@cathoderay 

very interesting and a shame it's so tedious to do.  Have you tried a scatter graph of ambient vs energy consumed?  It's quite a good predictor of energy use and way of comparing different approaches. I did one a while back to measure the difference between fixed flow and weather compensation. 

Hi @cathoderay 

I think we’ve managed to prove that every house performance is different. 

it occurs to me you might have a lot of thermal mass in your property. Would that be the case? Do you have a large house with high ceilings or brick/stone external walls.
We have insulated 80% of our outside walls internally but kept thermal mass in internal walls and one large new insulated concrete floor. we also have over size radiators throughout. 
I think this means we recover relatively quickly. Last night was 6C outside so it cost us a bit more this morning to recover. EG room temp dropped to 16.5 compared to 18.5 the day before. And it took 2 hours to get to 19.5C.

1st hour 2.5kw

2nd hour 1.5kw

3rd hour 1kw 

Our WCC was operating at 38Cflow@6C

so I would say we are looking at 2.25 kw increase over steady state for those 3 hours at a 6 deg outside ambient. But our HP was off from 9.30pm to 7am saving us 9.5 hours operation with no cycling or defrost cycles. Say 7kwh less 2.25 = 4.75KWh per night. 

Can you describe the fabric of your building in a constructional way eg walls windows and floors and thermal envelope. 

PS I worked out yesterday that if I converted the energy saved to the cop of our heat pump it would raise the performance from a cop4 to a cop6.4

Posted by: @kev-m

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Have you tried a scatter graph of ambient vs energy consumed?

I hadn't, but now I have!

Interestingly, this is the tightest of all the scatter plots. If I do it as a linear plot, R² = 0.9507. Need to bear in mind that at the left hand end, on the coldest days, the rooms weren't all reaching design temps. 

Posted by: @sunandair

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it occurs to me you might have a lot of thermal mass in your property. Would that be the case?

I think it probably does. It's an old stone cottage with solid floors downstairs. It's also very leaky, though I am slowly fixing the leaks. One definite characteristic, whatever the reason, is that it takes forever to recover from a setback on a standard weather comp curve. This is why I am so interested in having the option of adding in a boost. It is also listed, which means I can't go around doing things willy-nilly.

The rads are big enough, mostly K3s, but the heat pump capacity/output at lower ambients is insufficient, a consequence of the 'a 14kW heat pump for a 12kW loss, what could possibly go wrong' supplier deadly sin, in this case Freedom, or, as they are known in this parish, Headroom Heat Pumps. Any boost in cold weather is going to involve very high LWTs, possibly hot enough to boil an egg, though there is a strong possibility my 14kW unit can be magicked into a 16kW unit by flicking a few dip switches. This has been discussed many times on the forum, and if I do it, the first run will be a trial in mild conditions, when having heating isn't mission critical.

If I've read your figures right, your steady state uses 1 kHh per hour, recovering from a ~2 degree setback uses an extra 2 kWh (in total, over 2 hours). This suggests setback and boost offers you substantial savings over steady state, over a ~12 hour period (setback period plus recovery period) you used 5 kWh, if you had stayed on steady state you would have used 12 kWh.

Hi CathodeRay

You wrote “If I've read your figures right, your steady state uses 1 kHh per hour, recovering from a ~2 degree setback uses an extra 2 kWh (in total, over 2 hours). This suggests setback and boost offers you substantial savings over steady state, over a ~12 hour period (setback period plus recovery period) you used 5 kWh, if you had stayed on steady state you would have used 12 kWh.  End..   

We had a 12 day period trial with 19 deg daytime temp and 2 degree setback at night as a trial while away over Christmas and our average consumption over that period was 0.75kw per hour. 

thanks for your insight on setback benefit. 

@sunandair

Thanks for posting the video, which confirms much of the advice being provided on RHH.

I'm about to get a Homely controller with a new Samsung 8kW AE080BXYDEG fitted (one of these https://midsummerwholesale.co.uk/buy/samsung-heat-pumps/samsung-stealth-8-heat-pump ) which is currently sitting on the drive in a cardboard box. Also getting flow meters fitted on the ASHP flow, the heating circuit and to the DHW as part of a research project, so hopefully will have a fair bit of data to share with the world in a few months time.  I was reasonably keen to just use the Samsung ASHP controllers, but they don't seem to have the best reputation.

