Ground Source Heat Pumps

nosha123

geotherm wrote: »

so the immersion is set @ 6kw, therefore the 410hrs relates to 2460kw use.

I seriously suggest that you contact ice energy and get an engineer out to sort this problem.
With the ground loops running under 1c in, the additional heat is cutting in probably 1hr after the compressor has started.
It is possible that the unit because of your previous indoor settings of 21/22c stepped up into the 3kw input mode, thereby increasing consumption further.(now we have adjusted room stats to 19/20º perhaps the issue is solved?? Am going to take daily electric meter readings to see if usage looks like its dropped)
also, try and obtain from them the thermal analysis or your property from which they sized the pump. Got this info now (see my above posts)
give them the running hours of the unit for both the compressor and electrical backup.

(sent them all readings too)

paceinternet

nosh, I think you have probabaly got an ok system that is providing the heating required. See what geotherm says as well.

For anyone else coming back to read this, it goes some way to confirm what I said a while ago, and really "Ice" should have been more open about how it would run and the costs. They should have given you the choice of a bigger unit to compare the capital and running cost with the one you have. You probably would still have chosen the solution you have because:
1. We have had 2 quite cold months while it has been running so far and it has cost you about £200 extra. If the heat pump could have provided that heat, it would have cost about £70 for the compressor, so you have paid £130 extra.
2. Maybe we will get another 30 days in a 12 month period where additional heat is needed, so costing you another £70 extra.
3. Total extra spend is about £200 a year.

A 16kw heat pump would cost an extra ££?? to save £200 / year. A 14kw model might have been a good compromise, but if your "additional heating" running hours are not increasing on days when it is, say, above 0degc, then you should be ok.
Have you said where you are in the country and any idea how many days are below zero (assuming zero is somewhere near where additional heat is required)?

lovesgshp

Thanks Nosha for the update. At least they gave you an answer. We would probably have undersized by 10% of the peak load, so a 14Kw unit. The difference on the E14 to the E11 is only 0.9Kw @ 0-35C. I don't know UK costs, but maybe 1-2K more for the installation. You have had a harsh winter this year and I hope that with the revised settings that the operating costs reduce to a decent level.
I did like the comment "I don't think there is a sizing issue".!!!
Please keep us updated.

nosha123

I cant thank you enough Geotherm for your help.. and to everyone else too!!! Really very much appreciated!

I'll be back if i have any more queries!!! You can be sure of that ;-)

Fort_2

Geotherm wrote: »

If anyone wants info on these, then please let me know, as have had one for over 5 years.

Hi, maybe you could help me with some info about gshp. I have it in my house. we had a leakage of antifreeze somewhere, i called plumbers who fitted it and they thought it was in the ground loop on connection where it goes down into the ground. It is bore holed. They exposed connections do redo them. But after they finished boiler started giving alarms ( Low pressure switch) and ( HTF out under limit T11). We didn't know what is causing it, and phoned ice energy.
They think it could be air blockage in the ground loop,
Or faulty sensor. Anyway they sending engineer on site, but that would be only in a month, and they suggested switching to immersion heating until they come.
How do you think, if i keep on using heat pump and just reset it when alarm occurs by pushing AKNL button, would it cause any harm to heat pump?
It is 3 bedroom house with underfloor heating, and hot water being heated by gshp. Do not want to use immersion to heat everything.
Also after they did repairs on the ground loop, there is huge change in temperatures on gt10 and gt11.
Gt10 is 5.6- 5.8 and gt11 varies from -3.5 to -12, and alarm occurs.
Thanks for your time.

lovesgshp

Fort wrote: »

