PRICE OF GROUND SOURCE HEAT PUMP OR JUST SOLAR PANELS FOR UNDERFLOOR HEATING?

Having almost got our casaletto finished it's time to start to think about our 300m2 two storey stone casale. It's currently half underground on the 1st floor but we were thinking of digging out an intercapedine at the back to really dry it out. Because it's such thick stone we hoped to have underfloor heating supplied from an affordable energy source as it would help keep a pleasant, not too damp environment as we could safely run it when not in Italy and without huge cost. My questions are:- 1. A ground source heat pump in the UK seems to be £10-15k fitted, is this comparable to Italian prices? 2. Could we get away with having lots of solar panels (luckily the pitch of the roof means you can't see the roof at all so aesthetics doesn't come into it) to do the same job and supply our electricity too? The roof is South facing and we are in Lazio near Rieti. Many thanks!

There are experts on this forum for this area and no doubt they will recommend more than one option.

Our casa has a very similar setup but sadly WITHOUT the 'digging out'. This one side, north facing, is (in effect) partly underground and suffers from the worst of the damp that we have. The walls are up to a metre thick and what we need is VENTILATION. I'm guessing that whatever solution you put in place you will also still benefit from ventilation?

V

In answer to your questions Rachel68.
My rough estimate on the size of your house, would be probably a 17kw output unit, but could get down to a 14kw. The prices of pumps will vary between manufacturers.
Insulation levels are the main design criteria, so suggest you get the analysis of heat loss by room as a priority, to get a idea of pump size required.
Do the fitted costs you are quoting, include excavations for the loops?
Alternative, is a ASHP, cheaper and easier to fit.
With the PV are you thinking of electric underfloor, or water based with solar panels?

In my opinion you are asking for a 'one stop fits all' solution which really doesn't exist!

To get electricity from the sun you need a Photo Voltaic solar collection system. (sagraisolar knows a lot about these). 
You collect the sun, send it to Enel where they bank it as electricity, and it comes back to you very affordably when you need it. 
I suppose you could effectively run an electric cabled underfloor heating system this way but the economics would need careful examination.

To get energy from the sun you might choose a water-based solar panel system - but for one of these to be of sufficient size to make a significant contribution to heating the house it will create problems for you getting rid of heat in the summer.

The heat pump will supply heating needs (via underfloor tubes carrying water, if you like), and a water based solar system could assist the heat pump - but here the installation costs are getting a bit extravagant, and you haven't supplied yourself with any electricity!

So - perm any two from three (and then add a woodburner) 

The "one stop fits all" option is really the heat pump with a DHW tank. Mine here is a single unit with a built in tank and is the size of a fridge freezer (60cm x 60cm). Dhw water production is approx 20% of annual usage, so therefore cannot see the point or cost of adding solar hot water. (Summer months it operates for about 1 hour per day (160 ltrs tank ).
Yes, Rachel68 would need a seperate DHW tank due to the system size. Also 3phase electricity. I do not know if she is resident status, but if so could go onto the Special D1 tariff for heat pumps.

http://www.geotherm.it/esempi_impianti_progetto_6_geotermia.html

A combination of ASHP (or GSHP) and solar PV panels can be very effective. Solar PV sized to cover average useage so putting some into the system and taking some out. Initial cost of ASHP plus PV likely to be in the same ballpark as GSHP (but Geotherm/Sagriasolar can advise better re costs) but GSHPs tend to have a longer life expectancy before needing replacement than ASHPs.

I was looking at ASHP plus solar before the DI tarrif was anounced, waiting to get confirmation I am on it as had to wait until residency got confirmed, but had a bit of a problem re solar. Would have been very cost effective on normal tariffs but with the reduced cost of D1 tariff the payback is a quite bit longer. I do not have a large storage tank, a 200l high efficiency (ie very well insulated) tank is sufficient for the hot water and costs surprisingly little, it also heats up quite quickly if there are guests and a lot of hot water is being used. It is early days yet and I am still monitoring but with 2 of us I am currently estimating the hot water as costing less than E1 per day on the D1 tariff in southern Italy. The ASHP feeds the underfloor heating directly. A large buffer tank 1000l to 2000l can reduce running costs by building up heat during the day (essential if you are using solar or altternative sources of heating to directly supplement the heat pump), particularly with ASHP which are more efficient the warmer the ambient temperature, or if the system is running near capacity as a reserve for when the heat pump cannot produce enough.

A lot of factors to consider and any system needs to be tailored to the property and the heating requirements of the household as well as and also taking into account local climate conditions.

