Ariston NUOS Air to Water HW Heat Pump

shane 007

So as to not interupt the LVP Renewables thread & following requests to install a water meter to my system, I done exactly that.

The background:
Installed Ariston NUOS 250L Indirect Air to Water Heat Pump
Installed 22/06/2013
Also installed approx 5 years is a Kingspan Solar system.
Incoming well water temperature circa. 10°C
Set NUOS temperature 55°C
Number of house occupants: 2 x Adults + 2 kids (girls 10 & 8)
Efergy Electrical Monitor monitoring the NUOS only & installed since 22/06/13
Water Meter installed on 09/03/14 at 16.00hrs. The NUOS was not running at the time of the installation and was at 55°C.

How it is installed:
The NUOS is taking its air directly from outside and exhausting its cold air directly to outside. There is an electrical 1.5kw immersion back up but this is not swtich on in Green Mode unless the incoming air temperature falls below 0°C to protect the heat pump.
There is no installed back up from my oil boiler.
The solar can only top up from 55°C as the system is always upto the set temperature of 55°C in the morning. On very good sunny days, I have noticed the cylinder temperature hit 59°C - 60°C over the winter. One occasion it reached 66°C. I would prefer if I could set up the system that benefits fromt the solar gain first and then tops up with the NUOS, but I checked with Technical & I'm afraid it won't allow this. I can set it on a timed temperature achievement but I found that if I use a quantity of water before this time, it calculates that it cannot now achieve the 55°C in the given time frame & brings in the immersion.

I installed the water meter on the cold feed supplying the NUOS on Sunday 09/03/14 at 16.00hrs. The meter reading was 0.200m³ as it arrived with an already clocked reading of 0.350m³ & I couldn't be bothered blow back anymore!
The meter reading is hot water actual reading & not mixed reading as the location of the meter is on the cold feed to the NUOS, so the reading is actual what is coming out of the NUOS. The meter is WRAS approved & cost €35.00 delivered from the UK.
I took a reading today at 16.00hrs so this gives an exact total of 15 days.
I downloaded an electrical energy usage as an hourly reading so I could accurately give a usage from the 16.00hrs meter install to 16.00hrs today, so the volume usage exactly matches the electrical usage.
I was quite surprised to see an actual usage of 2,426 litres of hot water over the 15 days. Thus giving an average daily usage of 161.7 litres per day.

At home, I have been warned to keep my mouth shut & not monitor the before & after of my wife's showers. I have also been told she can use as much hot water as she likes & if I mention anything about NUOS's, hot water, meters, electricity to her, I would most likely to have all of the above surgically removed from my deriére. :eek:

Outkast_IRE

Very interesting read there. Its a real shame it cant be set up to allow the solar to get its chance first before kicking in, as the larger the Temp difference between the cylinder and panel the more efficient the solar would be, so your taking a hit in that regard, but overall It seems like a good setup

shane 007

Yeah, I even asked them could they re-design the pcb to allow this as they agreed it was an oversight in the design process.

Saying that, if somebody doesn't have solar & asked me to install a NUOS & solar together, TBH, I would try & talk them out of it. The cost of the solar would never be re-couped because of the low running costs of the NUOS. The NUOS on its own would be more than sufficient on delivery & running costs.

Scruff

what were the costs of installing each if ye dont mind me asking?

shane 007

Scruff wrote: »

what were the costs of installing each if ye dont mind me asking?

It would depend on the system parameters, 200 litre or 250 litre, air ducting parameters, condense pipework feasibility or condense pump required, roof work or through walls.

Generally for 200 litre approx €3,250 installed & €3,650 for the 250 litre installed, including vat & labour.

freddyuk

Are you monitoring the outside air temperature or would that be possible to add it to your database?

shane 007

freddyuk wrote: »

Are you monitoring the outside air temperature or would that be possible to add it to your database?

