navitron
 
Renewable Energy and Sustainability Forum
Welcome, Guest. Please login or register.

Login with username, password and session length
News: Anyone wishing to register as a new member on the forum is strongly recommended to use a "proper" email address - following recent spam/hack attempts on the forum, all security is set to "high", and "disposable" email addresses like Gmail, Yahoo and Hotmail tend to be viewed with suspicion, and the application rejected if there is any doubt whatsoever
 
Recent Articles: Navitron Partners With Solax to Help Create A More Sustainable Future | Navitron Calls for Increased Carbon Footprint Reduction In Light of Earth Overshoot Day | A plea from The David School - Issue 18
   Home   Help Search Login Register  
Pages: 1 [2]   Go Down
  Print  
Author Topic: Would it pay to go on to economy 7  (Read 6041 times)
martin
Hero Member
*****
Offline Offline

Posts: 15733



WWW
« Reply #15 on: April 23, 2011, 11:31:29 PM »

Finding unbiased results is very difficult - DECC reckon "3.2" (http://www.decc.gov.uk/en/content/cms/what_we_do/uk_supply/energy_mix/renewable/explained/microgen/gshps/gshps.aspx), many studies use a lot of "manufacturer's data", which at the very least is going to be based on perfectly optimised systems - as I said, I reckon that a "fair" real world estimate is a yearly average of is "3", and if you get the design right, there is a chance you may actually see that sort of performance in action.

I seem to remember that there are is at least one report due out any moment (if it hasn't already been released) on "actual" results which are fairly pessimistic about their claimed efficacy (I'm sure it's been mentioned on the forum)

From general experience of claims about the advantages of different technologies, I think it's wise to take manufacturer's claims with a very large pinch of salt, and always err towards the most conservative figures available.........
Logged

Unpaid volunteer administrator and moderator (not employed by Navitron) - Views expressed are my own - curmudgeonly babyboomer! - http://www.farmco.co.uk
billi
Global Moderator
Hero Member
*****
Offline Offline

Posts: 8936



WWW
« Reply #16 on: April 24, 2011, 05:12:08 AM »

.... i guess  COP discussions in relation to CO2 will start to vary depending  on supporting renewables in each country

Heating and hot water could be a way to store energy in a renewable energy designed country  to buffer the grid

A smart metering Idea  would help


 But i have the feeling , the UK or what i pick up here on -the renewable energy forum-  is stuck in a nuclear as the solution debate and renewables  are  too expensive ( while Pint prices rise     Lips Sealed)   stir


So i am getting kind of "schizophrenic" in relation to electricity use, cause  in my fathers land only the new built PV
of  2010 could power 3 million electric cars (9000 miles per annum ) - so a fuel station   built for 3 million cars in one year (theoretically ) for the next 20-30 years

A lot of Diesel could be saved for other uses

But this is only theoretically and the automobile-industry in my fathers land just seems to fail  Undecided


Same ,some how for heatpumps , sure too early for me to promote  , especially  when countries seem to be stuck in never-ending debate about the mystery of false information of energy supply and nuclear will solve it !

The answer to
Quote
Would it pay to go on to economy 7
will be.... yes BOB we can do it!  Grin (if you explain your mates , the reason the pint went up 2pence )



....and will get cheaper later , cause renewables will produce renewables

Billi












« Last Edit: April 24, 2011, 05:26:04 AM by billi » Logged

1.6 kw and 2.4 kw   PV array  , Outback MX 60 and FM80 charge controller  ,24 volt 1600 AH Battery ,6 Kw Victron inverter charger, 1.1 kw high head hydro turbine as a back up generator , 5 kw woodburner, 36 solar tubes with 360 l water tank, 1.6 kw  windturbine
mpooley
Hero Member
*****
Offline Offline

Posts: 723


« Reply #17 on: April 24, 2011, 10:42:49 AM »

How do I work out how large a tank i would need to store all the heating needs of my house for a whole day?

thanks
Mike
Logged

It's not easy having a good time. Even smiling makes my face ache.

