HRV - Not convinced

bakerlite

Well - Not convinced yet i guess.
Living in my house for 2 years now and I find that the HRV system is just pumping freezing air into the house especially noticeable September on.

Then again its not rocket science I guess -

The unit itself is 85% efficient on paper (I can only presume this does not account for pipe run lengths and insulation quality)

I have two extract points and 6 inlet points.

For the system to be as 'efficient as it can possibly be' the two extracts must pull as much air as the six inlets put in.

Also my bathroom is not particularly warm and one of the extracts obviously is there.

So if its say 18 degrees inside and as it was for much of last winter 4 degrees outside that's a 14 degree difference.

Lets imagine i have the most amazingly well installed system and it is in fact working at 85% efficiency that's an 11.9degree temp exchange so that cool air coming in is now 15.9 degrees.

Theoretically, I guess that's what it should be but there's no way that's happening for me - the air coming in is absolutely freezing.

Its no problem when the stove is on - we have a brute nuclear power plant of a multi fuel stove which is 30kw which puts 8kw to the room and 22kw to the rads - when its on the house is warm and you cant sit within five feet of the stove!

But one hour after the stove dies down, not even one hour its bloody freezing because all that air getting pumped in is cold.

My latest idea is to run another extract from over the stove which looks like it can be done easily - This way the air going to the exchanger will be a hell of ALOT warmer - but I am slow to pump said warm air out of the house into the night sky!!

Sorry if this post lacks direction - Its been on my mind for a good while and i feel a little bummed out that after spending the money on what is considered energy efficient technologies that my house is freezing!!

Any thoughts on HRV at all? I'd be interested to hear others opinions and more importantly experiences.

On the plus side the house is always nice to be in by that I mean the air is always fresh and no condensation.

Thanks for reading

BryanF

sounds like there is something wrong with your MVHR system. have you got the person who designed/installed/commissioned it back in?
also what was your air-tightness test results?

bakerlite

Unfortunately the company who provided the solar, alurads and mhrv went belly up and disappeared.

I would like to get an air tightness test done allright - maybe there is a company who does the air tests and thermal imaging for reasonable costs, I would be VERY interested to see the results!

Mothman

Does the HRV have a summer bypass?

Carlow52

how often were the filters cleaned changed?

Have u looked at the surfaces in the heat exchanger. are they clean?

is the fan speed set at the max 'Occasional high demand' setting?

Have u checked to see if all connections to xchanger are airtight

From an energy point of view if u are not exhausting hot air then u cannot expect much heat exchange.

Close off one exhause and stick a fan heater [ hair dryer] up close near the other one and see how much hot air comes back

bakerlite

Carlow52 wrote: »

From an energy point of view if u are not exhausting hot air then u cannot expect much heat exchange.

Indeed - I fear this is the main problem with how it is set-up at present.

It does have a summer bypass mode but it is fully automated.
Filters changed regularly

I will inspect the chambers and do the fan test tomorrow

thanks!

MicktheMan

pm sent

gear_ie

Could you let us know the make and model of the MVHR?

bakerlite

It's an Orcon hrc 300

beyondpassive

might be worth seeing this thread http://www.boards.ie/vbulletin/showthread.php?t=2056430204&page=2

Do the ducts run in the cold attic, I've seen a few systems installed with only 100mm quilt and foil wrapped around some flexi's.

It worth noting with stoves that the rated power is for slow growth seasoned wood, also look at the burn curve below, they only work at high output and efficiency for a short period.

creedp

Do the ducts run in the cold attic, I've seen a few systems installed with only 100mm quilt and foil wrapped around some flexi's.

Intertested in this statement. Originally my rigid pvc ducts were only covered by that foil wrapping!! but were subsequently also covered by 100mm glasswool. However, I had noticed that the air from the supply vents was also quite cool and have asked the installer to come back and test the fall off in temp between extract and supply. What would you consider an acceptable level of insulation around rigid pipes in a cold attic?

beyondpassive

creedp wrote: »

What would you consider an acceptable level of insulation around rigid pipes in a cold attic?

