# Heating System for new build query



## sman (12 Jan 2009)

Hi, I am just working out construction drawings for my new build bungalow. I would like to make the house airtight, use increased levels of insulation, and use MHRV to minimise heat loss. I had also planned on putting in underfloor heating in the living areas with rads in the bedrooms. I plan on using solar panels for hot water for showers etc. and then condenser oil burner for heating. My question is, am I wasting money putting in underfloor when I am also paying for extra insulation and MHRV. 

  Would I be better off putting in aluminium radiators instead of the added expense of underfloor? 

  One builder I spoke to recommended going with underfloor throughout the whole house and dropping the MHRV as the Electricity costs are too high for this but I think having an airtight house is the best way forward. Anyone aware of the typical running costs of MHRV?

  Any opinions welcome… need to make a decision on it fairly quickly and afraid I’ll end up choosing the wrong thing


----------



## Abbica (12 Jan 2009)

We got our MHRV airtight house done but system not being turned on until the end of this week so costs can't comment on on running. But the whole point really is that you don't need underfloor heating nor radiators. The ventilation system works on its own, backed up by a condensing boiler to boost the whole unit when it is really cold and needed and once you have it on for a while you can turn it off and the heat that it previously kicked out will stay in the house as it is airtight, minimal amount of heat loss, as you will see if you search this forum, no matter what heating system you use, the key is always insulation, the more the better.


----------



## baldyman27 (12 Jan 2009)

I've spoken with a couple of plumbers recently on this subject and from what I can glean the best and most efficient system longterm is underfloor heating fed from an oil condenser boiler (the Grant boiler was the one most frequently mentioned), coupled with solar panels tied to the hot-water system. 

There seem to be problems with the heat exchanger for asthmatics, though this is based on hearsay, I can see how it would make sense. Ventilation is important, personally I don't like the idea of a 100% sealed house.

As mentioned, insulation is key. 125mm foil-backed high density is the minimum requirement for underfloor and should be well worth the initial cost.


----------



## sman (12 Jan 2009)

Thanks for the replies. decisions decisions to make. hate to spend 8 grand extra on underfloor heating and then have it sitting there unused. 



Abbica said:


> We got our MHRV airtight house done but system not being turned on until the end of this week so costs can't comment on on running. But the whole point really is that you don't need underfloor heating nor radiators. The ventilation system works on its own, backed up by a condensing boiler to boost the whole unit when it is really cold and needed and once you have it on for a while you can turn it off and the heat that it previously kicked out will stay in the house as it is airtight, minimal amount of heat loss, as you will see if you search this forum, no matter what heating system you use, the key is always insulation, the more the better.


 
Abbica... when you say it is backed up by a condensing boiler. this must be heating either underfloor or rads


----------



## baldyman27 (12 Jan 2009)

sman said:


> hate to spend 8 grand extra on underfloor heating and then have it sitting there unused.


 
The solution to this is to split the house into zones with controls/timers for each zone. I.e. have the bedrooms on one zone timed for night and morning, kitchen/living area on a separate zone, timed accordingly. Its very easy to leave the pipes out for rads when you're building should you decide that they're a better iption down the road.


----------



## Abbica (13 Jan 2009)

Hi Sman, we have solar panels on the southside roof which will heat up our water, we have the ventilated ducting throughout our airtight house for heating, so no radiators or underfloor, the heat flow goes through the ducting, so say its winter and the water isn't hot enough we turn on the boiler for a bit to give it that extra heat and the same applies for the heat, the boiler heats up the air that will dispel into the house, clean fresh air that is warm, like a car heater so to speak. Don't ask me technical stuff on how it works but its the latest in passive heating. No one, not one builder coming into our house can figure out how it will work, all they say is' 'jaysus, I will have to come back and see how this work'. I think they think we are been conned!!!


