Target U value figures are 0.35 for walls, 0.25 for floor, 0.2 for roof and 2.2 for windows.
I thought the allowance is 60W per person? I would expect occupancy to be less than 10. Toilets, stairwell, kitchenette, reception etc.
regards
But in economic terms gas is still the best.
Typical? That is best case. The average is far lower
Which means sweet FA to the punter and his bills.
What is needed is abstract thinking.
If the water flows and its for heating it might be better to mechanically convert the flow energy to heat.. water wheel driving a braked shaft with the friction heat being carried to the building by pumped water.
The same is probably true for windmills if he wants to put a few on the roof. About 60% of the energy is turned to heat in the generator/gearbox AFAIK so putting the generator in the building will save all that energy to heat the building.
The SST of the North Sea currently ranges from 13C around Shetland to
17C of the SE corner.But with a flow of relatively warm water just above your buried slinky I suspect the slinky can be somewhat smaller than one buried in normal ground. Heat can be transported in quicker by the flowing water compared to (more or less) just conduction in a ground buried slinky.
Bet the EA would ob ject to the laying of slinky in river bed though. Or English Nature if they got to hear of it, probably a rare Crayfish or their might be a rare Crayfish and they'll want a full wildlife and impact survey carried out... FFS, there will be a bit of disturbance during the installation but after that bugger all, water temps down stream might a tad lower but I bet they'd soon recover.
It needs realistic thinking.
Gas boilers are cheap. Gas is cheap to run. Heat pumps are expensive to install. At best they cost the same as gas to run.
I doubt he has the flow to turn a genny powerful enough to heat the place - he would need a thermal store as well.
It needs a water cooled windmill to extract the heat.
That's good. Experience suggest with windows and adequate ventilation that WILL average out to about 1.,.
60W for the person, and a further 140W of lighting, and general equipment is my reckoning. Making cups of coffee, strip lighting, PC, shared printer, router PABX etc etc etc.In winter, lights tend to be on most of the day.
I am trying to quickly calculate what square meterage I have here..18x7
I did some ground source heatpump calcs, and they reckoned a hard wired unit with soft start on a single phase could just do the job, with a ground loop of around 400 meters length in wet clay.
I've got an acre or so to play with, so that's not a problem. The problem was the heating tank (which could be just immersion using the heat pump as a preheater) and the upstairs, which is small bore rads and fan convectors that need at least 65C to even start fanning - thermostat switches.
Essentially all that would need replacing. BIG job. Then oil came down in price and I shelved the idea.
How much land have you got to work with?
Oh, but it is.
A typical power station carbon efficiency is around 45%. More if its nuclear, or wind.
At least 50% of your heatpump usage will be at 4:1 uplift providing a 'carbon fuel efficiency' of 180%.
The rest around 135%.
In essence a heatpump uses summer solar energy to provide the rest..
This is the key point. In terms of *fuel burnt* to useful heat produced, a heatpump is capable - using low grade solar energy - of providing up to 200% thermal efficiency.
If you arrange the heating to work -on - say - 40C water at most, you can keep the heat pump in its most efficient zone.
That's not a very high temp, but if the whole floor is one massive radiator absolutely crammed with pipes, its enough.
Oh, its *way* better. Slinkies are relative crap by the way, long pipes laid in flat loops are way better. Add moving water to the mix and there is no local cooling of the heat exchanger. You wont be freezing the subsoil, just subjecting the pipes nearest the pump to a layer of ice, maybe, but even that's unlikely.
Id hazard a guess that 100-200m of pipe on the river bed would be adequate.
What might work is to dig a pond fed from and exiting to, the river, and put the pipes in that.
But any trenches dug below local water table would likely be very effective as well.. The river would serve to keep the soil wet and conductive.
That is what a slinkie is.
Until it freezes then you may have to reverse the heat pump to thaw it.
20l falling is giving (almost) 200N force, through 20m is 4Kj, that's 4Kw as you're doing it once a second. Seems possible.
But he's far more likely to have a lot more water and a lot less head if the land is flat enough for agriculture.
Those of you factoring in the waste heat from lights, computers, etc. might like to consider where that electricity comes from.
Andy
A nice little Nuclear power station not 50 miles from here..
In message , The Natural Philosopher writes
About 90 acres:-)
Realistically one would only lock up land which had no prospect of other development or sale.
The bit I am considering is a 1/4 acre strip bordering the river. Mean water table is around 18" (higher in the winter) so wet!
