Heat Pumps - post here.

RandomAccess

Question for comments.
If we get the extreme weather that has been forecast I would like to know what to expect.

Such as at what air temperature does a heat pump stop effectively stop working.

If there is heavy snow I presume it may get drawn into the heat exchanger.

And in apocalyptic scenario where there is deep snow the intake outtake vents are going to need to be cleared. Perhaps the heat pump needs a roof in such a scenario.

These are just thoughts, so if you have relevant information please post it.

I think sure source heat pumps are potentially vulnerable to such severe weather events.

KCross

RandomAccess wrote: »

Question for comments.
If we get the extreme weather that has been forecast I would like to know what to expect.

Such as at what air temperature does a heat pump stop effectively stop working.

If there is heavy snow I presume it may get drawn into the heat exchanger.

And in apocalyptic scenario where there is deep snow the intake outtake vents are going to need to be cleared. Perhaps the heat pump needs a roof in such a scenario.

These are just thoughts, so if you have relevant information please post it.

I think sure source heat pumps are potentially vulnerable to such severe weather events.

Bear in mind there are two main types of heat pumps....

Air to Water
Geothermal

Air to Water is affected by extreme weather like you suggest. Anything below about 5C and it will start to become inefficient as it has to use energy to defrost itself.

For Geothermal, there is nothing exposed to the weather. The entire unit is indoors and the only outdoor element is the underground collector which is unaffected by such weather.

There are other HP types as well but not as common.

RandomAccess

I meant to state air source but I'm struggling with an overzealous auto correct that effs up what I type and then I make mistakes trying to clean up the mess.

I hoped the threshold temperature was quite a bit lower. That may cause us some problems so.

KCross

RandomAccess wrote: »

I meant to state air source but I'm struggling with an overzealous auto correct that effs up what I type and then I make mistakes trying to clean up the mess.

I hoped the threshold temperature was quite a bit lower. That may cause us some problems so.

I believe its a misconception that the defrosting only occurs below 0C. It happens at higher temps than that due to moisture in the air hitting much colder parts of the outside unit and freezing. It then has to defrost that.

Water John

Since many of these A2W are installed in countries like, Sweden, i would hope they would continue to work, at low temps. They will however be less efficient.

KCross

Water John wrote: »

Since many of these A2W are installed in countries like, Sweden, i would hope they would continue to work, at low temps. They will however be less efficient.

The week ahead is the hardest test A2W heat pumps will have had to endure in this country for quite a while.... sustained sub-zero temps for a week. Daytime temps around zero and night time temps at -7

There will be a lot of defrosting going on!

You'll find out quick enough how efficient your heat pump is this week!

Water John

The last severe spell, a good few years ago, can't remember the year. One of the cheaper models was in trouble. Think they went, off the market. Hope most come through. But no doubt will run a much bigger electricity bill.
Just make sure any snow doesn't drift against it.

I take it all you heat pump owners have ngiht rate electricity ?

samdeluxjones

I don't because sparks said it wouldn't make much difference. Our bi-monthly without heating is €190 average, which is 95% daytime usage.

But after reading here i'm thinking twice about it. Just done first year so can compare second year against it. Annual bill was €1480 total. Reckon €400 odd of that was heating alone.

I will post ATW HP readings to see how it handles the cold spell.

RandomAccess

Has anyone retrofitted monitoring to their heat pump setup?
I saw a few products from a web search but I'm not sure how nature they are and some are quite DIY such as

https://heatpumpmonitor.org

Main reason being that if there was a fault and the system performance/efficiency hit the floor I would like to be alerted sooner than later.

Just an idea currently.
My device is a Stiebel Eltron.

KCross

samdeluxjones wrote: »

I don't because sparks said it wouldn't make much difference. Our bi-monthly without heating is €190 average, which is 95% daytime usage.

But after reading here i'm thinking twice about it. Just done first year so can compare second year against it. Annual bill was €1480 total. Reckon €400 odd of that was heating alone.

I will post ATW HP readings to see how it handles the cold spell.

Maybe your sparks doesnt realise how heat pumps work?
If you have a HP you should have night rate electricity.

Do you have appliances that have delay timers on them? If you shift those as well to night rate it will more than pay for itself.

samdeluxjones

samdeluxjones wrote: »

I don't because sparks said it wouldn't make much difference.

You're joking ? why would he say that ?

My night rate is about 7.4 cent per Kwh and about 17 Kwh day, yes higher rental of 50 Euro's a year but that pays me back in a month or less, well if I were to compare it to paying for diesel it would pay me back in a week by charging the car at night.

You can run the dishwasher, dryer , washing machine at the night rate if convenient, saves more.

RandomAccess

Our heatpump heats water also, the majority if which we use during the daytime. The water is heated on demand rather than just overnight (our apartment immersion system worked that way).

I have considered a night meter but really id need to gather stats beforehand to prove if it makes sense.

