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Author Topic: Old farmhouse project  (Read 2607 times)
Stuart_M
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« on: September 06, 2019, 09:47:45 PM »

Hi All,

We about to start a new project and would value some input from the experts on here to check we’re heading in the right direction and suggest anything I’ve overlooked.

We are buying the family smallholding which comes with about 8 acres of land, a small copse and a couple of barns. The house is about 170 years old, 4 bed, about 1700sq ft and needs lots of work. Currently it is heated using an oil burning range boiler and topped up with a wood burning stove and open fire.

I’m keen to include renewables into the refurb and trying to workout the best order to fit them.

First job is to keep the heat in. Windows and doors need changing for double glazed, the loft was topped up a few years ago so has about 150mm. Front wall (south facing) has cavity wall insulation but the other three are solid.
Is it worth looking at external insulation for the west facing wall?

The heating system modernising, The existing oil burning range is inefficient so we’d like to be replace it with something more efficient and cheaper to run.
The options seem to be:
1) new oil boiler
2) ground source heat pump or maybe air source
3) pellet boiler
4) LPG
5) combination of the above

Each have advantages, different costs to install and issues integrating them into the existing system. Solid floors mean underfloor heating is out but almost anything else could be fitted in.

I process enough logs each year that converting one of the log burners to one with a boiler coupled to a thermal store with PV and a main boiler would give me backup options.

Which option would people go for and what have I forgotten to include?

Stuart
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rogeriko
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« Reply #1 on: September 06, 2019, 09:53:33 PM »

If you cannot put in underfloor heating forget all about Ground Source Heatpumps and definately do not even consider Air Source. Pellet boilers are incredibly expensive to run as is LPG. A nice new oil boiler is what you want with as many wood burning stoves as you can fit.
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pantsmachine
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« Reply #2 on: September 06, 2019, 11:13:50 PM »

Insulate the absolute hell out out of it and once you've budgeted for that, think again, go more but make sure you have airflow. That's prime.
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« Reply #3 on: September 07, 2019, 12:29:59 AM »

Get some calculations done on the existing setup to work out where the heat is going you can then model what effect the various changes wil have in terms of  heating, for example would external wall insulation be worthwhile or would you be better off isulating on the inside.

Gut feeling is that in an old property without UFH you will need qiote high temperatures in the CH system to supply the radiators so GSHP or ASHP would probably be disappointing but migt work in spring/autumn. Like Roger, I would guess a condensing oil boiler would probably be you best option, but make sure you understand how to keep it in condensing mode and not just as it gets installed.

Oil can be a little smelly, so avoid putting it in the kitchen if you can.

The calculations and modelling should give you a clearer picture of what may be suitable at whay cost.

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brackwell
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« Reply #4 on: September 07, 2019, 07:51:12 AM »

Yes a new boiler but depending on the age it could well need new rads and new plumbing and a hot water tank. Does it need rewiring as well, probably does. Rip out intermediate ceiling and rewire and replumb now why you have the opurtunity.  This is not a big job once the trades are lined up. At this stage block up or remove any disused chimneys.

Old houses loose most of their heat through draughts and these were necassary with open fires and range cooker/boilers but now they are your biggest enemy.

Make sure the wood stove is of a modern type and take the air from the outside.

Once you have the oil boiler you can then think about reducing its use/cost by deciding how much you wish to use the wood. This is very much a personal thing depending on work patterns, age/fitness, desire to be green,supply of wood,locality etc.

Some people would use the RHI system to replace the whole hot water/CH system with wood and this may be a way to consider reducing the cost as some of these systems can be self funding.  This needs to assessed before the oil boiler and other mods because that is when the subsidy will be the greatest. This could be a self controlling pellet boiler if work patterns decreed. Others perhaps can advice.

Wall insulation would work well on the solid walls, others on the forum have done it.

Modern building regs i believe are 300mm for loft insulation for good reason.

