New Build, 7 months in with a Danfoss heatpump

@Ray Donovan
Good to hear you didnt let old fashioned ne sayers put you off either.
One thing i would advise, like yours my house was designed with two chimneys. When we purchased, and had decided on heating source, i took the chimney down in a room with it on an external wall. We left one in the living room, it was an internal wall and left an air supply, and with the idea being we would like the look and feel of a fire of winter. Was one of the first things we picked aswel was a wood burning stove but as we moved in May, we decided it could hold off until end of summer to go in. One thing led to another and none was ever installed. We are thinking now of going down the route of maybe an electric stove just for the look as we struggle to see when we would ever light it with the heat we have. Both chimney are air intake are sealed up and is looking like they might stay that way.

@Robert Allen
Best of luck with your build and try and enjoy! If you are like me you will be secretly loving the whole process and be quite disappointed when it is all done!
I am happy to send on the contact info for the Heat pump guy i used and the supplier of the mhrv system bits who gave me a great deal as i picked up equipment from his warehouse myself!! Where are you based?
Pretty sure i contacted most of the heat pump installers in Ireland, several in NI and even a few in UK during my search and have all the quotes about the office somewhere. To give you an idea of what you have to look forward too, my calculations pointed to an 8KW heat pump. I have quotes there stating i need to use a 16KW heat pump. I have quotes from 16k to 37k. Price was not ever the deciding factor but im sure you will find it heart warming to know that the guy i used was second cheapest!! And the only guy who didnt fall under my questioning!!
Regarding the mhrv, again i contacted as many as i could find. I found one guy down the country, cant remember his name, only one who could stand to any questions but his price was about 3 times what i could buy materials for. Everyone else who i spoke to and quoted where a shambles. Ask about flow rates, cfm, cross talk etc and none had an idea. The material supplier i used was very good and answered loads of my questions and i did all the spec and installing myself. Is good documentation out there about best practices, and i used the uk building regs as the base for all my calculations. I still have to get a vaneometer and balance each room but that is just fine tuning.

@sparks3000
No problem, i work at home average 4 days a week, misses works here 3 days a week and we aint the most efficient with alot of gadgets, media server etc running ha.
Period Cost Units
10-Mar-13-Apr €103.65 295
13-Apr-14-Jun €179.26 961
14-Jun-17-Aug €162.18 839
17-Aug-12-Oct €168.12 884
12-Oct-09-Dec €191.07 1031

We moved in at end of May, so all before that was drying out, work being done etc.

@rolion
We went with geothermal and borehole. Personally i felt for the slight extra premium i was getting a more tested technology, was slightly more efficient, more proven over a lifetime and easier to manage.
We have no access to natural gas and consumer gas would not have a patch on geo. Even if i did have access to natural gas, i would have serious reservations and i would guess that heat pump would still prove to be more cost effective over its lifetime.
A big attraction to the heat pump is also the idea of being totally energy dependent at some stage. I researched PV panels etc but i just couldnt make the numbers work. I am hoping that more items like tesla powerwall come where i would shift to night rate and use the powerwall be my source for daytime power. I have no doubt that PV will come down in price and within the next 5 years or so it may be an investment i will be making.

Hi zulutango,

1:My site is covered in old trees so the idea of having to dig that up to lay pipework was never that appealing. Given that vertical borehole are proven to be more efficient and the cost to dig around trees etc, we went with borehole. Was 3850e. The supply, fitting and commission of heatpump and underfloor was 16.5k.
The quotes i got for an oil boiler, oil tank, boiler stove, stove box, all associated rads, pumps, valves etc. all supplied and fitted with first fill of oil was around 15k.

2: Yes, underfloor to whole house. It is essential for this type of system. I labored to the installer for two days to do the whole house. A simple process. I would imagine for the small amount of euros people save by using alu rads upstairs only for example, would be offset by the higher running costs or more unstable temps.

3: No problem. As i was the first new house the insulation installer completed with the cavity insulation, part of the deal was that the house would be air pressure tested (at his expense) before final payment to confirm its results. The magic number agreed upon was 3m3/hm2 which i thought was ambitious ha. The test was done with no internal plaster or floor, no tape on windows, a big sponge up the chimney, and a few crudely placed pieces of plastic under external doors. The result came in at 5.1 which i was quietly impressed with given the level of "sealing" at the above areas. We shook hands on me buying the materials to tape all windows and doors out of final payment and i did the work myself. As to what it is at now after tape, plaster, floors etc. i would guess maybe 3 but really have no idea. I am happy enough it is to the level that i am getting good use and need for the mhrv so i am happy enough. And given the fact we see literally no bugs in the house i am assuming it is fairly well sealed.

Hi zulutango,

4: We have used concrete slabs at first floor level so we had no issues with anything structural. I went with 130mm insulation on ground (made up of a 70mm + 60mm) and a 70mm screed. Upstairs was 60mm insulation with 70mm screed. I was 50/50 about using insulation upstairs but we used a solid slab which would soak up plenty of heat and kept the "insulation will pay for itself" moto in my head! I have read of people who have used a thin screed or "in-joist" system on timber constructed first floors but we wanted to go slab for noise etc. so i didn't look much into it.

5: My downstairs wall uvalue would be made of skim, scratch, 100mm block, 60mm foil back board, 40mm icynene, blcok, plaster. Upstairs be same except no foil back and 100mm icynene. Im sure somebody smarter than me could figure that out. Woindows are munster joinery passive, somewhere around 0.6/0.7.

