Open To Ideas - Heating System Rethink

[tarrel]

We're in the process of moving, and I'm racking my brains to think of an ideal heating system.  I keep going down specific paths, only to find there's something I hadn't thought about (I'm new to this, would use contractors to install, but have done a lot of reading on-line).  I'd like to describe our situation and invite some ideas, ideally from anyone who shares some or all of our circumstances:

The House:
3-bedroom, stone-built cottage, circa 1830, located in a sheltered location in the northern Highlands of Scotland.  Solid stone walls.  Dry-lined by previous owners (don't know if there is insulation beneath the dry-lining).  Grade C listed building.  New, self-contained studio in garden (approx 22 ft x 18ft), with steel pitched roof, with elevations facing SE and NW respectively.  Main building has single-glazed sash windows.  Limited insulation in loft (which I will fix).  Upstairs rooms have partly sloping ceilings.  There is a large kitchen/dining/hall area that stairs go up from.  There is a chimney over the built in electric hob, which a cooker hood currently vents into.

Current system:
Oil-fired combi-boiler driving pressurised CH system, consisting of radiators with thermostatic valves.  Boiler is outside (Grant).
Open fire in lounge
Electric cooking

Lifestyle:
We are in during the day on most days (my wife works from home, and I pop in and out).  We have family living a long way away, so will sometimes need to go away for days at a time.  We have a sizeable tract of woodland and, to all intents and purposes, an infinite supply of free softwood logs.

Desires:
- Remove the dependency on oil
- Make use of the free fuel
- Capitalise on RHI if possible
- Happy to have a system that requires "hands on" tending, but need to have a back-up as well, especially if we are away in the middle of winter.
- The house is nicely finished and we'd like to avoid too much disruption / ripping-out, etc.

Kind of ideas I've been playing with in my mind (not all at the same time!):
- Solar thermal on the SE elevation of the studio roof
- Batch-burn log boiler
- Rayburn or similar solid fuel cooker / boiler
- Wood burning stove in front of fireplace in lounge, with back boiler
- Thermal store
- Retaining oil boiler as back-up

I have a gut-feeling that the design of the house, combined with our lifestyle, is pointing to an "always on" kind of solution.  The house seems to have a high thermal mass, and takes a while to heat up if it's been unheated for a while (we've had it a couple of years and have been letting it as a holiday-let up till now).  I quite like the idea of a stove / range cooker in the kitchen area that could heat some of the upstairs if we left the doors open.

So, what could we do?  Any suggestions, obvious or completely out of left-field, gratefully received!

[desperate]

Have a look at CRAC here

http://www.navitron.org.uk/forum/index.php/topic,8465.15.html

along with all sorts of muppetry and plonkery it shows how we combined a WBS/ boiler with solar thermal and a gas boiler as backup. Like you I have an almost unlimited source of free logs, that fact made our mind up on the WBS aspect, solar thermal is THE most cost effective way of harvesting energy from the sun, again a no-brainer for us. It works pretty well but the thermal store is the weakest link, standing losses and heat up time, but nothing drastic.

Then it comes down to your lifestyle and requirements, underfloor heating would fit well with long periods of occupancy, but less well with the fact you want to minimise disruption. Thermal storage is ok to achieve a system if you have no other choice, but you will always have to bear the standing losses, less of a problem if you can house it within the heated envelope of your house.
Before any of that though, insulation and draught proofing is key to making any system work well. Can you post a floorplan of your house with a few dimensions, it makes it easier to think through.

PS personally I wouldn't bother with the RHI as it will restrict who does the work, what gear you can use and very likely inflate the price inordinately, but I am of course an ornerry bu55er

Desp

[tarrel]

Thanks for the feedback and link.  I'll work on the floorplan.  Don't know how to post it though!

[desperate]

Any teenagers around?? or like me, knock up a quick hand drawn sketch, photograph it and then post the photo, crude but effective, thats why some folk call me Desp CBE

Desp

[tarrel]

Happy to create a photo/jpg, but don't know how to post that either!

[desperate]

Click the additional options tag just below the active area when posting a reply and then browse for your piccy double click it and it will appear at the attach box,

 sheesh what do I know I spent months on this forum before I even knew what a browser was

If you get really stuck theres loads of people here who can help you much better than me, heating systems I can do, computers

Desp

[tarrel]

Cheers!  Watch this space for floor plan.

[dhaslam]

It is probably best not to have too many woodstoves  to tend.    One good boiler with  a  matched  heat store  should do the job.    You need to have a good setup for wood storage close to the boiler as well.    If you have good boiler, and  oil boiler as backup  a small dry stove  should suffice for the living room. 

Good insulation  gives better standard of comfort  as well  as saving fuel so you may have to redo some of the insulation if it is not adequate, particularly  all north facing walls.   

It would probably be  worthwhile to have oversized solar panels  to give  some solar heat  in  spring and autumn.    Old houses benefit more from  early season solar heat because they tend to  slower  to warm up  naturally. 

[tarrel]

@ desp:

Here's the floorplan (hopefully!)

[stannn]

Tarrel
I don't know whether the 3.8m width is internal or external ( I hope it's internal) but its not a lot and you will be reluctant to reduce it by adding internal insulation. So I guess that you need to drill a modest hole (or several) in the dry lining and look for insulation. You don't mention the floor type and this may be significant too.
Stan

[derekmt]

I would definitely think floor & roof.
1) improve drainage around immediate  outside of  house to improve thermal characteristics of ground
2) consider lots of insulation  plus thermal stores under the floor

[dhaslam]

Pity that the chimney isn't in the centre of the house.  A double sided inset stove with a small back boiler would fit  nicely.      Is there space in the roof over the lounge for a tank?

[tarrel]

@ Stannn: Dimensions are internal.  Walls are around 0.5m thick, maybe more.  Not sure about floors.  There is laminate flooring in the kitchen and what look like regular floor boards in the lounge.  The survey reckoned these may have been laid on a solid floor.  The front edge of the property is below ground level, especially at the LH end, and it has been tanked.  North is roughly top of the page, fwiw.

Thanks for the thoughts so far.

[tarrel]

@ Dhaslam: Not shown on the diagram is a chimney above the cooker in the kitchen.  The cooker hood vents into it.

The lounge is single storey.  There is a pitched roof above it, but I haven't found out a way to access the space.

Couple of pics attached:

[derekmt]

A lot of old houses had an shallow narrow covered drain at the base of the outside wall. Problems may occur if this isnt there in one form  or another, as this ensured that the inside earth floor was kept dry.