What is the type and size of your home?

Do you have any heat loss calculations?

Do you have any of the following within your system, buffer tank, low loss header or plate heat exchanger?

No problems on the questions. 😎 It took a while to get anywhere with this. I wish they could make them more simple. 

In Schedule (accessed by pressing the cog) you can set up a schedule for hot water on and hot water off. Also make sure it's on standard not forced or economy. Economy often doesn't get the water hot enough and Forced will use boost heater (immersion) and whatever it had to heat the water as quickly as possible. You could also check the disinfection settings. If it's doing a 60 degree plus heating too often that'll cost. 50 degrees should be hot enough for hot water too. Ours is 48 and plenty warm enough. 

My daily COP drops as low as 2.4 when it's cold (less than 4 degrees). I'm in West Wales on the coast so we don't have many days below 0 but when we do we can use 40-45 KW a day. 

Its a large detached T shape brick built home. I think about 2500 sq ft. Supposedly a B on the EPC. It was built from derelict 40 yrs ago, so a little drafty through some doors and windows nowadays.

I'm going to go with a yes for the buffer tank, no for low loss header. Not sure what the plate heat exchanger would look like.

I think I added photos.

Edit: and I'm trying to find the heat calcs. It's my parents system. I'm just the middleman...

@craig1980 The hot water is on Standard at the moment. The immersion is metered separately (I assume that is IMM on the meter?), and it barely uses anything. Is there any way to tell how often the HP switches from rads to hot water? I guess I could just switch to a schedule and see if usage goes up or down.

I'd be happy with 2.4 on a cold day 🙂 . 

Photos. One thermostat runs upstairs and one runs downstairs, though I think the Samsung controller considers them all one zone.

I'm not sure what the black thing in the corner is.

Posted by: @catapult

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Photos. One thermostat runs upstairs and one runs downstairs, though I think the Samsung controller considers them all one zone.

I'm not sure what the black thing in the corner is.

I can't see any photo's.

Fixed it. Took a hot minute to work out the right buttons to press.

@catapult I'm not really sure if you can see how often the hot water turns on. Mine has always been on a schedule. 

Schedule is dead easy to set up. Probably worth a try. 

Posted by: @catapult

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Its a large detached T shape brick built home. I think about 2500 sq ft. Supposedly a B on the EPC. It was built from derelict 40 yrs ago, so a little drafty through some doors and windows nowadays.

I'm going to go with a yes for the buffer tank, no for low loss header. Not sure what the plate heat exchanger would look like.

I think I added photos.

Edit: and I'm trying to find the heat calcs. It's my parents system. I'm just the middleman...

The buffer tank can cause problems with transferring the heat energy from the heat pump to the heat emitters and hence lower the overall efficiency.

If you have a suitable thermometer I would suggest measuring the temperature of the four pipes connected to the buffer tank to see if there are any large differences.

Do any of the water pumps have any form of speed control?

@catapult We have pretty much the same setup as you, (Samsung Gen6 16kW, a house where we measure heat loss of the walls/windows via wind chill factor, rather than U value, most radiators have dedicated pipes from a manifold).  Only differences is ours is about 170sqm (1830 square feet) and we have two rooms converted to highly insulated underfloor heating.

Nice photos, installation looking good, mine needs some tidying up in terms of cabling.

I am new to heat pumps, and you will surely get some great advice from others on this site.  What I have learnt so far is summarised as follows ....

For an ASHP CoP is [mostly] about 1 thing, and one thing only (the difference in temp between the Outside Air and the Flow Water Temp you are trying to achieve).    [For running cost, CoP is a key factor, but obviously, so is heat load and the cost of electricity].

Key "functions" summarised as follows.

CoP = f(Ta, Twout)

Heat Load = f(property, desired temperatures, outside air temperature [Ta])

Cost = f(Heat Load, CoP, cost per kWh)

Given you have pretty much no influence on the Ta [for ASHP], CoP is all about minimising Twout.  This normally means increasing flow rate (lower temp carries less heat) and increasing [effective] emitter size either physically such as UFH/larger radiators or with fans.  Reducing heat load, obviously helps here as well, though the assumption is at this stage you have done what you can in that area.

I also have a vented cylinder, and that is one of our challenges.  I am trying to stay under 55 deg for hot water as well as be efficient.  I think the hot water is lowering my CoP significantly and is something I am working on e.g. can I get my tank temp down to say 48 rather than 55 and still have a decent shower (wip)

Our CoP since Dec 24th (when I switched it on) is as in below image, this for your comparison. Taken from remote UI and heat output adjusted up by 7% as I don't use glycol.  I am running at a flow rate between 28 and 34, depending on needs.  My flow rate is 24 lpm on heating, 30 lpm on hot water.  I am about to change some stuff to improve flow rate, once done can share the outcome.  We target 20 for living area, 23 for bathroom, and 16 for bedrooms.  Not quite managing that for bedrooms over the last couple of days, but as those rooms should be UFH by end of year, we are living with that for now.

I lot of info, but maybe some is useful / and or triggers further responses.

@derek-m The good old hand test suggests all 4 pipes are a similar temperature. I'll try and source a proper thermometer. 

The three pumps have three set levels. Currently all running on the highest level. I think they can technically also run on "proportionate", or whatever the P stands for,  but they aren't wired for that. I had a look at the Grundfos manual and it suggested proportionate wasn't suitable for systems with a bypass, which I think I have.

Current flow rate is 32.6lpm. Is that reasonable?