The Vent pipes should have the same depth of insulation as the cold roof, so 350-400 of cellulose or fibreglass. We have built an osb box above the joists and filled with insulation to maintain the same level of insulation around the distribution pipes as you would have between ambient and room temp

BryanF

bakerlite wrote: »

Unfortunately the company who provided the solar, alurads and mhrv went belly up and disappeared.

I would like to get an air tightness test done allright - maybe there is a company who does the air tests and thermal imaging for reasonable costs, I would be VERY interested to see the results!

interesting:D so your 'not convinced' but yet you didn't get any professional to test the system? and you put up with it for the last two years:o nor did you get an air-tightness test when the building was constructed/unit commissioned..

I wouldn't be 'convinced' its the 'energy efficient technologies' fault;)

its sounds to me like short-cuts were taken from all directions: on the product, specification, installation, commissioning and professional involvement.. this seems like a good example of short-cuts giving a technology a bad rep:eek:

creedp

BryanF wrote: »

interesting:D so your 'not convinced' but yet you didn't get any professional to test the system? and you put up with it for the last two years:o nor did you get an air-tightness test when the building was constructed/unit commissioned..

I wouldn't be 'convinced' its the 'energy efficient technologies' fault;)

its sounds to me like short-cuts were taken from all directions: on the product, specification, installation, commissioning and professional involvement.. this seems like a good example of short-cuts giving a technology a bad rep:eek:

To be fair BryanF, your are a professional in your field and consequently what might seem like absolute common sense to you may not cross the mind of a once-off self builder like the OP or myself. The use of all those little smilies reminds me of the top of the class pupil slagging off the class dunce (no offence intended OP!!) Its all very well to say that everybody should be an expert in everything but thats simply not the case and increasingly so will never be the case with the relentless march of technology innovation. What it does bring into sharp focus is that self-building is an increasingly shark infested waters with so many 'expert' threading water waiting to pounce on unsuspecting self-builders who unfortunatley don't give themselves enough time in the planning phase to properly research their projects. I argued before that the real professioanls should be more overtly selling their wares to ensure that the so called experts cannot continue to get away with installing inappropriate technology inapproriately in once off self-builds.

To the OP I can only say unfortunately you are not alone and refer you to beyondpassive's earlier post which advised that ducts should be covered by between 300 and 400mm of insulation in order to max efficiency of heat recovery unit. After that best to get in a professional ... Q is who might that be??

creedp

beyondpassive wrote: »

The Vent pipes should have the same depth of insulation as the cold roof, so 350-400 of cellulose or fibreglass. We have built an osb box above the joists and filled with insulation to maintain the same level of insulation around the distribution pipes as you would have between ambient and room temp

Thanks for the advice ... bloody hell is all I can say. Im sure BryanF will be getting back on slagging me off over this:). I will have to go back into attic and upgrade the insulation around ducting. The problem I found was that when I was looking at the ducts lacts time was that some were strapped to the rafters making it difficult to wrap with insulation. Another job I didn't supervise or didn't have supervised!

BryanF

creedp wrote: »

To be fair BryanF, your are a professional in your field and consequently what might seem like absolute common sense to you may not cross the mind of a once-off self builder like the OP or myself. The use of all those little smilies reminds me of the top of the class pupil slagging off the class dunce (no offence intended OP!!) Its all very well to say that everybody should be an expert in everything but thats simply not the case and increasingly so will never be the case with the relentless march of technology innovation. What it does bring into sharp focus is that self-building is an increasingly shark infested waters with so many 'expert' threading water waiting to pounce on unsuspecting self-builders who unfortunatley don't give themselves enough time in the planning phase to properly research their projects. I argued before that the real professioanls should be more overtly selling their wares to ensure that the so called experts cannot continue to get away with installing inappropriate technology inapproriately in once off self-builds.

To the OP I can only say unfortunately you are not alone and refer you to beyondpassive's earlier post which advised that ducts should be covered by between 300 and 400mm of insulation in order to max efficiency of heat recovery unit. After that best to get in a professional ... Q is who might that be??

your dead right, very unfair of me, and off topic. though it gets under my skin that short-cuts are taken, and and either the technology/system or as with the recent with priory hall the consultants (or the lack of) are blamed.
Many people seem to go it alone and then have problems as a result, which are only manifesting now as running costs become more of an issue. but were deep in the economic s**t and moneys to tight to rectify.. at least by us highlighting this, other self-builders may not make the same mistakes.
I felt it was important to pick at the OP (the post not personally) as it initially reads to a lay person as a damming report of MVHR, when in fact its the OP that is ultimately responsible for the issues raised..

