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New Build, 7 months in with a Danfoss heatpump

matrat

Hi all,

I used this forum alot during my self build so wanted to share my experiences now having being in the house 7 months.

General Spec;
- House was built to square in 2009, 100mm cavity, already had 60mm foil back board in place.
- 3000sq ft
- Munster Joinery triple glaze windows and doors.
- Pumped the remainder of the 40mm on ground floor and full 100mm cavity from floor slab up with Icynene Technitherm Closed Cell Cavity Wall Insulation.
- Pumped roof with Icynene LD-C 50 Spray Foam Insulation.
- Had air test done at this stage and decided to tape windows internally with pro clima Contega Solido SL.
- 130mm insulation ground floor, 60mm insulation on first floor slab.
- Self designed and installed 2 NUAIRE - MRXBOX95-AB-WH1 units, one for upstairs, one for down.
- Local installer for Danfoss DHP-H Opti 8 SP

I appreciate that this is not everyones idea of a great spec, but naturally i was budget restricted and as this was a self build with no contractor or architect, all decisions where made by myself based on my own personal research. Multiple quotes where sought for every item and i did a substantial amount of the work myself. I have no trade or massive experience, but given some of the cowboys that were recommended to us, i genuinely feel myself and youtube have done a better job.

Naturally i have my opinions on all of the above products/companies but i wont go into them here. Feel free to message me if you have any questions on any of them.

House is set up that bedrooms have stats, all set to 21.5, all other areas are about 23 (wife loves heat).

This is the first house i have ever spent much time in which was built to this kind of spec and honestly i could never go back. No draughts, no smells and lovely uniform heat. We have no other heat source than HP. What has surprised me the most is how quickly the house heats you when you come in from the cold. No need to stand next to the fire, a few minutes and you are warm. Biggest downfall is constantly leaving the house and having no coat or jumper on! :rolleyes:

Regarding the HP, i am overall extremely satisfied, i am keeping an excel file tracking the running times and costs associated (happy to share) and here is the headlines;
- The unit had cost 334.27 by the time we moved in. This is hot water used cleaning, and bringing whole house up to around 24c from cold and wet.
- Average WEEKLY cost for ALL domestic hot water, that is all showers and washing etc.(we have used dishwasher twice as the hot water is so readily available) is 4.23e.
- Average cost for heat is a bit trickier as there is much more variation naturally. I will list the average WEEKLY cost per month;
June = 1.81e
July = 2.16e
August =1.06e
September = 3.80e
October = 11.21e
November = 22.52e
December = 22.17e

Again, these are WEEKLY costs!!! All costs taken at either the exact rate charged per unit by my provider, or 19c for the last few weeks in December for which i dont have a bill for.
I contacted Danfoss direct, they advised the following;
For the heating function, the machine uses 2kw/h
For domestic hot water, the machine uses 2.7kw/h

I record the times the unit has being on every Saturday, as of yesterday, 224 days in total, thats 32 weeks;
Total cost for heating has being 321.87e
Total cost for DHW has being 139.55e

That is total house cost of 461.42e which i am very pleased with.

As maybe you can tell, overall i am delighted we chose to go down the HP route, we very nearly had it wrote off assuming it would be too expensive but it just isnt when you do the maths for a few years.

Hope this helps making someones decision easier and any questions please let me know!!

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Water John

PM sent.

faulty

Hi,
This thread is super, some great and helpful information on it. I have just started a self build, the builder/project manager is doing the full job. We are installing a Danfoss A2W heatpump for UFH heating on both floors within a 2400 sq ft house.

Would anyone have a good estimate of the cost of the Danfoss heatpump. We are getting the Danfoss DHQ-AP 11Kw installed. Danfoss was recommended to me as possibly more expensive but best A2W heat pump on the market.
What would be the break down of the Heat Pump and associated Maxi unit?
UFH costs?
Installation costs?

This is a PC some on our building quote, but need to know the expected cost for our budget.

Any help would be great appreciated, thanks.
Faulty.

PM if necessary

BarneyMc

KCross wrote: »

@BarneyMc, do you have a meter attached to your HeatPump and know exactly what it is costing you per year? Care to share? Also, what size house is it?

Unfortunately not. No meter but would like to get one. Also, just paid an electric bill but we only moved in Dec 23rd and only submitted a meter reading the other day. My next bill will give me some indication.

My house is 2800 sq feet, 250mm pumped cavity, 160mm PIR insulation in the ground floor, 400mm mineral wool in the attic.

