New Heat Pump - Energy Monitoring

windyboy

Hi,

Getting a Nibe 8kW heat pump installed in the next couple of weeks into our new 2 storey ICF house. (We will have dual tarriff meter) I would like to record the energy usage of the heat pump. I was looking for some advice on how best to record the energy usage , fit a kW/h meter in the fuse board or buy an energy monitor like Owl/Efergy/Wattson?


Cheers,

Windyboy

Condenser

You can fit a electrical meter used for sub-boards on the power supply to the heatpump. I'd fit it near the HP myself rather than in the board. It will give you the kilowatt usage so if you multiply it by the cost of day rate it will give you your worst case running cost. TBH you shouldn't need night rate for a 8kw heatpump in any case so the costings would be spot on. You can pick the meter up in any electrical distributor.

windyboy

Condenser wrote: »

You can fit a electrical meter used for sub-boards on the power supply to the heatpump. I'd fit it near the HP myself rather than in the board. It will give you the kilowatt usage so if you multiply it by the cost of day rate it will give you your worst case running cost. TBH you shouldn't need night rate for a 8kw heatpump in any case so the costings would be spot on. You can pick the meter up in any electrical distributor.

Thanks for your advice - can you advise why you say that I shouldn't need night rate?

Windyboy

Condenser

At 8kw, if installed properly and sized properly, your energy bills should be so low that the benefit of night rate would be off set by the standing charge associated with availing of it.
My advice would be to get the night rate meter installed at connection stage but don't sign up for the night rate tarriff for a while. See how your system is running and the costs involved and then decide if the cost savings would offset the standing charge.

rebellad

I have a heat pump and use the Owl Energy Monitor, it is the business as I can see how much each day is costing. Cheap enough and easy to fit

stackerman

Ive a Nibe heatpump, and if you go into the control panel, there is a section which will give you the figures you are looking for (or at least there should be). Mine is 3 years old, so unlikely to be the same control panel, Nibe or your installer should be able to help you on this.

I also have a night rate meter, and its a God send. Keeps the cost good and low, esp in this weather. Took me a few mts though to find the best setup of the heatpump, and had a few frights when I got my first few bills :eek:. Every house will be diff, so you just need to keep an eye on it, learn as much as you can about how to use it, and give it the time it needs to tweek it.

Works a treat now though

creedp

@Keving. Do you mind me asking what set up you eventually settled on? For example given you have a night rate meter are you either only or substantially running you heat pump during the night to heat floor slabs or do you also have it set to come on for a boost at evening time. Alternatively, do you run it at night and then allow thermostats to control heat pump during the day so as to only demand heat when needed on an individual room basis.

I am installing a heat pump in the face of some resistance from some quarters owing to its high capital costs and potentially crippling electricity bills so I would like to hit the ground running when it comes to set up!!

Thanks

stackerman

Hi creedp, I do the latter (I think ). One of the things I love about it, is that once set up right, you can just walk away. No oil topups here with 3 ft of snow outside

It runs mostly at night, with the stats doing the rest. I have the stats down lowish and so not too much work done during the day. One thing I found though is that my good wife (like most I know) thinks she cant be warm enough and would just turn up all the stats and say nothin to me. That can be sorted out (without argument) by just playing around with the graphs in the control panel. So for example, her good self thinks she has turned it up to say 25 :eek: but the graph pulls that back down a few degrees or more. The OH is then happy with her 25 degrees (its all in the mind ) but you arent paying for it, or fighting about it.

Just take the time to sit down and think about how you live, what rooms are used and when etc etc. Make sure your installer takes the time to set it up right and be sure to be there when he does and get him to teach you. There is alot to it, but the booklet it fairly good (just add notes into it as you go). It will save you alot of money and hastle.

Its the best thing I did in the house, along with my glass fronted wood burner (some heat).

Best of luck.

creedp

keving wrote: »

Hi creedp, I do the latter (I think ). One of the things I love about it, is that once set up right, you can just walk away. No oil topups here with 3 ft of snow outside

It runs mostly at night, with the stats doing the rest. I have the stats down lowish and so not too much work done during the day. One thing I found though is that my good wife (like most I know) thinks she cant be warm enough and would just turn up all the stats and say nothin to me. That can be sorted out (without argument) by just playing around with the graphs in the control panel. So for example, her good self thinks she has turned it up to say 25 :eek: but the graph pulls that back down a few degrees or more. The OH is then happy with her 25 degrees (its all in the mind ) but you arent paying for it, or fighting about it.

