Ecodan ASHP - what the best DHW setting for a single man living on his own?

dllive

Hi,

I have an EcoDan ASHP with a 240 litre cylinder.

After years of having lodgers Ive finally got the house back to myself. 

Its always made sense to have the DHW kept at a constant temporature (55 degrees) because anyone can have a shower or do their washing up at anytime knowing there would be hot water available.

However, now its just me, I wonder how best to handle the hot water? I take maybe 1 or 2 showers per week (I spend time at my girlfriend's) at non-specific times (ie: whenever I get back from a run, which could be at any time). I do the washing up most evenings at 6pm. Other than that, I dont use any hot water.

So it is really worth heating a whole 240l tank each day just to do a bit of washing up? Should I just leave the cyclinder to maintain itself at 55 degrees?

Thanks

matelodave

Try turning the temp down to 45-47 degrees and then just running it for an hour a day. There's no advantage in keeping it hot all day. We get away with 45 degrees and TBH we could actually get away with heating every other day if the timer would allow it.

Reed_Richards

If you run your hot water heating for an hour a day then the best hour is when it is warmest outside, probably mid afternoon.  That also means your cylinder won't have lost much heat when you do the washing up at 6 pm.

dllive

Thanks guys. And you think heating it mid afternoon for an hour would be enough for a shower the following day at - say - 11am?

The showers I have are nearly always after Ive had a run, so I dont need it particularly hot anyway.

I will have a play. I think I know how to set the timer on the DMH.

It will be interesting to see whether it takes more energy to heat the cylinder to 47 degrees for an hour per day as opposed to maintaining the tank at 47 degrees. Whats your intuition?

dllive

OK, Ive just set the scheduler so DMH comes on at 47 degrees 3pm - 4pm.

Can I just check the other DMH settings with you?
Max temp: 47
Max temp drop: 7
Max op time: 60m
Mode restriction: 30 mins

Its running in Eco mode (as opposed to Normal mode).

Does anything above need tweaking?

Thanks

Reed_Richards

dllive said:

It will be interesting to see whether it takes more energy to heat the cylinder to 47 degrees for an hour per day as opposed to maintaining the tank at 47 degrees. Whats your intuition?

I think this is science rather than intuition. 

If your maximum temperature is 47 C and your maximum temperature drop is 7 C then the average tank temperature will be 43.5 C (if you don't use any hot water - it might differ slightly from that according to your usage).

If you heat the cylinder to 47 C once a day and it loses 0.5 C per hour (say) then the average temperature would be 41 C.  So at a lower average temperature the cylinder will lose a bit less heat per day so reheating it should cost you less money.

Heat pumps can sometime be counterintuitive w.r.t. energy usage but in this case I think it is straightforward.

dllive

Thanks @Reeds_Richards. 

Ive been keeping logs of Kwh consumed/delivered and COP  for the past year.It will be interesting to see how this change will affect the DHW COP. 

Just to be clear: Should my girlfriend make an impromtu visit and decide to have a bath (which is entirely possible!) and the water is only luke warm, do I just press the Play button on the DHW for 30 minutes, and then put it back on schedule mode?

matelodave

In the end its a case of suck-it-and-see. We heat out water to 45 degrees for about an hour every day  and even after a couple of showers there's still enough hot water at around 38-39 degrees 24 hours later.

We dont spend ages in the shower, I can do the full monty in around 2 minutes and use around 12litres, my wife takes a bit longer but only a 3-4 minutes. Our shower head is an EcoCamel low flow unit (pinched from our caravan) and it gives a more than adequate shower, so we don't use a lot.

Mines a Daikin and has the option to overirde the timer if we need more , like when the kids and grandkids come to stay - we dont' have a bath so everyone has to use a shower when they come and we've never run out of hot water (200l tank)

markin

Shower 2 times a week, It may save a lot just to have it at 35 and just boost before you go for a run.

Set back 4c, 5 days with lower heat loss.

Gabs616

dllive

Do you have any updates on the above?

What is you current situation?

I am in a similar situation, and I was wondering if you have managed to find a solution. 

Thanks Gabs

MultiFuelBurner

Gabs616 said:

dllive

Do you have any updates on the above?

What is you current situation?

I am in a similar situation, and I was wondering if you have managed to find a solution. 

Thanks Gabs

What's the issue Gabs?

Like the advice above for the three/four if us in the house we have set the hot water to 45oC and set the schedule on the Ecodan controller to every other day in the  afternoon when the sun is hitting the heat pump. Costs 1-1.5kwh on average.