Carlow52

Folks just dont see the value of professional advice: they are much more lightly to pay for golf lessons than arch/eng fees:D

about2build

I am in a position that reading these post recently has opened my eyes:eek: to whats out there as well, indeed many of the contributors on this very thread are responsible for much of what I have learned. So much so that some of the professionals I have spoken to get lost in conversations with me and resolve things by saying ah thats overkill or you dont need that or did you rob a bank etc So though I have become more aware of airtightness and creating an envelope reducing cold bridges etc if the block layer isn't experienced in this what do you do.....will he listen to a airtightness specialist telling him what to do or maybe the answer is in getting a block layer au fait with this quality of finish....are they out there? and are they relatively affordable?

beyondpassive

[QUOTE=about2build;75397896 I have become more aware of airtightness and creating an envelope reducing cold bridges etc if the block layer isn't experienced in this what do you do.....will he listen to a airtightness specialist telling him what to do or maybe the answer is in getting a block layer au fait with this quality of finish....are they out there? and are they relatively affordable?[/QUOTE]

This is at the heart of low energy building, you have to have to have it worked out down to each tape and nail. You can't rely on a contractor or tradesman to drive the quality of insulation integrity and airtightness. It needs to be drawn up in detail before 'er a shovel is dug in the ground and I'd add before even the job is priced. I'd even go further and say the details need to be thought about before planning is submitted, as we have been crudely designing houses based on rough €90 or €110 per square foot turnkey rules of thumb and trying to maximise floor space without a thought for how or to what standard it is built, and my own bug-bear ; not considering the 13.5 % VAT and connections/contributions. By the time it comes to site, the builder has no flexibility to anything but bog standard and details are made up on the back of a chip bag. But It'll be grand.

Back to the topic; when it comes to MHRV you really cant just 'lob it in' and hope she'll be right. It needs to be designed, with flow volumes and rates calculated, slow bends, adequately sized drops and well insulated and drained supply and extract.

creedp

BryanF wrote: »

your dead right, very unfair of me, and off topic. though it gets under my skin that short-cuts are taken, and and either the technology/system or as with the recent with priory hall the consultants (or the lack of) are blamed.
Many people seem to go it alone and then have problems as a result, which are only manifesting now as running costs become more of an issue. but were deep in the economic s**t and moneys to tight to rectify.. at least by us highlighting this, other self-builders may not make the same mistakes.
I felt it was important to pick at the OP (the post not personally) as it initially reads to a lay person as a damming report of MVHR, when in fact its the OP that is ultimately responsible for the issues raised..

I am not having a go personally BryanF its simply that there seems to be a huge variance between what is seen as the norm from professionals like you on this forum and a significant proportion of the same 'professionals' who one comes across on the ground. Because of this uniformed gits like me end up listening to 'sharks' who sell completely inappropriate systems or advise that they should be installed in a completely inappropriate sub standard way. Take the MHRV system I installed. I was stupid enough to listen to the 90% efficiency blurb but completely forgot to ask how uninsulated ducting would severely impact on this efficiency. I know, difficult to comprehend but true unfortunately for me. By the way I completely accept the criticism levelled at me that I should have done my research, I should have a a bit of cop on, I should have hired independent experts to oversee and question these issues but I didn't. One of the advantages of being on these forums is to learn from your mistakes or if you are lucky enough not to have already embarked on your build to re-appraise your plans to date.

Mothman

For me ventilation is the most important aspect in my home for healthy living.
It is needed to remove all the toxins, moisture, air borne bugs etc.

To achieve this with a hole in the wall or ventilation strips in windows etc seems pure madness to me especially when temperature outside is several degrees below zero. In houses I visit I often see this hole in the wall blocked with newspaper or the window ventilation strips closed (to keep out the winter gales) and the resulting air in house being stagnant.

