Hi

With the price of oil going through the roof we decide it was time to look at alternative sources of heating. I have spent much time over the past few months gathering as much information as I can from suppliers and various Forums which has been a great help.

I'm after recommendations as to the best way to combine a Multi-Fuel Boiler with an existing oil fired boiler. When I first started looking into this a number of people recommended a "Dunsley Equaliser". Then various suppliers said that I would be far better off using a Thermal Store Tank. I was initially directed to DPS who technically appear to be very good but so far have failed to deliver on any hard recommended system information/configuration. Because of this I started to look at other suppliers, including European one's mentioned in these forums. We also intend to have the cavity walls filled with insulation. We need the system to provide DHW and CH.


So here is my situation and I would much appreciate any help/advice.

1. What I want the system to be able to do automatically is that if there is sufficient heat available from the wood burner and Thermal Store that the Oil fired boiler remains off. If however there is insufficient heat available at this point the oil fired boiler will fire up to supply the required heat until such time as more heat can be supplied by the wood burner. For this read lazy but realistic !

2. We live in a 4 bedroomed detached rural house that is generally considered to be a cold house. Currently it's heated by an oil fired boiler (80,000btu). The house has 17 radiators of which 12 are used all the time when heating is required and 5 only occasionally. There are 2 bathrooms one with a Power Shower. Our existing system is gravity fed, ie Expansion tank in the loft. (Hope this is correct term)

3. The new multi-fuel boiler will be placed in the same room as the existing oil fired boiler, a large kitchen, which itself is one of the coldest rooms in the house.

4. We have a free unlimited supply of wood. (Lucky us !)

5. I would like the ability to easily add Solar Panels to the system at a later date.

6. I had narrowed down our choice of Wood Boilers to an Arrow Stratford TF 90 which appeared to be capable of supplying the required heat but was unsure if this was overkill and that the TF70 would suffice. However I noticed some negative comments about these stoves within the Forums so I am now unsure whether this is a good choice.

7. We wont be installing the system ourselves. I'm leaving it to the professionals.


So recommenedations and general advice on the following would be appreciated

1. Which Make/Size of thermal tank

2. Which Multi-fuel Boiler ?

3. What Control systems required ?

3. Any other things to be aware of.

Thanks.

Hi

Thanks for your comments. I'm a total newbie to all this.

The house is old, detached and in a rural location. We are having cavity wall insulation and increased loft insulation installed along with more D/Glazing as part of the onslaught to reduce our huge annual heating costs.

We were as I mentioned above going with a Dunsley Neutraliser but had so many knowledgable people and suppliers tell us that this is now "Old Technology" and that is innefficient compared to a Thermal Store that we started to look at Thermal Stores. They look to be a good way of storing heat from various heat sources and then be able to release it on demand. This as understand it would mean that the Wood burner/boiler doesn't need to be constantly going. It also means if I understand it correctly that you dont have to top it up with wood so often? Can you tell me in laymans terms why you think a neutraliser is the better way to go.

One thing I'm also unclear about with thermal stores is that from looking at the various brochures they are all appear to be very heavy, ie around 230 kg for a 1000l tank. If these are dry weights what would the total weight be when filled ? Would you have to reinforce the floor if the tank is situated on the first floor in a large airing cupboard for instance??

All help/comments gratefully received.

Hi,

Yep I agree with the above. There is a vast difference between a stove with a back boiler in a fire place and a “wood boiler”, in that the later is a “combustion / gasification boiler” with little output to the room and is not ascetic but functional. A occasional wood stove (nice to look at) will work with a neutraliser, but better to have a bigger store which is a neutraliser (no copy right on that term), the neutraliser can only work when there is steady output and steady demand. It has no capacity for storage. Decide what you want to do first, and where this will be and perhaps when.

Cheers, Mike up North

Colin. You dont need a thermal store with a wood burning stove- you can have one but its not essential. You dont need a neutralsier either- again you can have one but its not essential.

We have a wood burner with back boiler that is hooked up to the central heating and the hot water which can both be heated by an LPG bolier if the stove is off. Selection of the boiler/stove/hot water/central heating is all handled by thermostats/zone valves and a small industrial PLC controller.

One thing that often gets overlooked when planning a stove with a back boiler feeding a pumped system is the need for a vented gravity circulation loop from the back boiler. This gravity loop is used to dissipate excess heat from the back boiler if things get too hot. Generally this is a hot water tank with a dedicated gravivity/convection fed coil in it for the stove and also a 28mm vent pipe just in case things get out of hand and you need to vent steam!! The hot water tank has to be a minimum capacity depending on the back boiler KW output- the stove manufacturer will advise.

Unless your structural engineer will verbally advise you for free, I would speak to your local BCO first- your taxes pay his wages!! If you a are tactful in the way you present things so as not to alarm him you may get a verbal suggestion as to how to beef things up- probably in an overengineered way but cheaper than using a structural engineer.