If there's any particular data that'd be of interest, let me know.

Might also be worth keeping an eye out on the Cambridge house in this list, I note they've got a Homely controller: https://heatpumpmonitor.org/

Will see how we get on!

Regards,

cswd

I see they have added LG now....

Daikin & Mitsubishi coming?

Solar, batteries, ev integration coming...

Has anyone got any info on initial installation costs  (either with ashp install or as a retrofit)...

Is there an annual cost too?

I see the base cost is just under £200 + vat

https://midsummerwholesale.co.uk/buy/homely

I'm guessing the ASHP needs to be Internet connected? My LG Therma V has no WiFi or ThinQ so I guess needs that too.

the homely is the thing that has the internet connection. It connects with a physical wire into the local control bus of the heatpump in order to "take control" of the heatpump. you have to make this wired connection.

For samsung, you have to install the modbus module "MIM-B19N" into the heat pump to expose this functionality. For LG it looks like that functionality is already there - compare and contrast the "installation components" in the installer diagrams on Midsummer.

I might be tempted to get one (a homely) as I've already got the samsung modbus module. I'm talking to that bus module from home assistant, that is working fine for reading performance data in near real time, but I've had no luck getting it to accept commands from me to tell the HP what to do and not sure I have the time/energy to bother with it much more. if homely have done that work already maybe I'll just pay them for a slice of that.

Posted by: @tim441

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I see the base cost is just under £200 + vat

https://midsummerwholesale.co.uk/buy/homely

I'm guessing the ASHP needs to be Internet connected? My LG Therma V has no WiFi or ThinQ so I guess needs that too.

 

So homely would appear to do what a correctly adjusted and optimised manufacturers system should do.

The video was interesting since it claims that a LWT of 30C would keep a home warm at an outside temperature of 1.5C. I wonder how they achieve that fete, unless they only install them on a passivhaus.

Is there not a monthly fee charged also?

@derek-m it looks like  a wee bit more than that , because they have more sophisticated user-facing controls and scheduling systems than what most mfrs do out of the box (certainly more sophisticated than samsung, but thats not hard) and they claim to do TOU tariff awareness and the like as well. On the other hand, the WC that it does and most efficient run-temp behaviour that it should achieve, one could indeed assume to be the same as a correctly adjusted / optimised mfr system. but that is assuming you have such a setup of course! the house size and temp should be nothing to do with it, it should still be able to optimise a large leaky house.

As far as I can tell from reading their documentation, their functional behaviour is:

• the homely "hub" takes full control of your heat pump by direct wire, reading all possible data from the heat pump to monitor its performance
• a homely "sensor" (separate device) reports on the internal temperature of your house to the hub. only a single sensor 🙁
• the homely hub reports all the above data to their cloud servers, which do all manner of processing (Thats where their secret sauce is) and turn that into outputs to send back to the heat pump to tell it to go on / off / faster / slower/ hotter / cooler (etc.)
• an app is used for the user interface with which you can set heating and hw "schedules" and tell it about when you have access to cheaper electricity, etc.

I don't see a monthly fee anywhere in their specs. at this price as a flat fee one off, I may be tempted to take a punt and report back to this forum (once it goes cold!)  

It's interesting to note that it's taken me over 2 years to get to grips with optmised weather compensation... not sure I'm quite there even now!

Installer was generally quite good at both design & installation EXCEPT for setting it up with LWT of 50deg (later told me they always do that to avoid callbacks - instead of educating customers on WC etc).

Once I got WC running we now operate with

24x7 working

Just 1 deg setback 9pm to 5am which I manually flick to 2 deg if mild.

21deg daytime temp as we are at home 

LWT is currently set to just 25deg to 45 deg.... based on outside temp -4 to +15

I think that means at

outside -4deg (or colder) LWT = 45deg

0deg LWT = 41deg

5deg LWT = 36deg

10deg LWT = 31deg

15deg (or warmer) LWT = 25deg

I don't really use inside temp because installer put the controller in a warm bathroom! But set it to 16 to 22 deg as a base.

Underfloor heating and modern extension for main living areas. But ancient cottage is also supplied from ashp (underfloor heating downstairs, rads upstairs). 

I will experiment more with LWT temps this winter. Possibly I can tweak the upper end down a degree or 2. But I think I am reaching the limits for my system. Any other views?