HRV was a standard spec in my house. This was 14 years ago. At that time most local trades people did not know what it was :eek:

But it is fantastic. I get my ventilation, but I also get to keep the vast bulk of heat which is getting more expensive to produce in the house. There is a slight noise which can be heard when house is quiet...which is not often with 3 kids
It does cost to run, less than €50/year in electricity and there are the filter costs. IMO an extremely small price to pay for healthy air.

We hang the laundry inside and it's dry in 12 hours

BryanF

creedp wrote: »

I am not having a go personally BryanF its simply that there seems to be a huge variance between what is seen as the norm from professionals like you on this forum and a significant proportion of the same 'professionals' who one comes across on the ground. Because of this uniformed gits like me end up listening to 'sharks' who sell completely inappropriate systems or advise that they should be installed in a completely inappropriate sub standard way. Take the MHRV system I installed. I was stupid enough to listen to the 90% efficiency blurb but completely forgot to ask how uninsulated ducting would severely impact on this efficiency. I know, difficult to comprehend but true unfortunately for me. By the way I completely accept the criticism levelled at me that I should have done my research, I should have a a bit of cop on, I should have hired independent experts to oversee and question these issues but I didn't. One of the advantages of being on these forums is to learn from your mistakes or if you are lucky enough not to have already embarked on your build to re-appraise your plans to date.

no bother
here's the thing, as a follow-on to Bpassive's on the button comments: the person advising/helping/designing/supervising/signing-off on your behalf should be independent of product/installer/builder/salesman - otherwise any 'expertise' is biased. Biased expertise is fine, its breathes passion, but needs to be filtered imo sometimes before it gets to the clients ears:)

If I may take the analogy that an arch/designers role as a sort of like a GP's - as in if he/she doesn't know the answer he/she brings in/asks the guy that does... but the 'GP' remains in your corner, your best interests in mind, must be willing/able to justify decisions and has enough knowledge to direct your home construction ...including the blockie and the air-tightness installer..

tessabout

Hi - was reading your discussion re:HRV. We built a new house last year did all we were told, took advice from "experts". House is so well insulated it is extremely uncomfortable - we are so upset after spending so much money (3000 sq ft hse) - HRV was mentioned at time of build but was dismissed as costly and not a must - put vents in all windows. We now cant sleep - are constantly sick and have a 1 yr old (so worried she will end up with health problems). Have got two quotes for HRV upstairs only - 4500 euro. More money - dont know what to do?

BryanF

tessabout wrote: »

Hi - was reading your discussion re:HRV. We built a new house last year did all we were told, took advice from "experts". House is so well insulated it is extremely uncomfortable - we are so upset after spending so much money (3000 sq ft hse) - HRV was mentioned at time of build but was dismissed as costly and not a must - put vents in all windows. We now cant sleep - are constantly sick and have a 1 yr old (so worried she will end up with health problems). Have got two quotes for HRV upstairs only - 4500 euro. More money - dont know what to do?

Was a BER carried out?

Carry out an air-tightness survey first, you must know the expected air-leakage before specifying MVHR

If your house is not very well sealed up, MVHR may not be the right system and some other mechanical system might be more suitable - probably a cheaper install but possibly less energy efficient, but first things first carry out the air-tightness test:)

BryanF

BryanF wrote: »

Was a BER carried out?

Carry out an air-tightness survey first, you must know the expected air-leakage before specifying MVHR

If your house is not very well sealed up, MVHR may not be the right system and some other mechanical system might be more suitable - probably a cheaper install but possibly less energy efficient, but first things first carry out the air-tightness test:)

With regard to the MHRV, what happens if your completely airtight house goes faulty and is only pumping in 10% of the air it should. Is there alarms on these devices or is monitoring required ???There must be risks associated with them.

Do-more

Deleted User wrote: »

With regard to the MHRV, what happens if your completely airtight house goes faulty and is only pumping in 10% of the air it should. Is there alarms on these devices or is monitoring required ???There must be risks associated with them.

It's a good idea to fit carbon monoxide monitors in various locations around every home, they are similar in size and cost to a smoke alarm and will alert you to the fact that CO levels have risen above normal safe levels either from insufficient ventilation or a faulty appliance such as a stove or gas boiler.

