Heat Pumps - post here.

Curious Geroge

Wegian wrote: »

In what way is this incorrect?
The vendor assures me that no boost is required to heat DHW above 60 degrees.

Well, thats the furthest thing from the truth. Ask HPI to put it in writing !!

Or have a read here http://heating.danfoss.com/pcmpdf/danfoss_total_user_vugfe202_en.pdf

"To prevent the build up of bacteria in the water tank, the temperature of the water is increased at regular intervals using the integrated electrical heater (anti-legionella function). The factory-set time interval is seven days (can be adjusted). When the anti-legionella function is active, the heat pump produces hot water until the temperature for the start temperature sensor (5) has reached 60°C."

Or sign your looking at the AQ

http://www.heatpumpsireland.com/files/Danfoss_DHP-AQ_User%20Manual.pdf

"the water in the water heater is given extra heat by the integrated immersion heater to prevent the build up of bacteria, an anti-legionella function"

Now; start again and question every thing you were told to date and get it all in writing.

Wegian

froshtyv wrote: »

Generally speaking a house with HRV proposed is near impossible to pass with a heat pump on its own.

I hadnt bargained for this - I would have expected an expensive unit like a Heat Pump to achive part L compliance.
My Provisional BER has the Danfoss and MHRV in the report and it meets Part L with an A2 rating.

(Health Warning / Get-out Clause: There are inconsistencies in the way the report reads which I need to clarify with BER assessor)

sydthebeat

In my experience only heat pumps that are in excess of 500% spf have any hope of reaching part l compliance on their own. Most systems need at least one other bolt on technology such as pv cells

Wegian

sydthebeat wrote: »

In my experience only heat pumps that are in excess of 500% spf have any hope of reaching part l compliance on their own. Most systems need at least one other bolt on technology such as pv cells

Would a log burning stove do the trick?

Curious Geroge

Wegian wrote: »

Would a log burning stove do the trick?

Sorry Wegian but you need to go back to your BER accessor here. There is no way an A2W with a MHRV would pass Part L.

What model MHRV are you going with ?

For an A2 rating, what is the general spec of the house re cavity, insulation, roof, lined internally, makeup of the floor ?

Wegian

Curious Geroge wrote: »

Sorry Wegian but you need to go back to your BER accessor here. There is no way an A2W with a MHRV would pass Part L.

What model MHRV are you going with ?

For an A2 rating, what is the general spec of the house re cavity, insulation, roof, lined internally, makeup of the floor ?

Now that I have double checked the Axco MVHR C Range is included in the BER but not included in the Part L spec analysis so you are right, I need to revert to my BER Assessor.
House Spec - 150mm in floor, 150mm bead in cavity and 400mm in the attic.

Actually I need to double think selecting a Heat Pump at all now if it doesnt satisfy the Part L - is it worth the investment on its own merits?

FiOT

Curious Geroge wrote: »

Sorry Wegian but you need to go back to your BER accessor here. There is no way an A2W with a MHRV would pass Part L.

What model MHRV are you going with ?

For an A2 rating, what is the general spec of the house re cavity, insulation, roof, lined internally, makeup of the floor ?

Hi All,

Reading these new messages with interest (and slight panic)

We plan to go with a thermia heat pump and wood burning stove to achieve Part L conformance. Our Part L document from our BER assessor says we have 10.17 kwh/m2/y renewable contribution which passes with the regulations. He has included MHRV in the document too so I assume he has taken this into account? How does the MHRV bring down your renewable contribution?

Sorry, I don't fully understand all of this yet - still learning ahead of starting to build next March.

froshtyv

Wegian wrote: »

I hadnt bargained for this - I would have expected an expensive unit like a Heat Pump to achive part L compliance.
My Provisional BER has the Danfoss and MHRV in the report and it meets Part L with an A2 rating.

(Health Warning / Get-out Clause: There are inconsistencies in the way the report reads which I need to clarify with BER assessor)

If you look at the hot water efficiency adjustment factor in the report, and if 0.7 or 0.75 has been used then this is incorrect. It will be the BER assessor that will be pulled up on this if he is audited. Im not sure where that leaves you with regards the council if your house fails on Part L.

ecowise

FiOT wrote: »

Hi All,

Reading these new messages with interest (and slight panic)

We plan to go with a thermia heat pump and wood burning stove to achieve Part L conformance. Our Part L document from our BER assessor says we have 10.17 kwh/m2/y renewable contribution which passes with the regulations. He has included MHRV in the document too so I assume he has taken this into account? How does the MHRV bring down your renewable contribution?

