Solar Heating

[myabruzzohome]

I think we have almost certainly chosen the Calimax Twist wood pellet heater for our place as it looks ok and has capacity to heat small house/water.We don't have the option of a boiler room due to lack of space so we must choose a model that can fit in a living room.

Looking at the specs it seems to come with a heat exchange.Does this mean that we only need a dhw cylinder as well or is a thermal store/accumulater still required?? Confused!

Help!

[lotan4850]

My tuppence (for what it's) worth.

All these sophisticated heating systems are great; at commencement of any building project you should think of the envelope (meaning external walls. external roof and ground floor) the structure.

What you should be trying to do is insulate the house as much as possible and then add 50% more . Incorporating this is not easy in an existing structure, a ruin is easier and new is the easiest; and not all have come to Italy to live in a new modern house.

There are however methods available for different levels of fabrication; this may eliminate or reduce the size of your boiler and the level of sophistication of the heating system to an acceptable level and cost including running costs.

Insulation is the most cost effective operation you'll ever invest in; you will recoup this cost quickest of any other investment - the more the better there is no thickness too great - in my book.

What you should be aiming to do is .....
1. Insulate external walls with a min. of 14 cm*
2. Insulate the roof with a min. of 35 cm*
3. Insulate the roof with a min. of 15 cm* in the ground floor.
4. Reduce thermal bridging
5. Use windows with a u-value of min 1Kw/m2 K, 0,8 is better 0,5 better still.

*We are talking insulation thicknesses not wall thicknesses just to avoid any confusion.

To eliminate completely a heating system you'll need insulation at the following min. thknesses 30 cm (walls) 45cm (roof) 20cm (grd flr). Naturally this is easier to incorporate in a new structure rather than an old. Windows should be at 0,5 Kw/m2 K.

We built new incorporated 1-5 above (easy) and our heating/DHW costs for wood were €600 + gas mostly for cooking were €300 = €900/annum. In retrospect I should have increased the insulation thicknesses and reduced the need for underfloor heating. But it's a bit late now.

My tuppence worth!

!

[lupo]

Hi Iotan,
Any advice on types of materials and applications for the above? What if I want my limestone walls to stay solid enough to take wall plugs for shelves etc.? Is there a plaster, for example that incorporates insulation material?

[lotan4850]

Originally Posted by lupo

Hi Iotan,
Any advice on types of materials and applications for the above? What if I want my limestone walls to stay solid enough to take wall plugs for shelves etc.? Is there a plaster, for example that incorporates insulation material?

Lupo,
Yes there are products on the market place one called termolan - a lime/ cement plaster incorporating cork insulation. I have spoken to their technical staff to get a grip on it's composition and u-value. We had a difference of opinion as to vapor transgression and I would not personally use this on internal walls; external yes. Also thicknesses could be excessive to arrive at a high u-value.

Ultimately you should be trying to avoid the transgression of vapor through the structure this can be done in a number of ways (eg. 2 cm of cement based plaster, plastic vapor barrier, polystyrene insulation, et cetera), there is an ongoing debate as to the manner in which this should be accomplished. I'm old school and I prefer that water doesn't first enter the structure of the building and secondly any vapor in the air of the building is not not allowed to transgress through the structure and that external humid air cannot enter the structure. Then suddenly the building cannot "breath" and is where the debate lies; I could go into more detail but I won't bore you.

I have used successfully on refurbishments both external façade and internal face insulation normaly the external insulation has a higher thickness than the internal. Covered externally with a thin plaster or any other façade covering and internally with a thick plaster 2,5 cm thick; this would be more than enough to support wall shelves and kitchen cabinets. This reduces your internally applied thicknesses and gives you an adequate u-value; using say 5cm of insulation material allows you to hide services and boxes for switches and sockets. Avoiding channeling into the existing (in your case limestone walls) structure.

However it does not address thermal bridging (TB) which can be considerable if insulation is not carried out in an conscientious manner - TB for a structure can be the equivalent of leaving a 1.2 metre square window open all year round!

Hope this helps!

[AllanMason]

Originally Posted by NickZ

This week Carefour has a solar hotwater system for 1400. Designed to be hooked into your existing system. Only one panel and a 150 litre tank.

Originally Posted by simone-non-martini

Thanks...that's a hell of an improvement on the 30K we have been quoted (not by an Italian or English company I might add!)!

I wouldn't even try to defend the prices charged by some of the companies in the solar energy field, but you need to be careful when comparing systems.

I believe that the system Nick is talking about is the form of solar water heating most often seen in hot and sunny climates: solar panel and cylindrical stainless steel tank in one unit mounted on the roof. There's nothing wrong with this if all you're expecting is "free" hot water in the summer, but it does have its limitations. For example, I don't think it's the most appropriate form of solar water heating for our house because it can get very cold here in winter and I don't want the hassle of draining the solar system and disconnecting it from the house's DHW supply every winter and then doing the reverse when the danger of freezing is past. You also need to consider whether your roof will be capable of supporting the weight of system and the water it contains. On the plus side, the systems are mass produced and so very cheap. Or at least just about as cheap as things get in the solar field.