“Science is the belief in the ignorance of experts.” Richard Feynman
billi
Global Moderator
Hero Member
*****
Offline Offline

Posts: 8936



WWW
« Reply #18 on: April 24, 2011, 12:04:21 PM »

rammed clay and load it during the night perhaps is an option ....   instead of storing in a water-tank  at too high temps  and additional pumps running

Billi

 


* clay2.jpg (106.07 KB, 295x758 - viewed 369 times.)
Logged

1.6 kw and 2.4 kw   PV array  , Outback MX 60 and FM80 charge controller  ,24 volt 1600 AH Battery ,6 Kw Victron inverter charger, 1.1 kw high head hydro turbine as a back up generator , 5 kw woodburner, 36 solar tubes with 360 l water tank, 1.6 kw  windturbine
A.L.
Hero Member
*****
Offline Offline

Posts: 905


« Reply #19 on: April 24, 2011, 12:14:27 PM »

hi,

IIRC your house has a specific heat loss of a little under 500W/°K, given that you want to store heat for 17hrs without E7 you will need to store

500 * 22 (dt) * 17 = 178000wh or 178Kwh

assuming a usable storage range of 20°C you will need 178/(20*1.16) or 7.67 cubic metres of water

you will also need a 40kw heat pump not a 13 kw one to extract that amount of energy in seven hours and heat the house at the same time!

IMHO you would be better off getting the absolute lowest rate daytime tariff (about 9.5p?) as you will save on the daytime lights and applliance usage as well
Logged
mpooley
Hero Member
*****
Offline Offline

Posts: 723


« Reply #20 on: April 24, 2011, 12:41:45 PM »

thanks A.L
my tarrif is 8.0001p so yes normal rate looks best.
Logged

It's not easy having a good time. Even smiling makes my face ache.

“Science is the belief in the ignorance of experts.” Richard Feynman
dhaslam
Hero Member
*****
Offline Offline

Posts: 6775



« Reply #21 on: April 24, 2011, 02:03:05 PM »

hi,

IIRC your house has a specific heat loss of a little under 500W/°K, given that you want to store heat for 17hrs without E7 you will need to store

500 * 22 (dt) * 17 = 178000wh or 178Kwh

assuming a usable storage range of 20°C you will need 178/(20*1.16) or 7.67 cubic metres of water

you will also need a 40kw heat pump not a 13 kw one to extract that amount of energy in seven hours and heat the house at the same time!

IMHO you would be better off getting the absolute lowest rate daytime tariff (about 9.5p?) as you will save on the daytime lights and applliance usage as well

I don't think you should be thinking on that sort of scale for a new house.    My house is  about 220 square metres and uses  a 860 litre  buffer tank.  The heat pump only has an output  of  about 2 kW in cold weather so it only raises the water temperature by two degrees per hour  but there is a nine hour low tariff rate.    OK it isn't quite enough and it has to run for about five hours during the day as well.   The heat pump should have been a bit bigger  but it does provide most of the  heat requirement  and only costs  one euro at night rate plus one at day rate. 
Logged

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
sam123
Full Member
***
Offline Offline

Posts: 210


« Reply #22 on: April 25, 2011, 03:19:30 PM »

I am now thinking of going for a GSHP.
it will probably be between 13-15kw unit possibly using between 8000-9000kw/h per annum

how much of this would be used overnight? I havn't got a clue.

anyone any experience of this?
thanks
Mike

As we are a little bit more experienced here in Finland  whistlie I have few thinks to say:
- COP is related to ground temp vs. produced heat.
 * 30 degree to floor and 5 degree ground fluid temperature = 35 degree to floor and 10 degree ground fluid temperature

- every degree to add, means 0.1 to 0.15 to COP (or off from COP) = 5/30 COP 4 --> 6/30 COP 4.1 or 4/30 means COP 3.9
That means basically that you should try to keep ground temperature high and produced water temperature low.

If you install B I G tank and you try to warm it during cheap hours, that means:
 - you overheat stored water (COP goes down)
 - you get "extra long" working period (with extra big GSHP), which temporarily cools down your ground loop (COP goes down)
 

There is no reason to produce warm water other way than GSHP, because COP is still around 2 or more.

When you use floor heating you can load extra degree or two to your floor during cheap hours. That can be made directly with Scandinavian made GSHPs.
 
My advice is that buy Nibe or similar with 180-200 liter tank integrated. Put horizontal 400m ground loop if you have a space. Leave 1-1.5 meter between the pipes and do NOT dig them under 1 meter in UK. Something like 60-70cm will be optimum.