Sorry, I don't fully understand all of this yet - still learning ahead of starting to build next March.

Since you have not built yet why not build to PassivHaus standard and avoid the need for a central heating system? The MHRV alone would then be enough but you could include a woodstove for extra insurance and atmosphere.

BryanF

ecowise wrote: »

Since you have not built yet why not build to PassivHaus standard and avoid the need for a central heating system? The MHRV alone would then be enough but you could include a woodstove for extra insurance and atmosphere.

Are you a passive house designer?
I'm an Advocate for he passive standard, but there are no absolutes, and this post is misleading.
A passive house will still require some heating, albeit much lower than an equivalent A rated house ( op, this is mainly to do with build quality/certified products, orientation/solar gain, attention to thermal bridging and air-tightness,)

ecowise

BryanF wrote: »

Are you a passive house designer?
I'm an Advocate for he passive standard, but there are no absolutes, and this post is misleading.
A passive house will still require some heating, albeit much lower than an equivalent A rated house ( op, this is mainly to do with build quality/certified products, orientation/solar gain, attention to thermal bridging and air-tightness,)

Apologies for not being clearer in my post, I assumed the architect/designer would spell things out in more detail. One advantage of the PassivHaus approach is that a dedicated & expensive central heating system is not necessary. This makes more capital available for the building's fabric especially glazing, insulation, airtightness and detailing to avoid thermal bridging. This is what I meant by saying a central heating system would not be needed but I agree that supplementary heating is necessary in most cases. This can be provided typically by a 1kW heating element in the MHRV but the actual size depends on the building's thermal load metrics. Although somewhat frowned upon by some purists the wood stove (or pellet if convenience is an issue) can also be used for this or in addition to it. The MHRV can move the heat around to other parts of the house from a point source like a wood stove if it is not centrally located to distribute heat by natural convection alone. A stove also adds a cosy factor that most people appreciate. In any event the PassivHaus approach has a lot to recommend it and should be the national standard for dwellings and office buildings in my opinion but that is another debate! Therefore I also believe that anyone building a house at this moment in time should aim to reach or exceed the PH standard and it need not have a significant cost implication.

THE DON FANUCCI

FiOT wrote: »

Not a expert but here's my experience!

We were in the same position as yourself in deciding, there really are so many options. We spoke with lots of different companies about lots of different options.

We got our provisional BER done so we knew the heat demand of our new build first and this helped companies to accurately determine what type/spec heat pump we would need. We kind of felt in the end when we got all of our information that geothermal wasn't worth the extra money upfront. Due to the low heat demand of our build, we'd be a long time seeing the money back - if ever! One of the companies told us that the savings in heating bills with geothermal over air to water would only be about 70/80e a year. Obviously, that may not be right and motives may be questioned with that info but from my own research, they seem to be not far off the mark!

I suppose a question I would have is how you know you need a 10kw heat pump before you've decided which one you're going for? The size of your heat pump surely varies from system to system, house to house. Again, I could be wrong!

One thing about air to water heat pumps too that I found was that some models achieve the Part L compliance on their own whereas some require extra renewables too (PV or Solar) to meet the regs. The one we went with will achieve the regs on it's own so no need for anything else which is fab - one less moving part in the process!

Talk to companies and see what they're offering and I can't stress enough how important it is to go with a reputable company, I have read horror stories on here.

Best of luck!

Hi Fiot can you PM me details of your heat pump type? are you happy with it? does it make loud noise? -thnaks for your help

MENACE2010

Hi

@ Don , Question does not really stack up.
Air Source heatpumps do make noise , actually the noise could increase with the drop of outside temperature correct placement is key .
We have a airsource heatpump and after the third winter I think i have the settings right. in other words the house is comfortable with a drop on cost on the electrical bills (also global warming was a great help ) .
Our swedish pump fulfilled the part L. I did not consider solar ( water of PV at this point ) i have made arrangements for retro fit .. eg cable ducts etc if there is a change needed/

Wegian

Menace,

Would you share Pump model and running costs pls?

You can send by PM if you would prefer!!