Ah here, what do you want, blood?

dathi

thanks shane it proper data like this that people have been looking for, also dont think any of of us usual moaners had any problems with your nuos it was the other system. pity you cant solar first then nuos oh and when those 8 and 10 year olds hit 13 your you can add a zero to your 161 ltrs a day

Dtp1979

dathi wrote: »

thanks shane it proper data like this that people have been looking for, also dont think any of of us usual moaners had any problems with your nuos it was the other system. pity you cant solar first then nuos oh and when those 8 and 10 year olds hit 13 your you can add a zero to your 161 ltrs a day

And add 10 to your age

John T Carroll

Would it be correct to say that if the Starting Meter Kwh reading on 9/3 was subtracted from the Final Meter Kwh reading on the 24/3 that this would equate to your accumulated usage of 28.6 Kwh ?.

shane 007

John T Carroll wrote: »

Would it be correct to say that if the Starting Meter Kwh reading on 9/3 was subtracted from the Final Meter Kwh reading on the 24/3 that this would equate to your accumulated usage of 28.6 Kwh ?.

It used 28.6kwh to heat 2,426 litres of water at a cost of €5.15.

John T Carroll

Thanks, that gives a COP of about 4.24, (2426*(55-12)/860/28.6)

shane 007

John T Carroll wrote: »

Thanks, that gives a COP of about 4.24, (2426*(55-12)/860/28.6)

What's the 860?
I can only presume that the higher than normal COP is the contribution from the solar.
I think I picked a particular bad day & worked out the COP to about 3.4.

jimf

Dtp1979 wrote: »

And add 10 to your age

and minus 50 from your pocket :eek:

John T Carroll

860 is (nearly) the recriprocal of 3600/4.19. It assumes that 1 litre of water is equal to 1 kg and converts kj to Kwh. Of course 1 litre of water only equals 1 kg at 15C, but, in general it gives a very acceptable number for quick calculations of energy. It can also be used in energy calculations for flowrates combined with the deta T of a heat exchanger, if you had, say, a flowrate of 2 Litres/min with a delta T of 10C, then the energy (per hour) is 1.4 Kwh, ( 2X60X10/860). If water/glycol is the circulation fluid, the energy would be approx 1.26 Kwh as a factor of aprox 0.9 is applied for the specific heat of water/glycol.

Re the Solar effect on the COP, I dont know where (in the country) your Solar system is, but I harvested ( a measured) 25 Kwh for the above period so if we take this as indicative then the NUOS energy input is 96.3 Kwh (121.3-25) and the COP was/is 3.37 (96.3/28.6).

Should also, in fairness, allow for cylinder losses which are probably 1.5 Kwh/day, this would give an improved COP above of 4.15. (121.3+22.5-25)/28.6

860 is the recriprocal of 4.19/3600, but calculations are correct.

shane 007

That sounds absolutely spot on.
I calculated on day one from Sunday 16.00 to Monday 16.00. On the Sunday at 16.00, the NUOS was already at 55C. We used 225 litres of hot water between then & Monday 16.00.
The Monday never stopped with heavy rain & the solar collector never got above the T2 temperature to come on.
I calculated the COP a little differently to you & came up with 3.4.
Your way of calculation seems a lot more better & more precise.

Thanks for your very informative input. It is greatly appreciated.

John T Carroll

No problem...should also have thanked you for installing the flowmeter.

shane 007

John T Carroll wrote: »

No problem...should also have thanked you for installing the flowmeter.

My wife wouldn't thank me. She's developed some strange new growl since it went in!

dathi

shane 007 wrote: »

My wife wouldn't thank me. She's developed some strange new growl since it went in!

wait till you install a flow switch with a timed shut off valve on the hot supply to shower then you will hear howls:D

John T Carroll

Re the "Timed Temperature Achievement", could you disconnect the Immersion ( or fit an isolating switch) or would this confuse the NUOS programmer?.

shane 007

Update for full month of March.
I have included water usage in the spreadsheet with times of readings, but just remember to deduct 200 litres for totals if calculating from installation date.
I have also attached so far of April's figures as today is exactly 4 weeks (28 days) since the installation of the water meter. My usage seems to have increased to an average of 173 Litres/Day :eek:

shane 007

John T Carroll wrote: »

Re the "Timed Temperature Achievement", could you disconnect the Immersion ( or fit an isolating switch) or would this confuse the NUOS programmer?.