MicktheMan

BryanF wrote: »

Was a BER carried out?

Carry out an air-tightness survey first, you must know the expected air-leakage before specifying MVHR

If your house is not very well sealed up, MVHR may not be the right system and some other mechanical system might be more suitable - probably a cheaper install but possibly less energy efficient, but first things first carry out the air-tightness test:)

@BryanF: From reading the post, I think tessabout's house may well be too airtight for window trickle vents but as you say a att will determine this.

@Tessabout: What was the insulation spec and also the airtightness spec. Which expert dismissed a mechanical ventilation system? Can you describe in more detail why you feel uncomfortable in the house?

BryanF

Deleted User wrote: »

With regard to the MHRV, what happens if your completely airtight house goes faulty and is only pumping in 10% of the air it should. Is there alarms on these devices or is monitoring required ???There must be risks associated with them.

goldfish can survive for days when the water gets murky/discoloured(what a poor analogy:D) As Do-more said most MVHR systems are now integrated with a CO sensor and I prefer units that have an RH sensor also, but even if the MVHR system stopped working, your going to eventually feel the space being stuffy just as the OP is claiming.. remember the air tightness even in a passive house is not 0;)

there is maintenance required with MVHR - the filters need to changed periodically (generally yearly or bi-annually) as per manufacturers warrant instructions. I would say that if the filters were left for a couple of years then fire could be a more rational fear - but in saying that I understand there has only been one known case of that (a Canadian story where mvhr systems have been used by a large % of the population for decades but one Muppet never did any maintenance)

just like the issues with the waste treatment units - try to choose a MVHR system that allows for easy maintenance, that can be done yourself - and where the filters are straight forward to clean out or cheap to replace. this also a good reason why the system should not be in the attic + its more efficient inside the thermal envelope.

@ MIck, that was my first thought re vents, but the A-test will answer that - another possible actual cause for the sickness being experienced, is the construction materials, insulation, PVC, boiler flue gases etc + finishes and furnishings in the house. carcinogens etc are rarely discussed and most people never consider them an issue (even when painting the kids bedrooms - which I believe is mental!) but a lack of ventilation like the OP is experiencing, brings such issues to the fore especailly for the first year of occupancy in a new home.

@ tessabout- there is no such thing as just installing MVHR upstairs - the more i think about you retro-fitting MVHR, the more I think you'll spend a lot more than 4.5g installing ridged ducts, extracts and intakes covering 300msq and making good the house afterwards.
IMO get a specialist in, who is not an MVHR supplier, to consider all the options like Demand control mechanical extract or even that system the Norseman is selling on his site:)

there are more options the could be researched also, like just installing more vents..

L driver

Tessabout,
Have a look at fiwi hrv if mechanical ventilation is required in your house. It might suit your situation.

BryanF

L driver wrote: »

Tessabout,
Have a look at .... if mechanical ventilation is required in your house. It might suit your situation.

do you have personal experience of this unit Ldriver ?

BryanF

L driver wrote: »

Tessabout,
Have a look at fiwi hrv if mechanical ventilation is required in your house. It might suit your situation.

your Viking going by another name are you?

Do-more

BryanF wrote: »

your Viking going by another name are you?

There is also another international company which has recently introduced a decentralised hrv unit which to the best of my knowledge is based on fine wire technology.

I'll pm you a link maybe you can check it out!

No scratch that, the one in the link I sent you uses an enthalpy plate heat exchanger although the end result is similar to the fiwi units i.e. Hrv without ductwork.

tessabout

Hi all - thanks for all the advice. Can anyone recommend an impartial "expert" - re: mechanical ventilation? Have looked up wifi ventilation aswell but very new to this country - dont really want to be one of the first!
Do need to do something quickly - lots of sleepless nights - opening and closing windows. We wake up most mornings feeling ill (e.g. headaches, sick tummies, dry eyes, sore throats). One thing - we have no condensation on windows etc - very dry - hrv installer that called thought this odd - any ideas?