I'm sort of cooking the books regarding the HP. I'm on a dual tariff so only let the HP run at night. The house stays warm the whole day so no need to run it during the day at all. No idea what I'm saving but I'm sure it must be something.

Anyway I think you can get too carried away with costs, etc. When you get to a certain point, going the extra mile may not be worth it. I'm so happy with the house and how even a temp there is throughout. Also the fresh air with the HRV system is super. It's such a pity to see houses built to 'ach sure it will do' standards.

Water John

Ah, I'd say -3 units is enough to cook your dinner.

matrat

Happy to have some input daphne, hopefully it all works out for you.

Something i keep trying to remind myself is that ok i could have built for cheaper, but realistically 800 euro for all heat and hot water per year is pretty dam good to me. Is impossible to compare to anything i have ever lived with before. Wake up at 5am to go to bathroom, no running over cold tiles or jumping from mat to carpet to keep feet warm. Sure it may be overkill to have the heat on 24/7 when it not always required, but i would be happy to be paying 800 euro to have it only when i needed it. The rest is a bonus!! Came from a 7 year old townhouse about half the size with electric shower, gas, a stove and immersion and the difference is shocking. Did up some bills there recently to compare and it is crazy. The heat here is so comfortable and relaxing and the MHRV keeps the house so fresh and airy ha. Smells dont linger, windows dont steam, its all good.

In a stranger turn of events, when i started tracking the heat pump usage, i very stupidly didnt start and record the esb for the whole house. So have gotten several esb bills that always seemed low but been low, i didnt question ha. Now after reading the unit for the first time in 6 cycles i think, they have noticed the difference. So got a nice whack of a bill. Nothing ludicrous and spent some time yesterday just validating that makes sense and all does. They simply just estimated too low. But amazingly, somehow since the bill is large, 460 euro, then i divide the bill by the units charges, im only paying 15.6c per unit as opposed to 18.9c ha. I guess its a rounding issue and the larger count of units has watered down the standing charge and levy but overall happy ha. So have updated my excel file and from tomorrow on i will be recording both HP hours and esb units to house so i can get a baseline of how many units the house uses. For example, over Nov & Dec, the HP was on average using 21 units a day, the esb bill for the same period shows an average daily consumption for WHOLE HOUSE of 18 units.

daphne

Another comforting comment Matrat! I was hoping the stoves would be visual features as opposed to absolutely needing them to heat the place. Hopefully we'll be the same as you.
@Water John, we have air tightness detailing - taping at doors and windows, scratch coat inside, membrane in 1st floor ceiling and we're pushing for 1 ACH which may end up 0.5 higher but at least a good bit better than 3. MHRV installed...

Water John

It is the sealed envelope, as much as the insulation.

matrat

daphne wrote: »

I'm a bit concerned about the relative large envelope we have - narrow plan. Will need all the insulation we have I think. The whole thing is a bit of a leap - you just hope that you've got enough insulation and the bills won't be nuts. I'd say you'd be advised to fire on your stoves in very cold weather to do some of the heavy lifting. We will have to wait a good while to judge on what it's costing us as hope to move in summer...

Hi Daphne,

Without knowing spec, sizes etc. i couldnt comment on that but i felt that with our restricted structure make up we may need a supplemental heat source to keep us comfortable in winter. Truth it that with the system constantly monitoring and adjusting input based on temps inside and out, it never gets to a stage when u culd light a stove. We are now 99% sure we will fit an electric stove to fill the gap, purely for aesthetic reasons. No doubt if u had the system on a time clock to not run during day for example, then yes the stove would provide quicker heat to the communal areas in the evening time while the system comes up to temp over the whole house. But as partially discussed before, it is not been proven that using the machine this way is more cost effective, and the cost associated with buying the stove, connecting air supply etc would pay for alot of esb to power the machine that has to be offset for it to be a value proposition. Again without knowing spec etc. i can only advise on my experience, but for me, paying for chimney flues, the construction of the chimney, chimney pot, guard for the top, flashings, ductwork in floor for air supply etc. was a waste of money. I could have built a dummy brace and slotted in the electric stove and would have been a fraction of the cost. Maybe a tenth of the cost, and that would be a generous electric stove. Put it another way, if in stalled a stove, given the true cost before i light it a single day, it would cost me around 6 years of esb on the HP. Maybe more.

daphne

I'm a bit concerned about the relative large envelope we have - narrow plan. Will need all the insulation we have I think. The whole thing is a bit of a leap - you just hope that you've got enough insulation and the bills won't be nuts. I'd say you'd be advised to fire on your stoves in very cold weather to do some of the heavy lifting. We will have to wait a good while to judge on what it's costing us as hope to move in summer...

