Ämne: Air to air heat pump: what to choose and consumption

[mcbota]

Hello!
 Happy blessed Christmas to all of you!
 I am from Romania, having a house where I have installed underfloor electric heating. The house is not yet finished , but I live there; only the exterior is  not painted ( I have  10 cm of polystyrene insulation over a 38 cm brick wall); the electric underfloor heating system works good enough, but I think with not enough heat in the rooms to heat the walls substantial and so keep the warm for a long period. I compare this system with my fireplace which I have in living room and I can see that the walls there keep the heat much better being heated with woods. I have read about air to air heat pump efficiency, and I am thinking  at this system. The house is about 160 sqm on 2 floors, almost equal divided. Please tell me if this system can be much cheaper than the one that I have? Which is the best solution for such a system to choose and  please tell me if you consider is a good choice and is worthy to make an upgrade to my heating system! What consumption can have at such an air to air heat pump for my house considering that the average outside temperature during the winter is around - 5 degrees Celsius!
  Thanks for answering and me
   All the best,

[Carl N]

It is usully to assume that an air/air heat pump needs less than half as much energy as direct electricity, maybe one third if the climate and the house plan is beneficial. It can be combined with electric floor heating as comfort heating, but more comfort will of course cost a little more.

[mcbota]

What I am not sure it is the fact of running cost and especially because of the house which has 2 floors. Do I need two small air to air heat pumps or one with 2 indoor units? What kind of heat I will feel: radiant heat . or just warm the air or also the objects? Has anyone an example of consumption at different outside temperature and indoor , for a house?
P.S
  Sorry for so many questions and sorry because I dont know swedish language

[TUCSONOR]

A bit warmer climate were you lieve. http://www.yr.no/place/Romania/Bucuresti/Bucharest~683506/statistics.html
With "only" 10 cm insulation, 160 m2 and -5 ºC you are pretty close to the need for heat as scandinavian standard insulated house. How is you window? Modern well insulated? how much insulation in the roof?
I pressume you house will need approx 200W/ ºC difference in/out. So , when having -5 ºC and 22 ºC, you are in need of 4.4kW, minus the heat from light, fridge etc.
If you got a pretty open house, one pump like MB FD25 VABH in first floor would be enough. But for improved comfort you could buy two smaller pumps, for instance cheap selfmountig split on/off Zibro pumps. www.zibro.com

[mcbota]

Thanks Tucsonor for the answers!
  The windows are triple glazed and the roof is a flat one with 10 cm insulation of polystyrene high density! My options are the same as yours but I am not sure if the performance/quality of Zimbro are good enough. Can you estimate a consumption for my house at 22degrees inside and lets say -5 outside.?

[TUCSONOR]

Thanks Tucsonor for the answers!
  The windows are triple glazed and the roof is a flat one with 10 cm insulation of polystyrene high density! My options are the same as yours but I am not sure if the performance/quality of Zimbro are good enough. Can you estimate a consumption for my house at 22degrees inside and lets say -5 outside.?

If my estimate is correct for your house (Never seen it ) you are in need of 5.4kW at -5 ºC. An average heatpump got approx a COP round 2.5 at -5, so your consumption would then be 5,4/2,5= 2,2kW.
Two Zibro SC1332 would give you the heat needed.
If you are a "handy man", you can easy tweak the cheap pumps performance so they became better, as for instance this norwegian guy have done: http://www.byggebolig.no/index.php/topic,34566.0.html

[mcbota]

The house is not so opened; I have tried to attach a picture but is bigger than 400 kb; however if this or around this will be the consumption, will be very nice. I will look better at that Zibro SC 1332 and see if is good enough and I will manage to buy two from Sweden or Norway, at a good price, because here are not very popular.

[mcbota]

What I dont know exactly is why on some details is written that Zibro is air conditioning and on other that it is heat pump? ( and this is available for other brands too) Here are the attachments of my 2 floors house! Do you think is enough one or do I need two heat pumps to be efficient?

[styrman]

Hi

I would believe that 2 completely separate units will turn out to be cheaper than 1 with two indoor uni
Check this out: http://www.comfortableclimates.co.uk/

I would also suggest extra insulation to the roof....
Maybe extra 20cm with cellulosa fiber 

Good luck

Robert

[mcbota]

Because I have a flat roof and I have already made an 10 cm insulation with polystyrene high density and put the insulation against water, I was thinking to make an extra insulation of the roof but the only possibility is to make on the inside part of the roof, in the rooms. So I am still thinking to the best solution, to not make too many changes and disturb the paint and everything  that is OK in the rooms. Thanks for the advices and for the link, Robert! I saw also MB FD 25 VABH and MB FD 25 VA, the first being the nordic option and the second saying that is only an air conditioning. Which are the difference and performance, between such products, generally speaking?

[mcbota]

http://www.eclimatizare.ro/catalog/split-de-perete-140029
From this products , available in Romania, do you consider that any of its are good as performance and quality for heating my house with a confortable temperature. running costs?

[TUCSONOR]

http://www.eclimatizare.ro/catalog/split-de-perete-140029
From this products , available in Romania, do you consider that any of its are good as performance and quality for heating my house with a confortable temperature. running costs?

All of them will do. Out of the prices, I would recommend getting two of these: http://www.eclimatizare.ro/cumpara/sistem-mitsubishi-msz-fd-25va-muz-fd-25-va-1261451 instead of cheaper ZIBRO that do not have the electronic expantion valve. Note, the cheaper MB pumps then the model FD25 might have capilar expation valve, so no better then the ZIBRO. You will be very happy with the FD25, and I believe it will give you good payback as you probebly have many days with between 0 to 10 ºC were you need heating, and the FD25 have very good COP in that range.



 

[mcbota]

I will appreciate you forever if you said that just one is enough!!!!! I understand that I need two, to have the best performance. Is there any difference between this one and the nordic FD 25 VABH? Do you think that two of these will be the best solution and best effciency? Many thanks for all your and advices!

[TUCSONOR]

I will appreciate you forever if you said that just one is enough!!!!! I understand that I need two, to have the best performance. Is there any difference between this one and the nordic FD 25 VABH? Do you think that two of these will be the best solution and best effciency? Many thanks for all your and advices!

You should manage with one, but for the comfort two is recommended. There is long discussions on this forum for what is the differences. The VABH modell have better defrost (more secure defrost) then the VA, and higher output on lover temperatures then -5.
If I were you I would installed one FD25VA in the first floor, and seen what happened the firts winter. The payback for one more will be some better comfort, and very little in the total cost as I believe one pump will cover 80% of your need.
Use the search on the forum, there is a lot about how to improve the FDVA25 for defrost if you experience build up of ice. Good luck.

[mcbota]

Where I can find the exact covered surface sqm for heating, for MB FD 25 VA , because some as polarpumpen, gives up to 160 and others give only 35 sqm?  Thanks !