Defra boiler stove Options

[cjw001uk]

Hi Guys,

I've been reading the forum for a while as I'm about to begin renovating a house and would like to install WBS and Solar to move away from Gas as much as I can.

Its a smallish south facing 3 bed semi with  4 full size rads and 3 1/2 size ones. 
My main priority is Hot Water (i'm happy to keep the gas boiler for CH as I hope to insulate well and not need it too often!)

There is an existing back boiler on the gas fire .. I was planning to open the fireplace, take out the back boiler and install a boiler stove. I would then link that directly to a thermal store along with some solar tubes and connect the old gas boiler as a backup.

But..im in a smoke control area.

I've been looking and the Dunsley "Yorkshire" http://www.dunsleyheat.co.uk/yorkshirestoveCH.htm is the only Defra approved stove with a built in back boiler. This is a 12kw beast and i'm worried this will be far too big for my house and I'll struggle to feed it enough wood.

I did call Dunsley and they assured me the stove would work fine if I ran it at 1/2 capacity but I don't see how it can as the water tank is so huge.. surely if you halve the output you need a smaller tank or you'll never get the water in the pipes heated and moving up to the thermal store.

The other Defra approved option I've seen is the the Charnwood flue boiler http://www.charnwood.com/charnwood-flue-boiler.asp which gives 3kw output (enough for HW). Has anyone ever used one of these things ?

Any real life experience or advice would great - I've called a few installers but they all have their own favorite methods and dont seem keen on Solar at all and I've not been able to find a stove shop which carries the Dunsley Yorkshire in stock (bad sign..)

thanks

Chris
 

[Countrypaul]

I think you need to look at a loader such as the laddomat 21 - this allows a back boiler to operate at full temperature and efficiency without passing cold water to the back boiler all the time. The effect is that the back boiler is then utilised only for the amount of heat you are putting out, so if you run it at half capacity no problem.

Paul

[AndyJ]

Hi Chris -
  I'm in a very similar position to you - even down to seriously looking at the Dunsley Yorkshire. We've seen the dry version of the Yorkshire at a local discount stove shop - but a couple of places say they can order one without problem. I'm slightly worried about the output to room (I'm intending to well insulate the whole house) and my other half isn't convinced about it's appearance (says it's more of a "kitchen" stove than a front-room one!!) but there didn't seem to be any alternative. Thanks for the link to the Charnwood Flue Boiler - I'll look into that.

  On the water temperature point, my guess would be as long as you limit the rate at which you take heat out of the boiler to about the same it's being replenished by the fire, then you should be able to maintain a similar high temperature. If it's thermosyphoned (i.e. gravity flow) to the thermal store/DHW cylinder then nature will probably conspire in your favour (slightly lower boiler temperature means less vigorous gravity flow, so less heat removed), if pumped then it would just me a matter of matching the flow rate (pump speed) to the achievable heat transfer rate - and as Paul said, you'd usually control the return temperature anyway, which would have a similar effect.

  - Andy.

[dhaslam]

You can put some firebricks into the  sides of the stove that will reduce the size of the fire  without reducing combustion temperature and it will reduce heat to the room  a little.     There will still be the same area of  boiler exposed and with suitable flow control on the  water circulation  there should should be  a slightly better proportion of the heat output going to water. 

[renewablejohn]

I have a Dunsley Yorkshire boiler and it is brilliant. You must however understand how it works as it is not the same as a traditional back boiler. Whats so special about the Dunsley is the fireplace is all ceramic therefore achieves high temperatures and is not cooled by the back boiler so a laddomat is not required to keep the boiler temperature high. The boiler is set behind and above the ceramic fireplace and the flue path goes between the boiler and ceramic fireplace. Because the air vent is thermostatically linked to the boiler temperature you just stoke up the fire and the fire will automatically regulate itself depending on boiler temperature demand. As for fuel used it is very economical due to its efficiency and the automatic thermostat. You still have the option to control the fire with a simple air control but normally we run it on automatic.The only downside is that it gets very hot if you have children I would not feel safe without a fireguard. Also you need to open the door with the proper tool unless you have asbestos fingers.  The reason why you wont find them in stock is because there is a waiting list and the factory in Huddersfield cannot produce them fast enough.