Just take the time to sit down and think about how you live, what rooms are used and when etc etc. Make sure your installer takes the time to set it up right and be sure to be there when he does and get him to teach you. There is alot to it, but the booklet it fairly good (just add notes into it as you go). It will save you alot of money and hastle.

Its the best thing I did in the house, along with my glass fronted wood burner (some heat).

Best of luck.

Thanks Keving

Interesting strategy you have adopted there ... do you not miss the arguing and battle of wills over control of the thermostats?? I suppose its down to the maxim what you don't know won't hurt you!

In relation to your heat pump setting I will have to discuss this with my installer as I like the idea of running the heat pump as little as possible during the day but I suppose that depends a lot on the levels of insulation/airtightness achieved and detailing out of cold bridges. As you say experience will eventually determine the most optimum setting for the pump. My installer does not like putting thermostats in every room, especially those that are continuously lived in. His view is that these rooms should be maintained at a std temp and he achieves this with a master thermostat which effectively has two heating zones - ground and 1st floor - the former set at 20c and the latter 18c. He says within that overal set up he will install a max of 2 individual room stats in each zone and these should be placed in rooms that are not routinely used so that they can be maintained at a slightly lower temp, eg 15c. This approach he claims will result in a more steady use of heat pump rather than it having to respond to the individual room stats calling for heat at different times to maintain their differential temps.

Anyone got any views to offer on this approach.

Thanks

Condenser

Hi Creedp,

Ideally you should view your house as one zone and allow the weather compensation on the heatpump adjust the temp you are putting into your floors. This will ensure the maximum efficiency of the heatpump at all times as the HP is matching the actual heatlosses from the house at any given outside temp.

Introducing thermostats into the system throws up a number of problems. Firstly, the heatpump has to cater to the highest set thermostat so is working as hard as if the whole house was brought up to temp albeit for a shorter time.
Secondly, when stats shut down they restrict the flow of water to the heat exchanger which limits the amount of energy the HP can disperse to the water. This throws the refrigeration cycle of the HP out of sync therefore reducing efficiencies.
Thirdly, using stats will probably increase the amount of startups your HP will have in a day even if a buffer is installed (A buffer tank must always be installed where stats are present) . This presents two problems. Startups draw the most power and frequent startups shorten the life of your system as a compressor has lifetime spec it was designed to as regards startups.

You should really be looking at your building envelope as an insulated box you are trying to maintain heat within, rather than trying to limit the movement of heat from room to room, which by the very nature of a house is impossible to do in the first place. You will have a more comfortable living space and a better return from your HP

creedp

Thanks Condensor. That is the approach advocated by my installer, i.e. he is not in favour of stats but is prepared to install a limited no in each heating zone if I insist. There will be one room in each zone which will only get occasional use - I will discuss with installer the merits of installing stats or whether it is counter productive to do so.

Thanks again

Condenser

If you install any stats make sure you install a buffer. If you don't you'll be asking for high bills. Personally I think stats are a waste of time and wouldn't install any. You won't save any money by keeping these two rooms cooler. The heat will migrate from the warmer rooms to these. Keep the house at one temp and use your night setback to reduce temp at night. Start the heatpump about 2 hrs before the first person is up to have the house up to temp and take advantage of night rate if you choose to use it. I disagree with heating your house through the night as it makes the house uncomfortably hot at night. And because night is generally the coldest period you maximise the heat loss as the differential between you inside temp and outside temp would be at its greatest

creedp

Condenser wrote: »

If you install any stats make sure you install a buffer. If you don't you'll be asking for high bills. Personally I think stats are a waste of time and wouldn't install any. You won't save any money by keeping these two rooms cooler. The heat will migrate from the warmer rooms to these. Keep the house at one temp and use your night setback to reduce temp at night. Start the heatpump about 2 hrs before the first person is up to have the house up to temp and take advantage of night rate if you choose to use it. I disagree with heating your house through the night as it makes the house uncomfortably hot at night. And because night is generally the coldest period you maximise the heat loss as the differential between you inside temp and outside temp would be at its greatest

I'll discuss the night set-back option with installer - does it mean that the master thermostat is set at e.g. 20c during day hours but reduces to say 18c at night so as to stop the HP kicking in during these hours when everyone is asleep in any case.

