Heat Pump Running Costs

newhouse87

https://www.boards.ie/discussion/comment/121635328#Comment_121635328

Unreal usage in this weather. My hp cycles too much below x28 but not hope 27 would, get my house to 22/21.

Eleusis

I have no idea how to see if my ecodan is short cycling. Does anyone know is there a way to find out?

johndoe11

https://www.boards.ie/discussion/comment/121635328#Comment_121635328

That is unreal low. What part of the country are you in? Not the Midlands i bet with that sort of consumption and current weather!

Eleusis

https://www.boards.ie/discussion/comment/121635690#Comment_121635690

Yes in midlands. . Leitrim. Was -6 this morning at 7am

newhouse87

https://www.boards.ie/discussion/comment/121635807#Comment_121635807

Have you a lots of loops in your ufh? Haven't seen that low flow temp these conditions before.

Scoopsire

https://www.boards.ie/discussion/comment/121635328#Comment_121635328

What type of work had you done on your house? Assume lots of insulation upgrades?

ColemanY2K

https://www.boards.ie/discussion/comment/121635263#Comment_121635263

Used 40 and 45kWh over the previous two days respectively and averaging around 50 during this cold spell.

What you say could be where I'm going wrong as I have removed the actuators but all the stats bar 1 are set to 21 degrees and were previously 22 or 23.

It's a pity the cold spell is coming to an end as it'll be hard to judge if reducing the temp setting on the stats makes a difference.

johndoe11

https://www.boards.ie/discussion/comment/121635807#Comment_121635807

Fair play to you. My house is A1, If i ran 27 flow (with presumably 20-22 return), my wife would run me. The house would be 17/18 degrees. My flow is 32.5 at -6.

Same temp here last night, I used more than you in about 6 hours.

newhouse87

https://www.boards.ie/discussion/comment/121635920#Comment_121635920

I would try running a fixed flow of 31 for say 13 hours and on again at 9am. See how the house reacts. That's my exact schedule. Best I found so far. Again though that doesn't mean it will work for your house. Have you insulation done?

ColemanY2K

https://www.boards.ie/discussion/comment/121635916#Comment_121635916

Airtightness is just if not more important. I'm guessing they have an airtightness rating of less than 1 ACH and bags of insulation. Deep retrofits of bungalows can achieve passive levels of performance.

Eleusis

13 loops. I think it's low cause build quality and insulation is very high. House has a continuous unbroken wrap of insulation. UFH throughout. It's also airtight, triple glazed with heat recovery.

newhouse87

https://www.boards.ie/discussion/comment/121635991#Comment_121635991

The unbroken wrap must be it, hard to get that done properly. I'd have the rest myself.

ColemanY2K

https://www.boards.ie/discussion/comment/121635966#Comment_121635966

Almost finished, I reckon another two/three evenings and it'll be done. It's hard to get a good run at it with me having to work during the day, spend a couple hours in the evening with the little one and on top of that out of the country 2 days a week.

Cheers for the advice. First thing I'll do is reduce the temp on the stats to see what happens and then Iook to set a schedule to see how the house reacts.

newhouse87

https://www.boards.ie/discussion/comment/121636061#Comment_121636061

Hectic alright. Yeah just have 1stat calling for heat for the 13hours then have setback overnight. Open loops.bestvtry when insulation done. Note your current settings too as my way may not work for your house.

feelings

Our a2w hit 75-85kw usage yesterday. Previous two days 55-65 each day, had been 20-25 up to the cold spell. 😔

TimHorton

https://www.boards.ie/discussion/comment/121637856#Comment_121637856

Is that what you were expecting when you installed the system?

newhouse87

https://www.boards.ie/discussion/comment/121636061#Comment_121636061

Label each actuator for what loop it is before removing. You could try dominatinmc approach first, fixed flow before my approach. He has similar usage to me.

randombar

Hi Folks,

Usage for the last four days with my ecodan split unit. (250m2 house)

https://capture.dropbox.com/7EHIAXwX0rhz4B6j

I've limited the flow rate to improve the COP (COP = 3 ish at the moment) and I've also disabled that immersion.

I'm also using the temperature mode rather than weather comp, I've 4 hrs cheap rate so try and blast the heat in the place for four hours, unfortunately most of the cheap time is spent heating the water rather than space heating.

Some people have said I should heat the water all the time rather than the cheap rate but that doesn't make sense to me.