----------



## sman (13 Jan 2009)

thanks abbica. i understand now. makes sense i suppose. someone mentioned this to me before at a selfbuild show, but i had assumed it was just an addition to conventional heating. i.e. the pipes carrying hot water to the rads or underfloor are passed through the ducting. I hadnt thought of just having the pipes going through the ducting as the heating source. be very interested to know how you get on with this


----------



## sman (13 Jan 2009)

baldyman27 said:


> The solution to this is to split the house into zones with controls/timers for each zone. I.e. have the bedrooms on one zone timed for night and morning, kitchen/living area on a separate zone, timed accordingly. Its very easy to leave the pipes out for rads when you're building should you decide that they're a better iption down the road.



thanks. i understand having the zones alright. just wondering should i put in underfloor at approx 8k extra or is MHRV efficient enough to almost reduce the need to heat the house at all. If it is, i should go for cheapest heating system as it would be rarely used


----------



## Wobs (14 Jan 2009)

HRV systems are not heating systems from what I have seen. They are ventilation systems which heat the cold air coming in to house with stale warm air that they are removing from the house so that there is little change in the air temperature. They usually take this air from areas such as bathrooms and kitchens which would usually have higher temps due to cooking and steam etc. But you still need to be able to heat your house first unless it is a passive house ( extremely well insulated and air tight house that has no heating system at all).

I would think from the info you have given Abbica that your oil boiler will be coming on most of the time in the winter to heat your house.

I am no expert by the way, it just what I have gathered from reasearching these systems myself.


----------



## Abbica (14 Jan 2009)

Hi wobs, I know what you mean and I do believe we will have to turn on the oil boiler in the winter almost every evening but because it is a passive airtight house the point is, it need only be on for 1 - 2hrs (I am presuming), as the heat that it throws out will stay in the house, no need to have it on for ages?


----------



## sydthebeat (14 Jan 2009)

sman said:


> thanks. i understand having the zones alright. just wondering should i put in underfloor at approx 8k extra or is MHRV efficient enough to almost reduce the need to heat the house at all. If it is, i should go for cheapest heating system as it would be rarely used



as wobs has stated...
the hrv system is not a heat producing source.. what it DOES do is conserves heat already produced by your heating system..

whether or not to go for UFH as compared to rads should be based on other issues
(1) UFH is more economical as it runs at lower temperatures than Rads
(2) some people like having rads to dry towels etc... this is possible with UFH but is an extra cost
(3) UFH is aesthetically more pleasing as you do not see rads under windows.. it also allows you to be more free when laying out a room
(4) UFH generally allows you much more control over your heating system, and thus allows you to conserve energy better.


----------



## Bov 1 (14 Jan 2009)

Hi All,
First time poster so bear with me.  Planning to build my own house using ICF system to relatively low U-values but maybe not 'passive' standards.  However i'm having trouble sourcing heat system info!  In addition to HRV I was planning to use UFH  down stairs and rads upstairs powered by wood pellet burner.  Wise decision??  Also, why is it not advisable to have an open fire in an 'airtight' house?

Thanks in advance
Bov 1


----------



## sydthebeat (14 Jan 2009)

ill answer the second question first...
basically because an open fire mean there is a large 200mm diameter hole in your construction... ie the chimney flue. Its pointless building an 'airtight' house and then deliberately putting a large hole in it.

to answer your first question.... what you need to do is work out your heating demand first, before you can specify a heating system. the DEAP software can be used to do this, but if you want a more precise figure get the design put through th phpp software.
Once you know what your demand is, you can then go about sourcing a system to meet this demand.

for example.. two passive houses built in carlow have a small 1.7 kw/hr electric air to air heat poump as their heating source...


----------



## baldyman27 (14 Jan 2009)

Bov 1 said:


> Hi All,
> powered by wood pellet burner. Wise decision??


 
Don't have personal experience of wood pellet boilers but am in regular conversation with an SEI registered plumber who has told me horror stories about them, including nests of rats in the silo, among other less horrifying tales.

Maybe people who have wood pellet systems can give testament as I am only going on hearsay, though there are probably numerous threads already on the topic.


----------



## DavyJones (15 Jan 2009)

sydthebeat said:


> whether or not to go for UFH as compared to rads should be based on other issues
> (1) UFH is more economical as it runs at lower temperatures than Rads
> (.



syd, have you any stats on that? 

UFH has maybe 20 times more water in it than a radiator system. More water = more energy required to heat it.

UFH does run at a lower temperture but for much longer periods as compared to a radiator system, higher running temperture, shorter running time.

UFH has a slow warm up time, not ideal for a cold snap in August when you just want to turn heating on for an hour.


----------



## Abbica (15 Jan 2009)

God, you lot have me worried now, we don't have any alternative heating source, all we have is the solar panels, HRV system, condensing boiler with the air tight passive house. It is been commissioned by a heating engineer????


----------



## sas (15 Jan 2009)

Hi Abbica,

What airtightness result did you achieve on your blower door test and what insulation u-values did you achieve? You built direct labour, right?


