Air Source Heat Pumps

nande2000

andrewlato wrote: »

Hi again,
With reference to my previous thread i have more data on how HP performed.
I've collected some data after fitting sub-meter on HP circuit(no immersion heater connected). We had some various temps so it's good for us see how S1200 coped(or not coped).
I have 7 rads fitted with a total output of 10175W(at delta50deg-manufacturers data). They are oversized by around 20%(calculated heat requirement for gas/oil boiler was around 8.5KW).The total volume of water in the system is 155ltrs (rads,pipes and buffer).
I have disconnected immersion heater so my data is purely for HP and circulation pump(CP). The CP is using 72W in 3rd gear. The HP+CP power input comes to 2.9KW regardless of temp(tested at range from 1deg-8deg) and is significantly more than Trianco claims in their manual. Being non-inverter type i just dont understand why (according to Trianco manual) the power input varies between 2.35-3.05 kw)? But anyway-back to numbers:
I have insulated all the external pipes now so heat loss is minimal.

1. I set temp on the programmer at 50deg with 7deg outside and it took around 1h to recover temp in buffer from 33 to 50deg. It looks like HP is able to produce 10kw at 7deg. Temp in the house around 21deg. It works for about 1h and cools down for 2h.

2. I set temp at 50deg with 1deg outside and pump will work all the time because it cannot reach 50deg.It is still using around 3kw per h but cannot produce 10kw that radiators are able to emit. I lowered temp to 47 and it was also struggling to reaching it.This is the point where pump is going all the time and your bills are getting out of hand.

3. I set temp at 45deg with 1deg outside and it would get there but house gets only about 19deg.The time it took for water temp to recover from 23deg to 45deg is 1h 20min. It cools down after about 1h50min and HP comes on again.It uses 4kwh

4. I set temp at 47deg with 2 deg outside, i get 20deg in the house, it takes 1h25mins to recover buffer temp from 27to 47deg. It gets quite quickly to 43 deg then it struggles a bit but gets there in the end. Uses 4.2kwh in process.

I've worked out that when temp outside is above 3deg and you set water temp at or below 50deg the HP will use an acceptable 29kwh per 24h costing me below 3pounds(on E7) a day for heating alone. One 24h period it's gone up to 48.7kwh!!!(due to low ambient temp at night and too high water temp set on programmer) The issue here is HP not being able to produce required heat output at low ambient temp and by trying to achieve required temp will stay on all the time until user changes settings or temp outside improves. This is very costly!!!
From the heating performance graph (Trianco manual) you can work out that s1200 is not a true 12kw HP(by European Norm). It should be tested and COP measured at -7/35 ,2/35 deg, and 7/35 deg like main brands are. HP apparently has 12kw at 20deg- that is useless info if you using HP for heating only-you are not gonna use it for heating when temp outside is 20deg. Trianco claims to be 'World leading heating engineers" - why wouldnt they test their product to EN like all the others?

Im yet to see it working at below 0deg temp.Im interested about defrost mode-how much the performance will drop -lets say -at -5. I have not yet connected immersion heater( will be connected through E7- to protect myself from huge bills). I just dont want HP to get 'lazy' and work off the back up.It will also make it a bit harder to work out what HP is really worth in terms of KW(should it use immersion-that is) . Im thinking of installing Heat Meter on pipes and the true COP will then be known- it's just the cost of it-around 150quid...
Now we are told that cold weather is coming so i should get a chance of testing it further. And i shall let you know about the outcome...
So far my bills between 28/dec and 12/jan that is 15days cost me 62pounds for all electrics that includes occasional heater coming on when newborn has a bath. The prices im paying are 12.6p day, 4.73p night and 23p standing charge.These prices will go up at next top up in line with current Sparks Energy Prepayment tariff.
Above data shows that you really need to monitor your HP in order to understand how it works and set it up according to your needs.
Thanks for reading.
Andre

Good stuff. My Ecodan 8.5kw has now used 831 kwh in the 45 days since it was installed. That is just bare HP usage as its not linked to the immersion.

The worst day ive seen so far was one of the days in early Dec where it was -4 in the day and -8 at night. I set the CH flow temp to 47 degc and left the heating on all day and the pump used 51 kwh (owch). Since then Ive replaced my wireless room thermostat with a much more reliable wired programmable one and the pump is off for 6hrs in the evening/early morning.

Looking forward to see how we cope with the upcoming cold snap.

zeupater

andrewlato wrote: »

Hi Zeupater

Sorry, but you misunderstood- the prices im paying on E7 are 12.6day and 4.73p night. The way i calculated 3pounds a day cost of heating is:
29kwh x 7h(E7)/24h= 8.5kwh on E7-rate 2 x4.73p = 40p
29kwh x17h(remaining h in a 24h period)/24h=20.5kwh (on rate 1) x 12.6p= 2.58 pounds
Total for day 2.98quid plus standing charge
Hope that makes sense

Hi

Okay ... so can you move more of the 'heavy lifting' heat provision to the E7 rate, even if the kWh.thermal/kWh.electricity is less efficient in order to make more use of the lower nighttime tariff ..... ?

We lose heat at a rate that you don't need heating for much of the day ..... log burner fueled for ~7 hours yesterday & ~3.5 hours so far today .... it'll be a little cooler in the morning, but not really noticeable, and any heatloss will be replenished tomorrow .... if it gets really cold outside we'll put on a sweatshirt before seriously extending the burn hours, long cold spells we might fuel for ~13/14+ hours, then if the house temperature still drops the heating will go on .... If the ambient temperatures were decent I'd be looking at running an ASHP overnight on E7 and if ambient temperatures at night and during the day were both low, i'd sill look at running the unit as much as possible overnight on E7 ....