Thanks

THE DON FANUCCI

Is there big Tanks taking over the utility room with all air to water heat pumps?

ecowise

THE DON FANUCCI wrote: »

Is there big Tanks taking over the utility room with all air to water heat pumps?

From a Fraunhofer Institute report on heat pumps:

"Air source heat pumps using reverse cycle defrosting are usually equipped with buffer storage. Furthermore, buffer storage ensures the minimum flow rate which the heat pump requires."

buffer storage = tank/cylinder

Interestingly they also conclude that generally direct heating systems (i.e. no buffer tank) are usually more efficient in absolute terms but I guess the operational benefits of a buffer tank outweigh a reduction in efficiency (SPF reduced from 2.9 to 2.7 approx. in their study under German climatic conditions).

Theimprover

I got a quote for the following, its a 2700sqft house.

Daikin 11kW Split System complete with Integrated 260ltr cylinder €8290 ex

Brink Renovent 400 1 unit, Ducting Components
Installation & Commissioning €4,970 ex

Underfloor Heating 148 2m €3256 ex

Can also get Panasonic Aquarea Air to Water Heat Pump Split System 12kw supply only for €4400

Would this be a reasonable price? Would anyone have some links that they could send to me to buy online?

murphaph

How did you size the heat pump you need?

Heat pumps are funny, bigger is most definitely not better (google heat pump cycling)

Theimprover

murphaph wrote: »

How did you size the heat pump you need?

Heat pumps are funny, bigger is most definitely not better (google heat pump cycling)

A supplier quoted me after I gave them my plans.

murphaph

I'm not being funny but you should be very careful here and ensure that your system is actually designed and laid out according to your needs and the physical properties of your new house. Even here in Germany where things are supposedly "done right", you have to double check what's being said to you (and especially what's being sold to you!)

-Do you have any idea of the total heat demand for the property? (in the UK and here in Germany, an analysis according to EN 12831 is required for a new build like this to determine the heat demand for each individual room and for the building as a whole.

You must understand, that without knowing the heat demand of each room, it's not possible to lay out the heating circuits correctly (the spacing, the length of pipe, the diameter of pipe etc.) and you will end up with rooms (especially the bathroom) where you can't get it up to desired temperature on the coldest days. Bathrooms are particularly problematic because they have the highest heat demand (you're typically wet and naked in them) and at the same time have less space in which to lay the pipe as shower trays and baths are usually not piped under (though you can and often should!).

Once you've correctly calculated the heat demand for each room, you can calculate the overall demand and with it the heat pump you'll actually need to achieve that heat demand on the coldest days before the heat pump's immersion heater kicks in (something you'll want to avoid, but NOT at the cost of hugely over sizing the heat pump as you then have another problem: heat pump cycling, when the heat pump is so powerful it can very quickly satisfy the heat demand of a building and shuts off soon after coming on, then the process begins again and again and this costs a fortune in electricity as the most energy intensive part of running a heat pump is starting the motor up. Once it's running it is very efficient. Cycling also reduces overall life of the compressor. A heat pump's compressor will only do x thousand cycles before packing it in.

Have your suppliers mentioned heat demand or the design or spacing of the heating circuits? If not, I'd want to know why not. have they mentioned the flow temperature of the system? You can compensate a badly installed system by jacking up the flow temp to a point where the heat pump is operating totally inefficiently. This often happens.

If you don't invest the time now to understand how heat pumps work (not the deep technical details) in conjunction with a low temperature surface heating system like UFH then you will likely end up with a second rate system that costs far more to run than it should and can never be economically recitifed as once the pipes get buried in the screed, that's usually it.

Have you a secondary heat supply planned at all? Log burner or something? That changes the dynamic if you are prepared to use such a heat source to support the heat pump on very cold days.

First and foremost, make sure your insulation and airtightness is up to scratch. Money invested here is the best spent money of all.

Theimprover

Thanks for the reply, we are trying to achieve a passive house. My architect has made contact with someone that we will be meeting next week who is going to fill is in on all the needs that we will need to do to achieve this.

