Slater
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| posted on 25/11/11 at 09:31 AM |
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Advice on Ground Source Heat Pump System?
Hello, I have a friend who is thinking about installing a ground source heat pump system to "help" heat his domestic hot water. He has
sufficient land area : 4 off 50m trenches 1m deep x 1 m wide are required, and has been quoted 8,400 pounds for the install (including Heat pump,
water storage cylinder, ground loop, commisioning package, VAT. Not including earthworks), by ICE Energy Heat Pumps.
He lives close to Aberdeen, so the ground will be cold!!!! The house hot water is currently heated by oil and it's not cheap to run.
Does anyone have experience/advice on this.........Does it actually work?? but mainly, will it save money in the long term?
Will it be less efficient in the colder Scottish ground????
Thanks
Keith.
Why do they call Port Harcourt "The Garden City"?...... Becauase they can't spell Stramash.
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ssc28
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| posted on 25/11/11 at 09:42 AM |
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Yes it does work, Aberdeen isn't an issue. At the depth needed for the installation the ground will be at a constant temperature. The outside
temp won't effect the system. He will basically be raising the temp of his domestic hot water so that less energy is needed to heat it to a
level where it will heat his home.
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owelly
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| posted on 25/11/11 at 09:58 AM |
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ISTR albertz on here lives up near John O'groats and he has nothing but his GSHP for heating and hot water. Try sending him a message.
http://www.ppcmag.co.uk
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mcerd1
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| posted on 25/11/11 at 10:01 AM |
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quote:
Originally posted by Slater
.....Does it actually work??....
yes they work, they just need a temperature difference to work from
Think of it like this - your 'moving' some of the heat from the cold ground to the hot water by adding a little work from the pump
(second law of thermodynamics) - there is no such thing as cold - just less heat!
So the system is exactly the same as your fridge only the hot bit on the back of the fridge heats your water and the cold bit inside is the earth
The third version of this type of thermodynamic cycle is to use the heat difference to run the pump as a motor (aka the Stirling cycle / engine)
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pewe
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| posted on 25/11/11 at 10:34 AM |
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IIRC a mate's neighbour in Shropshire installed one and though it worked his garden suffered because it had the heat drained out of it by the
pump.
His description of it was that the garden looked as if it had perma-frost for the whole of last winter.
That could be exaggerated but might just be worth looking into.
Cheers, Pewe 
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owelly
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| posted on 25/11/11 at 10:54 AM |
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The surface of the ground won't be affected at all by the drop in temp if the coils have been sited correctly. There have been reports of
industrial sized gshp systems causing freezing which has caused expansion and subsequent surface disruption but that was put down to a bad design and
I'm sure it was a bore hole type system.
I looked into this ten years ago and the figures didn't add up but having had a look more recently, the costs of hardware has come down and
efficiency has gone up, combine this with the 400% increase in gas prices, its definately worth a looksy.
http://www.ppcmag.co.uk
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quinnj3
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| posted on 25/11/11 at 11:37 AM |
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Hi,
A colleague installed a gshp when he built his house 3 years ago. He uses it for hot water and general heating using underfloor heating. The system
would be almost useless tied to radiators as they work at too high of a temperature. His electricity bill average £300 / quarter and that includes
home heating all year round, on demand hot water, cooking and general electricity usage. His house is about 2400 sq/ft. I reckon thats pretty cheap.
He has economy 7 tariff in place which means that after 11 or 12 in the evening to 7 in the morning his charge per unit is cut by half. He runs the
pump during these hours to heat a ballast tank.
my aim is to build my own locost wether it takes me a week or 10 years to get started, i'm sure i will sometime
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coozer
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| posted on 25/11/11 at 12:03 PM |
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I had a look at it along with solar and PV systems. The cost v payback was nearly 40 years for the ground source and 9~10 for solar PV.
All in, new builds have solar water heating on the roof so I would look at that first.
1972 V8 Jago
1980 Z750
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FASTdan
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| posted on 25/11/11 at 12:11 PM |
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I'm interested in this stuff but having recently had a look on the govermenty type websites it appeared that the figures stacked up to there
being zero benefit for a traditional house with GCH - which I found surprising. It also appeared you couldnt get a grant for any of it unlike
solar.
How much of it is possible to DIY? Can't be that much to it (aside from a lot of digging!). We've just bought a quite large edwardian end
terrace with a reasonable sized gargen so I need to start looking into some energy saving methods...
**edit to say the trench needs to be 2m deep so thats a lot of digging!! Looking on the energy saving trust website it all points to it not being
worth it unless converting from electrical heating systems. That is unless some of the 9-17k installation cost can be taken out?
Anyway, sorry im thinking aloud and hijacking this post lol.