I have no idea what you would be getting for your 30K, but I should hope it would do a lot more for you than supply 150 litres of hot water when the sun is actually shining!

Al

[myabruzzohome]

You point out that many of these methods do start to prevent a building 'breathing' which is what we are working towards with our old stone house.

Having removed cement off limestone which has been so damage its needed replacement we have seen first hand what happens when moisture is trapped in stone.Is there insulation material that can be added to lime plaster ?Hair is added normally but I suppose thats not hugely efficient!

We have had new wood double glazed windows put in and insulation on the roof but as we wanted to keep the original appearance of a pitch roof its just a layer of that foil stuff.

There seems to be a big conflict here between retaining original material/features and saving on heating costs.We have resolved the issue in the UK by keeping the boiler down on minimum setting and wearing jumpers !!!not very ideal.

One area I think could be insulated is the gaps between arches in the old brick ceilings.Ours are filed with old lime/sand earth mix but I suppose a replacement of those clay balls could improve insulation?

Interesting

[lupo]

Yes,
With our limestone building and three rubber stamps on the paper work about the historic and special nature of the house and its setting, we wont be using external insulation! Still, interesting stuff for those with stucco or other types of rendered finish. I've heard somewhere about polystyrene balls added to the mix, but that, intuitively, doesn't really convince or appeal. Like MAH, we'll probably rely on our sweaters. Mine will probably be particularly efficacious, once I have finished all the plastering in them...

[lotan4850]

Originally Posted by myabruzzohome

You point out that many of these methods do start to prevent a building 'breathing' which is what we are working towards with our old stone house.

Having removed cement off limestone which has been so damage its needed replacement we have seen first hand what happens when moisture is trapped in stone.Is there insulation material that can be added to lime plaster ?Hair is added normally but I suppose thats not hugely efficient!

We have had new wood double glazed windows put in and insulation on the roof but as we wanted to keep the original appearance of a pitch roof its just a layer of that foil stuff.

There seems to be a big conflict here between retaining original material/features and saving on heating costs.We have resolved the issue in the UK by keeping the boiler down on minimum setting and wearing jumpers !!!not very ideal.

One area I think could be insulated is the gaps between arches in the old brick ceilings.Ours are filed with old lime/sand earth mix but I suppose a replacement of those clay balls could improve insulation?

Interesting

The problem is more complex than so....

You don't make any mention where you have removed the cement plaster internally or externally or both faces?

a). Internally only water vapor has been slowed down or stopped moisture movement is entreing the structure from the outside in causing damage to the structure over time. Maybe issues with roof drainage and the like.

b). Externally only vapor is being held inside the structure and not able to evacuate to the outside and as there is no vapor barrier internally then vapor is free to condense in the structure. Causing danage as you described.

c). Both faces. moisture maybe trapped between but in the construction phase this will dry out without any problem if water penetration is avoided from other sources.

There are a number of issues that need to be addressed.

1. One needs to stop vapor entering the structure from internal heated areas and transgressing outwards. This is best done using plastic vapour barrier, polystyrene or min 2 cm cement based plaster there are other methods.

2. The external coat face needs to be less hermetically sealed so to speak. This means any water in the structure will transgress across the wall section outwards eventually drying out the wall.

3. Water penetration into the wall from leaking roofs and guttering, down pipes must be eliminated as these cause the biggest problems regarding moisture; so should be maintain on a regular basis. 2 above allows the structure to dry out outwards and stops warm water filled vapor moving through the structure and condensing in the structure.

The structure "breathes" outwards as we do evacuating vapor.

So you should when insulating try to have a vapor barrier internally and a less hermetically sealed barrier externally allowing the wall to dry outwards ("breathing"). Alternatively both barriers the same as I would apply. Giving the best energy efficient structure.

Hope this helps.

[lotan4850]

Originally Posted by lupo

Yes,
With our limestone building and three rubber stamps on the paper work about the historic and special nature of the house and its setting, we wont be using external insulation! Still, interesting stuff for those with stucco or other types of rendered finish. I've heard somewhere about polystyrene balls added to the mix, but that, intuitively, doesn't really convince or appeal. Like MAH, we'll probably rely on our sweaters. Mine will probably be particularly efficacious, once I have finished all the plastering in them...

Lupo,

Not only rendered and stucco houses - after insulation it is possible to finish off with a brickwork, stone façade. However wall thicknesses will be substantial issue.

Arrrrr.... The cost (heating) of these culturally historic buildings of Italy owned by the British community. In this case it's a question of wrapping up warm and looking for a cheap energy source with a high degree of sophistication for the winter months.

Lotan

[lupo]

... I take this as an endorsement Iotan!
P.S. Your second post on vapour transgression is especially helpful, thanks.