----------



## sydthebeat (15 Jan 2009)

DavyJones said:


> syd, have you any stats on that?
> 
> UFH has maybe 20 times more water in it than a radiator system. More water = more energy required to heat it.
> 
> ...



davy, my opinion is based on the premise that the building envelope is of high spec airtight type. Once the heat is generated within the dwelling, then every effort must be made to retain it. A rad systems is much better for a warm up / cool down type set-up.. .UFH is much better, and more economical, for a set-up designed to have a constant temp throughout the dwelling 24 hrs a day. This is the way things are moving to.

yes rads are more responsive, but increased controls over the UFH system and a better spec of construction ie min 120mm pu under UFH in a 75mm screed, can increase the responsivness of UFH.

again, i agree that UFH contains more liquid, but my first point applies here... the temp differentials in UFH should be in the range of 15-40.. .whereas rad systems tend to be about 10 - 70.. less temp differential means less energy required to heat...

abbica... if your house is a 'passive' house then then only heating source you require would be of a very small output... ie 2kw/hr or so... the condensing boiler would be more than enough...


----------



## DavyJones (15 Jan 2009)

Hi Syd,

I would be very interested in looking at stats that compare installation and running costs of both systems. 

I always belived we live in an unsuitable climate for UFH/low temp systems. It is more suited to a climate where you are certain that the heating would be on from October to february etc.

I hear alot of people with UFH complain of high fuel bills. I would not install it in my home and would be slow to fit solar panels/heat pumps etc.


----------



## sydthebeat (15 Jan 2009)

Davy... maybe have look here for examples of stats which may be applicable :
http://www.boards.ie/vbulletin/showthread.php?t=2055263818

I agree with a lot of what you say, but i am trying to push cleints towards the way things should be, rather than how they are......


----------



## MikeLavelle (15 Jan 2009)

I am not gogin to write a big long story for you. As i was not the person who got the system in but my friend raves about his system he got in his new house. 
Check out a company called EcoLiving www.echoliving.ie 
He reckons after 5 year he will have covered the cost and he has no more heating bills to pay. 
Cheers, 

Mike


----------



## Soarer (15 Jan 2009)

That link doesn't work.
I'm assuming it should be http://www.ecoliving.ie ?


----------



## Neadyk (15 Jan 2009)

Could somebody please advise the approximate cost difference for UFH to radiators for a 200sq mtr house.  We were originally quoted for UFH but changed to rads and want to know what the cost difference is likely to be. Thanks.


----------



## DavyJones (15 Jan 2009)

Neadyk said:


> Could somebody please advise the approximate cost difference for UFH to radiators for a 200sq mtr house.  We were originally quoted for UFH but changed to rads and want to know what the cost difference is likely to be. Thanks.



What price were you quoted for UFH?


----------



## Neadyk (15 Jan 2009)

Davyjones, we werent quoted any specific amount.  It was included in the builder's initial quote as a guideline.  When we decided to go with rads they said we'd be due the difference back.  From asking a few other builders/plumbers it seems to vary considerably.  The initial quote was issued in 2007. Any ideas?


----------



## DavyJones (15 Jan 2009)

Have quoted a few jobs recently with both as options. I will dig them out.


----------



## DavyJones (15 Jan 2009)

sydthebeat said:


> Davy... maybe have look here for examples of stats which may be applicable :
> http://www.boards.ie/vbulletin/showthread.php?t=2055263818
> 
> I agree with a lot of what you say, but i am trying to push cleints towards the way things should be, rather than how they are......




Hi Syd,

thanks for the link, interesting. Maybe we should do something similar here?.

I will research the heating and ele requirements for my own home and take into consideration installation cost and compare with alternative forms of heating.

I agree with the concepts but feel that it costs far too much to be viable at the moment .


----------



## sydthebeat (15 Jan 2009)

the concept of high spec insulation and high spec air tightness in order to reduce your heating demand certainly isnt high cost. Its all about proper design and attention to detail.


----------



## DavyJones (15 Jan 2009)

sydthebeat said:


> the concept of high spec insulation and high spec air tightness in order to reduce your heating demand certainly isnt high cost. Its all about proper design and attention to detail.




Your quite right.

 I like the idea of HRV. and insulation is key. However I have doubts about the best way to generate heat in the first place

why use a heating system E.G geothermal that can cost up to €30000 and thats before you lay a pipe indoors. UFH may cost as much as €30 per m2. It's a massive outlay to begin with. How long before you see a payback, if any?

