Air source heat pump and HRV systems

[JPF]

Hi all..

Has anyone experience of using a air source heat pump in conjunction with a heat recovery and ventilation system? I was wondering about using the exhaust of the HRV system to be the inlet for the air source heat pump. Is this madness, is it a workable system?

Cheers

JPF

[VikingHouse]

You can get both systems combined with this unit from Nibe http://www.nibe.com/heating/produkter/fvp/funktion.htm
I was considering using it with the Supply Air windows mentioned in the windows thread.

[babybuilder]

I was thinking of putting in a HRV unit but having looked at the micro heat pump from Ochsner(www.ochsner.com) I have second thoughts on this. HRV manufactures claim up to 95% efficiencies but I really doubt that this is the case. The combined micro heat pumps claim COPs of up to 6. Also, these heat pumps use the exhaust air to heat domestic hot water but unlike HRVs they allow for fresh air to enter the house through normal wall vents.
Anyone any opinions on the merits of these systems i.e NIBE's and Ochsner's?

[JPF]

Hi Babybuilder.

Are these Ochsner units very expensive by any chance??

JPF

[babybuilder]

I think around €3000 for a micro heat pump which heats water from exhaust air. Maybe VAT aswell. I,m meeting a rep on friday so I'll post an update maybe saturday 10th

[chavis]

Hi all..

Has anyone experience of using a air source heat pump (http://www.techstore.ie/Renewable-Energy/Heat-Pumps/Air-souce-Heat-Pumps.htm) in conjunction with a heat recovery and ventilation system? I was wondering about using the exhaust of the HRV system to be the inlet for the air source heat pump. Is this madness, is it a workable system?

Cheers

JPF
hi,
The most common type of heat pumps is the air-source heat pump, which transfers heat between your house and the outside air.

If you heat with electricity, a heat pump can trim the amount of electricity you use for heating by as much as 30%–40%.
High-efficiency heat pumps also dehumidify better than standard
central air conditioners, resulting in less energy usage and more cooling comfort in summer months. Even cold air is full of energy and air source heat pumps use the freely available heat in the ambient
air to provide efficient heating at air temperatures as low as -20°C.

[TKCE]

My understanding is that with a balanced whole house mechanical ventilation (with heat recovery) system, you cannot regulate the temperature in the individual rooms or even set up 2 zoned areas, i.e. living and bedroom zones. I was toying with the idea of using an additional heat source to boost the temperature of the incoming air over and above the temp. achieved with the heat recovery unit. I dismissed the idea on the basis that at 10pm on a winters night we would want 20 degrees in the livingroom, but 20 degrees would be too hot for the kids to sleep.

If any poster does know a system that allows different heating zones they might be so kind as to post. Any of the manufacturers that I spoke to were not enthused at the idea of addition heating into their systems.

[heinbloed]

To TKCE:
A ventilation system should be adjustable. So different demands of air quality can be chosen.
For example the PHPP (passive house planning package) demands the adjustment of each individual air outlet and inlet by competent staff. And a test report from the installer.
Most HRVs have some settings planned for: background ventilation in case no one is at home for a longer period, standard ventilation working in the modus to which it was adjusted by the installer and "full" in case someone has forgotten an open can of fish.

The ratio of removing/replacing the amount of air per room can be adjusted as well, for example two rooms could 'communicate'. Like room A.) receives 100l/minute fresh pre-warmed air and delivers at the same time 200l/minute whilest room B.) receives 200l/min via the inlet but delivers only 100l/min to the room's outlet.
This type of setting is frequently used to couple extreme loads, like for example bedroom+ensuite.

Since only a fraction of the energy contained in warm stale air will be recovered by a HRV system there is usually a need to back-up this harvest by an aditional heat source, for example resistance (electric-) heating.

So to follow your sample the average house temperature would be around 19 degrees, meaning 20 degrees Celsius in the heated rooms and 18 degrees Celsius in the "unheated" areas. A competent installer will be capeable to offer many different solutions.

As far as I know ALL manufacturers of heatpumps offer the option to use aditional heating sources. Nearly all HPs are readily equiped to be used in a cascade or in co-firing. The information you received concerning the compatibility of several heating sources with a heatpump is WRONG.
Most HP manufacturers want to sell in the big markets, Germany being the largest market, subsidising HPs .... but they demand a minimum performance, the system's COP. And this SCOP is difficult to be met if not combined with other more greener sources of energy. For example solar thermal power.

[sinnerboy]

This is an innovation to combine solar thermal with HRV

http://www.nutechrenewables.com/products/viewlist.asp?ID=11

As it was explained to me - the solar energy harvested in winter contributes little to providing DHW - but can contribute a lot to pre heating supply air via the HRV unit

Have you seen this before Heinbloed ?

[TKCE]

Heinbloed, thank you for your reply, however I think you misunderstood the last paragraph of my previous post (probably due to my lack of clarity. :)
the manufacturers i was referring to was that of the whole house HRV system, not the heat pump. I spoke to a number and they nearly all followed the line that a HRV system was primarily a ventilation system and their recommendation was that I should not additionally heat the air over and above that provided by heat recovery. This is not my area of expertise and I cannot myself conclusively confirm or dispute these recommendations.

[Quack13]

This is an innovation to combine solar thermal with HRV

http://www.nutechrenewables.com/products/viewlist.asp?ID=11

As it was explained to me - the solar energy harvested in winter contributes little to providing DHW - but can contribute a lot to pre heating supply air via the HRV unit

Have you seen this before Heinbloed ?

This system has also been suggested to me. Sounds very interesting.

