Yes, it appears so. I can see in home assistant that the heat pump generally uses about 1.4kWh per day for the hot water and 3.0kWh for the legionella cycle as often nothing else is running then. The Daikin MMI tends to just round this up to 2 or 4kWh. I think over a year it'll be pretty accurate when taking heating into account too but day to day and for low usage its useless.
Heat Pumps: anyone have one/thought about it?
- Thread starter fish
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Hi everyone,
Just looking for some advice on my heat pump settings.
It was only installed in April so haven't really used the central heating option so atm, im just trying to find the best hot water options.
I currently have it on a timer; three 30min sessions a day. 0600 for 30, 11:30 for 30 and 1800 for 30 to try give me consistent hot water throughout the day. Its a 250l tank. Each session brings the tank up to 50decC and on friday I have a legionella cycle. I don't have solar or battery nor do I have a fancy tariff with OVO.
My app tells me im using 2kWh per day with COP (since install) of 4.57 for the year. Its still about 4.5 for each month.
Does this sound right? is there a better way of setting this up?
Just looking for some advice on my heat pump settings.
It was only installed in April so haven't really used the central heating option so atm, im just trying to find the best hot water options.
I currently have it on a timer; three 30min sessions a day. 0600 for 30, 11:30 for 30 and 1800 for 30 to try give me consistent hot water throughout the day. Its a 250l tank. Each session brings the tank up to 50decC and on friday I have a legionella cycle. I don't have solar or battery nor do I have a fancy tariff with OVO.
My app tells me im using 2kWh per day with COP (since install) of 4.57 for the year. Its still about 4.5 for each month.
Does this sound right? is there a better way of setting this up?
Soldato
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Seems about right. My hot water SCOP is 4.3.
Unless you have some one susceptible to Legionnaires disease it's probably not worth running a legionella cycle, especially if you get through a lot of hot water.
We have ours set at 55c and it's a 190 ltr tank so don't bother.
If you Google Heatgeeks have a very good write up about it.
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I've not these these posted yet, absolute genious.
The TLDW is they have used a plate heat exchanger in place of a cylinder for hot water and it works well enough to match a combi and it fits in a space which is smaller than a typical combi and as small as the smallest combi's on the market.
The TLDW is they have used a plate heat exchanger in place of a cylinder for hot water and it works well enough to match a combi and it fits in a space which is smaller than a typical combi and as small as the smallest combi's on the market.
The bit I find odd, is they always said size the heat pump to the heat loss, now they're are saying, it's fine to fit a 7kW heat pump, even if your heat loss is only 5kW or less, as 7 kW is the minimum recommended heat pump size for this heat exchanger.
It may be because the SCOP loss on heating of moving from say a 5kw to a 7kw vailent heat pump probably isnt significant and as long as the SCOP is good enough, its going to be on par or better than a gas boiler on heating still.
Don't forget, some manufacters sell the same heat pump at different power ratings with the only difference being a softtware de-rate, the key issue is the minimum output, not the maximum. For example, my 6k daikin is physically identical to the 4kw and 8kw models in the same range, the minimum output on all of them is identical.
Clearly the above solution isn't ready for prime time (the heat exchanger needs a lot more insulation for a start), it needs a fair amount of development to get it into a marketable product but as a proof of concept, it's pretty genious.
Don't forget, some manufacters sell the same heat pump at different power ratings with the only difference being a softtware de-rate, the key issue is the minimum output, not the maximum. For example, my 6k daikin is physically identical to the 4kw and 8kw models in the same range, the minimum output on all of them is identical.
Clearly the above solution isn't ready for prime time (the heat exchanger needs a lot more insulation for a start), it needs a fair amount of development to get it into a marketable product but as a proof of concept, it's pretty genious.
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I wonder what Octopus are up to with their tariffs. It seemed odd to me that there was no email about the prices from 1st July. It turns out that is because they haven't changed despite the price cap falling.
It appears that on Intelligent Go, Go and Flux the rates remain unchanged, but oddly this doesn't apply to Cosy, where the rates have dropped. Here for example, the cheap slots on Cosy are down from 13.6p to 12.1p and the day rate down from 27.6p to 24.8p. It might be worth doing the sums come the coldest part of winter, as it wouldn't take many units to bring up the average cost to above the Cosy cheap rate. The only issue is with having an EV.
It appears that on Intelligent Go, Go and Flux the rates remain unchanged, but oddly this doesn't apply to Cosy, where the rates have dropped. Here for example, the cheap slots on Cosy are down from 13.6p to 12.1p and the day rate down from 27.6p to 24.8p. It might be worth doing the sums come the coldest part of winter, as it wouldn't take many units to bring up the average cost to above the Cosy cheap rate. The only issue is with having an EV.
I shall probably be OK, no doubt I will use some peak units, but with 29 kWh of storage which only needs to cover 5:30 to 23:30 it will hopefully be only the very coldest days we use peak rate, so can't complain.
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Soldato
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I could be wrong, but hot water demand is always a hell of a lot higher than heat demand. It's very hot water at very short notice, so it may be sensible to scale up a little to deliver on your hot water. Unfortunately, the peak heat demand and hot water demand can coincide as well, so that's a factor.
On my system it will only do one or the other, so even on the coldest day if you have a shower the heat pump will only reheat the hot water tank then when done go back to the heating.
That doesn't make sense. Efficiency is not a factor of cost
Correct the price of electricity has nothing to do with the the COP. COP is a factor of how much watts goes in and how much watts comes out, price has nothing to do with it, so I'm unsure why people keep talking about prices and off peak power
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If you can use off peak power then it's substantially cheaper to run, and you don't need to chase the best scop, choosing to chase lower running costs can often decrease scop.
I'm not too fussed about my scop, as I have 29 kWh of battery storage, only the very worst winter days will likely see me import outside the cheap rate.
Soldato
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Sizing is generally done to peak though, whichever that is (typically DHW in a commercial setting)
Takes me down to about £4300 for eco install.
Similar fir me. A price i am happy to pay, but trouble is i would need at least a 12kw heat pump and they won't do it. Yet.