As you know opting for night rate means your day rate is higher also, not just the additional flat fee.

KCross

RandomAccess wrote: »

Our heatpump heats water also, the majority if which we use during the daytime. The water is heated on demand rather than just overnight (our apartment immersion system worked that way).

I have considered a night meter but really id need to gather stats beforehand to prove if it makes sense.

As you know opting for night rate means your day rate is higher also, not just the additional flat fee.

~ €45/yr extra standing charge for night rate
~1c/kWh more for day rate

But half the price for night rate (7c vs 14c/kWh)


With a heat pump the half rate at night is more than enough to pay for the increased standing charge and the 1c/kWh extra by day.


Lets say you use the average amount of electricity for a house in Ireland.... ~3500kWh/year(if you have a HP you are probably using a lot more than this).

The extra 1c/kWh by day would be €35. Add on the €45 extra for standing charge and all you have to do is use €80 worth of night rate to break even.... thats 1100 units, which is only 3 units on average per night.... its VERY easy to use 3 units per night. I'd be surprised if any heat pump owners didn't use multiples of that per night as an average.... and then add in things like shifting dishwashers etc to night rate you save even more.


Put one of those kWh meters on your heat pump and see how many units it uses this week.... that'll answer it for you pretty quick!!: )

RandomAccess

Yep, sounds sensible. Will look into it this evening. Had been meaning to do so anyways but have been too busy with new house and baby so it fell way down my ever expanding Todo list!

Ray Donovan

My electricity figures for my first year in my house with A2W, UFH, MHRV (2,700 sq ft) are E1,326 which is E221 per bill. That covers everything. I lit one fire in my stove in that year.

KCross

KCross wrote: »

Lets say you use the average amount of electricity for a house in Ireland.... ~3500kWh/year(if you have a HP you are probably using a lot more than this).

The average electricity consumption is more like 5,500 Kwh , no ?

KCross

Deleted User wrote: »

The average electricity consumption is more like 5,500 Kwh , no ?

No, in the past it was 5000+ but with the advent of LED lights and significantly more efficient appliances the average has dropped well below 4000kWh.

https://www.boards.ie/vbulletin/showpost.php?p=102466419&postcount=25

It's not long ago I think I got that figure off the ESB site, LED's shouldn't make much difference as they're not that much more efficient then CFL if at all and we've had them years.

The real difference LEDs made is in small light fittings such as GU10 where CFLs were not so good. So perhaps on that basis.

KCross

The 5000+ figure was from 2011 and the 3500 figure was updated in 2015 so things changed quickly enough.

The newer A rated appliances also help.

Water John

The LED lights are the visual (pun intended) manifestation of economy. The appliances, like TV, washing machine, tumble dryer, dishwasher etc, are the business end of energy saving, as KCross mentions.

antoinolachtnai

The lower figure is the median. The higher figure is the mean. The median is a more relevant figure for most people.

KCross

antoinolachtnai wrote: »

The lower figure is the median. The higher figure is the mean. The median is a more relevant figure for most people.

The mean is 4127kWh for all domestic customers which includes high demand users like farmers which would really skew the figures for the 3-bed semi-d user.

The mean value for customers on 24hr rate is 3595kWh.... this is the majority of people.

The median is 3500kWh so the mean for 24hr meters and median are pretty close.

Bottomline, the 5000kWh figure is well outdated based on the 2015 recalculations.

Speaking of appliances, we recently got a new heat pump dryer and it consumes about half the energy or maybe not quiet as much as half because it takes a bit longer to dry. But very impressive.

However I expect there are not a lot of people who will pay for a heat pump dryer.

Water John

Yeah, they must be one of the, best buys, in new appliances. Bought 2 for family members.
Bonus, clothes are lovely out of it.

KCross

Water John wrote: »

Bonus, clothes are lovely out of it.

Intrigued.
Why would that be any different to a standard dryer?

Water John

Water John wrote: »

Bonus, clothes are lovely out of it.

Yeah herself and my Mother was very impressed with the clothes out of it.

KCross

KCross wrote: »

Intrigued.
Why would that be any different to a standard dryer?

I think it's down to the fact they're gentler on the clothes, don't come out burned to a crisp.

Water John

They come out soft and fluffy, more like outdoor drying. This is the verdict of other family members. Probably because of lower temp, longer drying time.

KCross

Water John wrote: »

They come out soft and fluffy, more like outdoor drying. This is the verdict of other family members. Probably because of lower temp, longer drying time.

We are going a little OT but it is still technically about heat pumps!

My dryer (not a heat pump type) has a humidity sensor so it senses what heat and length of time to dry the clothes as opposed to the old type dryers which just blasted the clothes for a set period of time and hence they could come out fried!

Once you have a humidity sensor I think the fried problem goes away. I suspect the heat pump dryers have that too and its more the humidity sensor than the heat pump itself that makes it better in that regard?