[Edited on 25/11/11 by FASTdan]
NEW danST WEBSITE NOW LIVE! Bike carbs, throttle bodies and more......
http://www.danstengineering.co.uk/
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NOTE:This user is registered as a LocostBuilders trader and may offer commercial services to other users
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Slater
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| posted on 25/11/11 at 12:20 PM |
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Thanks guys, I have U2U'd albertz, will see what he says.
Why do they call Port Harcourt "The Garden City"?...... Becauase they can't spell Stramash.
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bi22le
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| posted on 25/11/11 at 01:18 PM |
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It seems there are many people on here that can help.
My wife works in the building services industry and is a senior engineer, and soon to be chartered. She knows about that sort of stuff. If you need
some further inside or professional advice Ill get her on here to respond to any U2U.
I thought my wife would contribute nothing to this site as she knows fudge all about cars. It seems I was wrong, just a matter of time!!!
Biz
Track days ARE the best thing since sliced bread, until I get a supercharger that is!
Please read my ring story:
http://www.locostbuilders.co.uk/forum/13/viewthread.php?tid=139152&page=1
Me doing a sub 56sec lap around Brands Indy. I need a geo set up! http://www.youtube.com/watch?v=EHksfvIGB3I
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big-vee-twin
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| posted on 25/11/11 at 01:58 PM |
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I'm a Chartered consulting engineer in the Building Services industry. I can say from much experience designing these systems from imperical
data, do not expect the GSHP to cost less in terms of running cost.
The problem with heat pumps is they loose capacity when it gets cold, this is not true when using deep ground bores but in a shallow trench it is true
to say the water temperature in the pipes get get down to zero degrees and not the 12 degrees the sales people will talk about.
The increase in cost of electricity over the past few years has outstripped any running cost benefits.
Also the efficiency of the Heat pump only is quoted and not the efficiency of the system including circulationg pumps. If the installation is a
reasonable size, having a pump circulating water through the ground burning electricity actually negates the efficiency over a traditional gas
boiler.
They are more efficient than LPG however.
A GS heat pump is slightly greener than a gas boiler, but a gas boiler and Solar hot water heating combination is just as green and a lot less costly.
Duratec Engine is fitted, MS2 Extra V3 is assembled and tested, engine running, car now built. IVA passed 26/02/2016
http://www.triangleltd.com
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FASTdan
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| posted on 25/11/11 at 02:18 PM |
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quote:
Originally posted by big-vee-twin
I'm a Chartered consulting engineer in the Building Services industry. I can say from much experience designing these systems from imperical
data, do not expect the GSHP to cost less in terms of running cost.
The problem with heat pumps is they loose capacity when it gets cold, this is not true when using deep ground bores but in a shallow trench it is true
to say the water temperature in the pipes get get down to zero degrees and not the 12 degrees the sales people will talk about.
The increase in cost of electricity over the past few years has outstripped any running cost benefits.
Also the efficiency of the Heat pump only is quoted and not the efficiency of the system including circulationg pumps. If the installation is a
reasonable size, having a pump circulating water through the ground burning electricity actually negates the efficiency over a traditional gas
boiler.
They are more efficient than LPG however.
A GS heat pump is slightly greener than a gas boiler, but a gas boiler and Solar hot water heating combination is just as green and a lot less costly.
Thanks for that info - sounds like a no-go to me then. An ex-boss of mine was having the deep bore holes put in at his new farm house complete with
grants from the government. It was costing him a lot but he reckoned the payback with his size installation was only a few years. But as I understand
it the deep bore holes are a world apart from the shallow trench systems....
NEW danST WEBSITE NOW LIVE! Bike carbs, throttle bodies and more......
http://www.danstengineering.co.uk/
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hughpinder
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| posted on 25/11/11 at 02:30 PM |
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The enegy in / energy out ratio is affected by how hot you need to get the water. If you have underfloor heating or other low temperature heating
system working at (say) 30 DegC you can get good efficiency (4 or 5 kw out for each kw in I believe). If you want to use 'normal'
radiators at 60/70 DegC expect more like 2 or 3kw for 1 kw input.
People often forget to factor in mainenance costs on this sort of set up / lifetime of the underground bit etc, and I believe the maintance cost are
quite high.
I'd suggest one of the pellet burining type boilers if you want a cheap to run and not to messy solution, or if he doesn't mind a load of
old pallets lying around, and a bit of manual labour, heat any size house you like for next to nothing, with one of these, like wot I use:
http://www.dragonheat.co.uk/choosing-your-dragon.html - Ok it cosyt about 7K for me to install, but at my house I'm using 4500l of heating oil
less per year(about £2800pa saving!) - Get a big one and selll the excess heat to the 10 houses either side of you!
Regards
Hugh
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scootz
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| posted on 25/11/11 at 02:41 PM |
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We researched this when building our house three years ago.
The 'expert' advice we got was that GSHP were great for the environment, but were unlikely to save you any money!
