MHRV in sunny Fermanagh

trevboy

Hi

Hoping to build in Fermanagh in then near future.

Am going for a pretty airtight construction, and will be using heat recovery.

Could anyone point me in the direction of reputable suppliers, with efficient systems.

If you have personal experience let me know as well.

PM me if you want.


Many Thanks

:D:D:D:D

kenneth2

The MHRV quotes i've gotten for a 3000 sq foot house is around 6K no way it's worth that !!
i'd say just put in window vents and don't bother with the MHRV

anyone else get silly quote's for these systems ?
Or am i mistaken in thinking they should only be around 3-4 K ?

Juantorena

My quote is about 6.2k - 2600sqf build.

Hard to know, really, what the worth of MHRV is..particularly here in Ireland seeing as there is very little experience of it (in domestic settings, anyway).

It's a decision which must be made, I guess, with a view to the overall heating solution for the house. Vents in windows/walls are cheaper...but they let heat out which needs to be replaced and cold in which needs heating...

But as I said, we're all learning about these new technologies in this setting...we'll know in about five years time perhaps!

OP - I can pm you my supplier - Galway based so not sure about delivery to Fermanagh - if you like...

Retro-Fit

MHRV is only worth doing when its part of an integrated design approach where the house is designed to be heated without a conventional heating system for base load. It is not a bolt on option for a low standard build. Airtightness should be less than 2 air changes. Wall U -Values should be less than 1.8 with solar gain maximised.

If systems are integrated into the overall design savings can be made, however if the ductwork has long duct lenghts and lots of bends you will need to oversize the fans to cope and its gets more expensive. With a compact design the cost should be around €5,000 incl installation, excl VAT.
The system can work out economical if you combine it with a small boiler or heat pump to distribute warm air around the house.

Its main advantage is air quality, an important issue with nearly 1/4 of Irish kids developing asmatha. That price wouldn't go far on presriptioninhailers and doctors visits.

To design a building to an appropriate standard for the coming decades, use first principles of design or use an integrated scientific approach such as the Passive house planning package. This package can help you ensure that your fuel bills will remain under €700 euros per annum for the coming decade rather than the €5,000 it will be in 10 years time. At projected energy prices, the MHRV will pay for itself in 3 years.

GoneShootin

Juantorena wrote: »

My quote is about 6.2k - 2600sqf build.

Got the same price for the same size house *high five*.

My approach to the MHRV question is:

- Do air tightness test once house is "sealed". If air tightness is good then MHRV is worth considering. Otherwise to hell with it.

- Batten+counter with enough space to take ducting if I decide take the MHRV route down the line.

6k is a long way towards another couple of solar panels!

gman2k

GoneShootin wrote: »

Got the same price for the same size house *high five*.

My approach to the MHRV question is:

- Do air tightness test once house is "sealed". If air tightness is good then MHRV is worth considering. Otherwise to hell with it.

- Batten+counter with enough space to take ducting if I decide take the MHRV route down the line.

6k is a long way towards another couple of solar panels!

Gonna be difficult to install a mhrv system once the house is 'sealed'
Do it right the first time, airtight the house and install a good mhvr system at the one time. See post above re designing the house properly, along passive principles.
As for the extra couple of solar panels - get the system designed correctly in the first place, extra panels over and beyond what's necessary will not add efficiency to your system - It's not like your going to get hot water all of a sudden on a cold wet windy day just because you oversized your system...

kenneth2

Just so you know the same people ( a group in the west of ireland )
charged just under 4K for a similar house just over 2 years ago.
and now they are charging 2K more !!!
Very odd it's not like the box has changed ...

anyway if anyone knows of a few good MHRV systems at reasonable price,
PM me the names of the sales office, if they are looking for the business i would consider installing one,
but not at 6K .....

Leadership

In the same boat as OP, I have quotes for 2500 sqft home in Cork ranging from €5.5k > €9k (that was joke!). Seriously considering installing a system myself Something similar to this http://www.rvr.ie/Products/SDV303/0_236_233/

kenneth2

I just got told by 2 companies that for my house (approx. 3000 sq/ft ) it would cost around 4K to do the ducting alone....