Charlie Charolais

KCross wrote: »

@BarneyMc, do you have a meter attached to your HeatPump and know exactly what it is costing you per year? Care to share? Also, what size house is it?

we have an A2W going since 24th jan, we fitted a dual tariff meter on the decided HP power supply, i will keep you informed & hopefully myself sane!

matrat

Would also be very interested in your stats Barney, just to do a comparison with what is a superior structure to mine and see the actual difference

KCross

BarneyMc wrote: »

This is exactly my setup solid, non dry-lined, wide cavity walls. I could unplug the HP and the family wouldn't notice the drop in tem for a few days. Super comfortable living!

@BarneyMc, do you have a meter attached to your HeatPump and know exactly what it is costing you per year? Care to share? Also, what size house is it?

BarneyMc

daphne wrote: »

Yes, the idea of heat pump is low water temperature circulation which is not a very responsive system when you're talking about moving the temperature of a house. It requires high insulation levels to be effective in terms of comfort to occupants. Any little bit of heat that is generated by the system is retained and also heat energy is stored by the walls and material of the building. As you were saying - dry lining is not really optimum solution.

This is exactly my setup solid, non dry-lined, wide cavity walls. I could unplug the HP and the family wouldn't notice the drop in tem for a few days. Super comfortable living!

matrat

Yeah it is simply down to education, but in fairness suppose it is getting on in age now and is alot better than no standard. A conversation i had a few days ago with the in-laws around upgrading their house really brought that home, a 25 year old home that raised several children, a house that contains both a boiler and non boiler stove, the ventilation system is essentially draughts. No window vents, no hole in wall vents etc. 1 generation of difference between that house and mine and is more than a few differences.
Traditionally this country waits until UK regulations have been in place a few years and copies most of it so with the level system over there and the push to make a level mandatory for all new builds will hopefully filter to us in the near future. And i love the idea that you can make a reasoned case to build a house in a location that typically would be an issue by compromising to build it to such a high level as to have little to no impact. Is such a good compromise. You want to build a house in a scenic location owned by several generations of your family, ok, build it level 6. Great setup

daphne

Yes, the idea of heat pump is low water temperature circulation which is not a very responsive system when you're talking about moving the temperature of a house. It requires high insulation levels to be effective in terms of comfort to occupants. Any little bit of heat that is generated by the system is retained and also heat energy is stored by the walls and material of the building. As you were saying - dry lining is not really optimum solution. As for air tightness and MHRV, while we don't have very low temperatures, we are definitely one of the windier climates in Europe. Draughts from bathroom fans and trickle vents must account for a lot of heat loss, comparatively, in this country.
The annoying thing is the BER classification which people take to be the "be all and end all". People just lobbing a solar panel on the roof to attain a higher BER is nuts, especially when it gives a false notion of the houses real energy performance to prospective buyers.

matrat

Yeah i agree with all this, i read an article back early in the process from some design manual in europe and it said that designers need to take a whole house approach and think of heating, domestic water, insulation, ventilation, glazing etc. as all pieces of the same overall element. That is more likely to be better in the long run to split a budget relatively even over all items than it is to focus on one or two. Point in case is with some 8-10 year old houses now that had HP fitted from new. I looked at one back before purchased current place, asked several times to see esb bills to validate this claim of great setup by estate agent. House never felt overly warm inside and naturally no bills where ever produced. You can be sure a large chunk of budget was spent on that HP, but vented double glazing windows didnt exactly improve upon its good basis!

daphne

Thanks Matrat. Yes, it seems there are natural limitations on what you can do with conventional masonry build. Everyone you talk to who has built house say 2013 and before seems to be sceptical re heat pumps. We pushed our house designer to 200mm cavity - anything beyond we were told we were getting into trouble re laying the inner leaf blocks - reaching across from outside scaffold not an option. Pumped cavity was default solution due to ease of installation and achieving best U-value for your buck. With 200mm cavity, the need for inner dry lining to make up U value not required it seems.
On airtightness, we pushed in the spec for a 1ACH - I hope this pays back but it means they're being pushed to being a bit more careful with taping up and blocking holes. Why not go the extra mile with the ACH if you're putting in the MHRV anyway. In terms of overall build cost and the cost of UFH, fancy heat pumps and triple glaze windows, it isn't a big cost. It looks like a neat and simple solution for ventilation. Hopefully it proves so!
I think the solution on the whole self build energy thing is to do your own research, use the regs only as minimums and talk to a supplier of heat pumps who will also look at the whole house in terms of insulation, design etc. I think Passive house standard should be taken as the target/benchmark but ultimately seems to me hardly attainable with block built house. I'm not entirely convinced of the payback in an Irish climate. I admire anyone who goes down this route tho. It is the less trod path and alternative construction methods are a bit scary for most people...

