Condenser boiler or heat pump

We have a ground source heatpump and it costs a fortune to run.

We use about 11,000 kwh per annum. National avg is about 4,500 i think. House is 275 sq metres.

Thinking of getting 20 panels sth facing and a 10kw battery to somewhat mitigate the heatpump costs.

Just hope im not throwing good money after bad.

The heatpump is danfoss and was installed about 14 years ago. I dont understand it or its setting. Theres no app and i have no zonal heating. Just a centralised thermostat. Parts of house are cold other parts are perfect temp.

Id love to just get someone to come out and review the entire set up and advise on how to optimise it and control it. Who knows, maybe it already is optimised. All I know is i pay a fortune in leccy bills.
 
jim said:
Thinking of getting 20 panels sth facing and a 10kw battery to somewhat mitigate the heatpump costs.
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If I were you I would hold off doing this until I fully understood if and why the energy consumption is high. Maybe consider a heat loss survey to find any easy wins on the heat loss side of the equation.
jim said:
I dont understand it or its setting.
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This might have something to do with it too. I would advise that you educate yourself. Google 'heat geek'. UK based but they give some really good pointers.
When was the last service done and did you ask the technician to explain the system / use / settings to you?

Is the 11000 units total electricity consumption for the year or just the hp consumption?
 
11,000 is total consumption mainly driven by heatpump and size of house.

The heatpump is always running in background. My understanding is that it runs based on outaide temp not inside - does that sound right? And if so - why would heat loss in house be relevant? Because its going to run regardless based on outside temp?

Service done about 7 months ago. Technician explained some things to me, i have a very basic understanding of it. The jist was to leave the pump alone to run low and slow and only adjust the centralised therm if needs be.
 
Cork22 said:
Very interesting topic above, any further info on the subject?

I have 20 year old double glazed windows but the house has had the cavity walls pumped and attic insulated.

Debating about the one stop shop upgrade for about €30k (excludes windows but includes a new front and back door) and wondering will I still save money. Sounds like I will if system sized correctly. I am also going for Solar PV with a 5-10kw battery. Thanks.
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We were initially going down a one-stop shop route for external installation, solar and a few other things. Initial price to us before grants was €65k for what we were doing. Walked away from it in the end and went with local suppliers instead. A number of reasons for that
  • Considerable cheaper then going down the one stop shop, 5 figures cheaper overall but it does require you to in effect be your own project manager, but for something like this, that's not difficult
  • Response times from the one stop guys were awful. Also, very hard to get clear answers out of them that was not an effort to upsell
  • Snagging was much easier with a local supplier, if I couldn't get him on the phone, I just walked over to where they were doing their next house
  • Much greater flexibilty from the local guys. For example, in my case, we needed to get some external cables removed from the house, "who is your electrician? Ah yeah, we know him well" and it got sorted in a few hours

Just make sure they are all SEAI certified installers, plenty of cowboys out there. We got audited by the SEAI afterwards and all was fine.
 
jim said:
11,000 is total consumption mainly driven by heatpump and size of house.
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This does not seem so outrageous if it's your total household electricity usage. My gas usage in a 128m2 detached 1989 C2-ish house is 13,000kWh or so, electricity (before EV's, solar, etc.) was a further 5,500 kWh approx. At a SCOP of 3.5, that 13k of gas would translate to 3,750 kWh or so, giving me a notional total of 9,250kWh. Your house is over twice the size of mine.
 
jim said:
My understanding is that it runs based on outaide temp not inside - does that sound right? And if so - why would heat loss in house be relevant? Because its going to run regardless based on outside temp?
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There will be a heating curve set on the heatpump which basically tells it that for outside temperature of X it should send water into your heating system of temperature Y. The curve is adjustable though and would have been set at installation time such that your house feels comfortable.

If you were to reduce the heat loss of your house through improved airtightness etc, you could then adjust the heatpump heating curve to send slightly cooler water to the house and still end up with your house being as comfortable. Small changes to the heatpump curve can have really big impacts on the cost to run the heatpump because they become less efficient the hotter water you ask for it to send.

FWIW we used 6000kWh last year to heat a 400sqm A2 house and hot water with a very efficient new air-to-water heatpump. Your figure does not sound too outrageous to me.
 
jim said:
We use about 11,000 kwh per annum. National avg is about 4,500 i think. House is 275 sq metres.
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That value dates from 2017 when the CRU reduced it from 5,300 at a time when there were far fewer heat pumps in the mix. The average household also consumed 11,000kWh of gas or oil at the time. Those figures were derived from real usage data at the time, and house size was not a factor. As yours is twice to three times the average size, it's unlikely you will ever see average consumption.
 
Zenith63 said:
There will be a heating curve set on the heatpump which basically tells it that for outside temperature of X it should send water into your heating system of temperature Y. The curve is adjustable though and would have been set at installation time such that your house feels comfortable.

If you were to reduce the heat loss of your house through improved airtightness etc, you could then adjust the heatpump heating curve to send slightly cooler water to the house and still end up with your house being as comfortable. Small changes to the heatpump curve can have really big impacts on the cost to run the heatpump because they become less efficient the hotter water you ask for it to send.
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This ^^^^ Couldn't have said it better myself
 
jim said:
The heatpump is always running in background. My understanding is that it runs based on outaide temp not inside - does that sound right? And if so - why would heat loss in house be relevant? Because its going to run regardless based on outside temp?
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Your fridge is a heat pump except it works in reverse. What would you think would happen to your fridge's power consumption if the fridge door was left permanently slightly open? Excessive heat loss in a house is akin to leaving the fridge door open.
 
