ASHP's and how to use them economically?

shinytop

akwexavante said:

Just had a look at the operation manual for the control unit.

It suggests that i can achieve the things that have been suggested, but then doesn't describe how to actually do it!!

I need to sit down in front of the control unit and explore its menus and work out how to do this.

The unit is on an East facing wall and probably at it's warmest, say between 10am and noon, just before the sun no longer shines directly onto the unit.  However, the general wider air temperature is probably at its warmest on average between 3pm and 4pm every day.

When i find out how to do this, can i assume that the pump will heat up the water in the tank to a set temperature, say 50 degrees, then turn off when the target temperature is reached?

Simplistically...... if i have a schedule to heat DHW say between 11am and 12 noon the pump will turn on if the water is below 50 and begin heating up the water until either the water reaches 50 or at 12 noon whichever happens first?  I am aware that there will be a temp zone say 45 to 50+ where the pump doesn't do anything, otherwise it's forever on and off inefficiently.

Simplistically, yes! There may also be a setting where the DHW is limited to a time whatever your timer says.  Mine is 60 mins.  Although DHW normally takes priority, you don't want it on too much because when the DHW is on the heating is off. You can also change the 45-50 number you mention - mine is set to 10.   

akwexavante

Are you saying that if you have a schedule of an hour for DHW the heating goes off for the whole hour even if the pump doesn't need to heat up the DHW?

Are you saying that if i have a schedule for an hour, but the pump only kicks in for 30 mins you have to wait another half hour (Total of one hour) before the heating comes back on?

Or are you saying that if i have a schedule for an hour for DHW the pump will heat up DHW until either 50 degrees is reached then switch the heating back on when achieved or wait until the hour expires before switching the heating back on. Hoping my words make sense!

matelodave

akwexavante said:

Are you saying that if you have a schedule of an hour for DHW the heating goes off for the whole hour even if the pump doesn't need to heat up the DHW?

Are you saying that if i have a schedule for an hour, but the pump only kicks in for 30 mins you have to wait another half hour (Total of one hour) before the heating comes back on?

Or are you saying that if i have a schedule for an hour for DHW the pump will heat up DHW until either 50 degrees is reached then switch the heating back on when achieved or wait until the hour expires before switching the heating back on. Hoping my words make sense!

Yes, it does make sense and that's what it does.

For more info on how to use the controller, have a look at a few Youtube video's.  My Daikin is 12 years old and so there's not much info about anymore but there's more for the later controllers.

However a few tips, a heatpump cant usually manage to get temps above 55, so make sure that neither the flow temp or water temp are set higher than 50-55, lower if possible. Any use ogfthe back-up or boost heater will dramatically increase your energy consumption.

1- Make sure the immersion heater (called the boost heater) in the hotwater tank isn't being used by ensuring that your hot water is set to less than 50 degrees (or even disable it)

2 - Disable the back-up heater if you've got one - mine has a 6kw element and was originally set to come on if the outside temp dropped below -3. I've shut it off.

3 - make sure weather compensation is set and see how you get on by reducing the flow temperature and the compensation slope - the lower the flow temp the more efficient the heatpump is - ideally you need to run it longer at a lower temperature than if you had a conventional boiler with much hotter temperatures.

Think of it like a car journey, you get better fuel consumption at 50mph than you do at 80 but it takes you a bit longer to get there, heatpumps are the same, it's reckoned that each degree you increase the flow temp you'll increase the running cost by 2.5% so get it as low as you can comensurate with a reasonable heating time and comfort.

4-ideally dont shut it off overnight, just reduce the temperature by 2-3 degrees, so the place doesn't get stone cold.

4 - whenever you tweak, make sure you keep a note of the original settings, only tweak one thing at a time, give it a chance to settle down (usually a couple of days) before re-tweaking and finally keep some notes so you know what you did and what the result was.

I set up a spreadsheet with all the settings that were available, noted the default values, noted the actual set values and then tweaked each setting (if appropriate) one at a time until I got it just about right - it's well worth the effort to maximise comfort and minimise running costs