As far as doing it well, i set out to achieve as good of results for what my budget allowed. My budget by no means was big either, and my current unfinished house reflects that but to me it is more important to do things right and let the rest come as it does. The way i seen it my time was free so i did as much research as i could. My personal experience is that the vast majority of tradesmen in this country have no interest in evolving, make things as easy as they can for themselves and take no pride that they are involved in building somebody's home. As such i used as little tradesmen as i physically could, and the ones i picked met my specific needs. As far as shops and retailers, building, plumbing, electrical merchants etc., very early on in the project i realized that if didnt undertake all research and find what was best for myself, then i would be subject to their advice, which 99% of the time is rubbish. I live in a town with 2 large builders merchants. I ended up only working with one man out of around 30 staff between the two places. I have since found out he self built, so no surprise there. Also, the prices can be crazy. I priced a local glass company to make a shower panel, i got a custom made panel, a toilet and a set of taps from a supplier in another country for the price they quoted me for the panel alone!

Hi Water John,

Yeah i agree the smaller heat demand of highly insulated houses means there is less difference. However i still find the ufh to be the most efficient and the alu rads are purely a cost saving exercise. It was worth more to me to sacrifice other areas of the build.
And yes i would imagine that using ufh on joist construction could be costly but it is an option. We were sold on slabs for several reasons, noise, having block walls upstairs, walk in showers etc. and the fact we could use ufh, was a no brainer for our needs.

BarneyMc wrote: »

Can I ask what temperature is your UFH water (leaving the HP) set to?

Hi Barney,

That is actually something i have being meaning to do now for some time is plot the heat curve to determine that. I haven't played much with any of the settings as it has worked so well out of the box. But i do want to get a better understanding of the process so as i say it is something i intend to start recording.

Just checked the machine and is reading the following setings for the curve;
Heat Curve = 29 deg
Min = 15 deg
Max = 55 deg

I don't have any of the adjustments set and heat stop is 17 deg.

Temperatures read;
Outdoor = 5 deg
Supply line = 27(30) deg
Return line = 26(55) deg
Hot water = 51 deg
Integral = -6
Brine In = 6 deg
Brine Out = 6 deg

With the supply and return so close, naturally the machine is not on at present. I don't know what the numbers in the brackets represent so if anyone could shed any light on that, would be much appreciated.

Kind regards
Shaun

BarneyMc wrote: »

Thanks John. I have an A2W HP and 55mm liquid screed floors but solid 6 inch block walls. The house retains the heat really well albeit not in the floor. Does the 37C water temp seem a bit high? I would like a slow gradual heat up of the house during the night and a low water temp is my guess to a longer compressor life and better running costs.

Hi again Barney,

Do you mind if i ask what way you are running your machine? I assume when you say "a slow gradual heat up of the house during the night" that you are running a on-off approach? How do you find it?

I was tempted by this but couldn't find any documentation of someone who had tried both ways to see how much, if anything, could be saved. And with being at home during the day i didn't want to be in a position of a possible temp drop and having to wait until evening/night to bring it back up. Be very interested to hear others experience with it though.

murphaph wrote: »

Personally I think room stats with UFH are largely a complete waste as the reaction time is so slow. You turn the stat down and it closes the valve to that room but the result is felt hours later as the slab has so much latent energy. Worse in the morning when you get up and turn the stat up you'll be out and gone to work and having your lunch before the room is up to the temp you wanted. You could factor in an offset I suppose once you figure out the reaction time but this is not the path I've chosen to go down. Each to his own however.

I honestly think you need to set the temps you are happy with (preferably hydraulically by balancing the system rather than closing off the flow to a room periodically as happens with room stats) and then control the entire house with the heat curve.

At the end of the day the slow response time of UFH is the main (only?) disadvantage of the system compared to high flow temp boilers and rads which respond very quickly to demand. I would still choose UFH over boiler + rads any day though. The even heat it delivers is phenomenal. I'm constantly amazed that when I come into the house it feels toasty warm but I cannot tell where the heat is coming from. The floor is not even luke warm to the touch.

We achieved a "natural set back" in the bedrooms by installing carpet there. It obviously acts against the UFH and insulates it more than the rest of the house (tiles) so I didn't need to do anything there.

I agreed with you originally but i am glad that i didnt go that route. The stats just give enough control to have the bedrooms slightly cooler than the main areas. And it is very possible that this just happens to be during the night and by the time i get up in the morning, the whole house has become balanced and the stats are redundant. But to have it cooler just when going to bed and getting to sleep then it is worth it for me. Given how warm my wife likes the main areas of the house, i am glad we have this control. If i built the house as a single man, would have being one zone and no stats. O what a life i could have had!!!!

Great to hear also you have used carpet and dont find any real notice other than slower reaction. Did you got for one with a low TOG or was that a factor? We have went with laminate floors over tiles in most areas as was a bit scared of carpet having an impact but the stairs are to be carpeted and i always hated the idea of carpet stairs meeting laminate on the landing so maybe it may be a solution to carpet the landing also. As you say, the carpet slows the heat but to my understanding it doesnt use the heat if that makes sense, so yes you need to generate more heat to come through the carpet but it will eventually all end up coming through the carpet or back into the floor so isnt like its wasted as such!