Very interesting read here http://passivehouseplus.ie/magazine/upgrade/ireland-s-first-fully-passive-retrofit.html

MOTM

Methodology for heat pumps in DEAP now updated. http://www.seai.ie/Your_Building/BER/BER_FAQ/FAQ_DEAP/Energy_Requirements/How-do-I-assess-heat-pumps-in-DEAP-.html

RMDrive

We have a horizontal collector covering a large part of our site and it has worked really well over the last 8 years. Last year I planted some tress and shrubs over the area as I was sick and tired of cutting the grass. I've since been told that this isn't smart as over time the roots could damage the collection pipes.

So ... are all tress and shrubs a no-no over the collection area? Which ones are ok? Are there other down-sides of planting, such as reduced efficiency or anything?

Any advice appreciated.

murphaph

Hmmm, a passive house of that size shouldn't require an 11kW heat pump or anywhere near it. We are building a 212m² house the moment here in Germany and we are not trying to, nor will we achieve a passive house standard and even for our build, the 11kW unit the house builder recommends is very questionable. The 9kW unit below would likely be fine AND the outside temps get much lower here than anywhere in Ireland.

Theimprover

I will have a lot more info on what will be required in the next week or so, I'd imagine we wont really need much of a heating system if we are to achieve passive.

ecowise

RMDrive wrote: »

We have a horizontal collector covering a large part of our site and it has worked really well over the last 8 years. Last year I planted some tress and shrubs over the area as I was sick and tired of cutting the grass. I've since been told that this isn't smart as over time the roots could damage the collection pipes.

So ... are all tress and shrubs a no-no over the collection area? Which ones are ok? Are there other down-sides of planting, such as reduced efficiency or anything?

I understand your frustration with grass cutting! However planting trees over the collector field is not recommended. Tree roots can penetrate deeper than horizontal collector depth (actual depth can vary a lot depending on tree type & growing conditions) but trees with strong tap root systems such as oak, sweet chestnut & walnut are particularly likely to go deep. This takes years, perhaps decades, and maybe you will have a different heating system by then! Another thought that occurs relates to efficiency. Tree root systems will tend to make the soil drier and thereby reduces its thermal conductivity and therefore collector efficiency. This could be especially problematic if you use your HP in summer even if only for hot water. There would also be a reduction in direct solar gain by the ground due to shading by the trees. Just some thoughts but you can still choose if you wish to leave the trees and not have to cut that grass!

RMDrive

ecowise wrote: »

I understand your frustration with grass cutting! However planting trees over the collector field is not recommended. Tree roots can penetrate deeper than horizontal collector depth (actual depth can vary a lot depending on tree type & growing conditions) but trees with strong tap root systems such as oak, sweet chestnut & walnut are particularly likely to go deep. This takes years, perhaps decades, and maybe you will have a different heating system by then! Another thought that occurs relates to efficiency. Tree root systems will tend to make the soil drier and thereby reduces its thermal conductivity and therefore collector efficiency. This could be especially problematic if you use your HP in summer even if only for hot water. There would also be a reduction in direct solar gain by the ground due to shading by the trees. Just some thoughts but you can still choose if you wish to leave the trees and not have to cut that grass!

Thanks a million for the reply. I think I'm resigned to getting to of the trees, however I'm wondering if the shrubs would be ok?

Although your points about water content and solar gain should maybe make me think about taking up the whole lot :eek:

ecowise

Although less of a problem than trees personally I would not plant shrubs either but it is not a black and white situation. If you are getting significant benefit from the shrubs then it is understandable that you might choose to keep them. You might check the shrub varieties that you have in the unlikely event that they have particularly deep roots.

hellsbells83

Hi

We're about to start a house build and we are deciding on heating system. We are interested in air to water heat pump with under floor heating. Just wondering if anyone has any experience with this system. I've read really mixed reviews some that it's really expensive to run and others that it's efficient. I think I've established that it is much more expensive with rads, not suited to that really.

My main concern is that it has to be on all the time from October. I know the pump isn't running constant there would be thermostat that would mean pump would only be on when drops below certain temperature. We both work so won't be home during the day. So essentially the house will be heated even though no one is there.

We were going to get the house a well insulated as possible, good Windows, heat recovery system and air tightness. So I'd hope we wouldn't need heat much, so in that case air to water heat pump seems like a massive investment where we could put oil system I Just to have for cold weather where required.

Anyone any experience with air to water heat pump or any feedback

BarneyMc

I have a query regarding A2W HPs and dual tariff meters here. Can someone please advise? Thank!