Air Source Heat Pumps

Andy_WSM

jeepjunkie wrote: »

Ahhh... Perhaps the wireless thermostat needed new AA batteries being a few years old. Yup problem sorted, DOH!

I have fallen into the same trap myself and actually replaced the receiver module thinking that was where the fault was. Of course, it worked for 24 hours and I felt very clever. Then the realisation the next day that the fault remained and it could only be the transmitter suddenly gave me a cold shudder as I remembered the batteries were several years old. No battery low symbol lit, despite there being one on the unit.

matelodave

My system has eight programmable wireless thermostats to control the u'f heating zones in each room.

It's easier to set up a regime to change all the batteries every two years, on clock changing day in March so they all get a new battery and the extra hour at roughly the same time.

[Deleted User]

Andy_WSM wrote: »

I have fallen into the same trap myself and actually replaced the receiver module thinking that was where the fault was. Of course, it worked for 24 hours and I felt very clever. Then the realisation the next day that the fault remained and it could only be the transmitter suddenly gave me a cold shudder as I remembered the batteries were several years old. No battery low symbol lit, despite there being one on the unit.

LOL!

I should add the above steps took me two weeks been so busy...

Cheers

[Deleted User]

matelodave wrote: »

My system has eight programmable wireless thermostats to control the u'f heating zones in each room.

It's easier to set up a regime to change all the batteries every two years, on clock changing day in March so they all get a new battery and the extra hour at roughly the same time.

Eight _pale_

Just one for me [for the fancoils] and a fixed one for the bathroom UFH.

Cheers

Cardew

Air_Source_Heat_Pump_Man wrote: »

Somewhat surprisingly, the RHI is looking like it will support heat pumps on gas grid homes, this will offer savings against gas but not in the order of those against oil or LPG.

By 'gas grid homes' do you mean properties where gas is available in the area - but not connected, or with gas connected?

Here is a fairly balanced(IMO) Daily Telegraph article on heat pumps:

http://www.telegraph.co.uk/property/propertyadvice/jeffhowell/9873472/Jeff-Howell-can-a-heat-pump-cut-my-heating-bills.html

lovesgshp

Cardew wrote: »

By 'gas grid homes' do you mean properties where gas is available in the area - but not connected, or with gas connected?

Here is a fairly balanced(IMO) Daily Telegraph article on heat pumps:

http://www.telegraph.co.uk/property/propertyadvice/jeffhowell/9873472/Jeff-Howell-can-a-heat-pump-cut-my-heating-bills.html

That is a well balanced answer in the Telegraph, Cardew. Our studies here, where all energy prices are high, showed a 4 year payback on LPG, with 7 years on mains gas. This was on a GSHP, which is more efficient than ASHP.
I would say to a prospective customer, if they have mains gas, then stay with it, unless this RHI, (which we do not have in Italy), is going to give a high return on the investment and therefore reduce the payback time.

Cardew

lovesgshp wrote: »

Our studies here, where all energy prices are high, showed a 4 year payback on LPG, with 7 years on mains gas.

How do you define 'payback' in Italy? - where you don't have RHI.

In the article the cost of the ASHP system was £14,750.

The Householder was paying £1200 to £1300pa for gas CH.

So taking the higher figure of £1300 and let us say an ASHP cost only £1,000pa then(simplistically) the 'payback' period would be 49 years.

lovesgshp

Cardew wrote: »

How do you define 'payback' in Italy? - where you don't have RHI.

In the article the cost of the ASHP system was £14,750.

The Householder was paying £1200 to £1300pa for gas CH.

So taking the higher figure of £1300 and let us say an ASHP cost only £1,000pa then(simplistically) the 'payback' period would be 49 years.

The calculation was based on a GSHP unit against LPG and was a study completed about 6 years ago at Italian prices. Energy cost here for electricity is up to 33 euro cents per kwh excluding standing charges, once you use over 4400Kwh per year.
I did say that the householder should stay with Mains Gas, as he already has it connected.
If you would like a excel document comparing prices here, then will send you it quite happily if you send your email address by pm.