[davec]

If I recall correctly from my own research 3 years back...

At the time the Dunsley was one of the only boiler stoves approved for 100% wood-burning in smokeless areas. However, who would argue if you install a stove burning anthracite or other 'smokeless' fuel and chuck the odd log on occasionally? There are loads of 'multifuel' boiler stoves on the market. Note that the Dunsley is not unique in having thermostatic air control... most I looked at seemed to have this and I second renewablejohn - the thing will self-regulate to boiler demand rather than KW rating.

Also, if you're worried about overheating, look at 'inset' boiler stoves - they put less out to the room.

[Micol]

Chris, I can only echo much of what has been said.  I have just recently installed a Dunsley Yorkshire in our living room (bought over the net from Firestove.co.uk, I think - they were the cheapest), running with a loading valve (a Termovar from Automix) and feeding a 210 litre thermal store (from Newark) - with an oil boiler as well.  We didn't like the black colour (Dunsley only do black) so we've sprayed it with "honey glo brown" high temp paint from Calfire (from Stoves on line) - it looks much better and is fine in the living room (we also sprayed the SS flue pipe).  I removed the thermostat vial from the pocket in the boiler and I've attached it to the return pipe (before the loading valve) - so now the thermostatic control on the Yorkshire turns up or down to suit the temp of the return water - it works great.
We are VERY pleased with it - living room nice and warm (& the stairs and landing - the stairs are in the living room) and it keeps up with the CH except when the outside temp is really down (like now - minus 7C here at the moment!) - significantly reducing the amount of oil we burn.
Our living room is about 4.5 x 6m and the stairs lead off it and we are toastie.  However, the Yorkshire will turn down quite well. 
One quite serious point - I put a "dump" stat and MV in to dump heat from the store to the CH radiators if the temp in the top of the store reached around 85C - I'm very glad I did as this has turned on a number of times now - we've been running the stove pretty high in this cold spell and obviously, when the CH was satisfied, the stove could only heat the store - if we'd not have a dump system, it would probably have boiled.  Bear this in mind.

Have fun!!!

Micol

[bovnet]

Any tips on getting this beast from the pallet into the fireplace ?

[renewablejohn]

Any tips on getting this beast from the pallet into the fireplace ?

Two wheel running barrow  

Plus 3 foot length of 3 x 2 wood so that you walk the stove into its final position

[qeipl]

Any tips on getting this beast from the pallet into the fireplace ?

It's only 200kg.
A sack barrow will handle it.
(pump the tyres up hard).

[bovnet]

Ok thanks will try the sack barrow then the 3x2's

I only require 2 of the four ports, can i blank remaining. Any pref for top bottom or diagonal for the pair i need ?
Is it usual to attach some pipe work before manourvering in to fireplace then fabricate connecting bits through the side wall ?

[Tigger]

When we installed our Hunter Stove, I stripped as much off it as I could to get the weight down.  Doors off, firebricks out, grate out etc etc.  It was then slid into it's final resting place by putting some 'formica' type plywood down so that we could 'slide' it into place.

If you're only using two ports then yes, go diagonal.  Our pipework goes straight backwards through the outside wall so the 28mm compression fittings were fitted before we slid it into place and the pipe work was fitted up afterwards.

[renewablejohn]

OK Just to clarify  where I come from a sack barrow is a running barrow due to the fact that when you had 12 stone sack of corn on the barrow you were expected to run with it into the grain store.

We fitted and tested all pipes prior to putting in the fireplace. We only used two ports diagonally but fitted two drain cocks to the to spares for ease of drain down and bleeding of air from the boiler. Also fitted flexible pipes between boiler and fixed pipework to allow adjustment. Also dont forget flue pipe access for chimney sweep brush.

[bovnet]

Thanks guys for the advice. Stove now in and had its first few days running.

The yorkshire is connected via pair of ports to thermal store. The pump is controlled via a solar differential controller. As i understand with the yorkshires autoair control the pump can simply be disabled and the fire shuts down. Do people do this with a switch for going out and maybe a timer too ? If i add these further controls do i need an 85c stat as detailed in the manual ?

My manual safety is a gravity/plate heat exchanger with mains water cooling due tank being below stove.

Steve