Heat Pumps - post here.

So potentially dumb question here

I've been watching a lot of Heat Geeks and the content so far is brilliant. But there's one video which is bugging me a bit, the one about leaving the heating on all the time

So I get the basic idea, a heat pump is most efficient when it's running for a long time at steady load

You set the flow temp low enough that it's at maximum efficiency when running, but not too low that your house is cold. You use the thermostats as heat limiters instead, and use a setback temperature at night to ensure the house doesn't overheat

Here's my issue with that, how can that work best with night rates?

On one hand, nighttime is generally colder so the heat pump will probably be running more at night anyway. Using a lower setting at night would save energy and is cheaper to run anyway, so that makes sense

However, you'd have a fairly constant drip feed of electricity consumption during the day when it's expensive.

This doesn't seem like the best approach, so I'm wondering if it's worth sacrificing some efficiency to heat up the house in the early morning on night rate and minimise the daytime electricity consumption

Anyone have any thoughts on this?

I think most heat pumps have fairly decent controllers, although they might not make great provision for external control

Mine for example can have different temperature settings at certain times on the downstairs controller (upstairs is a dumb mechanical thermostat unfortunately)

Normally it's just set to 19C all the time but maybe I'll try setting it to 21C around 5am for a couple of hours to heat the house up and hopefully it just sips energy for the day

It's slightly moot because I'll be getting a battery soon as well as solar panels. But if I can stop the heat pump from drawing a lot of power then it'll fit into the solar generation curve more easily

we have Breton slab floors so the zones tend to work as zones. You can heat the main downstairs living area without the greenhouse upstairs.

biggest issue we have is glass. You can set the heat to get to the temp you want by morning. Then you get a really sunny day and it can push it up 4-5c more. Easily enough solved we just open a door to a hallway that leads to the stairs for an hour and it dissipates through the house but not ideal.

your wife and mine must be related. Everything is 2 degrees higher than it should be. I end up going around in a t shirt and getting the look….

Yeah ours is reversed the glass is in the living area where you generally have it a bit warmer then if it does lose the run of itself we open the door and the heat will rise to the bedrooms.

it is tricky to get things perfect though especially if you get big fluctuations in the weather and outside temp. We’re pretty airtight but on an exposed location so wind creates a vacuum. After the cold weather of last week i’m finding the house hot but I suppose that’s the slab releasing the latent heat that has built up over the previous week.

Still better than the neighbour who ran out of oil a few days back and just got his delivery yesterday. Needless to say he’s borrowed a few of my T-shirts, your right though @the_amazing_raisin i should buy pants, could end global warming 😂

My Thermia A2W is set to 18 with stats set to 20. I was away for Christmas and checked today. Operation time for heating was 97 hours since 24th December, 16 hours a day. To my mind this seems quite a lot.

House is insulated to high degree, brand new, airtightness test was just under 1.8.

It's fine for it to be operating for a long time if it's drawing low power, that's generally the way heat pumps are intended to operate

If you're away for a couple of days then consider using the holiday mode if there is one to set back the temperature to a lower level. Most heat pumps will warm the house back up on the final day of holiday mode so it isn't too cold when you arrive home

Good question.

Lads one more for the Ecodan users found this unit cost 125 and its pretty decent.

Also allows the melcloud Mitsubishi app on your phone which show energy usage and allows full control via phone ect.

installation & setup is very straight forward and do-able for the DIY'er.

I purchased from IITC but they dont have a web link below has links to manual and setup etc..

https://www.rvr.ie/products/melcloud-wi-fi-interace

I insisted on it from the beginning, the heat pump provider posted it out to me and I installed it. 5 years later couldn't be without it. From monitoring to looking at usage reports etc its a godsend for the Ecodan

I more or less do this.

About 2hrs before night rate kicks in I set the HP back a few degrees so that it’s not running coming up to night rate.

During night rate I have it set to boost a few degrees and also heat the hot water.

Then at the end of night rate it steps back again but does still run during the day as needed, but obviously not as much.

You need to tweak it to suit you and your house. There is no one perfect solution/setting.

The key things would be to realise that UFH takes hours to react so any changes need to be measured over days and you need to avoid large temp swings in your house.

Unfortunately my setup is a bit more basic. I've only a basic mechanical thermostat upstairs, downstairs is controlled by the smart thermostat for the heat pump 😬

I think the trick might be to set the downstairs to a lower temp at night and then raise it up to 21C around 5am. With the heat from the hallway radiator going up the stairs then it should warm the upstairs as well

Check with the rest of the occupants to see if they all have the same experience, if so, there may be a problem but also remember that electricity costs have increased massively.

My son and his neighbour who live in identical A1 rated homes with the exact same number of occupants and age profile have very different bills, son was charged for 700 units (bi monthly oct/nov) and neighbour was looking at a bill for 2100, they set up whatsapp group for small estate (26 houses) and have noted that about 15% of residents are experiencing very high bills, they are waiting for developer to get back to them.