Hi, maybe you could help me with some info about gshp. I have it in my house. we had a leakage of antifreeze somewhere, i called plumbers who fitted it and they thought it was in the ground loop on connection where it goes down into the ground. It is bore holed. They exposed connections do redo them. But after they finished boiler started giving alarms ( Low pressure switch) and ( HTF out under limit T11). We didn't know what is causing it, and phoned ice energy.
Did they repressurise the circuit after the work? It should be @ 1-2 bar?
They think it could be air blockage in the ground loop,
Or faulty sensor. Anyway they sending engineer on site, but that would be only in a month, and they suggested switching to immersion heating until they come.
How do you think, if i keep on using heat pump and just reset it when alarm occurs by pushing AKNL button, would it cause any harm to heat pump?
The pump will keep switching off if there is a fault in temperature ranges as a safety factor, but it does look like there is a air problem in the ground loop from your later comments.
It is 3 bedroom house with underfloor heating, and hot water being heated by gshp. Do not want to use immersion to heat everything.
Also after they did repairs on the ground loop, there is huge change in temperatures on gt10 and gt11.
Gt10 is 5.6- 5.8 and gt11 varies from -3.5 to -12, and alarm occurs.
Thanks for your time.

Heat delta is too high on GT10 - 11. Is the flow filter clean after you having the work done? Is the expansion tank 50% full? Have the loop air bleeds been opened after the work, when the pump has been running?

dnichcole

thechippy wrote: »

There is a major factor to consider with gshp's....

They are ok at first, as the surrounding temp is more stable in the borehole or ground loop than an ashp.

However, over a period of years, the temp around the borehole / loop gradually declines and the environment is unable to replace the latent heat at the same rate as it's extracted. This means that the efficiency of the system will gradually decline. This can and DOES happen, but it can be several years before it's noticed.

Youre quite right, the performance will decline over the years until you think something is wrong with your heatpump, but the problem can be that you have drawn more heat more quickly than the ground can replace. I have been charging my ground around the borehole with free solar heat for almost a year now, and I have totally reversed the ground chilling effect. Even after the coldest December in history, my deep ground temperature didnt fall below 10º because I had stored plenty of energy during the summer and autumn. My solar panel system is pumping 3,000 kWh down into the ground 48 metres deep. :j

dnichcole

I have the same make of heat pump, IVT from the same supplier Ice Energy. The main tech support guy has been ill for a few weeks over the winter, but prior to that, he gave excellent tech support.

He has allowed me to fiddle with my IVT to tune it quite a lot.
• I have disabled the Immersion heater function, so it has to keep working from the ground. During the month of December 2010, it never needed or used the immersion heater. With solar recharging, the ground temperature never fell below 10º. A year ago, before the recharging, the temperature of the deep ground was 5.0 degrees.
• The inner water tank of the IVT is scandalously un insulated, because in Sweden, the GSHP is often stored in a garage or outhouse and needs some heat loss to defrost it. If your GSHP is inside the house, you can greatly increase the insulation to the water tank, especially the bottom surface.
• I use the IVT's clock function so that it cannot try to heat water during the night. You can use the clock function to do the same for space heating.
• There is a telecommand function enabling you to turn it off remotely, and I wired this up to a relay so a simple B&Q timeclock can turn the GSHP off and on, without any risk of being on the main electrical supply.
• I now use this telecommand function, connected to a cheap cylinder thermostat attached to the copper wall of the water tank that turns off the water heating to prevent overheating (which is a problem on the IVT model)
• there are several other things you can do to tune it.
See my blog by googling 'chargingtheearth' for more ideas on this.
By doing all these things, and with a bit of PV on the roof we have managed to make our house better than Zero Carbon on space heating, and by this time next year, that could include water heating too.:j

dnichcole

You can get an Elster electric meter from somewhere like RS, set it up so that the heat pump electric supply goes through this (Elsters are heavy duty, no problem with that high current) and you can then record your actual electric consumption of the GSHP separately from the rest of the house. This enables you to judge the effect of improving house insulation, or of tuning the heat pump or of using solar heat for water or borehole recharging.

dnichcole

I have an IVT at the moment, and as it has a very long guarantee etc, I dont plan to change. But the experience has not been ideal. Next time, or if specifying for someone else, I would get a Sanyo integrated GSHP and water tank combi unit.