BryanF

tessabout wrote: »

Hi all - thanks for all the advice. Can anyone recommend an impartial "expert" - re: mechanical ventilation? Have looked up wifi ventilation aswell but very new to this country - dont really want to be one of the first!
Do need to do something quickly - lots of sleepless nights - opening and closing windows. We wake up most mornings feeling ill (e.g. headaches, sick tummies, dry eyes, sore throats). One thing - we have no condensation on windows etc - very dry - hrv installer that called thought this odd - any ideas?

PM sent

manufan16

beyondpassive wrote: »

The Vent pipes should have the same depth of insulation as the cold roof, so 350-400 of cellulose or fibreglass. We have built an osb box above the joists and filled with insulation to maintain the same level of insulation around the distribution pipes as you would have between ambient and room temp

If I plan to have mhrv in ground floor utlity room and also my roof is specified as a warm roof mean that I should not need 350-400 insulation around vent pipes?

BryanF

manufan16 wrote: »

If I plan to have mhrv in ground floor utlity room and also my roof is specified as a warm roof mean that I should not need 350-400 insulation around vent pipes?

around the intake pipe anyway- as otherwise you'll have a cold pipe (attracting condensation) travelling through your house to the central exchanger.

L driver

BryanF wrote: »

your Viking going by another name are you?

Hope that is tongue in cheek Bryan, and no I am not Viking. I am self building and I am just sharing my research. I don't have personal experience of it, but it looks a good system and simple and easy to clean and may suit Tessabout's situation. I would love to hear if someone has experience of it. In fairness to viking they seem reputable and genuine.

BryanF

L driver wrote: »

Hope that is tongue in cheek Bryan, and no I am not Viking. I am self building and I am just sharing my research. I don't have personal experience of it, but it looks a good system and simple and easy to clean and may suit Tessabout's situation. I would love to hear if someone has experience of it. In fairness to viking they seem reputable and genuine.

yes it was L driver no offence meant, its just we've been asked not to directly advertise a specific product or service on here

I too would like to here from someone who has used the system, as I've only heard from Seamus(viking) directly on its merits

Trigger007

The OPs problem was it being too cold from sept onwards, why would they need a summer bypass in that case? Also by properly insulating the ducts and pipes how is that creating heat? My understanding is that heat is distributed but only once it's generated. (from warm/wet rooms etc) What if its not generated in the first place? what if the heating has been switched off whilst on holidays, do you come home to a freezing house?
We're nearly at roof level and still trying to decide on getting one or not.

bakerlite

Trigger007 wrote: »

My understanding is that heat is distributed but only once it's generated. (from warm/wet rooms etc) What if its not generated in the first place? what if the heating has been switched off whilst on holidays, do you come home to a freezing house?

For me, This is the main issue
Our Kitchen and Bathroom are not particularly warm rooms, But If the Airflow is working correctly around the house the way I understand it is that the negarive pressure in these wet rooms should be drawing the warm air from around the house and into (and out through the HRV) the room.

That doesn't seem to be happening for me - maybe I need to turn up the fans to get more negative pressure going on but the thought of drawing in EVEN MORE cold air at this time of year is depressing.

Also considered an extract over the stove But was warned against another negative airflow point in a room that was specked to be positive pressure.

Dizzy from it at this stage.

fclauson

The key is installalation

If your warm supply ducts run though a cold roof space or even a cold space within the house then they will loose heat before they get to the grill in the room.

You have to make sure they stay warm or insulate the muck out of them (not the 25mm which is in the regs I am talking about 200mm or more !!!!)

Keep the the ducting within the thermal envelope as much as possible and then the system should perform much better

the OP should go into the loft space and see if the ducts have any insulation on them

AND just to comment on the above (which came in while I was typing)

there is a miss understanding about MHRV and Passive house - a Passive house HAS TO BE KEPT WARM - my house needs 3.5Kw at -2 and 6Kw and -10 PERMANETLY FED INTO IT - not in the morning/evening cycle we are all so used to

This is a BIG miss understanding by many. If you let the temp in the house fall then the MHRV will keep pumping but it will pump the colder air.

BryanF

bakerlite,
have you carried out the air-tightness test yet?

bakerlite

Unfortunately not -
While it may be false economy - Its a bad time of year for the cash outlay.
After Christmas I'll get the Heat Imaging and Air Tightness Done.