Water John

Yes rolion, know a few houses that decided to 'save' on build by not installing, madness.
One fella said, shur I open the windows when I can!!!

rolion

Also,dont forget AND ignore that with a good insulated house comes the fresh air/condensation /ventilation "hole in the budget" called MHRV !

matrat

Charlie Charolais wrote: »

Hi Matrat, how did you measure your electricity usage?

Hi Charlie,
My unit tracks the hours operating, i contacted Danfoss who advised what an hour operation is in KW/h, i track this number each week for the heat and domestic water separately and use my esb bill to determine my exact kw/h rate when i get it. Naturally it is within a tenth or two of 19c, but is more for my sanity to validate the machine isn't using alot more than it says.

BarneyMc wrote: »

matrat wrote: »

As they say, insulation is one of the very few items that will pay for itself.

Can you elaborate?

Hi Barney,
Is not much to elaborate on really, if you are sensible with it then it is proven that insulation will pay for itself if used correctly. For example, pumping a cavity wall, the cost of the pumping will be offset in "X" number of years by the savings you have made in heating costs. Same rule goes for most insulation applications, the cost will be recouped. Of course you can use insulation incorrectly which will greatly increase the time it takes, or maybe never pay for itself. Alot of builders now are getting the idea that insulation is a key selling point so are using it in not very efficient ways which will naturally cause some confusion and have people say that they have a highly insulated house but dont see the savings they expect. For example, i see alot of people using insulated boards internally in a house on a full fill 4 inch cavity construction. Yes this MAY be more efficient than not having the insulated board MOST of the time, but i would consider it bad practice in this age. Especially with a low heat source like A2W and Geo, it is much more efficient to keep all the insulation in one place, which can be seen with the increase in popularity of external insulation and 6 or 8 inch cavities. This also has the added advantage of using the internal leaf as a thermal store. If i had a choice of my structure, it would be a block on its flat internally and a pumped 6 or 8 inch cavity. Gets the best of both worlds.

BarneyMc

matrat wrote: »

As they say, insulation is one of the very few items that will pay for itself.

Can you elaborate?

Charlie Charolais

Hi Matrat, how did you measure your electricity usage?

matrat

daphne wrote: »

In process of building - trying to future proof with regards to insulation and airtightness. Planning on Danfoss A2W. It's reassuring to see some good reviews and not crazy energy costs. Will be interesting to see how much energy exactly is required.

Enjoy it daphne,
Yeah is definitely ways of doing it right. I was limited on structure of building and if could do that again then i would do it different and hopefully be cheaper costs again. As they say, insulation is one of the very few items that will pay for itself. Using it in the right places and the right way will make a huge difference also. See alot of people and builders using it wrongly.
I now have 259 days of recorded data, waiting on my latest esb bill to confirm but estimated around 614 euro so far. Given that hopefully the temp will be steady or rise from here to the 365 day mark, im hoping to be somewhere in the 800-850 range for a year of all hot water demand for two adults, two large dogs, and minimum of 21 deg temp on a 2900 sq ft house. Will be happy enough with that!! When i get some time i will calculate what the heat demand was from that and do some sums to see what it would have cost with an oil boiler, back boiler stove, immersion and electric shower!! Should be interesting!!

daphne

In process of building - trying to future proof with regards to insulation and airtightness. Planning on Danfoss A2W. It's reassuring to see some good reviews and not crazy energy costs. Will be interesting to see how much energy exactly is required.

rolion

matrat wrote: »