Hi John, sorry no this would reset the built-in time clock within the unit so the P1 & P2 set times would be at incorrect on a daily basis.

Secondly, the immersion is also used as a unit protection device to increase the water temperature within the unit, thus increasing temperature of the R134a in the coil to prevent from damage should the incoming air temperature in the unit fall below 0C.
This is instigated even in Green Mode.

John T Carroll

shane 007 wrote: »

Update for full month of March.
I have included water usage in the spreadsheet with times of readings, but just remember to deduct 200 litres for totals if calculating from installation date.
I have also attached so far of April's figures as today is exactly 4 weeks (28 days) since the installation of the water meter. My usage seems to have increased to an average of 173 Litres/Day :eek:

Using your Total March numbers and again assuming a cylinder loss of 1.5 Kwh/day and assuming that your solar gain was similar to mine at 74 Kwh then I calculated the COP at 3.07, the Solar Gain has a huge influence on the COP, it there was no solar gain for March, then the COP would have been 4.08.

shane 007

Cylinder loss for the 250 litre is 2.4kwh/day but from 65C. The 200 litre version is 2.0kwh/day.

How are you calculating your solar gain? From circulating pump run time along with data from http://re.jrc.ec.europa.eu/pvgis/ or have you calculating it based on flow & return temps, etc.?

shane 007

I will reset the number of hours counter on the controller & can check in a week & in 4 weeks time.
It won't give the solar gain but will give an indication of how many hours the solar pump is inputting.

John T Carroll

shane 007 wrote: »

Cylinder loss for the 250 litre is 2.4kwh/day but from 65C. The 200 litre version is 2.0kwh/day.

How are you calculating your solar gain? From circulating pump run time along with data from http://re.jrc.ec.europa.eu/pvgis/ or have you calculating it based on flow & return temps, etc.?

The COP at 2.4 Kwh/day loss would be 3.45 and at 2.0 Kwh/day would be 3.28.

If you read my very first post (Solar Energy Management) you will see how the Solar amount is calculated.

I have a 3.84 M2 Flat Plate (X2) setup, I have assumed that you have a 30 tube 3.229 M2 Evac.Tube seup, is this correct?.

shane 007

Thanks, I'll have a read of that.
Solar is 40 tube 4.32m2 Kingspan.

shane 007

Also location is Kilkenny.

John T Carroll

shane 007 wrote: »

Thanks, I'll have a read of that.
Solar is 40 tube 4.32m2 Kingspan.

In that case, your solar gain could possibly have been 99 Kwh for March, if so, then the COP is 2.94 at a 2 Kwh loss and 3.11 at 2.4 Kwh loss. I suppose, if the Solar system has a dedicated heat dump that this could be utilised over a few days at least to get a more accurate COP.

shane 007

John T Carroll wrote: »

In that case, your solar gain could possibly have been 99 Kwh for March, if so, then the COP is 2.94 at a 2 Kwh loss and 3.11 at 2.4 Kwh loss. I suppose, if the Solar system has a dedicated heat dump that this could be utilised over a few days at least to get a more accurate COP.

I have the 250 litre so the 2.4kwh loss.
I would think, but I haven't calculated yet, the COP is not far off the mark, perhaps a little higher.

The reason being is the reversal situation with the HP being at temperature first & the solar topping up. I have mine set to a flow rate of 4L/min with a delta T of 4C/8C. If the cylinder is at 55C the roof temperature would have to exceed 63C in order to switch on the pump.
Now I do think it does reach that especially when the T2 is recovering from morning showers but the gain run times are greatly reduced.
This is why it would be interesting to see the run hours on the controller, which is a Stecca SC200.