If I can't get anywhere with the EA I can clean out an existing cress ditch which is parallel to the river, about 7m wide and 75 long.
Space heating can be underfloor throughout and I can use a gas combi for washing etc.
I imagine there might be some *economy of scale* using one industrial size plant rather than several domestic units.
regards
We were somewhere around Barstow, on the edge of the desert, when the drugs began to take hold. I remember "Doctor Drivel" saying something like:
With that single sentence you've shown you've never had anything to do with river water pumping, don't have a clue about it and blow everything you ever spout about out of the water (pun intended). So, what else do you profess expertise in? Let's see... lots.
ALL OF IT BULLSHIT.
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Here, eastern Canada the possibility of pumping water out of a lake extracting heat from it and dumping it back was raised. But it was pointed out that in winter, which is when heat needed the water can freeze and go well below zero C! The ground temperature however is generally around 8 to 10 deg C. The temp. of the municipal cold water supply to our house, for example, via a pipe some eight feet down is, even mid winter, always in the range of 45 to 55 deg F. So ground loop heat pump systems apparently work well. Seemingly; for in ground systems plastic conduit is buried in ground somewhat below the frost line depth of around 40 inches, and a closed water loop is run through it. Air heat pump systems apparently run out of steam, as it were, at temperatures below say minus 6 to 10 C and just cannot extract enough useful heat out of the outside air at those temperatures! So auxiliary electric heating coils cut in in effect one has electric heating. Electric heating is common here with most of the generation, especially in this province by hydro. The incremental 'extra' investment for even a simple heat pump system, for a basic 1200 to 1600 sq. foot well insulated (as required by building codes nowadays anyway) home here is rumoured to be in region of $20,000+ Can. Roughly say 13,000+ UK pounds? That extra cost, in order to be profitable or at least break-even, has to be recovered by any savings in energy costs over a reasonable period of years. For someon who installed basic electric heating some 40 years ago the retrofitting cost, including some means of introducing the heat-pumped heat, using an air exchanger of warm water radiators, into the house would considerable!
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I just check ours here in the northern US, and it's sitting at 55 degrees F, but I'm not sure how much it falls by in Winter. That comes via an 80ft well out back, and the line coming into the house is about 8ft below ground level.
I thought they generally used something else for the closed loop, other than water, just to prevent freezing if there are any cold spots (particularly where loops meet).
Yep, I've heard that too - I think they're just about viable in the UK, but utterly useless here.
Same here - and with the rebates that the electric co. give for having electric heating, the overall cost is fairly competitive against propane.
It's expensive - but I think around half of that expense is in the digging and installation of the ground loop, so a DIY solution could provide significant cost savings, assuming a company exists that'll sell the bits of the system and let the user do the installation.
Unfortunately the 'leccy company do significant cost breaks for having a GSHP system - but of course it has to be a system on their 'approved' list, which is a disincentive for DIY...
cheers
Jules
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It only North of the permafrost line that the subsoil is frozen.. and if =
you go deep enough of course, you are into geothermal heat :-)
Its either dosed with antifreeze, or brine. Apparently the outflow from=20 the pump can and does end up covered in a sheet of ice, if not=20 insulated. They are after all just big refrigerators.. Its about -5C to=20
-7C apparently.
More or less the case.
My research came up with around =A36k for a system to be installed after =
the groundwork was done. I'd get my own digger in for that.
Ah. Bastards.
Do you mean you can't pump river water? Is it too thick?
:-) Dunno how deep that'd be around here - as I say, the water from 80ft down is pretty chilly, even in Summer.
Brine sounds somewhat preferable, in the event of a leak...
Yeah, not sure how deep the loops would have to be around here yet (as per my other thread about monitoring ground temps), but I suspect I could find someone to borrow a digger from (actually I know someone with a Bobcat, and that might just about do the job given a shallow enough approach angle, and depending on what the soil composition's like)
The cynic in me wants to say there are all sorts of backhanders going on
- but it's more likely that GSHP tech is just too 'new' (in general public terms) and so there's no provision for homebrewing a system and having it inspected by a professional who can tell the 'leccy company that it does indeed do what it's supposed to. (ditto with solar, wind turbines etc.) - hopefully that'll change a few years down the line...
We've probably got about 15Kw of electric heating at our place, but we only turned on half of the heaters last Winter, with the LPG taking up the slack - I need to run the numbers sometime and figure out how long a GSHP would take to pay for itself, assuming no subsidisation from the electric co for running costs...
cheers
J.
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