@tobdom, you have a PM

Hi Rolion,

I would be, and i am sure prospective self builders even more so, very interested to see some numbers behind this if you could supply them. Does not match any of my findings.
From my research PV & Solar are good supplemental sources, but given their cost, unless it is a retro fit, then when ROI is taken into account it is not a good solution. To design a new system in Ireland, it simple is not cost effective to include PV or Solar. People use them to supplement oil or gas systems, which is fine as they can reduce the use of those fuels during part of the year. But as a combined system, it is less effective than a GEO or A2W.
I agree that at this point in time, a gas boiler is highly efficient and combined with PV or Solar, can result in a cheaper alternative to GEO or A2W. When i did the figures assuming a 20 year life span, end result is that the initial cost saving now equals a negative net result. The legal requirement to have a gas boiler serviced annually alone takes a huge dent in the saving.
To me it is much the same as gasification boilers etc. there is an element of truth that they can be very efficient. But add in the time for labor, the fact that can anyone speak to owning one for more than 7 years, the costs to replace plates etc. then it just doenst add up. The idea that my time is free is a false economy for me and i suspect most people. If i used the same time to work then my time is not free and i would find a much larger net gain by working those hours than i would chopping wood or cleaning out boilers.

There is a reason that GEO and A2W are used in countries throughout the world more so that these alternative sources. When designed and installed right, they simply work.

Thanks.
Let me rephrase it: no one in his right mind will retrofit a heatpump to an older home OR that is not at least built at standards of BER A mimum. I heard gas boiler upgrades / replacements but not a single heatpump yet.I'm not a builder.

Re PVs vs tubes,i have both and they works fine only when God Sun decides to smile upon us !

Re "prospective builders" ... if they are the same fcuking people with no other scope than money and profit like the one(s) that built my house and for which i wanna meet and strangulate holes in his body / brain like he did with my house structure...then you are lost ! I will be pleased to meet a builder that can stand up in a conversation mhrv vs solar vs tubes vs boilers vs heapump vs airtight vs insulation !!!

Rant over...

BarneyMc

At a small trade fair in Monaghan tonight and asked a rep about PV to power my A2W HP. He gave me a ball park figure of €6K.
If this is anyway accurate then PV is not viable. We will be building on the moon before I'd see payback on that!

matrat

@tobdom, you have a PM

rolion wrote: »

Let's agree to disagree please.

Solar does makes sense.Both, PV and tubes, if they are well designed and used.
Heat Pump does not makes sense if a performant gas boiler is installed.

Both above are validated by a good sealed and insulated building.

Regards

Hi Rolion,

I would be, and i am sure prospective self builders even more so, very interested to see some numbers behind this if you could supply them. Does not match any of my findings.
From my research PV & Solar are good supplemental sources, but given their cost, unless it is a retro fit, then when ROI is taken into account it is not a good solution. To design a new system in Ireland, it simple is not cost effective to include PV or Solar. People use them to supplement oil or gas systems, which is fine as they can reduce the use of those fuels during part of the year. But as a combined system, it is less effective than a GEO or A2W.
I agree that at this point in time, a gas boiler is highly efficient and combined with PV or Solar, can result in a cheaper alternative to GEO or A2W. When i did the figures assuming a 20 year life span, end result is that the initial cost saving now equals a negative net result. The legal requirement to have a gas boiler serviced annually alone takes a huge dent in the saving.
To me it is much the same as gasification boilers etc. there is an element of truth that they can be very efficient. But add in the time for labor, the fact that can anyone speak to owning one for more than 7 years, the costs to replace plates etc. then it just doenst add up. The idea that my time is free is a false economy for me and i suspect most people. If i used the same time to work then my time is not free and i would find a much larger net gain by working those hours than i would chopping wood or cleaning out boilers.

There is a reason that GEO and A2W are used in countries throughout the world more so that these alternative sources. When designed and installed right, they simply work.

murphaph

The actual heat source is definitely the least important decision. In a properly designed and built modern home, the heat demand should be so low that the heat source is not really that important IMO. As long as the fabric is future proofed and can allow some other heat source to be slotted in instead without ripping the whole distribution system out then it's all good.

rolion

Water John wrote: »

The solar would have a particularly poor ROI. HP is the way to go.
Well sealed and good insulation.

Let's agree to disagree please.

Solar does makes sense.Both, PV and tubes, if they are well designed and used.
Heat Pump does not makes sense if a performant gas boiler is installed.

Both above are validated by a good sealed and insulated building.

Regards

murphaph

If you end up fitting oil then still go ahead with the UFH if you want to leave yourself the option of a heat pump in the future but make sure the pipe spacing is tight enough to support a low flow temp system (heat pump). You can't re-lay the UFH later. If the pipes are spaced at like 300mm centres you can forget running the UFH with low flow temps!