Heat pumps, lock-down and darkest Somerset

[pdf27]

1 minute ago, SteamyTea said:

Pumps and parasitic loads.

That's still going to be heating the working fluid though and eventually the house, so the only one that should contribute towards any reduction of COP below 1 would be the fan given that the working fluid for that is external to the system. Given that the fan power is <1% of the total, a COP of >0.99 is to all intents and purposes 1.

 

Just now, scottishjohn said:

power consumption to run the unit against actual heat recovery from the cold air

everything takes power to run and COP is measure of kw power IN  to  KW heat OUT

Yes. So how do you get a COP below 1 unless you're significantly heating the outside world? Essentially that requires your working fluid to be warmer than the outside world. That's fundamentally not possible with a split heat pump, and realistically coming only from the water loop losses for a monobloc.

 

3 minutes ago, scottishjohn said:

If we got -15c to -23c regularly every year in uk for long periods  --then thats when GSP would be a better choice-

Not totally sure about that - when you get into conditions that cold you start seeing a significant risk of permafrost. See http://cchrc.org/ground-source-heat-pumps-cold-climates/

[scottishjohn]

I am totally sure that GSHP is a better solution for colder climates 

but not that convinced on "slinky" type set up for cold climes 

bore hole yes

the extra work to bury slinky deep enough to work in very cold  climate with long winter -- could outweigh cost of bore hole

 

I will leave  @SteamyTea to explain why you are wrong about parasitic power losses etc --like power to run the compressor etc-

 

 

[SteamyTea]

3 minutes ago, scottishjohn said:

-like power to run the compressor etc

If you take a normal kitchen fridge, which is a heat pump and measure the load when it is running, it will draw about 100W.

An ASHP often draws about 5A when running, so that is about 1.2 kW.  So the compressor can detract quite a bit from the total performance.

Now I would hope that a half decent ASHP would stop the compressor (and the fan and associated fluid pumps) when there is no hope of getting any advantage.

So if the unit was purely running on resistance heating, the only parasitic load is a contactor or two latched on and the fluid pump (which you need anyway), so the CoP is near enough 1.

But if it is close to the operating minimum temperature, then all the gubbins may well still be working, plus maybe some defrosting cycles happens as well, this may reduce the efficiency to 0.5.

Does this matter, not really as if the unit is designed correctly, this is only for a very short period of time.

[Gone West]

22 minutes ago, scottishjohn said:

I am totally sure that GSHP is a better solution for colder climates 

but not that convinced on "slinky" type set up for cold climes 

My mate has a holiday home in Northern Sweden not far from the arctic circle. Him and some locals installed a GSHP for his holiday home and they used buried pipes not boreholes. They are a lot more self sufficient up there and just get on with things themselves.

[scottishjohn]

6 minutes ago, PeterStarck said:

My mate has a holiday home in Northern Sweden not far from the arctic circle. Him and some locals installed a GSHP for his holiday home and they used buried pipes not boreholes. They are a lot more self sufficient up there and just get on with things themselves.

 I,m sure there are places if there is no permofrost when nice soggy ground will work well with slinky  as heat transfer is 50%better through wet ground than dry .

 and a holiday home will not be used 24/7  all year round ,so I can see the extra cost of  a borehole could be prohibitive 

 but that does not mean that would not be the best solution long term   if you have months of -20c  temps 

Edited February 12, 2021 by scottishjohn

[Gone West]

1 hour ago, scottishjohn said:

 I,m sure there are places if there is no permofrost when nice soggy ground will work well with slinky  as heat transfer is 50%better through wet ground than dry .

 and a holiday home will not be used 24/7  all year round ,so I can see the extra cost of  a borehole could be prohibitive 

 but that does not mean that would not be the best solution long term   if you have months of -20c  temps 

Although he hasn't used it as much in the winter as the summer the heating is left on all winter because the temperatures are so low. He just does what the locals do.

[Hogboon]

On 12/02/2021 at 07:50, scottishjohn said:

I bet it don,t say its  COP ratio of 3 at that temp

As far as I can see LG's website says absolutely nothing about SCoP at all [is that the same as SCoP?] - but then I am left wondering what the point of these figures is. I can, with a bit of imagination, work out how many kWh of electricity have been used but have no idea at all how many kWh of heat the LG pump has produced. There seems to be zero useful data that I can extract from LG’s ‘Remote Controller’. I have looked under ‘settings’ and in fact have searched through ALL the ‘Remote Controller’ menu options but can find not a hint of ‘data logging’ or any sort of performance statistics, so a general question is;

 

Q1. Is such data recorded? And if so where/how can I access it? The ‘Remote Controller’ software appears to be v. 3.05.5a (Master)

 

Without such data how can SCoP be calculated? A couple of engineers from LG visited here a month or so ago and connected a laptop to the ASHP. I was getting around to doing the same myself a week or so ago when it decided to chuck it down - for about 4 days as I recall - and I have not summoned up the enthusiasm to remove all the panels again. Were I to do so, here's another question;

 

Q2. Is the data likely to require special software to access? or will it be some sort of CSV output?  

 

Many thanks.

 

P.s. Got daffs out in the garden now - eat your hearts out!  

 

[SteamyTea]

26 minutes ago, Hogboon said:

P.s. Got daffs out in the garden now - eat your hearts out!  

Had then down here for weeks.

[Chris Bottomley]

Hogboon,

With regard to the data recorded by the LG system that is accessible via the remote controller see my reply to your posts in the LG Therma V Mono Block Air Source Heat Pump Thread.

 

As far as I know you will not get a log of the heat pump output from the LG system, our remote controller is at the same software version as yours and I can't see any way to get it.  I can get this information for our system but we have an external data logging package installed with a heat meter, temperature sensors, heat pump and immersion consumption meters (RHI MMSP).  This gives a COP figure for our system but it can be quite sobering to actually see what the real world figure is- our system is in the region of 2 to 3 when heating.

 

With regard to plugging a laptop directly into the ASHP I would expect that you would need an LG software app installed on the laptop to talk to the ASHP, I suspect this would almost certainly not be available to the general public unless some one has got hold of the interface protocol and written their own version..

 

 

[Dan F]

On 16/02/2021 at 23:27, Chris Bottomley said:

I can get this information for our system but we have an external data logging package installed with a heat meter, temperature sensors, heat pump and immersion consumption meters (RHI MMSP).  This gives a COP figure for our system but it can be quite sobering to actually see what the real world figure is- our system is in the region of 2 to 3 when heating.

Is this the Pasiv Systems package?