The above needs to be done before PV as this can be done any time and would include fitting a storage battery at that time as well and then with the Electric vehicle --sorted.

Some old houses unless modified will not have a modern consumer unit with RCD trips and will not have the capacity to take on the wiring of a modern house. If this needs to be changed you need to check the main supply fuse to the house is at least 80amp and preferrably 100amps. Thats just what modern houses need /will need.

Ken

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gnarly
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« Reply #5 on: September 07, 2019, 08:44:26 AM »

I would tend to get rid of oil at the first opportunity.  Oil contains a significant proportion of benzene which is a volatile substance and a known carcinogen, so any “oil smell” either inside or near the tank is not healthy.  If you google you will find fuel oil companies that say oil is non toxic however this is not true!
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Stuart_M
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« Reply #6 on: September 07, 2019, 09:34:19 AM »

Thanks for the replies, think the answers to the points raised are below:

Cutting the heat loss is definitely the first plan of action.
I’m hoping that swapping the windows from single glazed metal frames to new double glazed ones will cut the heat loss and a pair of new doors will sort the gale that blows up the hallway. There are fireplaces in the bedrooms that could be blocked off too.

The roof ideally needs replacing and as part of that we’ll get it ready to do a conversion plus bring it up to modern standards for insulation. While they are doing that it seems to make sense to fit the brackets for PV?

The whole house needs a rewire as it doesn’t cater well for a modern lifestyle and while not dangerous I’d like old plug in MCBs replaced. The feeds to the outbuildings are either extension cables or twin and earth. It needs a load of ducts trenching in and an electrician with a van load of SWA to bring it up to a decent standard. The current fuse board is of course in the extension that could do with a rebuild so I might have to find a better location for it.
One positive is that we have three phase run to the pole by the back door so if I want it it for the workshop it shouldn’t be a huge cost to get it run in. Long term that could give me options for more PV as well.

Running cables everywhere will look untidy so I had considered battening the walls and plasterboarding rather than chasing into the old walls. There should be space to add insulation in at that point for the external walls.
I do like the idea of external insulation, the wall I’d like done is rendered already so it wouldn’t change the appearance much and as it is one we want to change as part of the roof upgrade the scaffolding etc will be up

Sounds like the consensus is an modern oil boiler which is one of the options I’d got round to in my head but wanted to sanity check with the forum. It should more or less slot in where the range is now (we have an electric cooker for cooking on most of the time). We may get caught for a tank relocation as I doubt the current location meets the regs. 
That was one thing that counted in favour of a pellet boiler along with there being less chance of the fuel going missing. Plus the RHI that Ken mentioned. Downsides are higher capital outlay, no space for a external hopper  so manual refuelling and I’d need to look at the fuel costs carefully.

I take Paul’s comment onboard and dream about one day having my own plant room but I think for now the boiler will have to be in the kitchen as it is next to the hot water tank. Depends how much of the hot water system needs replacing.

Think I saw a topic about log burners with boilers that put most of the heat to water so I’ll check that one out again. I definitely want one with an external air supply but also one with a relatively small output to the room as it is only 3.5 m x 3.5m. The current log burner can get the room up to shorts and tee shirt temperature even when it is snowing.

I should probably explain that my girlfriend’s grandad was living in the house up until this spring so it is somewhere we could live as it is (to the amazement of my mortgage guy) but we are keen to do right by the house and making a lot of mess in one go seems like the most cost effective way to upgrade it. That also explains the current oil bill and and log consumption as we kept the place at about 24 to keep him comfortable. In future we’ll wear jumpers!
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Tinbum
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« Reply #7 on: September 07, 2019, 09:48:30 AM »

Think I saw a topic about log burners with boilers that put most of the heat to water so I’ll check that one out again. I definitely want one with an external air supply but also one with a relatively small output to the room as it is only 3.5 m x 3.5m. The current log burner can get the room up to shorts and tee shirt temperature even when it is snowing.