HTH
Z

zeupater

andrewlato wrote: »

.... I have 7 rads fitted with a total output of 10175W(at delta50deg-manufacturers data). They are oversized by around 20%(calculated heat requirement for gas/oil boiler was around 8.5KW) .....

.... 1. I set temp on the programmer at 50deg with 7deg outside and it took around 1h to recover temp in buffer from 33 to 50deg. It looks like HP is able to produce 10kw at 7deg. Temp in the house around 21deg. It works for about 1h and cools down for 2h.

2. I set temp at 50deg with 1deg outside and pump will work all the time because it cannot reach 50deg.It is still using around 3kw per h but cannot produce 10kw that radiators are able to emit ....

Hi

Just noticed the above .... by "total output of 10175W(at delta50deg-manufacturers data)" I take it you mean deltaT50, in which case, with the room temperature of 21C which you mention, the radiators would be rated at 10175W at an average water temperature of 71C (21+50) ... at a water temperature of 50C your radiators would only be capable of providing ~29/50ths of their rating, so around 5.9kW, not 10 ....

Almost everything I've read relating to oversizing radiators suggests adding between 50% and doubling the capacity, depending on the anticipated system temperature .... perhaps a HP engineer could confirm this .....

HTH
Z

andrewlato

nande2000 wrote: »

Good stuff. My Ecodan 8.5kw has now used 831 kwh in the 45 days since it was installed. That is just bare HP usage as its not linked to the immersion.

The worst day ive seen so far was one of the days in early Dec where it was -4 in the day and -8 at night. I set the CH flow temp to 47 degc and left the heating on all day and the pump used 51 kwh (owch). Since then Ive replaced my wireless room thermostat with a much more reliable wired programmable one and the pump is off for 6hrs in the evening/early morning.

Looking forward to see how we cope with the upcoming cold snap.

Hi Nande
great kwh on your Mitsi. Have you got rads or UFH?

andrewlato

zeupater wrote: »

Hi

Just noticed the above .... by "total output of 10175W(at delta50deg-manufacturers data)" I take it you mean deltaT50, in which case, with the room temperature of 21C which you mention, the radiators would be rated at 10175W at an average water temperature of 71C (21+50) ... at a water temperature of 50C your radiators would only be capable of providing ~29/50ths of their rating, so around 5.9kW, not 10 ....

Almost everything I've read relating to oversizing radiators suggests adding between 50% and doubling the capacity, depending on the anticipated system temperature .... perhaps a HP engineer could confirm this .....

HTH
Z

Yes i meant delta T50, but didnt know how to properly calc rads output in the way you did. Thats something new ive learnt. And if you are right with your calc then Trianco should 'revise' heating performance of their product- s1200 as it would be misleading not only on KW(input) but also output at different temps.

andrewlato

BTW- last night (at 22.45)I changed settings on timer to see what will happen in terms of temp in the house so i set it to come on at 20.30-7.30 and then 12-15 in the aft.I also set temp at 55deg.It's 11 am now and 2deg outside. Overnight it used (from 22.45 until now) 27kwh that includes 23.2kwh on E7(3.31kwh average!!!). Best temp it reached was low 40s as it started going into Defrost(both Circulation Pump 'ON' and Reverse Cycle). At the moment I have 18deg in the house and just under 1h before it kicks in again. The temp outside droped to -1 last night. It also throws up error code 9 which Im now in process of sorting. Very poor performance from this HP...

nande2000

andrewlato wrote: »

Hi Nande
great kwh on your Mitsi. Have you got rads or UFH?

Hi that's with rads only. It is a hybrid system as we have a wood stove going most evenings.

andrewlato

nande2000 wrote: »

Hi that's with rads only. It is a hybrid system as we have a wood stove going most evenings.

Still good Kwh for weather

zeupater

andrewlato wrote: »

Still good Kwh for weather

Hi

The only thing that you can deduce from " 831 kwh in the 45 days since it was installed" is that it's used 831 kWh in 45 days ... you could average it to 18.5kWh/day (831/45), or 0.77kW (831/45/24), so effectively leaving a 750W electric oil heater on 24x7 would provide similar figures, but unfortunately the effective COP would be 1.0.

What would be required to make the figures meaningful would be the measurement of the heat provision against energy input, this being done by metering the system flow rate along with heatpump output and return temperatures ... you could then calculate a COP.

HTH
Z

nande2000

zeupater wrote: »

Hi

The only thing that you can deduce from " 831 kwh in the 45 days since it was installed" is that it's used 831 kWh in 45 days ... you could average it to 18.5kWh/day (831/45), or 0.77kW (831/45/24), so effectively leaving a 750W electric oil heater on 24x7 would provide similar figures, but unfortunately the effective COP would be 1.0.

What would be required to make the figures meaningful would be the measurement of the heat provision against energy input, this being done by metering the system flow rate along with heatpump output and return temperatures ... you could then calculate a COP.

HTH
Z

The property was rated at having a Heat loss of 8kw at -5 degc and the previous oil boiler it replaced was averaging 1100 litres of oil over the Oct - March period. In the really cold winter of 2009 we used 2000 litres in the same period. If we assume that 1100 litres is accurate that equates to 11000 kWh/6 months =1833 kWh/month. The heat pump is using 871 kWh over 45 days (831 was a typo sorry). Which is 600 kWh/month. As a very rough estimate of cop I make it 3.055.