Some pictures: http://www.rakentaja.fi/index.asp?s=/tv/tvtulostus.asp?id=1035

Cheers,

Sami

Logged
mpooley
Hero Member
*****
Offline Offline

Posts: 723


« Reply #23 on: April 25, 2011, 04:54:42 PM »

I am now thinking of going for a GSHP.
it will probably be between 13-15kw unit possibly using between 8000-9000kw/h per annum

how much of this would be used overnight? I havn't got a clue.

anyone any experience of this?
thanks
Mike

As we are a little bit more experienced here in Finland  whistlie I have few thinks to say:
- COP is related to ground temp vs. produced heat.
 * 30 degree to floor and 5 degree ground fluid temperature = 35 degree to floor and 10 degree ground fluid temperature

- every degree to add, means 0.1 to 0.15 to COP (or off from COP) = 5/30 COP 4 --> 6/30 COP 4.1 or 4/30 means COP 3.9
That means basically that you should try to keep ground temperature high and produced water temperature low.

If you install B I G tank and you try to warm it during cheap hours, that means:
 - you overheat stored water (COP goes down)
 - you get "extra long" working period (with extra big GSHP), which temporarily cools down your ground loop (COP goes down)
 

There is no reason to produce warm water other way than GSHP, because COP is still around 2 or more.

When you use floor heating you can load extra degree or two to your floor during cheap hours. That can be made directly with Scandinavian made GSHPs.
 
My advice is that buy Nibe or similar with 180-200 liter tank integrated. Put horizontal 400m ground loop if you have a space. Leave 1-1.5 meter between the pipes and do NOT dig them under 1 meter in UK. Something like 60-70cm will be optimum.

Some pictures: http://www.rakentaja.fi/index.asp?s=/tv/tvtulostus.asp?id=1035

Cheers,

Sami



thanks Sammi

that leaves me with a bit of a problem as the predicted temps i will be using are 6/45
that leaves me with a COP of 2.5 according to your figures.

Have i worked that out right?

Mike
Logged

It's not easy having a good time. Even smiling makes my face ache.

“Science is the belief in the ignorance of experts.” Richard Feynman
sam123
Full Member
***
Offline Offline

Posts: 210


« Reply #24 on: April 25, 2011, 05:30:16 PM »



thanks Sammi

that leaves me with a bit of a problem as the predicted temps i will be using are 6/45
that leaves me with a COP of 2.5 according to your figures.

Have i worked that out right?

Mike

Hi Mike

Those COP-numbers, which I was using, were "education purpose only". I think you get more COP in real life.

With GSHP you should NEVER use room thermostat, if possible. GSHP uses outside temperature measurement and adjust water temperature to floor heating (or radiators).

If you need all the time high temperatures, you should consider to add bigger radiators or add one konvektor (similar to ASHP inside unit) to system. If 45 degree is maximum temperature needed in winter, then it´s okay.

Over here is one GSHP-test with real COPs. As it is made in Sweden, only brine tempperature 0/-5 is used. Even few words of English there  Wink

http://www.stiebel-eltron.fi/imperia/md/content/lg/stiebeleltronsuomi/l__mp__pumpputesti_2006.pdf

Sami

EDIT: I have no doubt that you can get annual COP 4 or even more in UK. To achieve that:
- long ground loop with 1-1.5m space
- not too deep (absolute maximum 1 meter)
- use 40mm 10bar pipe. On borehole 6bar pipe.

Problem is not really ground temperature or water temperature in borehole. Problem is to transfer energy from source to ground fluid, inside the pipe. Plastic is great material for insulation, not for heat transfer.
We use also 3 or 4 pipes on borehole. Two down (slowly) and one up (fast). Or two down and two up. Just to get more heat transfer area...



etc.



link removed  good try  Wink  Billi
« Last Edit: April 25, 2011, 09:26:59 PM by billi » Logged
Pages: 1 [2]   Go Up
  Print  
 
Jump to:  

Powered by MySQL Powered by PHP Powered by SMF 1.1.20 | SMF © 2013, Simple Machines
SMFAds for Free Forums
Simple Audio Video Embedder
Valid XHTML 1.0! Valid CSS!