I'm considering doing the ducting myself ( cannot be that hard, famous last words ....)
drop pipes down the walls before it's slabbed ...

Does anyone else think 4K is a bit mad for doing a bit of ducting

As i'm typing this,
i just thought of something a little odd and maybe i'm wrong ....
but doesn't the ducting go behind the insulated slab? and so cause heat loss it's self ? if you left the heat in the room and didn't suck it out through a gap in the insulation to a colder area wouldn't that be more effectient ?

CJhaughey

kenneth2 wrote: »

I'm considering doing the ducting myself ( cannot be that hard, famous last words ....)
drop pipes down the walls before it's slabbed ...

Does anyone else think 4K is a bit mad for doing a bit of ducting

As i'm typing this,
i just thought of something a little odd and maybe i'm wrong ....
but doesn't the ducting go behind the insulated slab? and so cause heat loss it's self ? if you left the heat in the room and didn't suck it out through a gap in the insulation to a colder area wouldn't that be more effectient ?

Ducts usually go in the ceiling, and vent downwards in order to not puncture the external fabric of the construction and introduce cold bridging.

The ductwork should be insulated as well otherwise you will lose an unacceptable amount of heat.

HRV usually has extracts from the "dirty" rooms in the house(Bath,Utility,Kitchen) and feeds into bedrooms and living rooms this creates a constant movement of fresh air into the house and expels old stale air, this carries on all year round and in the summer good systems will have a bypass to allow the heatrecovery to be bypassed and just introduce fresh air.

A hole in the wall does exactly what you don't want, in cold windy weather it will introduce draughts, and in warmer weather it won't provide adequate air movement when you want it most.

HRV doesn't necessarily make a house more efficient but it does make a big difference to the quality of the air inside for the occupants if installed correctly.
Although in practice not having to open windows and doors to provide fresh air in cold weather usually means it is more efficient.

kenneth2

Funny that in none of the quotes mentioned anything about insulating the pipes and each was different some saying rigid ducting others saying flexible ducting...
I'd say the only way it's insulated is by wrapping a bit of insulation around a few pipes and that's probably only just where it's easiest to do it.

I think it's a bit of a rip off in Ireland at present, don't shoot me it's only MY opinion ....

I might have a chat to the builder and see what he says might even ask him can you get insulated rigid ducting (and see if he laughs at me :-) !! )
and if so how much would he charge to put it in..

Zilog

First off, I work with a company who design and supply MHVR (heat recovery ventilation) systems.
Like many other construction related sectors, there is a lot on information and misinformation on the subject.
You can build an energy efficient house without ventilation. However, it is impossible to build a healthy energy efficient house without ventilation; the heat recovery part aims to conserve as much heat as possible, saved through airtightness and insulation, whilst allowing ventilation to happen.

Self installs are possible. Installation is not difficult, providing a few simple rules are followed and common sense applied.
I am happy to try to answer any questions, either by PM or on the forum.

Regards, Declan.

Leadership

Zilog wrote: »

First off, I work with a company who design and supply MHVR (heat recovery ventilation) systems.

Can you design & supply one for under €5k?

trevboy

Leadership wrote: »

Can you design & supply one for under €5k?

Thinking the same myself.

Thanks for jumping on board this thread great comments.

It does seem like a lot of dont knows at the mo

Another question for those who know.

My calculated u-values seem to be good and i have been gathering advice on keeping the build as airtight as i can.

I will be building with blocks and concrete upper floor, will this make running ducting for downstairs impractical.

Let me know what you think.

And please send me any details of reasonably priced suppliers.

Thanks:D

Leadership

trevboy wrote: »

I will be building with blocks and concrete upper floor, will this make running ducting for downstairs impractical.

Let me know what you think.

Concrete floor is no problem, I am building air tight as well with concrete floors but ICF and not block.