And I am not expecting a passive house but what I was maybe naively expecting was not to have to spend 90 euros a week on fuel to keep the house at 17 Degrees If i have the heat recovery on - which I usually do. Though I must confess I am switching it to timer so It is off from 9am - 3pm.

I would like to think that I can improve it a little bit somehow

Trigger007

bakerlite wrote: »

And I am not expecting a passive house but what I was maybe naively expecting was not to have to spend 90 euros a week on fuel to keep the house at 17 Degrees If i have the heat recovery on - which I usually do. Though I must confess I am switching it to timer so It is off from 9am - 3pm.

This is exactly what I'm expecting to happen us. I know having the traditional "holes in the walls" for ventilation doesn't make sense either, but either way your going to be struggling to keep the house at a certain temperature, only with the hrv it's filtered air, bit of a price to pay I'm thinking...?

MicktheMan

bakerlite wrote: »

Unfortunately not -
While it may be false economy - Its a bad time of year for the cash outlay.
After Christmas I'll get the Heat Imaging and Air Tightness Done.

And I am not expecting a passive house but what I was maybe naively expecting was not to have to spend 90 euros a week on fuel to keep the house at 17 Degrees If i have the heat recovery on - which I usually do. Though I must confess I am switching it to timer so It is off from 9am - 3pm.

I would like to think that I can improve it a little bit somehow

Trigger007 wrote: »

This is exactly what I'm expecting to happen us. I know having the traditional "holes in the walls" for ventilation doesn't make sense either, but either way your going to be struggling to keep the house at a certain temperature, only with the hrv it's filtered air, bit of a price to pay I'm thinking...?

A mvhr system is primarily a ventilation system, i.e. it is there to ventilate your house. The hr part is there to make it an energy efficient ventilation system. It is not a heating system, you still have to heat your house. In order for hr to work, the following needs to be done properly:

proper duct design: I come across a lot of new installations where the system has been installed by the plumber with absolutely no design thought or input from anyone. "The best ducting is no ducting"

Installation / commission: based on the design above, proper materials, insulation, noise reducers, balancing etc by a competent experienced installer.

airtightness: critical. Anyone installing a heat recovery system without paying attention to and knowing the airtightness is, imo, madness. An att test costs nothing compared to the build cost and is one of the very few quantitative tests you can do on a house.

glenkeo

Hi I have a hrv in for just over a year now. This is only my own experience, I have a very well insulted house and spent a lot of time and money on air tightness. (If your house is airtight then you will need some way of getting fresh air in to your house be that a 4” hole in the wall or window vents). When I moved in the guy who did all the heating and plumbing and hrv convinced me to leave the heating on 24/7. i was sure he was mad... but did it. If there is no heat inside your house then the hrv will only cool your house down has it is not a 100% efficient. I have temp stats in every room set to 19 degrees so the house never goes below that, I use oil(1000L for the year), stove (coal and wood)and solar,(not in yet). I have air inlets in 3 bathrooms (no noisy extractor fans) kitchen (away from Cooker) Sitting room over stove, and utility room, and air outlets in 4 bedrooms, kitchen and living room at far end of room from stove. (External air kit on stove, this is a must). The ducting is well insulted and I have the unit in the utility has I need to clean filter and did not fancy going up in to the attic every few months.
I find the house always feels fresh I have a neighbour who built around the same time has me and did a great job on insulation and air tightness but decided against hrv, he regrets that now, when I go to his house I find the house is as warm has my house but just feels stuffy after a while.

BryanF

Trigger007 wrote: »

This is exactly what I'm expecting to happen us. I know having the traditional "holes in the walls" for ventilation doesn't make sense either, but either way your going to be struggling to keep the house at a certain temperature, only with the hrv it's filtered air, bit of a price to pay I'm thinking...?

trigger,
'expecting to happen'.. you know I wonder were self-builders in 2005 expecting that, 6 years later, their homes would be built to such a crap standard, that they could avail of grants, to retro-fit boilers, solar panels and insulation:o

may i express a rather harsh but imo fair assessment of bakerlite's mvhr system

• he has mvhr but never did any calcs on heat loss!! or tried to achieve any standard of air-tightness!!
• since then there has been much confusion as to the actual problem with the system, or how suitable/ effective his heating system is...
• all we know is its installed 2 years!! and he is not on good terms with the builders/installers, nor does he have a heating engineer or architect to fall back-on, yet he continues to complain, but does not seem to appreciate that any technology, often only works if its up to the job, installed correctly, and part of the bigger picture ie the rest of house is up to scratch.