Cardew

lovesgshp wrote: »

The calculation was based on a GSHP unit against LPG and was a study completed about 6 years ago at Italian prices. Energy cost here for electricity is up to 33 euro cents per kwh excluding standing charges, once you use over 4400Kwh per year.
I did say that the householder should stay with Mains Gas, as he already has it connected.
If you would like a excel document comparing prices here, then will send you it quite happily if you send your email address by pm.

Surely if electricity costs soar to 33cents/kWh for consumption over 4,400kWh pa, that makes heat pumps a worse proposition.

In UK the average annual electricity consumption, for properties that don't use electricity for heating and Hot Water, is 3,300kWh; and many use far more, especially house large enough to merit a GSHP being fitted. Surely Italy will have similar consumption.

Given that most of that 4,400kWh will be accounted for, that means that nearly all of the electricity consumed by the GSHP will be at that very high rate of 33 cents/kWh.

What I can't understand is the basis on which you conclude a 4 year payback for a GSHP over LPG. and 7 years over gas.

According to this document http://www.energy.eu/ (Nov 2013) the price of LPG in Italy is € 0.756 a litre.

A litre of LPG contains 7.4kWh so a kWh costs 10.2 cents.(and no Standing Charges)

You have to take into account the boiler efficiency, but even if your GSHP achieves an overall system COP of 3.0 the cost of a kWh of heat from a GSHP using electricity @33 cents/kWh(and ignoring standing charges) is roughly the same as a kWh of heat from LPG.

For Natural Gas the cost in Italy is 7.932cents/kWh.(and that includes standing charges) So if a GSHP achieved a COP of 3.0 or even 4.0, gas is still cheaper than a GSHP

The difference in installation costs* between a GSHP and a LPG/gas heating system is what? 15,000Euros??

So how are the 'payback' figures of 4 and 7 years derived?

Edit.
* That is assuming an installation in a new property. If the house already has a LPG/gas CH system then the cost to convert will be much higher.

lovesgshp

Yes Cardew, it was based on a new property. This is how it was calculated:
Excuse the "google" translator !!! Unfortunately I cannot include the charts, as "word" lets me copy them, but they come up blank in here, unless someone else knows how to.

E ' was carried out a careful analysis of the cost effectiveness of the investment. More precisely have been compared with the solution and the heat pump consisting of a plant with a boiler for heating . The assumptions taken for comparison are :


• Estimate competitor to traditional plant : plant gas wall boiler € 1,000 + VAT, wall mounted boiler complete with accessories € 4,500 + vat , mixing valve € 1,000 + VAT; DHW storage tank enamelled steel € 2,000 (in the case Geotherm steel, it is assumed the enamel because the steel would lead to an almost immediate recovery ) total € 8500 + VAT
• Cost LPG 0.65 Euro / l + VAT
• Power of LPG heater 11000 kcal / kg
• Assumptions on 79241250 Kcal / annoanno for heating
• Real yield of LPG boiler 90 %
• Average cost of Kwh 0.155 Euro
• Annual increase in cost Kwh 1 % ( on historical data )
• Annual increase in cost methane 4% ( on historical data )
• Time of observation 15 years
• The analysis is carried inclusive of VAT at 10%
• Hypothesis 7 kW thermal loads

The analysis is divided into four different types of calculation :
1 . Technical recovery time
2 . Net present value technique
3 . Technical Internal Rate of Return

Technical Recovery Time
The method tells us how many years you reach a balance between the amounts of the cash flows of the two investment alternatives considered. As shown in the graph (Fig. 1) , the recovery time compared to the second geothermal investment is 3 years . The weather is good , particularly content.


Technique of Net Present Value

The analysis of the NPV is absolutely the most appropriate method for assessing the economic viability of an investment : the future cash flows relating to this period are discounted at an appropriate discount rate (in this case 5% ) and are to be accepted only investments that have a positive NPV (difference between the discounted future earnings and initial investment) .
Consider the table on the side . The investment in this simulation geothermal features an NPV of 17700 Euro and thus significantly positive .



Technical Internal Rate of Return
The IRR of an investment is simply the discount rate that makes zero net present value , the method then consists in accepting only those investments that have an IRR higher than the interest rates of securities of equal risk.
Calculations made on the TIR shows that the higher cost of the plant with geothermal heat pump could be interpreted as if it were invested at an annual rate of return of 35%. [FONT=&quot][/FONT]