@bami My feeling is that the picture shows an expansion tank not a buffer, so that is good. I take it you were not given the specs and system diagram before it was installed? I thought that was mandatory?

A 120 square meter bungalow with decent insulation should be around 5kW heat loss. Im on my second one now and both had 5kW heat pumps with no problem. I would say my current bungalow has worse insulation than yours and is a lot older with several external solid walls.

I think if you can obtain the specs and they indicate a lower size then you have an improved position when asking for a replacement. Perhaps @editor you can advise?

I understand your financial position but you will soon burn through more electricity than a reasonable monitoring system will cost if your system is set up badly. You dont need to go the whole hog and get a heat meter, thermometer probes would be good enough to get a good idea. I use openenergymonitor and can wholly recommend it. This would be fine.

As I mentioned though an alternative course would be to get Homely which might be a similar price or cheaper, there are people on here who use and recommend it and you wouldnt need to understand the theory of heat pumps as it does all the optimising for you. If your SCOP is not better before next winter I would certainly consider taking out a loan to pay for it and use the savings to pay it back.

You should be able to approach the oil usage figures with the heat pump (COP adjusted) and then the solar generation is the cherry on top which will save money for you.

Similarly you might consider battery purchase in the same way and calculate an ROI based on the savings. Ive found that most savings are accomplished with just a small battery. 5kWh in my case. Fogstar sell very keenly priced batteries.

Posted by: @bontwoody

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Similarly you might consider battery purchase in the same way and calculate an ROI based on the savings. Ive found that most savings are accomplished with just a small battery. 5kWh in my case. Fogstar sell very keenly priced batteries.

FWIW I still cant make the case for a battery (if installed by a third party) stand up.  

I have gone down the tarrif route with 'manual' adjustments.  EON Next Drive gives 7 hrs of cheap leccy if you have an EV and is simple in the sense that all the cheap leccy is in one hit.  So schedule as much heavy use (eg washing machine, dishwasher, dehumidifier) as you can overnight, definitely don't do a setback, and you will save.

If you don't have an EV and don't have a heat pump that is supported by the OVO 15p offer (which I dont believe Samsung is at present), its a bit more difficult, compounded by the fact that the Samsung controller is a bit basic.  Octopus Cosy is the obvious go-to, but without a homely or battery and with the fairly basic Samsung controller, I cant quite see how to use it effectively.

@jamespa Similarly I cant make the case for another 5kWh expansion. However its difficult to quantify how much a small battery saves when using solar panels. The times when the sun goes behind a cloud for example. My gut feeling is that it might be quite substantial

I have to wonder if the cold lounge needs a much bigger, or additional, radiator to get sufficient heat output from water which is cooler than what the oil boiler would have produced. More emitter capacity should then enable a reduction in the flow temperature which is a key factor in achieving good, and economical, performance. The other rooms seem to be warm enough to accommodate lower flow temperatures. It may also be useful to invest in an infrared thermometer which can be used to check temperatures of radiators and look for cold spots in the walls. Wallrock thermal lining paper will make a small, but useful, improvement of the wall insulation.

Posted by: @jamespa

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Posted by: @bontwoody

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Similarly you might consider battery purchase in the same way and calculate an ROI based on the savings. Ive found that most savings are accomplished with just a small battery. 5kWh in my case. Fogstar sell very keenly priced batteries.

FWIW I still cant make the case for a battery (if installed by a third party) stand up.  

I have gone down the tarrif route with 'manual' adjustments.  EON Next Drive gives 7 hrs of cheap leccy if you have an EV and is simple in the sense that all the cheap leccy is in one hit.  So schedule as much heavy use (eg washing machine, dishwasher, dehumidifier) as you can overnight, definitely don't do a setback, and you will save.

If you don't have an EV and don't have a heat pump that is supported by the OVO 15p offer (which I dont believe Samsung is at present), its a bit more difficult, compounded by the fact that the Samsung controller is a bit basic.  Octopus Cosy is the obvious go-to, but without a homely or battery and with the fairly basic Samsung controller, I cant quite see how to use it effectively.

 

Same here @jamespa - we have a 12kW Samsung ASHP, solar and are currently considering adding a Tesla PW3, but no way do the numbers stack up financially.

