Posted by: @quakerquaker

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Q1 - is maintaining the water at those temperatures all the time sensible? 

Q2 - we have a cheap overnight tariff (for an EV, which is great) but struggling to work out how best to use that for the HP, because when it needs heated up depends on when it has cooled down. Any tips? 

Please keep replies reasonably simple - I am not a plumber! 

Q1 - Yes, thats why the tank is well insulated, the amount of energy lost is pretty small.  That said, as you know when you use most DHW, why not do scheduled reheat just before that time (subject to Q2).  Most, if not all, heat pumps allow you either to schedule reheats ('timed mode') or reheat immediately on demand ('DHW priority'), I'm suggesting to do the former not the latter. 

Note that in 'timed' mode it may require both conditions to be true ie it will reheat at the scheduled time but only if the DHW temperature at that time is less than the reheat point.  If so you may find you need to reduce the hysteresis (so it reheats when it cools eg to 43/45) to avoid it completely skipping a day and cooling too much.  After some trial and error I have mine set at 5C hysteresis (originally 10C) and once per day reheat.

q2 - With Samsung heat pumps your easy options to get absolutely the most out of a night time tarrif are limited because the inbuilt controller doesn't easily allow set forward (ie raising the flow temperature during cheap periods to slightly overheat the house, in order that you dont have to heat it so much during expensive periods).  However you can (a) schedule your DHW to be heated at night as opposed to on demand and (b) not do any kind of set back - ie run space heating 24x7 at a constant WC curve.   Thats actually exactly what I do (also with an EV tarrif).  My Vaillant heat pump is quite capable of doing a night time set forward but I haven't yet been bothered to set it up.  I am still getting about one third of my space and DHW heating electricity at the night time rate, so paying on average about 19p/kWh and, with an average COP of only just under 4, working out cheaper than gas.

As you newly have a heat pump please note that you may need to adjust the weather compensation (WC) curve and even balance the radiators a bit for optimum operation.  This is best done when the heating season starts up again (the absolute best time is mid season).  If you need a guide how to do this please ask.  Once you get WC right, which in fairness does take a bit of tweaking, you can pretty much forget it.  In case it hasn't yet been explained to you heat pumps are, in most circumstances, best operated 24x7 with all thermostats and most/all TRVs set at least 2C above the set point, so they act as limiters (eg in the case of solar gain) not controllers .  This is the polar opposite of how we typically operate boilers!

This article is worth a read if you are new to heat pumps.

Regarding the question in the thread title, the easiest way to turn the heating off in summer is on the main controller. The heating is on the left hand side of the main controller main screen - just press the power button to turn it on/off.

The most efficient way to heat the DHW tank is to schedule it to reheat once per day (assuming the tank is big enough). You can set this on a timer on the Samsung controller to come on overnight when your electricity is cheaper. Look for the gear icon (bottom right corner of control panel) and then select Schedule. You can add schedules for the on and off times for the hot water. Depending on the size of your water tank and desired temperature, it may take 30-60mins to reheat from cold. I set mine to around 45C, you should try to use a temperature as low as possible but which gives you sufficient hot water for the day (so you don't have to reheat twice), somewhere between 45-50C. The temperature in my tank often drops to low 30's or high 20's C before it reheats (the sensor is in the middle of the tank but there's still warm water in the top of the tank). If you need a hotter temperature (more than 50C) to last the day, then you probably need a larger tank or to reheat it twice per day. 

Reheating once per day on a schedule is a LOT more efficient than constantly topping it up on a 5 degree hysteresis.

Let me know if you have any issues and I can talk you through the options on Samsung controller.

This thread is of interest to me as its Samsung . Sorry to but in!

Can a gen 5 controller(currently cycles at 44c to top up to 50) be timed on cheap rates as I have Octopus Cosy and my partner insists on a bath late which is fine but the tank gets replaced in expensive rates after 12AM THEN CHEAP AT 4am. 

Perhaps Homely/ Havenwise might manage that better ? 

@quakerquaker : Do you have SmartThings set up? (the WiFi connectivity for your Samsung heat pump)

I should perhaps clarify my thoughts in view of the comments from @old_scientist (with whom I agree).