If I were to build a house tomorrow I would go for:

Radiator system
Condensing boiler.
This system would cost about €8000 in a bigger than average house. Running costs in a house with HRV and well insulated would be low.
Stove connected to heating system.
I would not fit solar panels but may allow for them to be retro fitted.


----------



## sydthebeat (15 Jan 2009)

DavyJones said:


> Your quite right.
> 
> I like the idea of HRV. and insulation is key. However I have doubts about the best way to generate heat in the first place
> 
> ...



if i was building tomorrow and i could build the envelope i wanted i would use:

a HVAC system with heat recovery.
A small electricial element in the HVAC system would be my heat source, heatingthrough air ducts.. .no water space heating at all.

Domestic hot water would be by solar panels alone.

This is assuming 'passive' standard build.


----------



## DavyJones (15 Jan 2009)

sydthebeat said:


> if i was building tomorrow and i could build the envelope i wanted i would use:
> 
> a HVAC system with heat recovery.
> A small electricial element in the HVAC system would be my heat source, heatingthrough air ducts.. .no water space heating at all.
> ...



Roughly, what would be cost of running small electricial element?.

Heat recovery in my opinion is a great idea. Something I wish to get involved in.

I have very little faith in current solar panels. How would you have hot water in the winter?


----------



## sydthebeat (15 Jan 2009)

I have no idea davy.... pipe dreams at the moment...

id ensure enough solar panels to suffice...

i know of a dweling in cork which is heated completely with solar tube collectors and a small wood stove... ive only seen pictures but the set-up is a approx 2500 litre external buffer tank fed off about 16 m run of tube collectors....

very interesting stuff...


----------



## Bov 1 (15 Jan 2009)

Sydthebeat, cheers for your reply, makes sense!  Out of interest, if were to build the envelope you wanted tomorrow what would it be?


----------



## sydthebeat (15 Jan 2009)

floor u value 0.13
walls u value 0.1 (max 0.12)
roof u value 0.1


----------



## Bov 1 (15 Jan 2009)

Cosy!  Hoping to get heat demand established shortly so i'l post info when do


----------



## Neadyk (16 Jan 2009)

That would be really helpful Davyjones.  Thanks.


----------



## DavidDagg (16 Jan 2009)

I built my new house Just over 2 years ago 2500sq Ft I was sick of listening to people running down under floor heating as I built My first house and back in 2002 and I was recommended by the builder and architect not to go for UFH and they convinced my other half  my good friends next door Put in UFH and I was very disappointed as I was over in there house very regularly and I had twice the heating costs and half the comfort. So last time I went to see Gerry Walsh In Tullamore www.Energysuperstore.ie He designed a system for me and gave me all the options I went for Under floor Heating Power by a Heat pump Costing me approx €1100.00 per year to heat my house and Hrv at a very low cost of €50.00--€75.00 per year We don’t know the comfort As one of your replies recommended a Condensing Oil boiler which was a cheap option but a lot more costly to run which Gerry gave me this option wit UFH  I took out an extra 10k on my mortgage and Heat pump will have its self paid for in 5-6 years.Do your own studies all I can say is from my experience and if you get the efficiencies from these salesmen a lot of the figures don’t add up Make your own decisions and you will not be far out.I know this is in most cases a lifetime decision.My wife would not go back to a house with radiators as she knows what she has know.You will listen to a lot of Gargle Like some telling you If there more water in the floor it will be morecostly to heat Once you get the heat up in the floor it takes very little to keep it hot There are a lot of Myths around But it works fine for me and is half the price of oil to run 

David Dagg


----------



## Soarer (16 Jan 2009)

Jaysus, that was hard to read!

Think I followed it though!


----------



## sas (16 Jan 2009)

DavidDagg said:


> There are a lot of Myths around But it works fine for me and is half the price of oil to run
> 
> David Dagg


 
So you've run this same house on oil previously and can back up this statement? Based on what price for oil and what price for electricity? Don't take this as an attack but there is no point in making statements but giving no context around them.

Incidently, as has already been said, your post was very difficult to read. You may want to consider full stops and paragraphs when posting here.


----------



## MacTheKnife1 (16 Jan 2009)

What was the difference in insulation between the house you built in 2002 and the one you built in 2007? I suspect there would be a dramatic difference between the two.


