticed that on old gravity systems the rads are sized far in access of room requirements. This practise was employed because the temp range of solid fuel appliances is difficult to control as it is at the mercy of wind and draught. Hence the stoker on large installations. And they are all out to work on domestic situations. There are real dangers associated with installing solid fuel boilers if your knowledge/experience is short of the mark. With regard to installing a heat leak rad above the cylinder and branching off the primary F & R. your electric bill would be high during summer months as the cylinder heat exchanger/coil would work in reverse and heat the rad up via immersion heater. I dislike writing that which you do not want to hear but its my opinion, the consequences of bad design can be dire. Good Luck

 

[Bernie2]

Hmm!

Gravity pipework is more like waste pipe work. You got to give it a fall or rise.

They don't like pumps on Primaries usually, because if they fail they can interfere with the systems natural circulation, in point they could stop it all together, which is something you don't want on a wood burner. And of course the Primaries are often extended to be used as a vent/expansion pipe. Block the free flowing route of expanding water in a poorly controlled wood burning stove and you can have a problem.

It may be okay with a free flowing vent of course. But when you hear a solid fuel system boiling over, you sure don't feel like hanging about to find out if its got one or not.

Basically I suppose you can say hot water rises, and cold falls, so the flatter the incline the less it rises and falls.

Good Fortune.

 

[tamz]

the consequences of bad design can be dire.

That's all i was saying before infact this is what i said

Post 1
What you are proposing will not work. There are ways to pump it but this type of thing really needs to be done with someone who knows what they are doing. Get it wrong and you could kill someone.

Post 2
Its not the flue i'm on about although getting that right is also essential.
A woodburner is an uncontrolled heat source and as such needs piping up correctly. It can't just be piped the same as a gas system as the heat source cannot be just switched off.
If the whole system is to be pumped (inadvisable) special controls need to be fitted to ensure safe operation. The F@E tank needs to be metal and a heat leak should also be incorporated.
That is why training and experience in these type of system is necessary not just read it out of a book. It should really be fitted be by a HETAS registered engineer.
There is a lot of power behind steam.

Wait to see how long it stays on.

 

[Edgy]

Hi, thanks. The Bosky looks relatively controlable and the Bosky installation instructions state that the hot water cylinder should eb above the level of the stove if possible and I read that to mean that if the cylinder was on the same level it didn't necessarily constitute a problem so long as a heat leak radiator was incorporated although I'm not sure whether it needs to be before or after the cylinder. Effectively, we do not intend using an immersion heater as the Bosky will be used for cooking year-round although I do intend replacing the existing 100 litre cylinder with something larger when funds permit.

I meant to add that the system would be plumbed with an injector tee with the gravity circuit feeding to the cylinder, heat leak rad and up six metres to the f&e with the pumped circuit being the other side of the tee and leaving the pumped side of the circuit (i.e. the central heating) untouched.

 

[justlead1]

Hi Tamz. I was not contridicting your post, just confirming it. Just to put a bit more meat on the bones. On a system with say 10 ft centre of cylinder to centre of boiler and no more than a yard away horizontal in 1" pipe for F&R the circulating pressure would be around one and a half inches water gauge taking a 20 degree temp difference between F&R. When you consider a circulator (pump) may work at 6 yards head. One starts to see why good design, falls, rises, machine bends to reduce frictional resistance etc are required. The slightest resistance will cause stagnation. By the way this scenario would only carry 6kw per hour.

 

[tamz]

I agree with you too. My previous posts were deleted but i still had them on a tab.

" By the way this scenario would only carry 6kw per hour."

This is why getting it right on the pipework is even more important now than it was years back. Most open fires and roomheaters and the like years ago only had an output of around the 20,000 to 80,000 btu mark. Now they are doing woodburners and stoves up to around 80 kw (270,000btu). More like a sectional
Get it wrong and they will know soon enough.

 

[Edgy]

The Bosky has an output of 64,000 Btu using wood, 70,000 with solid fuel.

I assume from the various kind replies that I do need to raise the cylinder above the level of the boiler and in that case, the cylinder will be around one metre from the boiler horizontally and one metre, minimum, above; if needs must, the cyliner can be positioned up to five metres up the wall before passing through the wall to the f&e.

However, I remain uncertain as to whether the heat leak radiator absolutely has to be before or after the cylinder - after would work a lot better as regards re-plumbing but I would welcome confirmation!

 

[justlead1]

Take cylinder as high as possible and take off F&R to heat leak at low level (Near boiler ) and run parallel will primaries and up to rad. This should prevent lose of heat from cylinder due to gravity when boiler off. With that size boiler you should take off an army of rads. Good Luck

 

[Edgy]

Many thanks

One final question;

Can I flue into a chimney that has another wood burning appliance on the same level? I have tried to find information on this but most of it seems to relate to the U.S. where some states allow this. How this works in France I'm finding it impossible to discover.

 

[tamz]

No. It needs its own dedicated chimney.

 

[Edgy]

Hello, I've started the installation this morning and hit what appears to be the only problem; the indirect cylinder is a Geminox with inlet and outlet on the top - I don't think this will work efficiently on a gravity circuit (please let me know if I'm wrong!) so, can I incorporate the existing pump on the cylinder and run it in tandem with the pump on the pumped heating circuit tied to the pipe thermostat?

I meant to add that for safety I'd tee the tank heating feed and outlet from the main 28mm expansion pipe so that the circuit wouldn't be blocked in the event the pump failed