Back boiler on log burner

[openspaceman]

15 hours ago, Boot said:

Just a note but surprised you found a back boiler stove being advertised - as of 2022 all stoves must now meet stringent particulate matter emission levels - as boiler stoves reduce the burn temperature / increase particulate matter they are in effect now band in the uk and it is illegal to fit one! Boot

Yes in essence; because traditional back boilers were literally the back surface of the combustion chamber they presented a less than 100C temperature to the firebox, this effectively quenches the flames and thus produces sooty particles, this is why the boiler surface always looks black from the tarry deposits.

 

There is no reason a stove manufacturer couldn't have the boiler  after the combustion was complete but at the same time the flue exit temperature would have to remain above the dew point of the exhaust gases and vapours.

 

I think there is plenty of scope for making use of some of the concepts used in pellet burners and chip stokers to make a high tech stove with water heating but I expect the price would be a bit steep compared with a metal box, some fire bricks and a ceramic glass door.

 

Or you could site a back boiler above a masonry stove.

[GarethM]

Problem is, with complexity comes the necessary safety side of the problem.

 

Pellet boilers are more similar to gas, if it detects a problem it stops and very quickly cools down to a safe temp, a backboiler loaded up with wood will just keep going until it explodes.

 

The old days of gravity expansion tanks have long gone since combi boilers arrived, which lent itself perfectly to back boilers.

 

If you're really needing the heat, your going to need to have space for a eco Angus and all the tanks etc.

[slim reaper]

On 07/05/2023 at 16:46, woodlover2 said:

Reading this thread I thought to myself there must be something on the market regarding heat exchangers and log burners ,so googled it and products at www.recoheat.co.uk seems like they could do the job ,from what little i read on there site it seems cheap and a possible solution?might be worth a click?

With the lack of draw one can get with modern highly efficient stoves  the issue  can only be made worse by removing even more heat with that system

Edited May 16, 2023 by slim reaper

[Mr Paul Derbyshire.]

Newbie here, first post on this site.

 

No matter how you frame it, fitting a water-filled boiler to a wood stove results in a chilling of the firebox and thus less than perfect combustion.  On the legal side alone this is now a no-no. Practically speaking there can also be problems with sooty flues, creosote build-up and such (hence the legal issues), as well as reduced heat output from the appliance itself.

 

If you go to the Rayburn cooking range site (a sub-division of Aga, or was - I think there might have been some changes of ownership there too), you will notice that Rayburn no longer produce solid fuel ranges  - wood or coal, whether with a boiler or not.  The last new ones available were marketed in 2021 and even then, there were only a limited number of models using solid fuel and, I think, only one model that used wood fuel and had a boiler.  Aga themselves ceased producing solid fuel ranges in the 1950's.

A good resource is Thornhill Cookers (Kent), a company founded by Graham Thornhill.  Beautiful cooking ranges but not one has a boiler and Graham gives reasons why somewhere on the site.

 

The only way to go for wood heating of water for CH and DHW is a dedicated wood boiler but the system will cost you tens of thousands of ££'s.  Then the labour to fit properly (plumber and sparky) will cost you a further four figure sum.  Froling (Austria) seem to be the market leader.
 

Here's a good video from several years ago highlighting that system.