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@Micks'r what about my understanding though, that the HP runs based on outside temp. If this is true then wont the heatpump run regardless of indoor temp i.e itll run based on outside temp?
 
jim said:
@Micks'r what about my understanding though, that the HP runs based on outside temp. If this is true then wont the heatpump run regardless of indoor temp i.e itll run based on outside temp?
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as @Zenith63 noted above the outside temp dictates the temp it is heating the water too to heat your house. It will stop running once the temp you have set on your internal stat is reached.

Are you running UFH? or rads or a mix?

your usage doesn't seem outrageous for the size of house and the fact you have no other heat source. Are you making sure you are on the most appropriate electricity tariff for your usage? i push a lot of our HP running (and do all my ev charging) at a night rate of 12.5c.
 
jim said:
@Micks'r what about my understanding though, that the HP runs based on outside temp. If this is true then wont the heatpump run regardless of indoor temp i.e itll run based on outside temp?
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Yes and if you were to improve the insulation or air tightness of your house and didn’t adjust the heatpump you’d find the house too warm and your heating bills would be the same. So instead you would reconfigure the heatpump to send a little less heat to the house because it is no longer required, and that’s how you’d see your cost come down.
 
@jim When 'Supply of heat' EQUALS 'Loss of heat' then a constant comfortable temperature in the house is achieved

So working backwards;

your house looses heat so you need to replace this heat to be comfortable. This means that your heat source (HP) needs to send warmed water through your distribution system (either UF or rads or a mix of both). The more heat loss you have the warmer that water needs to be and the harder your hp needs to work and the higher electricity consumption. This is the heat loss side of the equation.

Now, your hp will have what's called a heat curve set up in order to vary the flow temperature through your distribution system depneding on the the outdoor temperature. The lower the outdoor temperature the higher the flow temperature will be and visa versa. This heat curve is nominally set by the factory but every house is different so it needs to be individually optimised. This takes time, patience and understanding to get right and when left at factory settings or isn't optimised properly then the hp will consume far more electricity than it needs to. This is the heat supply side of the equation.

So to ensure that you are not wasting electricity you need to ensure both sides of the equation are optimised, i.e
1. Satisfy yourself that your heat losses are not excessive
2. Satisfy yourself that hp heat curve is optimised

By way of example, if you live in a draughty house which required your hp flow temperatures to be, say, 10 degC higher than they would otherwise be in a well sealed house of same size etc this could lead to a 50% increase in hp electricity consumption.
 
Thanks Mick and all. I appreciate the detailed reply and the time you took.

I think house is reasonably air tight, no obvious draughts and triple galze windows. I may get an airtightness test done. Was quoted 400 for this. But id then need to also address any identified issues as well.

I did play around with heat curve a while back but i dont k ow if its optimally set. The house is comfortable, I know that.

It sounds like i should keep gradually lower the curve until house isnt comfortable, then notch it back up to comfortable, and then thats the optimal point.
 
jim said:
It sounds like i should keep gradually lower the curve until house isnt comfortable, then notch it back up to comfortable, and then thats the optimal point.
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And you need to do this for both cold and mild weather to optimise to two points on the curve
 
@Peanuts20 well done, sounds like you got a good deal.

I'm at around €45k before grants and €25k after grants for HP, Panels, attic insulation, front and back door. I am debating about windows too and have someone calling out on Monday to take all the dimensions and get a final quote. I'll def compare to individual prices once I have 3 quotes.
 
@jim , like others have said, it sounds like you have a fairly efficient HP already. Your total usage of 11,000kWh for 275sqm puts you in the A2 BER rating.

So your bills are not expensive, you just have a very large house.

I've posted previously on some of the changes I've made to own HP set up. It has knocked a good bit off our usage but the biggest benefit was how much more pleasant the constant temperature is.

We've switched over completely to weather compensation so our internal stats do nothing anymore

Heat Pump/Heat Curve question

You can always make a list of your energy using appliances (oven, kettle, etc etc ) and estimate how often you use them, multiply by their consumption and get a good idea of what your energy consumption is There are also plug-in adapters that will measure the use of a single appliance if you...
www.askaboutmoney.com
 
@Micks'r thanks for the reply.

I am not living in the house fulltime as I live away but moving back in August for good. The house has been occupied about 95% of the year and the gas bill has been €1,250. I tried to get into Energia app to check usage but it keeps getting stuck.

House heats up in about 15 mins I think, doesn't cool quickly but the weather hasn't been freezing while we have been there such as last Xmas.

We have a gas boiler, I think at least 10 years old.

The house was built in 97 and is a 3 bed semi d with an open plan extension at the back (10 years old). The attic has been converted to another bedroom too.

I would prob keep stat at 20C but the misses usually turns it up. She loves keeping the hot water on for a few hours a day.

A small bit of mould around 1 of the windows in a bedroom alright but not major.

A small bit of a draft on the top floor alright but I'll try and seal it once I am back.

Thanks for any wise words in advance.
 
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