----------



## DavidDagg (16 Jan 2009)

Sorry my typing is not the best !!! I am not trying to argue but There would be at lease five other house around the Same size as Mine in the immediat area and mine would be running 45--55% the cost to run of the Ones on oil,I am anything but expert,Just thought my info would be handy as it is head wrecking to know What system to put in as I was in that position.


----------



## DavidDagg (16 Jan 2009)

The house around me would have very simular,Very well insulated


----------



## DavyJones (16 Jan 2009)

David,

What was your yearly fuel bill for the house you lived in, in 2002?


----------



## DavidDagg (16 Jan 2009)

Even up to 2006 it was always €1800-€2300 only 1800sq ft approx and not very well insulated But I was totally depending on oil


----------



## sparky78 (16 Jan 2009)

sydthebeat said:


> if i was building tomorrow and i could build the envelope i wanted i would use:
> 
> a HVAC system with heat recovery.
> A small electricial element in the HVAC system would be my heat source, heatingthrough air ducts.. .no water space heating at all.
> ...


 
I had considered such a system for my house but read that the hot dry air does not create the best living environment.
Any views on this?


----------



## HeadTheWall (16 Jan 2009)

The HRV system takes the stale air and removes the heat from it, pumps it outside and then takes in fresh air from outside. It then puts the heat back into the fresh air and pumps it back into the house through the ducting. The more efficient the HRV is the less supplementary heat you need.

              If you have a passive house your system could be up to 90% efficient meaning over 24hrs the temp would drop from 20c to 18c. (figures just for example) This is why a small electric element in the HRV would be sufficient for a passive house as it loses such little heat. A small stove could also be suitable as the supplemental heat source


----------



## MacTheKnife1 (17 Jan 2009)

HeadTheWall said:


> If you have a passive house your system could be up to 90% efficient meaning over 24hrs the temp would drop from 20c to 18c. (figures just for example)



I find it hard to believe these figures. I am in favour of HRV but I believe achieving such figures are next to impossible WITHOUT use of significant energy - ie a heat pump - which most HRV systems incorporate.

I know you are not making up these figures, the HRV sales people spout them all the time. The only problem is that they are practically impossible to achieve - WITHOUT supplying significant energy to the system. Would love for someone to come along and prove me wrong.


----------



## sas (17 Jan 2009)

MacTheKnife1,

Are you saying you doubt the whole passive house principle?

Incidently, most HRV system do no not incorporate a heat pump from my enquiries.


----------



## sparky78 (17 Jan 2009)

MacTheKnife1 said:


> I find it hard to believe these figures. I am in favour of HRV but I believe achieving such figures are next to impossible WITHOUT use of significant energy - ie a heat pump - which most HRV systems incorporate.
> 
> I know you are not making up these figures, the HRV sales people spout them all the time. The only problem is that they are practically impossible to achieve - WITHOUT supplying significant energy to the system. Would love for someone to come along and prove me wrong.


 
[broken link removed]
This is the SAP report from a HRV I was considering using done by the BRE. 
This does not have a heat pump.
This confirms heat recovery of around 90% with very little energy usage.


----------



## MacTheKnife1 (17 Jan 2009)

sas said:


> Are you saying you doubt the whole passive house principle?



NO!!!! - On the contrary I think the passive house concept is terrific. But I do doubt the 90% efficent claims for HRV - in fact I believe it is more like 40-50% - which is still excellent. I just wish salesmen would tell it like it is.  I would advise anyone building today to massively insulate, glazing to south, sheltered site etc etc ... AND use HRV but do not expect miracles from HRV. Use it as a simple ventilation system with some of your expelled air-heat recovered. And when I say some I mean a lot less than 90%.




sas said:


> Incidently, most HRV system do no not incorporate a heat pump from my enquiries.



Maybe I am not informed enough. But I see brochures that state things like....they use 20 watts - BUT they have a boost button which then consumes 250-350 watts - that, I guess, is the heat pump - what else can it be??? Maybe some form of electrical heating??

Is there a HRV expert here who can clarify? Where is the 300-350 watts going? It is not moving a fan - it must be either working a heat element or a heat pump.


----------



## MacTheKnife1 (17 Jan 2009)

sparky78 said:


> [broken link removed]
> This is the SAP report from a HRV I was considering using done by the BRE.
> This does not have a heat pump.
> This confirms heat recovery of around 90% with very little energy usage.



You are going to have to forgive my ignorance here. What does "90% heat recovery" mean? For example:

If the internal air temp is 20 deg C and the outside is 0 deg C - what will the incoming air temp be after it has passed thru the heat exchange system?? Will it be 18 degrees? My bet is that it will be at the very best 10 degrees. But most likely 7-8 degrees. 

