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Topic Title: Ground source heat pumps
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Created On: 22 January 2010 10:13 PM
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 18 February 2013 09:38 PM
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Zs

Posts: 2854
Joined: 20 July 2006

Metering is one thing I am going to be looking into. Because this is a remote installation I will be asking them for readings and details of normal usage. It looks, at the moment as though they are using about 42 units of billable electricity every day but I am asking for details of lights and cooking right now.

Now, before you jump I must tell you this; The connection to this enquiry comes via a certain Mr Paul Cook. I doubt that he knows who Zs is and that he once told her she was beautiful though (we met briefly on GN3), Nervous? You bet I am! Practically quaking in my Jimmy Choo's. However, are you brave, based in Cornwall and able to help if neccesary, with the installation of a separate meter? I agree with BOD and I doubt that there is one. What I can do from here is help the client to build a case. The previous similar client won their case and most of it was calculations on paper proving what was happening.

Yes, I will keep you firmly in the loop and informed. I have had a reply from another Ice Energy user and the instruction manual is only days away. He too has high bills on retrofit to existing radiators in his case.

Sparkiemike, nag me by private mail if there is anything you need to know about this one or the previous. We could talk on the phone for ease. But I will show you my calculations for this one if it goes further. To date I have not seen one of these installations which is saving the client money.

Like I once said on here, Green is a rich-man's playground. Shame. I would like to be able to correlate the electricity usage against the loss of Polar Bears compared to the original gas or oil usage against the Polar Bear loss.

Prepare yourselves to check my sums out loud chaps. I have a nagging feeling that this one has to be inscrutably correct, don't you?


Zs
 19 February 2013 10:27 AM
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OMS

Posts: 19592
Joined: 23 March 2004

Like I once said on here, Green is a rich-man's playground. Shame. I would like to be able to correlate the electricity usage against the loss of Polar Bears compared to the original gas or oil usage against the Polar Bear loss.


Well, if you consider the relative carbon factors for grid electricity, oil, gas, coal and biomass then grid electricity (being at best about a 45% efficient use of the power station primary fuel) is approximately 0.5246 kg/CO2 per kWh used and for gas it's about 0.1836 kg/CO2/kWh. 28 sec heating oil is about 0.28 kg/CO2/kWh and coal around 0.34kg/CO2/kWh.

Burning timber is about 0.04kg/CO2/kWh but the PM10 particulates are going to be highly problematic when more people start to use it.

So in terms of polar bears, you'll lose about 3 times as many using grid electricity (until we start greening the grid of course).

So in rough numbers, that GSHP needs to opertate at a CoP over 3 at all times to save any more carbon than the equivalent gas boiler and it needs a seasonal CoP much higher than that to get even close to breaking even in terms of operating costs against mains gas.

Add to that almost certain undersizing of the ground loop based on comments like "freezing the patio" and probably a need for "large" differences in source and sink temperatures driven by using existing radiators which were designed for for higher mean water temperatures and then throw in DHWS demand and it's all pretty certain that the installed system is a bit of a lemon - it's going to be operating in direct resistance heating mode for long periods. We've spoken before about ice energy and the systems they import.

So, green technology isn't neccessary a rich mans playground - like any system though, it does need to be suitably selected, sized and specified for it to work.

Without doubt, this one isn't.

Prepare yourselves to check my sums out loud chaps. I have a nagging feeling that this one has to be inscrutably correct, don't you?


Just meter the energy input (either with a check meter or via the internal monitoring) - from there it's quite easy to show what the thermal demand of the property is. Your client can estimate his DHWS demand quite easily (particularly if they have a water meter) and subtracting will be the Heating demand. You can compare that using degree days to see what other typical properties take and determine that the energy output is either insufficient or inefficient or both.

As your client for a copy of the EPC - they will have one as it's a recent purchase - if they don't tell them to go back to the solicitor and get one.

How big a south facing roof does the property have - 3-4 kW of PV might help, as most certainly would a buffer tank and some consideration of an E7 or E10 tarriff (for GSHP off peak is best because the ground temperature doesn't vaty (much) from day to night, for ASHP, you want PV input as you want to operate the ASHP when you have the warmest periods in the day ( and store via buffering for use at night).

Regards

OMS

-------------------------
Failure is always an option
 12 March 2013 09:45 AM
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jenylio

Posts: 1
Joined: 12 March 2013

I think your friend's heat pump is consuming more energy. i would like to advice him to use Wall Radiator or Bathroom Radiator instead of it ...

Edited: 12 March 2013 at 09:52 AM by jenylio
IET » Wiring and the regulations » Ground source heat pumps

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