Obviously I'm not very familiar with the HP way but I thought that the advantage of the night rate was that the HP could operate for a number of hours during the cheaper night hours in order to bring the floor slabs up to desired temp by morning. I suppose I was of the view that if HP was not operating/operating for a limited time during the day hours the slab would have cooled sufficiently by early am to require a number of hours to bring it back to desired temp. This heat would then be given out during the day with minimum further input from the HP and be ready for a significant top-up again the next night. I know this would require the HP to operate at full tilt during the night hours which might not be an efficient/effective strategy. In addition maybe Im very niaive in thinking that the insulation levels in the house would maintain the heat at a comfortable level so it would not need to be topped up during day hours. We will also have sealed stove which will be used during very cold weather and this should also assist in boosting temp during the day/evening.

Given that limited use will be made on the night rate electricity if HP isn't operating during these hours is it worth paying the extra standing charge required to perate dual supply?

Anyway I'll talk in more detail to installer re: issues/advice raised in this thread and hopefully hit the ground running with respect to an appropriate set up for my house.

Thanks again

Condenser

Unless your close to passive you won't keep the temp in your house all day. You will be re-engerising the screed at least once during the day.
This night rate business is a fallacy, a gimmick used to hide the inadequacies in a system.

Running a system at night to boost temp while you're under a 8 tog duvet is not a comfortable way to live. A person should never be afraid of their next ESB bill when running a heatpump. If they are they need to look at 2 things, their insulation levels (being completely honest with themselves) and their installer and installation because if one is right the other isn't.

Definately any HP under 11kw, if installed properly should not require night saver electricity. The one caveat to that, is when you have an immersion in the system that is topping up hot water or backing up a shortfall in the heatpumps performance in cold periods.

creedp

Condenser wrote: »

Unless your close to passive you won't keep the temp in your house all day. You will be re-engerising the screed at least once during the day.
This night rate business is a fallacy, a gimmick used to hide the inadequacies in a system.

Running a system at night to boost temp while you're under a 8 tog duvet is not a comfortable way to live. A person should never be afraid of their next ESB bill when running a heatpump. If they are they need to look at 2 things, their insulation levels (being completely honest with themselves) and their installer and installation because if one is right the other isn't.

Definately any HP under 11kw, if installed properly should not require night saver electricity. The one caveat to that, is when you have an immersion in the system that is topping up hot water or backing up a shortfall in the heatpumps performance in cold periods.

I'm glad I intervened on this thread as I'm getting some very interesting views on heat pump set up which will be very useful when I go about installing it shortly. My list of issues for my installer continues to grow.

My HP is rated at 12kw but doesn't have an inbuilt immersion to boost the temp in cold weather. My installer considers that if a boost in necessary then the HP is undersized. However, I will be using the immersion to boost the DHW even if only to deal with legionnaires. Consequently would I be foolish to install a dual rate meter and in ball park terms does anyone know what night time consumption would be required to break-even on the additional cost of installing and running the dual meter?

Thanks again

Condenser

What make of HP is it? If you are using an immersion at all I would recommend night rate. You'd need over €300 a year night rate usage to make it viable. With a immersion topping of your hot water you'll be looking at between 50c - €1 per day on the immersion alone.

Your installer is right in his assertion that if a HP needs any back up then its undersized.

creedp

Condenser wrote: »

What make of HP is it? If you are using an immersion at all I would recommend night rate. You'd need over €300 a year night rate usage to make it viable. With a immersion topping of your hot water you'll be looking at between 50c - €1 per day on the immersion alone.

Your installer is right in his assertion that if a HP needs any back up then its undersized.

Its a Waterfurnace Heat Pump. Even with hot water costing between 50c and 1€ a day night rate hardly justifies itself. I suppose if you add in using dryers/wmachines/etc (supervised obviously - Im a bit of an owl and often up till 2am) and the fact that the heat pump can operate for a couple of hours using the night rate, i.e. 5-7 am it might just about justify itself. I have to say I always thought it was a no-brainer but like everything else you have to crunch the numbers to be sure.