Should I be limiting the flow rate at all if I want to blast the heat? i.e. if I heat the place faster at 8c with a COP of 2.5 it's better than heating the place slower at 40c with a COP of 3.

ColemanY2K

https://www.boards.ie/discussion/comment/121638255#Comment_121638255

ya i've done that. lets see how it goes today.

mitresize5

https://www.boards.ie/discussion/comment/121632742#Comment_121632742

Hi,

Bill 860e - 2156 units used in billing period. Nothing to compare it to as we weren't in the house last year.

House is block built with 72.5mm internal insulation and pumped cavity, 600mm insulation in the attic, triple glazing new windows and doors

House size is 2350sq feet

Underfloor under polished concrete downstairs, radiators upstairs

Panasonic 9Kw heat pump

DHW set to 54 degrees - seems excessive

Stats set to 22 downstairs and 20 upstairs, have dropped them by 1 degree each

... the DHW looks like the first place to address, anything I've seen on line suggests 48/49 should suffice

any suggestions appreciated

thanks

dominatinMC

https://www.boards.ie/discussion/comment/121637856#Comment_121637856

Even without context (house size, room temps), that seems like crazy usage. Can you provide some details on the size of your house, BER/airtightness, room temps, flow temps? Plenty of advice on here to get that usage down

dominatinMC

https://www.boards.ie/discussion/comment/121638500#Comment_121638500

Is that electricity usage for 2 months? Although it's high, it's probably not drastically high for a new house(?) drying out.

Nevertheless, I don't think I'd attribute your usage to the DHW. By all means, reduce this to 50 degC, and you will see a difference, as the immersion heater is probably responsible for the heating from 50 degC+. However, what is your flow temp set to? If this is too high (as is often the case when HPs are installed), it would be responsible for large usage.

mitresize5

https://www.boards.ie/discussion/comment/121638563#Comment_121638563

yes - thats the usage for 2 months

its a renovation we're in since August so it has dried out a fair bit

flow temp is 30 now but I did see it at 45 last night when I checked

gandalfio

Change your upstairs stat to 18, and your downstairs to 20 and you'll notice a big difference in your usage/bills. Even with stat at 20, your living room will be warmer than that with people being in it, TV and lights on etc.

dominatinMC

https://www.boards.ie/discussion/comment/121638589#Comment_121638589

Okay, sounds like you're running weather compensation. Which I assume was set by your installer. My guess is that you need to modify your curve to suit your house. That will take some time, but worth it in the long run. 45 degC seems excessively high.

munsterfan2

250sqm new build ( 3years old) with a Waterkotte GSHP. Last few days have been at 15 - 18 kwh per day for heating & 3kwh for dhw. Here is the current heat flow curve - I have it at +1 during the day and a step back of -5 from 23:00 to 02:00 ( cheap rate kicks in ). The great thing about the cold is the solar panels are flying, with 25kwh generated plus the 14kwh usable of the battery I am not seeing too much daytime electricity usage

Room temperature in main living are holds steady, 21.5 - 22

staples7

https://www.boards.ie/discussion/comment/121638715#Comment_121638715

Id agree with this. Changing your hot water from 54 to 50 will be minimal change regards kw used. eg my hot water usage in very busy house is 2.5kwh per day summer and winter

The real damage is being done by the UFH heating. having it set to 22' is a killer. I know its subjective but 20' is comfortable.

on top of the above if you can run at night where its more than half the day rate I think this is the best step in terms of cost saving. Ive ben doing this for 6 years now. averaging yearly heating and hot water below E500 for the year. 2800sqft

keno-daytrader

210sqm 2 story we are using 3kWh for DHW and 11-13 kWh for underfloor in this cold spell per day. UFH flow at 29c , downstairs set to 21.5c A1 house, not quiet passive but not far off. I only use the heat pump in daylight hours.

keno-daytrader

https://www.boards.ie/discussion/comment/121638500#Comment_121638500

Limit the flow temp for your underfloor heating, there is no way the ufh should be run that high (45). You will see a huge difference in your usage, it happened to us also, the installers just set it on "dumb" mode so they dont get callbacks. Try max 35c for now and bring it down bit by bit over a few weeks until it wont keep room temp where you want it anymore, then bump up a degree or 2. Its trial and error for every house, but will so pay off.

Edit, sorry I missed that you had rads upstairs, but the same principal applies, experiment with getting that flow temp as low as you can get away with.

mitresize5

https://www.boards.ie/discussion/comment/121638765#Comment_121638765

thanks for the feedback - when you say modify the curve, what does this mean.