Ground Source Heat Pumps

dnichcole · 22 February 2011 at 12:27PM

Dear Nosha123
First, we have a well insulated house, but if you are satisfied that your house is reasonably insulated, lets move on. Ours is 120 sqm, yours is approx 280 sqm so there is a higher heating load for you.
Next, we have twin deep boreholes which are not as subject to seasonal change as horizontal ones. Yours being 1m deep seem to me to be subject to freezing in weather like we had in January.
*****Someone has just come to my office for a tutorial so I will have to continue this later.
See my blog on 'chargingtheearth' for the full story. Back later.

nosha123 · 22 February 2011 at 12:35PM

In response!
"we have a well insulated house"
Ours is a new build and is very well insulated... quite a bit beyond what building regs stipulate. Kingspan used throughout.
I still thikn that a £200 monthly bill is a bit steep - when a neighbour of ours has a loop in the river and their bill is £300 per YEAR! (house is smaller, loop is in water not soil...so yes specs are different BUT STILL!!!!)
We DO have an air con system fitted - that will store the heat in the ground.. so that should help 'charge' it for winter (only got unit commissioned in Oct '10)

Thanks dnichole speak later!

lovesgshp · 22 February 2011 at 1:30PM

nosha123 wrote: »

Hi Geotherm
Hope you are well over there in Italia!
Hi Nosha. Sunny today, yesterday rain nearly allday long!!
I have been doing almost DAILY readings of our elec meter and the GSHP hours of operation...
I have adjusted the room temps (via the Heat Pump... not the individual room stats) to 20º
The daily hours of operation... are averaging about 14hrs per day (Is this a more average normal usage?)
For your size of property, then depending on outside temps you are around the right level. Checking mine thismorning, from the same time yesterday, it had operated 14 hrs. We went to about 0C outside overnight. Last week averaged 11 hrs day.
Hours of additional heat source have only increased by 3 hours in 3 weeks - which seems MUCH better than before!!!!
That is probably relating to the refrigerant recharge, or outside air temps are getting higher.

And our meter is showing an approx usage of 60 to 80kWh per day.
Is that or the full house? 14 hrs @ 2.2 kwh is approx 31Kw + a couple of Kw for circulating pumps and immersion heater usage over the day approx.
This is all MUCH more normal.... the gas has been topped up too! Only 1kg of vapour was lost apparently.
It lost over 50% refrigerant!! E11 has 1.9 kg in total.
I am going to keep an eye on the readings...
What else can we adjust or fine tune to get the bills down more?
If not already set up, go into the timer menu on K2 and adjust the following: reduce the return flow overnight each day by -1.5c, (say between 10 p.m. to 5.30 a.m.)
Turn off DHW between say 10.00 p.m and 6.00 a.m depending on when you get up.

I still think that our usage is a bit on the high side.... and I am guessing the majority of it will be the heat pump (80kWh equates to £216.00 per month

Hope this helps.

lovesgshp · 22 February 2011 at 1:47PM

dnichcole wrote: »

Dear Nosha123 where are you living? In Finland?
My heat pump (the same model as you, possibly, the IVT C6) has used ONE hour of additional heat in the entire winter, and during this part of February, the average daily consumption is about 20kWh/day, and the worst it got during December was nudging over 30 kWh/day a few days.
The C6 uses 0.9Kwh less than the E11 so Nosha is heating 350 sqm approx. How many hours is yours running per day, as that is a better comparison, plus how large a house?
Perhaps it has to do somewhat with the depth or length of your store. Undersized boreholes or horizontal piperuns would cause the machine to run out of heat more quickly.

600 mtrs (300 ea for feed and return is quite adequate for a E11) As I stated earlier, if it had been a E14, then the additional heat input would have been lower. You also have to take in the refrigerant loss of over 50%.

nosha123 · 22 February 2011 at 6:18PM

Hi Geotherm

Thanks so much for your very valued input (I value all the other posters too!!!)
The refrigerant lost was 25%.. not 50%.. so I may have got my figures wrong! I remember it being a quarter of it lost! So that should clear that up.
WIll take a look at altering those settings you recommend...
I remember Ice Energy estimated our elec bill to be £70 per month for the heat pump... which sounds like they were being quite optimistic - but I would expect that!!! If it is using HALF the daily kWh then that would equate to about £100 per month which I guess for our sized house cant be bad... The usage figures I quoted are for the WHOLE house.. but considering we arent there in the day.. I thought it high (yes some items are on standby! TV etc) unless of course the cat is throwing a party every day when we are out! Plus I have stopped using the tumble drier as its the washing dries easily on the clothes horse at room temp!

nosha123 · 22 February 2011 at 6:20PM

all I can say too is - bring on the new govt scheme from april where we get cash for kWh!!!!

dnichcole · 22 February 2011 at 6:30PM

Back again Nosha123.
My house is 120 sqm. I have the timeclock set in the machine so that no hot water done between 10pm and 9am. I have a timeclock for the heating that is similar, from 930pm to 8am.
Another thing, if you have an integrated water tank. The IVT water tanks are not well insulated on the assumption that they are in Sweden in an outhouse or garage.
If yours is inside the house, there's extra insulation you can do. On mine, the bottom of the tank is entirely uninsulated, in order to prevent the engine room frosting up. So that can be totally insulated straight away. There are other small insulations you can do, eg, the pipes connecting from GSHP to heating manifolds or to the ground loop.
The biggest change I have done is to add a Solar panel to the circuit, rather as you have your air con unit putting heat underground, this unit puts heat underground, but far more. There may only be a few days a year when the aircon has enough heat to dump, whereas my solar panels have dumped over 2,900 kWh into the ground in the first 12 months.