Now please note that I am not knocking HRV - I think they are useful - just not as good as they are made out to be in terms of efficiency. But it seems impossible to me that you can recover 90% of the difference between the incoming and the outgoing air temperatures. Maybe my interpretation of 90% efficency is incorrect - but then I have met a lot of HRV salesmen.


----------



## sas (18 Jan 2009)

MacTheKnife1 said:


> NO!!!! - On the contrary I think the passive house concept is terrific. But I do doubt the 90% efficent claims for HRV - in fact I believe it is more like 40-50% - which is still excellent. I just wish salesmen would tell it like it is. I would advise anyone building today to massively insulate, glazing to south, sheltered site etc etc ... AND use HRV but do not expect miracles from HRV. Use it as a simple ventilation system with some of your expelled air-heat recovered. And when I say some I mean a lot less than 90%.
> 
> 
> 
> ...


 
Again, from what I've been told it is a moving fan. The boost button is to increase the level of extraction during showers, cooking etc. It has nothing to do with boosting the heat recovery capacity. It's simply to get moisture and cooking smells out quickly.

The passive house institute does accept that efficiencies (for some models) are above 70%. Apparently the performance of a HRV system has alot more to do with the actual design of the ducting than the HRV unit themselves. Something which seems to have completely escaped the local suppliers...

Some of the PHI certified systems are available with electric heating elements and small heat pumps. The heat pump equiped models are for houses that are falling short of satisfying the requirements for a passive house. The other is for houses that clearly meet passive standard.
This is what I was told by http://www.drexel-weiss.at/?setlng=1

As regards the efficiencies, my understanding is that it relates to the percentage of heat recovered from the stale air leaving the house i.e. 70% efficiency for 10 degree extract air means that the air actually vented to the outside will be 3 degrees, with 7 degrees having been recovered. That 7 degrees is transfered to the incoming air and has an effect on it but obviously that depends on the temperature of the incoming air. My physics isn't good enough to understand it fully but this is how I understand it in simple terms.


----------



## noelf (18 Jan 2009)

The best advice is keep it simple, all these new H.E systems are great until you need to find a service engineer. They are ten a penny when you dont need them but when you do they are like hens teeth.
You can have a simple system that is also efficient and not as expensive as some of the elaborate systems out there. Talk to a few Plumber/heating Engineer and ask them what he would have in their own homes and draw from that to form you own conclusion


----------



## HeadTheWall (18 Jan 2009)

MacTheKnife1 said:


> You are going to have to forgive my ignorance here. What does "90% heat recovery" mean? For example:
> 
> If the internal air temp is 20 deg C and the outside is 0 deg C - what will the incoming air temp be after it has passed thru the heat exchange system?? Will it be 18 degrees? My bet is that it will be at the very best 10 degrees. But most likely 7-8 degrees.
> 
> Now please note that I am not knocking HRV - I think they are useful - just not as good as they are made out to be in terms of efficiency. But it seems impossible to me that you can recover 90% of the difference between the incoming and the outgoing air temperatures. Maybe my interpretation of 90% efficency is incorrect - but then I have met a lot of HRV salesmen.



My rule No 1 is salesmen lie(The Majority). Start with that and do your own real research. 

Remember that a HRV system works in tandem with the envelope of the building, the better sealed the envelope is the less heat that will escape in the first place. There would be no need for HRV's in an airtight house if we wern't concerned about getting fresh air in and condensation out of the building. The house should basically keep most of the heat in, thats where you start from.  

The heat exchanger will have been tested and has to conform to what it says it's efficiency is, but that is in a lab environment. If you are hearing about them losing up to 50% heat it's probably not the HRV that is at fault. The heat is probably escaping elsewhere through the envelope

Head


----------



## MacTheKnife1 (18 Jan 2009)

sas said:


> As regards the efficiencies, my understanding is that it relates to the percentage of heat recovered from the stale air leaving the house i.e. 70% efficiency for 10 degree extract air means that the air actually vented to the outside will be 3 degrees, with 7 degrees having been recovered. That 7 degrees is transfered to the incoming air and has an effect on it but obviously that depends on the temperature of the incoming air. My physics isn't good enough to understand it fully but this is how I understand it in simple terms.



