I am still in a trial period with Havenwise and have several misgivings, but it has highlighted one aspect, i.e. the difference in SCOP for heating (i.e. November 3.2) as opposed to DHW which is stated as 2.2.
I understand that there are two settings for DHW heating and I am on the more economical of the two. DHW heating being called for at night, when there is a reduced tariff (actual time chosen by Havenwise), and peak power approaches 4kW but is relatively short duration.
I do appreciate that DHW consumption amounts to a little over 10% of the total
I do call for a high water temperature of 52C mainly due to long poorly insulated pipe runs that I can do little about.
All things considered, are there any steps I can take to improve the SCOP for DHW?
342sq m "Upside down" house in Algarve. Portugal
Mitsubishi PUHZ-120YUK 16kW ASHP
12 Solar Panels Growatt Inverter
2 x Growatt 7.5kW Batteries
Fronius EV Charger
Kia e- Niro 64kW
All things considered, are there any steps I can take to improve the SCOP for DHW?
Unfortunately COP for DHW will always be lower because it requires a higher flow temp and thats how the thermodynamics work. 52C is high however, you dont need more than 40 at the taps; 48 is more usual tank temp and some run at 45. If you are losing 12C in your pipe run I would be shocked, are you sure you are waiting long enough. If you have already selected ECO mode I cant see what you can do other than reduce the temp.
For long pipe runs other than to showers or baths there is an argument for point of use resistance electric heating. COP of 1, but if you run off 20l of cold water to get 20l of hot water and are heating at a COP of 2, the overall COP is only 1 anyway.
There is a balance to be struck between length of time for hot water to arrive and the amount of water wasted, against the higher temperature setting and in the winter months, this is what is comfortable.
I have plans to introduce a Grundfoss Comfort pump with a thermostatic valve between hot and cold supplies at the furthest point from the tank, when I can find a reliable contractor. This would be timed to deliver hot water, without waste, just before main use i.e at shower time etc
342sq m "Upside down" house in Algarve. Portugal
Mitsubishi PUHZ-120YUK 16kW ASHP
12 Solar Panels Growatt Inverter
2 x Growatt 7.5kW Batteries
Fronius EV Charger
Kia e- Niro 64kW
There is a balance to be struck between length of time for hot water to arrive and the amount of water wasted, against the higher temperature setting and in the winter months, this is what is comfortable.
I have plans to introduce a Grundfoss Comfort pump with a thermostatic valve between hot and cold supplies at the furthest point from the tank, when I can find a reliable contractor. This would be timed to deliver hot water, without waste, just before main use i.e at shower time etc
Basically you are planning on creating a recirculating loop. There are a couple of threads running about this with people complaining about high heat loss from the pipes and hence high consumption through running the pump 24x7. Switching and timing strategy needs some thought, according to your personal requirements
4kW peak of solar PV since 2011; EV and a 1930s house which has been partially renovated to improve its efficiency. 7kW Vaillant heat pump.
Basically you are planning on creating a recirculating loop. There are a couple of threads running about this with people complaining about high heat loss from the pipes and hence high consumption through running the pump 24x7. Switching and timing strategy needs some thought, according to your personal requirements
Yes, the Grundfos pump has a built in timer. However, the thermostatic hot to cold valve which is used with the Grundfoss pump doesn't get good reviews and I believe new houses sometimes have a built in return line from the furthest point of HW usage, but I could not provide that.
342sq m "Upside down" house in Algarve. Portugal
Mitsubishi PUHZ-120YUK 16kW ASHP
12 Solar Panels Growatt Inverter
2 x Growatt 7.5kW Batteries
Fronius EV Charger
Kia e- Niro 64kW