What happens is that a false celling is placed under the floor and the ducting will sit in that. There is narrow ducting available that has a slimline retangular profile.

A few examples are here http://www.rvr.ie/Product_Groups/0_236_249_246/

Zilog

Leadership wrote: »

Can you design & supply one for under €5k?

Hi Leadership, if you are handy at DIY, you can do a self install for well under €5K (excluding the dreaded Vodka And Tonic).
You are correct, for the ground floor, a false ceiling is the most practical. We do recommend ductwork in the following order:

1. Circular metal ductwork; where space is tight then transition to
2. Rectangular PVC ductwork (often referred to 'flatpack')

The larger the duct you use, the slower the air will move in the ducts and the quieter the system will be.
Flexible ductwork is definitely not recommended unless absolutely necessary. It has it's uses - a short 1m run of taut insulated acoustic ductwork before the diffuser (what you see in the ceiling) helps to eliminate any remaining noise.
For duct routing, going from 1st to ground floor is often accomplished discretely at the back of wardrobes, hot presses, etc.
Air tightness is the key, there is little point installing in a draughty or leaky building.

Regards, Zilog

william

Zilog wrote: »

Air tightness is the key, there is little point installing in a draughty or leaky building

I would like to explore this statement further. We live in an old leaky building - poor windows, no wall insulation etc. We will upgrade all of this within 2 - 3 years. Surprisingly, the rooms in the house have no hole in the wall vents which worries me from a kids health point of view as we don't open the windows at the moment so as to retain heat. Damp/mould is an issue for us also and this is due to condensation.

I am looking at MHRV systems primarily for three reasons:
- it delivers fresh air within the house, especially the bedrooms;
- if extracts steam from the bathroom and kitchen;
- even in a leaky house, it helps reduce the amount of heat leaving the building.

Are my reasons enough to justfy the €3,500 for a self install?

Many thanks,

Will

glenkeo

I am in the middle of self build, at the electric first fix stage, I am installing a mhvr, I went for a system that I saw in one of the self build show in Dublin, I liked the ducting. it is 4"(100mm) flexible surrounded by 2" (50mm) insulation, it comes in 10m lengths( jammed in to a 3ft box).
When i was at block work stage on ground floor i but in 1 extra row of blocks (9"/225mm) I had suspended metal ceiling dropped 7"(175mm) which is no different than the 2" or 3" standard, and still have 2.4m floor to ceiling height. it was quit easy to run ducting around this space just tee off for roof outlets. I am butting in a false wall in a shower above the utility to run the ducting up to the attic for up-stairs ducting. i am keeping the unit in the utility to make sure i don't forget to change/clean filter every few months. also the model i got needs a drain for moisture run off, this could be over looked has this is a job for the plumber.
The cost so far is €3700 for the unit 10 boxes of ducting 14 tees 2 outside metal grills tapes clips wall switch drain pipe. They quoted me €800 to install and €200 to commission the system when it is installed. Got some advice from my plumber so am installing myself and will get them to commission it so the warranty is ok.they sell over the internet and deliver nation wide.
Finally I am tapering all window and doors have a stove with external air source (no open fires) and no vents except cooker hood .

Zilog

william wrote: »

Are my reasons enough to justfy the €3,500 for a self install?

Hi Will,

The primary functions of HRV are as follows:
- Supply fresh air to the building and occupants
- Extract stale air and humid air
- Filter the fresh air
- Recover heat from outgoing stale air and transfer to incoming fresh air

You will get some benefit in having filtered fresh air supplied and stale moist air extract - the 'V' part of HRV. You will get little or no benefit on the 'HR' part - heat recovery - if your house is very leaky and air is able to leave the house by other means, such as through windows and other openings. This air does not pass through the HRV system, so cannot recover heat.

So, ventilation will help the condensation issue, but you will probably still have issues due to the temperature difference between your room air (warm) and your wall (cold) due to lack of insulation.

Hope this helps.