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Author Topic: Air or ground source + solar  (Read 8764 times)
neilydun
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« on: May 17, 2010, 08:01:47 AM »

Hi, I am after some advice if possible.
I live in a converted barn (converted about 15 years ago), which is well over a hundred years old. We have wooden framed double glazing with heat reflective glass through the building, and the building is insulated, altough this could be improved.
The overall living space is about 280 Sq. M, with approx 90 Sq. M of underfloor heating on the ground floor. The underfloor, and our wood burning stove manage to heat our house, even through this years harsh winter. A lot of the heat produced travels up through the lounge to the 1st floor and loft room, as the landing is galleried.
There are rads throughout the 1st and loft rooms, but as I said, we did not need these on this, or any other years since we lived here (8 years).
I have a 3.6 Kw P.V system on the roof, and currently I am using an oil fired boiler.
I would like to take advantage of the grant available for either a ground, or air source heat pump, and maybe a solar collector.
My question is which one is the better system?
The research I have done on the net seems conflicting. Obviously the air source would be far easier and less disruptive to fit, but I hear horror stories of how electric consumption soars, and when the temp drops below freezing they are not much use.
So would ground source be the better bet, I have about 380 Sq. M of usable space to use, I don`t even know if this will be enough area to make use of a ground source.
What is the likely cost of either system?
I would also like to mention that hot water is an issue. My wife and I have 3 son`s so we use a fair ammount of hot water. Can a air source heat pump produce plenty of hot water, even in cold temps, and what temp is achievable in the cold weather.



My thanks in advance for any information you could share.
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martin
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« Reply #1 on: May 17, 2010, 08:19:06 AM »

The simple answer is that what you've heard is pretty accurate - air source can be expensive to run (at today's prices- if they escalate as they must, they will become even more so) and is at it's worst in the depths of winter when you most need it, of the two, ground source would be far better, but more expensive for the initial installation.
Using the "what would I do" way of looking at it, I wouldn't bother with heat pumps at all (electricity, unless home-generated = escalating and hefty costs to run), but would look instead at the incorporation of solar hot water, and possibly replacing the oil-fired boiler with some form of wood-fired device. Smiley
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MR GUS
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« Reply #2 on: May 17, 2010, 09:37:30 AM »

Sounds like you've got room for a MASONRY stove, I'm sure someone will be along to "bang on" about them (see his sig)  Grin ...

What size stove fo you have, location etc, maybe a pic? ..Billy & daftlad may be assistance there, but ther are plenty of threads to them if you utilise the search facility.
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Austroflamm stove & lot's of Lowe alpine fleeces, A "finger" of Solar Sad
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neilydun
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« Reply #3 on: May 17, 2010, 09:57:11 AM »

Hi, and thanks.

I am not sure what rating my current stove has, but the opening at the hearth is about 1.8m wide x 1.3 heigh. Its located at the end of my lounge, just asjacent to the area which has an open ceiling, so a lot of the heat generated rises.
The only problem with using it with a back boiler or anything similar, would be that its completely surrounded by underfloor heating.
There would be no way to run any pipework from anything new to be located here, and the existing stove generates plenty enough heat, so much so, that when its hot you can`t get near it.
As for the haet pump, I do generate a little electric from home, as I have 3.6kw pv on the roof. I know thats not huge, but maybe a little offset?
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knighty
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« Reply #4 on: May 17, 2010, 09:58:34 AM »

do you have enough south facing roof space for lots of solar thermal ?


with under floor heating, I'd think this would be the perfect option ? (especially with a decent sized hot water tank)


maybe leave the oil fired boiler as it is, for if it gets really really cold...
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MR GUS
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« Reply #5 on: May 17, 2010, 10:06:51 AM »

neilydun, go & look for the backplate of your burner if not all browned out through heat, take a pic, if it was there when you bought the barn maybe it was simply thrown in there? as a cheap space filler, therefore innefficient (though i hope not) ..this will obviously affect the labouring & fuel expenditure, so bearing in mind the space to fill, i'd start by getting the make & model to work upon what's already in place maybe?
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Austroflamm stove & lot's of Lowe alpine fleeces, A "finger" of Solar Sad
Noli Timere Messorem
Screw FITS ..it is, & always has been about the environment (said the penny-pinching Scotsman)
neilydun
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« Reply #6 on: May 17, 2010, 10:29:50 AM »

Yes I do still have some roof space left, but the PV has taken up a fair chunk of space, I have maybe 25 Sq. M of roof space left.
The stove was fitted by us when we moved in. I am more than happy with the ammount of heat we get from it.