This is the key piece that bothers me. The salesmen tell me that they simply take the extract air and it passes through a mesh of tubes and the incoming air passes thru a mesh of tubes. Now both sets of tubes are in contact and so of course some off the heat from the outgoing is passed to the incoming. Very clever idea.

Now if interior temp is 20 C and outside is 0 C I maintain that they will NEVER get the new incoming air to a temp higher than 10 C - and even to get that far is some bloody achievement.

I am very much in favour of HRV - just want to understand the efficiency claims thats all.

And I totally agree with another poster - keep it simple. Insulation is great - it has no moving parts and will remain perfectly functional for 50 years or more. HRV is simply a fan and a simple heat exchange - even at 30 % efficiency I will take it.


----------



## noelf (18 Jan 2009)

I agree with Daveyjones, 
better to keep it simple while being efficient, after service should be a major issue you need to address.
Great having the most effective system out there, but a total pain when it sits down and you cant get it repaired let alone serviced.


----------



## DavyJones (18 Jan 2009)

I have found this thread really interesting and wonder is anyone interested in doing something like this http://www.boards.ie/vbulletin/showt...p?t=2055263818 here. Syd put me on to it earlier in this thread.

I think if we could get together installation c and running cost of systems it would give people a better idea of the system to pick for their own home.

Anyone up for it?


----------



## sas (18 Jan 2009)

DavyJones said:


> I have found this thread really interesting and wonder is anyone interested in doing something like this http://www.boards.ie/vbulletin/showt...p?t=2055263818 here. Syd put me on to it earlier in this thread.
> 
> I think if we could get together installation c and running cost of systems it would give people a better idea of the system to pick for their own home.
> 
> Anyone up for it?


 
I don't dispute the idea but I would wonder how many people on here actually have HRV?

That heatpump thread is different because everyone in the country that was building one offs fell for that craze over the last 5 years. Now the biggest Irish manufacturer of them has gone to the wall and no one will service the systems they put in. How long before lots of the little guys importing various heat pumps also disappear and leave people high and dry.

Of course this leads back to the question already raised about servicing and repair on HRV but I don't think it's quite the same issue as I've raised about heat pumps. The cost of a HRV system isn't massive (compared to say a heatpump) and they are not terribly complicated either I gather. Plus when kingspan start flogging something it certainly suggests that they are going mainstream, i.e. every plumber will know how to service them soon enough.

I also agree with the concept of keeping it simple but the issues are interlinked. Adding lots of insulation will only add benefit when a structure is airtight. If the structure is airtight all practicality suggests that HRV is the best way to ventilate.


----------



## DavyJones (18 Jan 2009)

True, but it is about comparing heating systems, size of property, insulation etc. you don't have to have HRV, heat pump etc. IF would even help people with existing system, different controls and the like.


----------



## noelf (18 Jan 2009)

sas said:


> I don't dispute the idea but I would wonder how many people on here actually have HRV?
> 
> That heatpump thread is different because everyone in the country that was building one offs fell for that craze over the last 5 years. Now the biggest Irish manufacturer of them has gone to the wall and no one will service the systems they put in. How long before lots of the little guys importing various heat pumps also disappear and leave people high and dry.
> 
> ...


 
Keep ot simple and efficent,
Simple simple. Simple stupid.
Sometimes the best is the easiest and simplest, 
The tolerances are very fine with these type of systems and yes they are great on paper.
But god help you, because no one else will, when, as the guys have said "you cant get parts or service"
You will have a very expensive white elephant and a very cold house and no hot water
Sad to say Ireland is only a large city in the grand scale of things and the market here is very limited. 
So best to stay with the main stream for service and reliability.
See if you can get feed back on systems 5-10 years old operating either here or the UK, say, Wales or Scotland.
Any system or controls should be sourced from an established manufacturer who has a strong share of the Irish market.


----------



## sydthebeat (18 Jan 2009)

noelf said:


> Keep ot simple and efficent,
> Simple simple. Simple stupid.
> Sometimes the best is the easiest and simplest,
> The tolerances are very fine with these type of systems and yes they are great on paper.
> ...



hrv systems have nothing to do with heat production.. whether central heating or domestic hot water...

its a ventilation system that lets you recover heat.

if at very worst the system breaks down or theres no parts etc.. you still have the best part of passive stack ventilation system, all youd need to do is fit trickle vents... not major at all...