If i may suggest, your at a stage in construction, where unless you are going for high levels of insulation and air-tightness, with thermal bridging considered, good consultants on board, builder working to drawings and specifications, don't bother with MVHR..


do ensure your provisional BER and your renewable requirements are considered. and the best of luck to you

Trigger007

If i may suggest, your at a stage in construction, where unless you are going for high levels of insulation and air-tightness, with thermal bridging considered, good consultants on board, builder working to drawings and specifications, don't bother with MVHR..

Well I certainly hope we've insulated enough, that was what we focused on most, along with the type of windows,i just hope we've done enough for a 3100sqf house. I guess I just need to get on to the architect now. Thanks for the advice on here

fclauson

Questions for your Arch:

1) Have you done thermal bridge calculaitons for each of the junctions across the building or can you certifiy that you have used the latest Accredited constructon details (ACDs available from the dept of environ website) to allow for the usage of the 0.08 DEAP thermal bridging values

2) when defining out how the windows should be installed did you specify that they should be taped for airtightness

3) WHEN will the blower door test be conducted - and what retention do we have over the builder if we fail to reach the currect regulatory standard


these answers could be interesting

creedp

fclauson wrote: »

Questions for your Arch:

1) Have you done thermal bridge calculaitons for each of the junctions across the building or can you certifiy that you have used the latest Accredited constructon details (ACDs available from the dept of environ website) to allow for the usage of the 0.08 DEAP thermal bridging values

2) when defining out how the windows should be installed did you specify that they should be taped for airtightness

3) WHEN will the blower door test be conducted - and what retention do we have over the builder if we fail to reach the currect regulatory standard


these answers could be interesting

The answer to 3) would be very intersting if you are in a situation witha bust builder and the only way you can keep the show on the road is to drip feed funds for materials and external subbies in order to try and get job finished. I know I went about things the wrong way but in my limited experience the theoretically correct way is not always achievable in the real word that some poor unfortunates find themselves in. I know as well that most people on here refer to heating engineers/consultants, etc, etc as if they were born into the world with this knowledge ready to burst forth but it is equally clear that there are a lot of poor unfortunates on here also who have never heard of these guys and certaintly weren't aware of them in advance of their builds commencing. You can now 'scorn at their simplicity' but thats a simple fact of life for them and it is truly unfortunate that we have a building industry in this country that has given a awful lot of people a awful lot of grief and in some cases left them with massivley expensive but seriously sub-standard builds. We hear a lot about the plight of negative equity but what about the plight of negative equity plus a seriously flawed house. At the end of the day the 'buyer beware' principle is all that will matter but it doesn't excuse the unbelievable incompetence and somtime downright skullduggery to be found amongst some in the fraternity of building professionals (of course not all). Rant over:)

bakerlite

Firstly -
Sorry - I should have named the thread more aptly - Maybe perhaps - MHRV, Do it 100% right or not at all.
I certainly don't mean to make out MHRV to be a Bad thing nor do I think people shouldn't install it.
In fact quite the opposite - The difference in Air Quality and Perhaps our health is noticeable too. And as stated before from march to september its perfect.
We are rearing 2 young children and have been blessed with good health since in this house and I wouldn't think it absurd to attribute at least some of that to good air/living conditions.
And I didn't mean to come across a complaining old bugger - I just find the air coming in really really cold - I think my system is not working correctly I came on here for advice, not to bad mouth anyone who is into MHRV.
The advice I have got is simple - Air Tightness and Thermal Imaging test essential.
When I have the funds after Chritmas I will carry these out and I will report back.
Who knows it could be something very very simple


Anyway I certainly don't mean to be making anyone up tight on here so apologies.