# Condensing or Non Condensing MHRV System



## BMD (23 Mar 2011)

Hi,

I have narrowed my choice of MHRV system down to two options;

1. Beam: Non Condensing, 85% Efficient, fan power 1.2 w/l/s, rigid ducting, remote control, programmable boost system, summer cooling

2. Proair; Condensing, 90% Efficient, fan power 0.9 w/l/s, rigid ducting, boost switches in rooms, summer by-pass

I want some advice on which might be the best system to go with. Is there a big difference in condensing and non-condensing systems? The selling point for non-condensing is that the air recirculated through the house still contains some moisture and therefore isn't 'too dry'. Does this make sense?

Also is there a big difference in the running costs for the two systems based on the fan powers and efficiencies?

Any advice appreciated


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## threebedsemi (23 Mar 2011)

Your BER assessor can input both systems into the DEAP software, which will tell you the running cost of each system for your particular house, if they are both registered in the software (if they are not, he/she will have to use 'default' options, which are useless). your assessor can advise you on this.
On the face of it the second one looks better, lower fan power is a plus, and the summer bypass system is in my opinion better than having a 'cooling' option. 
Having said that, I was not overly happy with the initial installation of a Proair system on a house I was involved with recently, but the problems were ironed out eventually. 

The first question to ask in these situations is: are you sure that you are building your house with sufficient airtightness to make any MHRV system work efficiently? Do not believe the speil of salesmen here, if you only build to the standard set out in the current building regulations, any MHRV system will probably end up costing you money.


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## onq (23 Mar 2011)

+1 what threebedsemi has stated and I note the following.

At the moment the regulations are dancing around the idea of full air conditiong for a building.
MVHR doesn't supply cooled, moisturized, dried or heated air to the internal spaces
MVHR is the "cheap" version of aircon, because it only reclaims heat.
The heated supplied air isn't filtered to the highest standards.

The potential problem that's waiting to happen in Ireland is that our super insulated and solar-gain-oriented houses will become virtually uninhabitable as the summer months get hotter over the years.
At the same time sthey will be unable to guarantee air quality in the winter in areas where everyone burns their fossil fuels and wood pellets locally.

Air quality seem to be the big question for city dwellers especially those raising children and it affects super-sealend-and-insulated hosues too.
Just opening the windows in the summer and closing them in teh winter won't provide all the answers

====================

That having been said, air which is too  dry is not good for you.
It can dry out the sinus membranes and lead to respiratory ailments.
This used to be a common complaint made by people who used to leave their central heating on all the time without properly "airing" the house.
One argument being advanced currently appears to centre on local vents in walls that are activated when the air quality drops below a certain level, whatever that means. 

There is huge difference in the perception of "being cold" between old and young (in general) and between active and inactive people.
Older inactive people being the worst sufferers and young active people the least, so here is some general advice.


 Put on an extra layer of clothes if its cold.
 Ventilate the house every morning.
 Get regular exercise every day.
  Lower your heating bills that way.

====================

Just remember, your overall energy usage relates directly to anything you use with a heating element in it.
Space heating is only a proportion of the energy used in a modern family home.
Cooking, making tea, washing clothes and dishes, having showers.
All these use huge amounts of energy in an average home.

[broken link removed] for more info.

Hope this helps.

 ONQ.

     [broken link removed]

     All advice on AAM is remote from the situation and cannot be relied                 upon    as a defence or support - in and of itself -   should     legal       action     be    taken.
     Competent legal and building professionals should be asked to  advise        in            Real Life with rights to inspect and issue  reports   on   the        matters    at     hand


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## BMD (23 Mar 2011)

Thanks Threebedsemi.

The air tightness spec on the house is high (3 m³/hr/m²).

I am more interested in the benefits of MHRV with respect to air quality rather than retaining heat but saying that I think it is senseless to have vents (holes in the walls) of every room with respect to retaining heat.

The other difference in the two systems is that Beam use G7 filters on the nilet and outlet, whereas Proair use G3 filters.

Are there any other suppliers that you would recommend. I have already ruled out those who use flexible ducting


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## fairygirl (23 Mar 2011)

Without being funny - as far as I'm aware, your air tightness spec is not high - it's a minimum that is needed for MHRV to be worthwhile. The current regulations are for 10m³/hr/m² and passive certification needs 0.6 m³/hr/m². From my understanding of it, unless you are at 3 or lower on the scale, MHRV would not be cost effective.

I'd suggest taking a look at Qualityhrv in Westmeath - Shane Millar is the guy to talk to. (He supplies Paul systems along with others)

The company Brink Climate Systems are also very reputable with an excellent standard product. 

Best of luck!


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## DGOBS (23 Mar 2011)

Becareful with the install, was in a house recently where there was boiler smell all over house, it was taking it in at the MHRV intake vent (boiler plume was suffering a courtyard effect and no dispersing) 

Also I believe one house was tested 2 years in MHRV and they found airbourne microbes and spores to hazardous levels due to mould growth in the ducting, and said what else would you expect in a country with such a damp climate!


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## threebedsemi (23 Mar 2011)

MLY
if your main concern is air quality, and not necesessarily heat recovery, it is worth looking at these articles, as there are other options at your disposal:

[broken link removed]

more detail on different systems here:

[broken link removed]


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## Troy McClure (24 Mar 2011)

MLY
What do you have for the running costs for the 2 systems?

Whats the problem with the filter types you have mentioned??

I was talking to a guy in the west who does passive house's and he mentioned the beam system as been excellent.


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