I can take some pictures, how do I attach them?








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martin
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« Reply #7 on: May 17, 2010, 10:33:05 AM »

as long as they're under 128k a piece, just click on "additional options" at the bottom of the reply box, and follow your nose, or use the "img" tags and cut and paste the internet url of the pics if you have them stashed with Flickr or the like............. Smiley
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Unpaid volunteer administrator and moderator (not employed by Navitron) - Views expressed are my own - curmudgeonly babyboomer! - http://www.farmco.co.uk
neilydun
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« Reply #8 on: May 17, 2010, 10:46:16 AM »

Hmmm O.k Ive not done this before, but I will try


http://www.flickr.com/photos/50303149@N06/

That should be the link. Maybe?
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Billy
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« Reply #9 on: May 17, 2010, 10:51:18 AM »

Worked for me.   Grin Grin Grin
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MR GUS
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« Reply #10 on: May 17, 2010, 10:53:14 AM »

Jeez that looks a beast of a burner!

Encore woodburner by Vermont castings...

Product Specifications
Ash Pan YES 
Log Length (Max.) 20 in.
EPA Emissions Rating 1.6 (grams/hr)
BTU/hr Range EPA Test Method 8,700 to 41,700 BTU/hr
Cast Iron Construction YES 
Heat Circulating Fan NO 
Flue Collar Size Oval 8 in.
BTU/h (Max.) 47000 BTU
Efficiency 76 %
Burn Time (Max.) 9 hours
Combustion Technology Catalytic 
Firebox Lining Cast iron 
Firebox Volume 2.1 cubic feet
Heating Area (Max) 1900 sq. ft.
Rear clearances (with optional shields) 19 in. to combustibles 
Weight 435 lbs.
Unit Depth 21 3/8 in.
Unit Height 25 7/8 in.
Unit Width 27 in.
« Last Edit: May 17, 2010, 10:55:44 AM by MR GUS » Logged

Austroflamm stove & lot's of Lowe alpine fleeces, A "finger" of Solar Sad
Noli Timere Messorem
Screw FITS ..it is, & always has been about the environment (said the penny-pinching Scotsman)
neilydun
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« Reply #11 on: May 17, 2010, 10:56:56 AM »

Yep, it was the biggest we could get at the time. Anything smaller would have been a bit lost in the space I think.
It really kicks the heat out!!
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neilydun
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« Reply #12 on: May 17, 2010, 10:58:35 AM »

And thanks for the spec`s
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MR GUS
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« Reply #13 on: May 17, 2010, 11:29:10 AM »

Makes sense to list em, others can use the overall effect of your combined components to guage things.
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Austroflamm stove & lot's of Lowe alpine fleeces, A "finger" of Solar Sad
Noli Timere Messorem
Screw FITS ..it is, & always has been about the environment (said the penny-pinching Scotsman)
dhaslam
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« Reply #14 on: May 17, 2010, 12:59:26 PM »

If you are using solar heating then you need to be able to store heat  for a long period.    There are some sunny days in winter that would heat the house  but the ratio is only about one day in six and they tend to come a few days at a time.    I am starting to construct a seasonal store.    For  cost reasons this is going to be  clay based because  the insulation used (straw) is  cheap   and it can be heated by warm air which is easier to heat than water.   The heat will be transferred to the house by two water pipes.  One will be used to preheat the air intake to the air to water heat pump and the other direct to the buffer tank that feeds the underfloor heating.  The collector area will be about 24 square metres and the  volume of clay inside the insulation about 200,000 litres but the heat requirement is quite low.   Heat was supplied this winter by the nominal 5kW  heat pump  but it had to run almost round the clock in the cold weather because performance is poor at low intake temperatures.  With the preheat system it should be back to  using the off peak hours only, costing about one euro per day in winter.           
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DHW 250 litre cylinder  60 X 47mm tubes
Heating  180,000 litre straw insulated seasonal store, 90X58mm tubes + 7 sqm flat collectors, 1 kW VAWT, 3 kW heatpump plus Walltherm gasifying stove
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