We are currently on Octopus Cosy, and our average import price over winter was 19-20p per kWh, which worked out significantly cheaper than gas or oil for us. We make it work by using an overnight (midnight-4am) setback and reheating during the cheap rate 4-7am slot. We also bump up the heat in the cheap afternoon slot and then switch off during the 3h peak, but the house does get unpleasantly cold in the depths of winter (we can easily drop 3C in 3 hours).

A 10-13kW battery would allow us to run constantly at the Cosy cheap rate of around 13p, which means we'd be saving around 6-7p per kWh, which just doesn't add up considering the £8-9k cost of a PW3 installation. We would also likely use more electricity running constantly further eroding the value proposition. So we have taken a rounded view also considering comfort and usability, plus green / grid friendly considerations.

Solar can make a significant impact, particularly this time of year if it's sunny in the morning (when it's not cheap rate). Our 3.6kWp array can power the heat pump for much of the day, although sunny afternoons have less impact as cheap rate Cosy import is similar to the solar export rate. A large solar array can probably power a smaller ASHP even on a cloudy winter's day.

@johnr 

An extra rad was installed in the lounge when the ASHP system was put in, so it has two (room measures 14ft x 20ft).

I had a lightbulb moment re the lounge this morning.  When I go in there first thing, when curtains have been drawn over the 3ft wide window overnight, it's toasty and warm.  The second I open the curtains the heat evaporates.

I assume from this that if I had the money to have triple glazing installed it would help the situation.

There are patio doors in the bedroom, which can also make the bedroom chilly, but the bedroom is south west facing so I get solar gain in there (it's been 25C in there all weekend) which is absent from the north facing lounge.

Posted by: @bami

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I had a lightbulb moment re the lounge this morning.  When I go in there first thing, when curtains have been drawn over the 3ft wide window overnight, it's toasty and warm.  The second I open the curtains the heat evaporates.

I assume from this that if I had the money to have triple glazing installed it would help the situation.

Curtains and the loss through the window is what I was thinking about overnight. I've got a 3m wide and two storey high north facing window in my hall. It's triple glazed but still leaks heat. Two reasons for this are (i) the standard UK triple glazing installation squeezes three panes of glass into a frame made for double glazing and (ii) big windows need metal reinforcement in the frames to provide sufficient thickness and this increases the heat loss through the frames. I would wonder if secondary glazing inside your current window may be more effective and less expensive than replacing the current window.

@johnr 

Hadn't thought about secondary glazing - definitely worth pondering, thank you!

Posted by: @bami

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An extra rad was installed in the lounge when the ASHP system was put in, so it has two (room measures 14ft x 20ft).

I had a lightbulb moment re the lounge this morning.  When I go in there first thing, when curtains have been drawn over the 3ft wide window overnight, it's toasty and warm.  The second I open the curtains the heat evaporates.

I assume from this that if I had the money to have triple glazing installed it would help the situation.

I hope there is a good view through the large window, Im imagining some fells, but realise that may be a bit optimistic.

I don't know how old yours is, but I found that replacing the glass alone (not the frames) in my 1990s uPVC double glazing with low e argon filled made a surprisingly big difference.  Might be worth getting a quote!  You want a double glazing repair man not a double glazing fitting company.  Obviously triple glazing or secondary double would be better.  We found this  to be effective on some Crittal metal framed windows we have which we dont want to replace.  There are now several suppliers, search acrylic magnetic secondary glazing.

@bami I have a large bay in my lounge and whilst the glass is cool, I dont notice a massive heat loss when the curtains are drawn. It might be worth checking the air tightness of the window edges. I fitted mine myself and every spare gap is foamed, but some I have removed are shocking with large empty spaces around the brickwork. If the fitters have used trims to cover the edges then its a simple job to remove one with a sharp knife and get access. Non invasively you might either feel for draughts on a windy day or borrow an IR camera, some electricity providers will loan them.

@jamespa 

I'm so lucky - I have views of the nearby Pennines from the picture window at the front (if you ignore the other bungalows annoyingly built in the way LOL!) and uninterrupted rolling meadows and the distant Lakeland fells from the rear of the house - it's one of the main reasons I moved from my pretty traditional lakeland cottage to a pug ugly 1970s bungalow 😆

@bontwoody 

There's definitely something amiss with the picture window.  I get lots of condensation on there in a morning and zero condensation on any of the other windows in the house.