wood burning stoves.....

[Stephen H]

Hi all.

We are looking into the logistics of a wood burning stove with a back boiler (to be used with a thermal store)

We have an inglenook fireplace in the lounge.

I have a question. As the thermal store would be in the room above the room containing the wood burning stove, Is it allowed to run the flow and return pipes through the register plate? The register plate is about 2ft by 5ft.

There is currently a 12 inch metal flue liner (theres a pub style gas fire currently). There looks to be enough room to fit a proper double lined WBS flue pipe through this 12 inch corrugated aluminium liner.

The chimney stack is half into the house and half outside if that makes sense.

The flow/return pipes would come up vertically behind the WBS, through the register plate, traverse diagonally between the ceiling - upper floor void, and then vertically into the thermal store.

If pipes through the register plate are not allowed, that would mean running the flow and return pipes up the interior walls of the lounge which would not be aesthetically pleasing.

Stephen

[Dave Liquorice]

AIUI teh register plate is only there to stop crap falling out of the chimney and to stop the room heat disappering up it. The flue gases are all enclosed within the liner. I can't see why the pipes can't pass through it.

Have a dig about on the HETAS webiste?

[The Natural Philosopher]

I dont see off hand why not.

I think you need to allow for a safety valve somewhere, but apart from that the double walled flue should keep any seriously damaging heat off the pipework.

I am not sure this is often dine, but I cant see a good reason why not. Register plates are cosmetic things only.

[Martin Brown]

One thing to consider is that there is supposed to be a convection based radiator somewhere that is close coupled to the back boiler so that if the main CH pump is unpowered due to a powercut with a blazing fire you don't immediately risk boiling in the back boiler.

That's what our heating engineers said when they fitted ours anyway. Ours is on the other side of the wall behind the main fireplace.

They also pointed out that the way it had been incorrectly fitted previously to a Baxi boiler completely defeated its intended purpose as a safety shunt for excess heat during a powercut!

Regards, Martin Brown

[Dave Liquorice]

The OP is having the wood burner connected to the store. Assuming that is a reasonable size that will take a far bit of heating before it boils. One still needs to think about how to deal with excess heat though. Surely one of the bonuses of a wood burner is to still have some space heating when the power goes off...

[Martin Brown]

Indeed. And light from the flames too. You can even boil water a lot less messily with a pan on the top than you ever could on an open fire. Only downside of wood burning that I can see is that the flue needs sweeping more often.

Where I live powercuts from trees falling on the power lines are not uncommon. At the moment (FX: touches wood) we are OK but it is pretty wild outside with various chunks of stuff flying about in the wind.

Regards, Martin Brown

[MuddyMike]

Sounds like a good system, tree falls down, cuts the power and supplies wood for the stove at the same time!

Mike

[robgraham]

Yes - absolutely, having just suffered that some 10 miles from Edinburgh, and I think the weather station is is less than 5 miles directly from us, so we and the local electricity suffered the 100mph gust. No damage to mine but the electrics went off at 9am and didn't come back till 4pm. I don't have a dump radiator, relying on the HW tank - we didn't quite get to the point of issue orders for all to have a bath !

Coming back to topic, I'm assuming that the OP is using copper pipe (28mm at least) for his feed and cannot see why is can't run quite close to the flue - mine's does; after all it is full of 'cooling' water so the pipe walls aren't going to get any hotter than the water.

Rob

[Martin Brown]

Our hot water ends up pretty scalding if the fire is on without the pump running (and the dump radiator works overtime). The pump will come on by thermostat provided that there is electricity available.

The risk might be that the flue in contact with a hot water pipe will lose heat and tend to distil tar onto the cooler side wall. They seem to faff about insulating the chimney void space with vermiculite - I presume to make the insert metal pipe nice and cosy when in use.

Regards, Martin Brown

[The Natural Philosopher]

I must polish up the chainsaw after todays gales

[Dave Liquorice]

Only 7 hours? We were off for 36hrs in one cut just before Christmas. It had only been back about 6 hours after a previous cut of about

6hrs.

What else? You aren't suposed to use plastic within 1m of a gas boiler let alone an uncontrolled solid fuel one. 28mm is the smallest recomended for a gravity loop.

Is that with the wood burner feeding heat store or just a coil within a cylinder of stored, potable, hot water? You could still fit a TMV on the cylinder output to limit the DHW temperature to something sensible.