I've been looking for an external air fed multifuel boiler stove and they are not that easy to find. At the moment I have a Brosley multifuel 30  Hercules and it's great but not external air. I bought a Dunsley Yorkshire stove second hand and a new external air kit. This kit has air slots to the room in it which to me totally defeats the purpose. It's not sealed at all!
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« Reply #8 on: September 27, 2019, 10:27:25 PM »

I came across the 'attic heat harvester' on the internet, which is a fantastic idea, because it costs so little to run. According to the blurb, it can produce "Supplemental home heating for the cost of running a light bulb". Brilliant for the shoulder months, and great if you are starting from scratch and have the right sort of attic. The access to mine is too tight and cramped. Also difficult to get the hot air downstairs where it is needed, unfortunately. Google it and see what you think.
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todthedog
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« Reply #9 on: September 28, 2019, 06:39:03 AM »

Above the insulation my loft is freezing in winter don't. want to pump that into the house.
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titan
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« Reply #10 on: September 28, 2019, 08:57:55 AM »

I don't know how handy you are with a spreadsheet but I would want to know the heating requirement before spending money on any system. It doesn't cost anything to do and well worth the time spent measuring wall,floor,volume  and glazed area. It is easy then to input the affect any changes will have.
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todthedog
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« Reply #11 on: September 28, 2019, 09:07:28 AM »

I had a solar dehumidifier whilst in Finisterre. A large black box with a computer fan and a tiny pv panel. Theory was air in box got hot, fan would then push heated air into the house. A complete  chocolateteapot worked in Summer when you didn't want hot air  with grey and damp conditions in winter when you did it failed to pass the go line. I could see it working in dry sunny and cold conditions but not in the UK or Brittany. Good luck.
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Tinbum
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« Reply #12 on: September 28, 2019, 10:09:39 AM »

I came across the 'attic heat harvester' on the internet, which is a fantastic idea, because it costs so little to run. According to the blurb, it can produce "Supplemental home heating for the cost of running a light bulb". Brilliant for the shoulder months, and great if you are starting from scratch and have the right sort of attic. The access to mine is too tight and cramped. Also difficult to get the hot air downstairs where it is needed, unfortunately. Google it and see what you think.

 chocolateteapot

spend the money on insulation instead!
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Stuart_M
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« Reply #13 on: September 30, 2019, 07:49:29 PM »

Things are progressing along slowly, got a bit side tracked as the mortgage company have decided that they needed a structural engineers report before they will be convinced that the house isn't going to spontaneously collapse. A nice gentleman popped round today spent 5 minutes looking at the cracked render and is happy that any movement was many years ago and the house is fine and will write a report to confirm that. The results of the remaining 2 hours can go in a different report and will form the basis of our todo list and as an added bonus I should get a CAD drawing of the house as it is to get me started.

It does look like we may have to find a way to ventilate the house while maintaining heat as there is evidence of damp in several of the walls. The concrete render on two of the external walls is likely to be adding to the problems by stopping them breathing so that might have to go. He recommended breathable external wall insulation as a replacement option. Our desire to keep the drafts out to reduce the heat loss might not work well with the damp, has anyone installed a MVHR unit? I like the theory and sale pitch but no idea if they are actually a good use of funds!

Quote
I don't know how handy you are with a spreadsheet but I would want to know the heating requirement before spending money on any system. It doesn't cost anything to do and well worth the time spent measuring wall,floor,volume  and glazed area. It is easy then to input the affect any changes will have.
Good point and definitely worth doing to see what the expected heat requirement is now. I'll have to read up on how to do the calculations but in theory I should be able to put the spreadsheet together.
 
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brackwell
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« Reply #14 on: September 30, 2019, 09:16:53 PM »

I have a friend who has a MVHR system and it is brilliant with every part of the house a uniform temp BUT it is a modern build airtight house.  I cannot see it working in your situation as i doubt you could get the building air tight enough.

Where is the dampness coming from ?  The dodgy rendering,the roof,the ground,unsealed unused chimneys ...
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