----------



## sas (18 Jan 2009)

noelf said:


> Keep ot simple and efficent,
> Simple simple. Simple stupid.
> Sometimes the best is the easiest and simplest,
> The tolerances are very fine with these type of systems and yes they are great on paper.
> ...


 
I'm curious, if you were building in the morning how would you build it and what would you heat and ventilate it with?


----------



## noelf (19 Jan 2009)

sas said:


> I'm curious, if you were building in the morning how would you build it and what would you heat and ventilate it with?


 
To be frank,
It would depend on the location.
I would use a conventional heat source.
I would use under floor heating on the ground floor.
I would check the water supply for mineral content.
I would use thermostatic controls in all rooms bar the bathrooms.
I would "not" use a range.
I would use a HE boiler, be it oil or gas depending on the location/availibitliy.
I would use solar panels but only as a secondary source, I like my showers and hot water heat recovery would be a major factor with me.
Ventilation would follow the recommended air change norms for individual rooms.
I would make sure the walls and attic were well insulated, as heat rises and walls act as convectors, windows also convect cold as well are adding solar gain depending on the weather.
If I lived in the ass hole of no-where and I almost do, I would hate to be reliant on a call out with a young baby in a freezing cold house and having to plug in electric heaters to keep the place warm while waiting for Mr €120.00 per hour and his mileage 
to replace a part that may take anywhere from 3 working days to 3 bloody months.
And believe me this is a regular occurance, ask anyone reliant on a Stanley or an Agga who's service is generally good except when you need then right here right now.
So efficiency is not just about the best enegry efficiency rating 
To me, its about common sense.
Be envoirnmentally aware? yes all day long, but comfort of mind and body is equally important.
Low wattage lighting is also great, they last a long time though expensive, use bugger all juice.
Light is not measured in wattage, energy is so they do emit loads of light, my drive is lit with them on movement sensors set at 1.2 so the local fox rabbit and rat population do not have parties while I am snug in my warm house.
My place is a shade under 300m2 and I burn about 2000L of kero per anum, so Two fills in my 1300L tank and I never let it run out.
I have a stanley and "I HATE IT" but the lady of the Manor wanted one, so there is a HE oil boiler going in this year and they stanley will be for astectics only..... and the system will be sealed. (hope there are no monir weeps or my heart will be broken sorting them id LS1 does not work)
The gaff is about 18years old by the way.
So instead of ripping it apart I lined all the walls with Insulated boards while redecorating and fitted TRV's to all the rads bar the bathroom and our ensuite a plated heat exchanger was fitted to the existing HW Cyl and did away with the coil by simply by passing it.
Hopefully up grading the wife next year too...lol
Thank god there is no acorn pipe in the house that I know of.......
This post will be deleted if not edited immediately the more I think about it I might build a new one ..lol
Or maybe a tent or caravan.......
Like I said everything looks good on paper, even the wife......
Been in the office too long without a doubt...... better go home.
Keep it simple and get few of qualified opinions and draw yours from the common average concencus.


----------



## MacTheKnife1 (19 Jan 2009)

noelf said:


> I like my showers and hot water heat recovery would be a major factor with me.



Would you care to explain a little more about this item, is there a product you have in mind..... would be interested to hear from anyone who has such a system installed.


----------



## noelf (20 Jan 2009)

MacTheKnife1 said:


> Would you care to explain a little more about this item, is there a product you have in mind..... would be interested to hear from anyone who has such a system installed.


 
Its called an alpha craft plated heat exchanger. from copper craft in Kylemore rd dublin, I am sure they a have web site.


----------



## MacTheKnife1 (21 Jan 2009)

They do have a website: http://www.coppercraft.ie/

But it gives no detail on the product you mention - that part of the site is being worked on currently.


----------



## Didi 66 (29 Jan 2009)

At the moment i have to agree with you. our HRV claims 80% efficiency but the reality is that it is closer to 50%. the house and ducts are very well insulated but the bedrooms are too cool (11-15 degrees last week). we are looking into getting a post heater radiator installed to warm the air going to the bedrooms.



MacTheKnife1 said:


> This is the key piece that bothers me. The salesmen tell me that they simply take the extract air and it passes through a mesh of tubes and the incoming air passes thru a mesh of tubes. Now both sets of tubes are in contact and so of course some off the heat from the outgoing is passed to the incoming. Very clever idea.
> 
> Now if interior temp is 20 C and outside is 0 C I maintain that they will NEVER get the new incoming air to a temp higher than 10 C - and even to get that far is some bloody achievement.
> 
> ...


----------