I agree with Geotherm that a solar water system to supplement is probably not worth it.  It would need to be oversized for just hot water in the summer period to give sufficient excess heat into the heating system in winter to make a difference. With the cost of providing hot water using an ASHP (or GSHP) being so little the payback would be many years. It was something I looked at but decided it was just not cost effective on the old tariff, never mind the D1 tariff.

Finally if you have any Italian Tax liabilities, or may have in the future, it is worth claiming the tax reliefs available for heat pump technology as that can help towards the cost.

Wise words all round so not much I can add.  My favourite would be a small Air source heat pump + wood burning stove + a heat bank.  As has been said - hard to justify solar when an ASHP is so good.  
If you are resident and there to fiddle about with a stove then you might find a stove plus a heat bank plus huge wet solar panels will service without many gaps.  Huge solar is very interesting as you build a flat solar profile by angling the panels with a winter bias so that the wider and flatter solar production graph overlaps with the wood burning season ... I won't bore you further as there is some chat and picures of the best stove and heatbank on
 
http://originaltwist.com/2014/03/19/heat-pumps-in-southern-europe-air-or-ground/

... what else?   PV rules changed to make the benefits linked to tax ... killed all that off overnight.
Underfloor heating is wonderful in all respects except in bedrooms where I'd go for the rapid response times of fan-coil units.

You could look at the new IVT AirX which is nearly as good as a GSHP. I may be going to Sweden in March to get some training on it, but it came out as the best in the Danish test results.
Maybe around Euro 16K with the DHW tank.
Edit:17Kw output unit

Sagraiasolar wrote:Wise words all round so not much I can add.  My favourite would be a small Air source heat pump + wood burning stove + a heat bank.  As has been said - hard to justify solar when an ASHP is so good.  If you are resident and there to fiddle about with a stove then you might find a stove plus a heat bank plus huge wet solar panels will service without many gaps.  Huge solar is very interesting as you build a flat solar profile by angling the panels with a winter bias so that the wider and flatter solar production graph overlaps with the wood burning season ... I won't bore you further as there is some chat and picures of the best stove and heatbank on http://originaltwist.com/2014/03/19/heat-pumps-in-southern-europe-air-or-ground/
... what else?   PV rules changed to make the benefits linked to tax ... killed all that off overnight.
Underfloor heating is wonderful in all respects except in bedrooms where I'd go for the rapid response times of fan-coil units.

Would this give you DHW only in the summer and at what volume?

stevegwmonkseaton wrote:Would this give you DHW only in the summer and at what volume?

I guess you mean the big solar array... it can be tempered down in the summer by mounting at a steep winter biased angle.
As a rule of thumb they can deliver up to 1kW/square metre so a 3 panel array of 7mq would deliver a max of around 7kW.
This is like having 2 immersion heaters running or the same as the back boiler produces on my favourite stove flat out.
Actually 2 panels at the normal 30 degree angle are usually enough but I prefer the 3 set to give more winter oomph... seeing as how the sun is free and panels are cheap.... for that reason we don't fit the more expensive and unreliable evacuated tube type.  To answer your question ... with 5 or 7mq you get loads of hot showers for 4 or 5 people but you need to store them up in a 500 litre heat bank.   If you are really going to do a pucka installation I can supply all the panels,tank, stove and for the ultimate, add another small tank to do my 'stripper circuit' which makes the panels run more efficiently in winter and extends the range of the tank for many more showers.  Pool heating is often really easy to add to the plot as schematically the pool heat exchanger just becomes another radiator in the house.
Here is a graph of solar production - 
https://originaltwist.files.wordpress.com/2014/02/solar-tilt-graph.jpg
I think 7mq tilted at 50 degrees vs 5mq at 30 degrees -- see they both have the same summer peak but the big array produces a lovely fat curve extending well into the shoulder months (wide enough to overlap with the wood burning stove).. for comparitive purposes the red line going across shows a gas boiler running for an hour a day.

I have a great deal of respect for sagraisolar (also for Geotherm) and they well outstrip my expertise in their fields. My input (as an architect - with a grasp of the fundamentals, but not the specifics) is to try and guide a client to a personal solution. Maybe a bit like a GP finding the right consultant, but only if they have a disease.

So much of the 'general discussion' (and I'm not talking about this forum, where the alternatives are discussed intelligently) is predicated on 'salesmanship' and 'tax breaks' (and also a sort of political correctness about sustainability) that it is shocking. 

There does seem to me to be, (almost exclusively amongst British people), a complete willingness to suspend disbelief when talking about the laws of thermodynamics, and also, within the same constituency, a fairly irrational belief that 'conventional' energy suppliers are all in a conspiracy to rip one off.