@quakerquaker asked 'Q1 - is maintaining the water at those temperatures all the time sensible?' and also said the hysteresis setting (diff between target and temp at which reheat is triggered) was 10C.  If its just slowly cooling and doesn't reheat more than once per day then that's OK.  If it reheats multiple times during the day then, as @old_scientist says, not OK. 

Best approach is generally one reheat per day on timer, again as @old_scientist says (and as I also suggested, but perhaps not as clearly).  As I said you may need to reduce the hysteresis to avoid it missing days.

Please keep replies reasonably simple - I am not a plumber! 

To use a cheap overnight or heatpump tariff you need to set the schedule for the hot water. Easy to understand manual for the Gen 5 Samsung is available on the following link:

https://renewableheatinghub.co.uk/wp-content/uploads/wpforo/attachments/1535/4707-Samsung-Installation-Manual-2022-Digital.pdf

Using the timer is more efficient for most people most of the time.

Thanks everyone for the advice. Really appreciated. I need to digest and read and test a bit, but for now: 

- sorry, realise my title was a bit misleading, was posting on a late train home. We do have the heating side switched off OK, it was really about how best to run the HP in the months (like now) when we only need it for hot water and nothing else. 

- pretty sure we are only on one reheat per day, but will monitor that more closely to double check

- no, not got SmartThings. I can see energy use via Octopus App. Would you recommend the SmartThings App in addition? Does that give me remote control over the heatpump??

- have all the manuals thanks, so will brace myself and have a go at scheduling! 

Posted by: @quakerquaker

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Thanks everyone for the advice. Really appreciated. I need to digest and read and test a bit, but for now: 

- sorry, realise my title was a bit misleading, was posting on a late train home. We do have the heating side switched off OK, it was really about how best to run the HP in the months (like now) when we only need it for hot water and nothing else. 

- pretty sure we are only on one reheat per day, but will monitor that more closely to double check

- no, not got SmartThings. I can see energy use via Octopus App. Would you recommend the SmartThings App in addition? Does that give me remote control over the heatpump??

- have all the manuals thanks, so will brace myself and have a go at scheduling! 

 

Great stuff. As you are on a cheap overnight EV tariff, I would schedule for the hot water to come on for the last hour of that cheap rate time period during summer. No point reheating it earlier, unless you need it earlier (e.g, morning showers for a very early start).

Come Autumn, once the heating goes back on, you may want to move the hot water to an earlier slot as you'll probably want the heating on towards the end of the cheap overnight period to preheat the house cheaply ready for the day ahead.

Do you have a battery or any plans for a battery? Come winter, when the heat pump is on all day, having battery storage to leverage those cheap overnight EV rates will make a big difference.

Posted by: @derekdeleon

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Please keep replies reasonably simple - I am not a plumber! 

To use a cheap overnight or heatpump tariff you need to set the schedule for the hot water. Easy to understand manual for the Gen 5 Samsung is available on the following link:

https://renewableheatinghub.co.uk/wp-content/uploads/wpforo/attachments/1535/4707-Samsung-Installation-Manual-2022-Digital.pdf

Using the timer is more efficient for most people most of the time.

Thank you

Posted by: @alfapat

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Posted by: @derekdeleon

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Please keep replies reasonably simple - I am not a plumber! 

To use a cheap overnight or heatpump tariff you need to set the schedule for the hot water. Easy to understand manual for the Gen 5 Samsung is available on the following link:

https://renewableheatinghub.co.uk/wp-content/uploads/wpforo/attachments/1535/4707-Samsung-Installation-Manual-2022-Digital.pdf

Using the timer is more efficient for most people most of the time.

Thank you

OK that was Gen 6. So Iam going to start a new thread as I need some help.

Posted by: @quakerquaker

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- no, not got SmartThings. I can see energy use via Octopus App. Would you recommend the SmartThings App in addition? Does that give me remote control over the heatpump??

 

SmartThings indeed allows remote control over the heat pump. But most importantly and why I was asking, if you have SmartThings set up you can make use of Havenwise.

In absence of that, I would indeed follow the advice that was given above to manually schedule your DHW for the cheap slots in your tariff. Good luck!