I am however a little reluctant to believe that is would look after all my space heating & DHW (when used with stove boiler). It just seems too good to be true.

[www.esavep.com]

Have a look at www.esavep.com for heat recovery and air source heat pumps..they have both working along side each other..

[selfbuilder]

This is an innovation to combine solar thermal with HRV

http://www.nutechrenewables.com/products/viewlist.asp?ID=11

As it was explained to me - the solar energy harvested in winter contributes little to providing DHW - but can contribute a lot to pre heating supply air via the HRV unit

Have you seen this before Heinbloed ?

Hi
I have been planning my build for the past few years and have finally achieved planning on a very sensitive site. I have been gleaning information from this site as a guest up to now in the hope of deciding on a space heating and dhw system that suits my building, the requirements and use of same by its inhabitants, is cheap to install and run and the bonus of hopefully being kind to the environment.
Having read and followed the forum discussions, for me there are two key components to a successful building and living system
1. a very well insulated and airtight building with thermal bridging eliminated and
2. A heating and ventilation system that relies on a resource that is readily available on the island of Ireland and is as carbon neutral as possible. This system should be simple to install, simple to use, have affordable installation costs and the different elements of the system should be capable of being operated from one simple to use panel. It should also be simple and cost effective as regards maintenance and repair as the need arises.

The difficulty is that there are so many divergent views out there. :confused:
I am at a critical stage in that I have to decide on my system in the next fortnight.
I would therefore be very keen to see Heinbloed's response to sinnerboy re the system as promoted by Newtech. This system recently featured in the July August 09 issue of construct Ireland magazine and to me using this system allied with a wodtke pellet stove as a primary heating system could fulfill my criteria as above. I am unsure as to how efficient a small internal pellet boiler would be but one of the users in my build, ie my wife, her preference is for an open fireplace. I am asking her to consider the internal pellet boiler instead. We will probably put a fireplace in our "good room" with a damper system on the chimney.

Is this system feasible and would it work with underfloor heating? Maybe there goes my simplicity:confused:
Slainte

[heinbloed]

Well, first of all the demand for enrgy should be calculated. As well as the demand for ventilation.
Only with this data a reasonable decission can be made, all other aproaches will very likely lead to an unsuitable supply. To big, to small, to noisy,to expensive, to inefficient etc..
Contact an energy advisor, a heating engineer with the detailed drawings and ask for advice.

About the pellets: Most are imported as far as I know.
About the vetilation: Free wind power blowing once or twice per day through the house for a few seconds doesn't cost a penny. Is a freel and local available commodity.
Solarhouses covering 100% of their heating demand usually have no special ventilation system, only doors and windows are used for the purpose.
When looking at the enviroment impact of a device we should concentrate on it's global warming potential.
Solar energy as such has a very high global warming potential, it is it's only cause....
But since the sun shines anyhow, like it or not, we can use it's power without having to worry about aditional bills.
So in principle a demand for energy covered by a renewed source is for free and without impact on the climate.
'Renewable' energy is not the same as 'renewed' energy - mind this misleading formulation/marketing trick of the salesmen!
Forrests are on the decline as well as arable land. Due to dessertification and rising seawater levels. So if some one tells you there is an enviromently friendly AND cheap timber fuel source ask him for the fixed price/kWh of this form of energy incl. VAT and delivery to the front door for the rest of your lifetime.......
Except for the solar power and maybe wind power there is no such guarantee.

An energy advisor will prepare a calculation sheet for you, showing the investment costs plus running cost plus maintenance and recycling costs for an energy managemant device, for example a ventilation system.
And he/she will also do the same for alternative methods so the investment returns can be compared.

Always look at the durability of the investments.
Installing for example a HRV system which might need a replacement every 10 years will leave only 10 years for recouping all costs. In a standard home situation this is hardly the case. Check out how long it takes at min. and at max. to recover the total costs involved.
And then look around who will give a guarantee.....

[selfbuilder]

Thanks Heinbloed for your honest reply and advice. I will do as you suggest and employ a professional to guide me.

[Gearoid1]

when using a hrv unit, it is a good possibility to add in an Ochsner Europa model (mini) in the extract duct before dumping the waste air. this source energy is efficient to supply all of the energy required to Ochsner heat pump for producing hot water. From a couple of projects that i looked at, it meets hot water requirements and more, loading the cylinder to 60'c operating from a cylinder stat when no hot water is required, the waste air from the heat recovery ventilation passes throught the Europa mini and gets dumped in the normal way.

[heinbloed]

What air flowrate would such an installation demand? At what temperature ? As far as I know the direct heatrecovery, heating the cold air coming in via a heat exchanger, allowes for most of the energy to be extracted for a fraction of the price of a heat pump? Delivering energy at peak demand without storage losses.

[YDB]

Hello Gearoid, I have considered the mini in the same way and also considered taking a duct from the heat exchanger off our Kal Fire Heat Pure to it or the HRV. What is interesting about the mini is their brochures show it operating within one room like a utility which would be more cost effective to install.

[galwaytt]

There is a large house in Kinvara heated with that nutech renewables solar-linked HRV system. No rads, no UFH, just that and a wood pellet stove in the sitting room, and it seems to perform well afaik.

The house is on the builder's website, here: http://www.pwc-build4u.com/

btw, no connection with me, or our company - know him as another local company.....

[Gerard2]

Hi all..

Has anyone experience of using a air source heat pump in conjunction with a heat recovery and ventilation system? I was wondering about using the exhaust of the HRV system to be the inlet for the air source heat pump. Is this madness, is it a workable system?

Cheers

JPF

Yes you can use an Ochsner Europa mini very common on the continent destributed in ireland by Ochsner ireland