To wish to be self-sufficient about energy is a noble goal (and it is achievable) but it isn't necessarily going to be your cheapest option - especially if you buy into the supply side and neglect your demand side. Reducing your energy needs is usually much more cost effective - insulate, then run the whole house of vanilla mains gas/electricity supply. Let Eni take the strain. 

(Life isn't always on the side of the good guys).

My question was probably not well put (something to do with travelling I think). We run a sansa boiler during the summer simply for DHW and it seems to be a bit of a waste. We did have the price of a simple solar system installed just for DHW in summer, but compared to the cost of running the sansa boiler (exc wear and tear on it), it would take years to pay back. However the sansa heating is very old and despite its robust nature I guess will not last forever, hence the question.

For dhw in summer what on earth dissuades you from an electric immersion heater? A scaldabagno (cost circa €100) from any ferramenta/builders merchant.

The Original Relaxed wrote:For dhw in summer what on earth dissuades you from an electric immersion heater? A scaldabagno (cost circa €100) from any ferramenta/builders merchant.

Probably the fact just about every house we looked at had one, they were all circa 1950 by the look of them and hanging over the bathtub/shower. So likely where to put it with minimum disruption, but you could well be right, it certainly would save using the sansa stufa which I guess is not too happy running in short bursts. I wonder if they would be cheaper to run, I reckon the sansa costs on average less than €0.40 per day in summer .

The Original Relaxed wrote:For dhw in summer what on earth dissuades you from an electric immersion heater? A scaldabagno (cost circa €100) from any ferramenta/builders merchant.

Well it's the cost of electricity that dissuades me.  At around 32c per Kw.hr a 3kW immersion heater nominally consumes €1 an hour so to compare with an hour of a 30kW gas boiler you'd need €10.  I expect some light users would get away with 2 or 3 hours of the immersion so over some 200 days the expenditure range is €400 - 2,000.  For a system with abysmal response times I'd say that was a lot.  Solar heating (with immersion back up) need not be mega expensive and it is very DIYable for less than €2,000 and it's green - one or two of us really do want to do our bit to save the planet.

Might be worth having a look at this type of solution Steve.

http://www.ariston.com/ww/Air_sourced_water_heaters/NUOS_EVO_WH

I'm sorry you got the impression I was calling you a 'salesman' - I thought I'd made it quite clear that I find both you and geotherm very informative straightforward posters!

I don't accept your calculations on the immersion heater running costs though! Typically the Italian ones are 1.5kW, 80/100 litres and I've lived with many of these for a long time. They give enough dhw for two people. They are heavily insulated, thermostatically controlled, and can be run on a timer (making them usable on a 3.3kW supply). It is difficult for the immersion heater to consume more than 3kWh per day, so let's say €1 per day - compared with the 40c per day cost of running the sansa boiler.

I accept it is neither very cheap to run, nor green, but for the application which Steve is outlining (not permanent occupancy) I think it is a valid proposition, and nothing like as costly to run as you suggest. Plus, the installation cost is pretty well negligible, and there are no maintenance issues.

They don't have to be located at high level in the bathroom, they work from mains water pressure so they are fine at floor level. They don't have to be in the bathroom - but obviously pipe runs should ideally be as short as possible - (often the best location is closer to the kitchen sink).

Apologies Relaxed - have removed my rant - coffee too strong!.  As for costs... energy is what it is ... spend less and get less or as they say "yer pays yer money and yer takes yer choice"

We have a small immersion unit which was installed as a 'temporary' fix for three months six years ago.  Needless to say we still have it and it is remarkably efficient.  We get two showers out of it and then it needs half an hour to heat up again. 

However, our best investment has been a solar shower outside.  This is plumbed into the cold water and through the best months of the summer we find we don't use the inside shower at all.  It has a proper thermostatic valve and looks good too.

Not sure if I am now in the right area to post this !! Apologies if I'm wrong .........again ! Copy follows:

Any of you gurus out there know what the RULES are regarding a 'certificate di agibilita'.

We had some works done on our property here some years ago and had a new, updated certificate provided (cost about €2k I think !!).

In the last few days, we have had a bit of electrical work done (not a lot!), do we now need a new certificate ?! What are the limits of works that requires you to update the certificate?

If we were to sell up, would the 5 yr old certificate do the job ?

Cheers,

V

I think it may depend on what the extent of the new electrical works are, but I am not an expert on the rules.
If there is no electrical wiring diagram supplied with the original certificate, then I would not think you would have a problem, unless you made major changes.
Even if we install a heat pump that requires a 3 phase increased supply, then I have not heard of a new certificate to be required.

Thanks Geo, I don't think the house has any wiring diagram ! The electrician just comes and adds/changes things !

V