We were advised to go for the roof-mounted solar water-heating panels instead and they've worked out really well.
It's Evolution Baby!
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mcerd1
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| posted on 25/11/11 at 03:17 PM |
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what sort of cost are you talking about for the solar ones Scott ?
(I'm assuming mine would be a similar setup to yours if I did it....)
also can these systems work with a gas combi boiler ?
[Edited on 25/11/2011 by mcerd1]
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foskid
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| posted on 25/11/11 at 03:50 PM |
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Another option he may like to consider is a Air sourced heat pump, installation costs are a lot less Circa £2000 but offset by higher running costs.
It works like a fridge in reverse, electric powered but that could be supplemented by solar power or a small wind turbine, obviously dependent on his
location/circumstances.
He knows nothing and thinks he knows everything. That points clearly to a political career.
George Bernard Shaw
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big-vee-twin
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| posted on 25/11/11 at 07:06 PM |
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Running lower temperature water heating systems do improve energy but a COP of 5:1 is incredibly ambitious.
When a heat pump capacity is quoted it is quoted at an ambient temperature of 7 degrees, this is a European standard that all manufacturers quote
capacity against
So a 20KW heat pump is only 20KW at 7 degrees water temp, with Ground Source loop running at around zero in winter the output falls to about 12KW.
So if you need an output of 20KW when its cold you need to buy a 30 KW unit to compensate.
Also the efficiencies are also quoted at the 7 degrees temperature. (i.e. the 5:1)
So again in winter the efficiencies drop to around 2.5 :1, so one KW of electricity in and 2.5KW heating out this is actually called coefficient of
performance (COP)
However, gas costs around 3 pence and electric around 9 pence so a cop of anything less than 3 and the heat pump will cost more to run.
I have specified/Designed - Ice Energy, Mitsubishi, Daikin, Dynaciat, Dimplex, Delonghi, Water furnace equipment and they are all the same - you
can't alter the laws of Physics.
I have specified both large and small, deep bore, shallow trench and Air Source heat pumps over the last 6 years since it became fashionable and they
all over promise and under deliver without any doubt. Many of my clients are now complaining about high running costs, unfortunately lower emissions
does not mean lower costs.
Don't get me wrong there is nothing wrong with the technology and it does work, but please do not believe all the hype.
Duratec Engine is fitted, MS2 Extra V3 is assembled and tested, engine running, car now built. IVA passed 26/02/2016
http://www.triangleltd.com
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MkIndy7
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| posted on 25/11/11 at 07:36 PM |
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wow it really is refreshing to hear some of the truths about all this...
Being Gas Safe Registered and seeing lots of these things being installed and always highly sceptical about getting something for nothing (how can you
really extract the heat from something that has no heat left basically).
I believe it does have its benefits where as described its sized properly and feeds the right heat emmitters etc
I think the best soloution sounds like underfloor type low temperature heating running on the solar/ground source untill something like 7deg and then
as efficient as possible condensing gas or solid fuel boiler below that, but obviousley the install costs would be greater.
But as people are supposed to be installing these as a long term 'green' soloution this would be technically the best as your using all
the components at their optimum.
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big-vee-twin
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| posted on 25/11/11 at 09:05 PM |
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The issue with any heat pump is that they were initially designed as cooling equipment.
But they do work and its not black magic.
A simple explaination of how it does what it does is this - When you pump up a bike tyre using a hand pump we all know that the body of the pump gets
hot as you compress the air, all a heat pump does is compress a gas which increases its temperature.
Its just basic Physics.
Duratec Engine is fitted, MS2 Extra V3 is assembled and tested, engine running, car now built. IVA passed 26/02/2016
http://www.triangleltd.com
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matt_gsxr
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| posted on 25/11/11 at 09:40 PM |
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Why are there no gas powered Ground Source Heating Systems. Gas powered engine driving a pump.
That would minimise the cost.
The waste heat from the inefficient motor could be used as heating. Is it just the issue of moving parts/reliability/complexity?
Using a 500deg flame to warm water to 70deg upsets my thermodynamic sensibilities.
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big-vee-twin
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| posted on 26/11/11 at 10:36 AM |
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There are Matt, very expensive though.
Duratec Engine is fitted, MS2 Extra V3 is assembled and tested, engine running, car now built. IVA passed 26/02/2016
http://www.triangleltd.com
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scootz
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| posted on 26/11/11 at 02:13 PM |
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quote:
Originally posted by mcerd1
what sort of cost are you talking about for the solar ones Scott ?
(I'm assuming mine would be a similar setup to yours if I did it....)
Also can these systems work with a gas combi boiler?
IIRC is added £2k to our central heating system bill, but that was 'all-in'
Not sure if it will work with a combi-boiler... we use one of
these
Our tank is one of these.
You're welcome to come round for a nosey if you want.
It's Evolution Baby!
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